Environmental engineers handbook - Chapter 8 pdf

8.1
REMOVING SUSPENDED SOLID CONTAM-
INANTS
Algae Control
Carbon Particles
Gravity Settling
Solids Disposal
Foundry Sand
Laundry Wastes
The Problem of Commercial Waste
Treatment Systems
Quality of Effluent
Mill Scale
Design Parameters
Operational History
Mineral Tailings
8.2
REMOVING ORGANIC CONTAMINANTS
Aldehydes
Biological Oxidation
Air Stripping
Carbon Adsorption
Cellulose Pulp
Wastewater Volume
Effluent Characteristics
Methods of Treatment
Research Problems
Food Processing Wastes
Water Reuse
Water Conservation
Elimination of Water Use

Wastewater Treatment
Hydrocarbons
Design Basis
Operational History
Pesticides
Pesticide Removal in Natural Aquatic
Systems
Biodegradable Replacement and
Controlled Self-Destruction
Biological Treatment Processes
Chemical Flocculation and
Oxidation
Activated Carbon Adsorption
Reverse Osmosis
Incineration
Research Trends
Phenol
Solvent Extraction
Biological Treatment
Carbon Adsorption
Chemical Oxidation
Starch
Biological Treatment
Textile Industry Wastes
Viruses and Bacteria
Chlorination
Ozonation
8.3
REMOVING INORGANIC CONTAMINANTS
Aluminum

Bicarbonate
Removing Bicarbonate Alkalinity
Cadmium
Sources of Cadmium-bearing Waste-
waters
Treatment Methods
Calcium
8
Removing Specific Water
Contaminants
I.M. AbramsԽD.B. AulenbachԽE.C. BinghamԽL.J. BollykyԽT.F.
Brown, Jr.ԽB. BruchԽR.D. BuchananԽL.W. CanterԽC.A.
CaswellԽR.A. ConwayԽG.J. CritsԽE.W.J. DiaperԽJ.W.T. Ferretti
ԽR.G. GantzԽW.C. GardinerԽL.C. Gilde, Jr.ԽE.G. KominekԽ
D.H.F. LiuԽA.F. McClure, Jr.ԽF.L. ParkerԽR.S. RobertsonԽ
D.M. RockԽC.J. SanthanamԽL.S. SavageԽS.E. SmithԽF.B.
TaylorԽC.C. WaldenԽR.H. Zanitsch
©1999 CRC Press LLC
Chromium
Reduction and Precipitation
Ion Exchange
Cyanides
Chlorination
Ozonation
Fluoride
Hardness
Ion Exchange
Lime and Lime-Soda Ash Softening
Iron
Controlling Iron with Bacteria

Removing Iron Salts
Lead
Treatment Methods
Magnesium
Manganese
Mercury
Properties
Sources of Contamination
Methylation of Inorganic Mercury
Methods of Removal from Water
Nickel
Silica
Insoluble Silica
Soluble Silica
Strontium
Sulfate
Ion Exchange
Evaporation and Crystallization
Reverse Osmosis
Biological Reduction
Sulfide
Zinc
Ion Exchange
Precipitation
8.4
INORGANIC NEUTRALIZATION AND
RECOVERY
Boiler Blowdown Water
Spent Caustics from Refineries
Phenolic

Sulfidic
Steel Mill Pickle Liquor
The Pickling Process
Disposition of Spent Liquor
8.5
OIL POLLUTION
Effects on Plant and Animal Life
Toxicity
Marine Organisms
Plants and Oil
Sources and Prevention
Oily Materials
Detection, Identification, and
Surveys
Prevention
Methods of Control
Characteristics and Composition
Mechanical Containment
Mechanical Recovery
Application of Agents
8.6
PURIFICATION OF SALT WATER
Conversion Processes
Desalination Plants
Desalting Processes
Multieffect Evaporation
Vapor Compression Evaporation
Multiflash Evaporators
Freezing Processes
Vacuum-Freeze Vapor Com-

pression
Reverse Osmosis
Electrodialysis
The Future of Desalination
8.7
RADIOACTIVE LIQUID WASTE
TREATMENT
Low-Activity Wastes
Precipitation
Ion Exchange
Evaporators
Dilution and Release
Hydrofracture
Bituminization
High-Activity Wastes
Generation
Storage in Tanks
Conversion to Solids
Storage
©1999 CRC Press LLC
Algae Control
The types of algae and the concentration in wastewater
depend on residence time, climate and weather, amount
of pollutants entering the pond, and dimensions of the
pond. Normally, small unicellular types of algae develop
first, e.g., Chlorella.Because of their physical dimensions
they are difficult to remove by the processes listed in Table
8.1.1. Longer residence times lead to the development of
larger algae and other plankton, which is more readily re-
moved. The algae concentration affects the choice of re-

moval process and the rate of treatment. Because of their
light density, the dried weight of suspended solids is not
an efficient measure of concentration. Algae are normally
measured in volumetric or areal standard units (Anon.
1971). In surface water supplies, concentrations may be
as high as 30,000 cells per milliliter (ml), this can be much
higher in nutrient-rich waste treatment effluents. A com-
bination of processes may be the best treatment, e.g., cop-
per sulfate addition and microstraining, as used on surface
water supplies in London, England.
Carbon Particles
Carbon particulate matter suspended in waste effluent
must be either controlled or removed prior to discharge.
Wastes associated with the carbon black and acetylene in-
dustries are of concern. These wastes may contain up to
1000 milligrams per liter (mg/l) carbon particles in sus-
pension; in most cases this carbon concentration must be
reduced to less than 50 mg/l suspended solids. Usually,
these solids settle readily and are removed by gravity set-
tling and/or flotation.
Individual particle sizes range from a submicron to
larger than 100 micron (
␮
). Larger particles settle, whereas
smaller particles float. Transition size particles remain sus-
pended almost indefinitely unless forced out of suspension
by mechanical or chemical means. Unless a highly clari-
fied effluent is required, suspended matter may not have
to be removed as it amounts to a small proportion of to-
tal solids concentration.

GRAVITY SETTLING
Two types of gravity systems are available: (1) settling
Lagoons, which provide retention time for solid particles
to settle as sludge. These must be cleaned periodically; and
(2) mechanical Clarifiers, which remove suspended solids
and also rid bottom sludges mechanically.
The settling lagoon requires a minimum capital invest-
ment. Cleanout costs are high compared with the me-
chanical clarifier operating costs.
Settling devices are usually designed on the basis of over-
flow rate, gal per day (gpd) per sq ft of surface area.
According to the Ten State Standards (Great Lakes-Upper
Mississippi River Board of State Sanitary Engineers 1968),
this rate should be in the range of 600 to 1000 gpd/sq ft.
In designing the carbon settling lagoon, frequency of la-
goon cleaning must be considered, and the lagoon must
be sized accordingly. Carbon sludge will settle to a den-
sity of 5–20% solids.
©1999 CRC Press LLC
8.1
REMOVING SUSPENDED SOLID CONTAMINANTS
TABLE 8.1.1ALGAE REMOVAL PROCESSES: MERITS AND FLAWS
Algae
Removal
Process Advantages Limitations
Copper sulfate Simple and inex- Creates toxicity; only some algal
pensive forms attacked
Chlorine Simple and inex- High doses needed; not all algae
pensive attacked
Coagulation and Positive removal of High chemical doses needed; dif-

settling all types of algae ficult sludges produced
Sand filters Positive removal of Rapid filter clogging may occur
all types of algae
Microstraining Simple and inex- Not all algal forms removed
pensive
Air flotation Positive removal of Not all algal forms removed;
all types of algae sludges may be difficult to handle
As an example, a 5-acre lagoon, 5 ft deep, with an in-
fluent suspended solids concentration of 1000 mg/l and an
effluent concentration of 50 mg/l at a flowrate of 10 mgd
will retain almost 80,000 lb of solids per day. If the solids
settle to a 5% sludge density, the lagoon will be filled with
sludge in less than two months, as indicated by the calcu-
lations in Table 8.1.2. A settling lagoon design for this ap-
plication would probably be based on cleaning frequency
rather than on overflow rates.
The outfall structure of a settling system should retain
floating material and maintain laminar flow to prevent
solids from resuspending at discharge due to turbulence.
An underflow-overflow weir (Figure 8.1.1) efficiently pro-
vides such an outfall. According to the Ten State Standards
(Great Lakes–Upper Mississippi 1968), weir loading rates
should not exceed 10,000 gpd per linear ft of weir to as-
sume minimum resuspension of settled matter from tur-
bulent flow. For the example in Table 8.1.2, a weir 1000
ft long would be required.
SOLIDS DISPOSAL
Whether a mechanical clarifier, a settling lagoon or other
means of solids removal is utilized, concentrated carbon
slurry or sludge must be disposed of. Disposal methods in-

clude incineration, landfill disposal, reuse, and dewatering.
Removal and disposal of concentrated solids slurry is the
most difficult part of the carbon clarification system.
Eliminating waste at the source is ideal. Tightening pro-
duction controls and modifying the process can drastically
reduce waste losses and should be investigated before any
removal system is developed. No treatment system is jus-
tifiable without assurance that waste production is mini-
mized at the source. Frequently, waste carbon is a prod-
uct loss, and recovery is valuable. Keeping carbon out of
wastewater prevents problems in waste treatment.
Foundry Sand
Foundry melting emissions contain solid particles ranging
from coarse dust to fines of submicron size. Cupola emis-
sions are much coarser than electric furnace emissions,
which are generally less than 5
␮
.
Foundry melting dusts include combustibles containing
20–30% carbonaceous material. Iron oxides account for
nearly 60% of collected dusts; silica and miscellaneous
metallic oxides account for smaller quantities.
©1999 CRC Press LLC
TABLE 8.1.2EXAMPLE: SETTLING LAGOON FILL TIME
CALCULATION
Settling Lagoon Data:
Area ϭ5 acres
Depth ϭ5 ft
Flow ϭ10 million gal/day (mgd)
Influent concentration ϭ1000 mg/l

Effluent concentration ϭ50 mg/l
Sludge density ϭ5%
Carbon deposited per day:
(1000 Ϫ50) ϫ10 ϫ8.34 ϭ80,000 lb/day
Lagoon volume:
V ϭ5 acre ϫ5 ft ϭ25 acre-ft ϭ8.3 ϫ10
6
gal
Solids capacity of lagoon at 5% sludge density:
5% ϭ50,000 mg/l ϭ0.42
ᎏ
g
lb
al
ᎏ
Capacity ϭ0.42
ᎏ
g
lb
al
ᎏ
ϫ8.3 ϫ10
6
gal ϭ3.5 ϫ10
6
lb solids
Time required to fill lagoon with sludge:
T ϭ
ᎏ
8

3
ϫ
.5
1
ϫ
0
4
1
l
0
b
6
/d
lb
ay
ᎏ
ϭ44 days
FIG. 8.1.1Settling lagoon outfall structure.
Water curtains and scrubbers are used to remove solids
from foundry stack gases. Wet scrubbers also remove
acidic compounds. Scrubber water is treated to neutralize
acids and to remove solids prior to recirculation. Settled
solids are vacuum filtered prior to disposal. Most foundries
have a number of scrubbers working on different opera-
tions, and all effluents are combined and treated together.
In grinding and shakeout areas, the scrubber may be ei-
ther cyclonic or water curtain, which tolerates dirty feed-
water. However, abrasive materials of ϩ200 mesh should
be removed to avoid abrasion of circulating pumps.
For complete solids removal—down to smoke particles

from cupola emission gas—high-energy scrubbers such as
Venturis are required, which need clean water. Cupola
cooling water should also be clean to prevent heat ex-
change surface fouling. If water is used for slag quench-
ing, a mass of porous particles up to 1 /4 in is produced.
These usually float. Casting washing produces a slurry
with ϩ150 mesh sand. Most of these materials can be sep-
arated on a vibrating screen of approximately 50 mesh.
Depending on the recirculation system, grit separators,
settling basins, or clarifiers are used. A hydroseparator re-
moves fine sand down to approximately 50
␮
. Removal
of finer solids requires chemical treatment with lime, alum,
and possibly a polyelectrolyte to produce clarified effluent
containing 10–20 mg/l of suspended solids. Disc, drum, or
belt filters are used for dewatering foundry waste solids.
Filter rates range from 25–40 lb of dry solids/hr/sq ft.
Some foundries have sand scrubber wastes. This differs
from dust collection water as it settles more slowly.
Overflow rates of no more than 0.3–0.5 gpm/sq ft can be
used. Filtration rates for sand scrubber wastes vary from
3–10 lb of solids/hr/sq ft.
Laundry Wastes
THE PROBLEM OF COMMERCIAL
WASTE
Commercial coin-operated laundry installations pose
problems when sewers are not available, and septic tank
or leach field systems are utilized. Because of the small
amount of land available for liquid waste discharge, ad-

ditional treatment is necessary. Treated effluent reuse
should also be considered.
Table 8.1.3 indicates typical waste flow (Flynn and
Andres 1963) from laundry installations on Long Island,
N.Y. A typical installation of 20 machines produces 4,000
gpd. Depending on soil conditions, this volume might re-
quire a much larger disposal area than is available. Table
8.1.4 describes typical laundry waste properties and com-
position as resembling weak sewage with the exception of
high alkyl benzyl sulfonate (ABS) and phosphate contents.
Large quantities of water are required for washing,
therefore alleviating both water supply and waste disposal
problems via partial or complete recycling of treated waste-
water effluents should be considered.
TREATMENT SYSTEMS
Septic Tanks
Septic tanks followed by leach field systems are often in-
adequate to process the quantity and quality of water to
be disposed.
Physical Methods
All laundry waste should be strained in a removable bas-
ket so that lint does not clog pumps and other equipment
in the treatment system.
Plan settling of laundry waste removes the heavier grit
particles washed out of clothes. Most biological oxygen
demand (BOD) is soluble, therefore settling has little ef-
fect on the BOD and chemical oxygen demand (COD) of
the waste.
Several types of filtration units are used to treat laun-
dromat wastes. A sand filter efficiently removes particu-

late matter. Pressures and filters usually require less space
than gravity sand filters. The latter is used following other
treatment methods and is little different from filtration
through soil. Filtration through diatomaceous earth filter
cake is highly recommended, since it removes bacteria and
some viruses, and is particularly effective in separating
chemical sludges. In diatomaceous earth filtration, prior
settling or sand filtration lengthens filter runs but will not
result in a better quality effluent.
©1999 CRC Press LLC
TABLE 8.1.3TYPICAL WASTE FLOW FROM A COIN-
OPERATED WASHING MACHINE
Average wastewater flow 89–240 gal/day
Maximum average flow 587 gal/day
Minimum design basis for
treatment based on a 12–hr day 550 gal/machine
TABLE 8.1.4TYPICAL QUALITY OF LAUNDRY
WASTES
Concentration, mg, per liter
Parameter Average Range
pH 7.13 5.0–7.6
BOD 120 50–185
COD 315 136–455
ABS (methylene blue active 33 15–144
substance)
Total Dissolved Solids 700 390–1450
Phosphate (PO
4
3Ϫ
) 146 84–199

Acidity as CaCO
3
91 73–124
Alkalinity as CaCO
3
368 340–420
Chemical Methods
Coagulation or precipitation followed by settling and/or
filtration has proven effective in treating laundromat
wastes. Alum alone at a pH of 4–5 may result in a 75%
reduction in ABS and an 85% reduction in phosphate con-
tent of the waste. Iron salts effect a similar reduction,
whereas calcium chloride can reduce ABS by 85%, but
this results in only a 50% reduction in phosphate content
at high doses.
In addition, ABS may be completely neutralized, us-
ing a cationic detergent. Tests must be performed to pro-
vide exact equalization with no excess of either deter-
gent. Substances to perform this are commercially
available. Phosphates are effectively removed by precip-
itation techniques. Alum, iron salts, and calcium salts at
high pH offer a high degree of phosphate removal. Better
than 90% phosphate removal can be obtained by cal-
cium chloride combined with adjusting the pH to 10, or
by lime, both followed by filtration in a diatomaceous
earth filter.
Physicochemical Methods
Considered a physicochemical process, ion exchangehas
not been successful in producing high quality water for
reuse from laundry waste.

Residual organic matter may be effectively removed by
contact with activated carbon.Granular carbon in an up-
flow pressure tank seems to be most efficient, although
adding powdered activated carbon to other chemicals prior
to filtration can also be effective. Activated carbon is also
effective in removing anionic detergents. However, high
ABS concentration exhausts the capacity of activated car-
bon to remove other organic matter, therefore prior treat-
ment to reduce ABS should be applied.
Biological Methods
When soluble organic material is present, it is difficult to
reduce BOD by more than 60% through chemical pre-
cipitation and filtration. To achieve high degrees of BOD
removal, biological treatment may be required. Although
there is an adequate bacteria food supply of carbon and
phosphorus in the waste, total nitrogen content may be
deficient for biological treatment.
Solids Disposal
Chemical precipitation solids and diatomaceous earth
solids are amenable to landfill disposal. Biological sludges
are treated similarly to septic tank sludges. The sludge
holding tank should be conveniently located for periodic
pumping by a local scavenging firm.
Suggested Treatment System
A schematic flow diagram for a suggested laundromat
waste treatment system is shown in Figure 8.1.2. After
screening lint, waste is stored in a holding tank to equal-
ize flow and provide sufficient volume for operating the
treatment system during normal daytime hours. A pump
can deliver waste to the chemical mixing tank where the

appropriate chemicals are added. A settling tank removes
the bulk of precipitated solids prior to diatomaceous earth
filtration. A pump is required to provide pressure for fil-
tration in the diatomaceous earth filter. Recycling to the
chemical mixing tank would be required during the filter
precoat operation.
Following filtration, activated carbon adsorption may
be practiced as needed. A final storage tank is provided
for adding chlorine if needed or for holding effluent for
future use. Settling tank sludges and diatomaceous earth
filter discharges should be collected in a sludge holding
©1999 CRC Press LLC
FIG. 8.1.2Laundry waste treatment
tank and pumped out periodically by a scavenger system.
This system should provide effluent satisfactory for dis-
charge or partial reuse.
QUALITY OF EFFLUENT
Chemically precipitated and filtered wastes can be disposed
in a subsurface system, provided that there is adequate
land to accommodate the hydraulic load. Biological treat-
ment may be necessary to improve water quality before
discharge into a small stream.
Water reuse should be considered because of the large
volume. Since chemical coagulants increase total dissolved
solids in water, complete reuse and recycle would contin-
uously increase total dissolved solids. Thus, chemicals
should be limited to prevent excess. Because the water is
still warm, heat energy can be saved by recycling treated
effluent. To control total solids buildup, an ion exchange
system is theoretically applicable. However, experience

shows that this system is not effective in treating laundry
waste effluents. Other uses for the treated water may be
found, depending on the water requirements of nearby in-
dustries. Recharging water into the soil uses the soil’s nat-
ural treatment ability and maintains a high water level in
the aquifer, providing water for the laundromat.
Mill Scale
This is a case history of the design, construction, and op-
eration of a wastewater treatment system established to
remove mill scale from water contaminated by steel mill
scale removal operation and to provide a closed system
enabling reuse of water for the mill scale removal opera-
tion.
The installed cost of the total system was approxi-
mately $600,000, including two parallel treatment sys-
tems assuring continuous 24-hr operation via available al-
ternate flow patterns for necessary equipment repair or
maintenance.
DESIGN PARAMETERS
To define the problem, existing system elements were re-
viewed (Figure 8.1.3). The original design specified a once-
through system capable of processing an existing flow of
3500 gpm with the capability to handle 7000 gpm in the
future. Effluent quality was to meet stringent state re-
quirements for discharge to the waterway. Applying
knowledge of stream quality to the original design re-
quirements raised question about the once-through con-
cept. It was noted that if process utilization of this water
did not require a higher quality supply than the polluted
raw river water presently used, the need for a once-through

system was questionable.
A system to treat this wastewater to meet stage dis-
charge standards would be very expensive. However, it
cost much less to treat this wastewater only to the extent
required by the process. Historically, this requirement was
met by the quality of a badly polluted stream. The cost
difference between a reuse system and a once-through dis-
charge system is substantial. Water quality design stan-
dards were key factors in system cost.
Table 8.1.5 lists the design parameters. Provisions were
also made for sludge and recovered oil handling with min-
imal expense and minimal personnel time required. The
original process flowsheet is shown in Figure 8.1.4. A
closed system of this type is susceptible to three primary
problems: algal accumulation, dissolved solids buildup,
and heat buildup.
Solving these problems requires bactericide and/or al-
gicide additives, blowdown and addition of makeup wa-
ter, and a system cooling tower. The original design in-
cluded a cooling tower hookup, if required, together with
a chemical feed system. However, makeup water from the
©1999 CRC Press LLC
FIG. 8.1.3Original water supply layout. A. Original plant wa-
ter supply line. (Raw river water was used without pretreatment
for mill scale removal process.)
TABLE 8.1.5DESIGN PARAMETERS FOR MILL
SCALE WATER TREATMENT PLANT
a
Wastewater Flow 3500 gpm existing
7000 gpm design capability

Primary Pollutants Iron solids (fines)
Oil
Heat
Treated Effluent Quality Continuous 24-hr reuse
Required capability
Acceptable Pollutant Content Iron (suspended solids)
in Effluent 600 ppm
Oil 150 ppm (plus
freefloating oil)
a
System to be as fully automatic as possible.
river was thought sufficient to compensate for evaporative
losses and to control dissolved solids buildup. Dissolved
solids presented no serious problem.
OPERATIONAL HISTORY
In operation, the system is entirely satisfactory. The cool-
ing tower was not installed originally because heat loss
through the system—due to the length of the lines and the
surface area of the tanks—was considered sufficient.
During most of the operating time, this was true. However,
during summer when ambient surface air temperatures oc-
casionally reach 110° to 115°F in this region, Joliet, Ill.,
heat loss was not enough to maintain comfort for per-
sonnel manning the spray nozzles in the plant. During such
periods, return water temperature rose to 114°F for a few
days. Therefore, a cooling tower was installed.
The sludge averages 50 to 60% solids, about the min-
imum water content for the sludge to slide easily from the
discharge chutes into catch buckets.
Oil-skimming devices are rotary cylinder units mounted

at the water surface level in the tanks. These units require
heat protection to prevent freezing in the winter. The
sludge is recovered; since it consists primarily of mill scale,
it can be sold as blast furnace charging material.
Strainers are 0.005 in units with 5,000 gpm capacity
each. These are in the system for insurance in the event of
heavy overloading of the settling tanks. This might occur
if one of the two parallel systems was shut down for pump
or ejection mechanism repairs when the mill is operating
at peak capacity.
Until now, the system has performed well, except for
minor startup and training problems. Mill operating per-
sonnel are pleased, because return water quality is far bet-
ter than the raw river water they were using.
Mineral Tailings
Wastewater from mining or ore beneficiation contains sus-
pended particles of fine sand, silt, clay, and possible lime-
stone. A large percentage of solids may be colloidal due
to their nature or as a result of milling and flotation pro-
©1999 CRC Press LLC
FIG. 8.1.4 Reuse system on steel plant water. (P ϭ pump; F
ϭ filter)
TABLE 8.1.6 SETTLING VELOCITY OF SILT AND
SAND PARTICLES IN TERMS OF
APPLICABLE OVERFLOW RATES
Particle Comparable Overflow
Diameter (mm) Rate cpm/sq ft
1.0 148.0
0.4 62.0
0.2 31.0

0.1 11.8
0.06 5.6
0.04 3.1
0.02 0.91
0.01 0.227
0.004 0.036
FIG. 8.1.5 Thickener for mineral tailings
cessing with reagents added to disperse the solids. Table
8.1.6 shows the velocities at which particles of sand and
silt subside in still water (American Water Works Asso-
ciation 1969) at 50°F.
Collodial particles cannot be removed by settling with-
out chemical treatment. Because of the chemicals added
in milling and during flotation, it is virtually impossible
to economically clarify mineral tailings, and mineral tail-
ing overflows from thickener clarifiers are usually re-
tained indefinitely. Figure 8.1.5 illustrates thickener de-
sign used in alumina, steel, coal, copper, and potash
processing.
—E.W.J. Diaper, T.F. Brown, Jr.,
E.G. Kominek, D.B. Aulenbach,
C.A. Caswell
References
American Water Works Association, Inc. 1969. Water treatment plant
design.New York, N.Y.
Anon. 1971. Standard Methods for the Examination of Water and
Wastewater.13th ed.
Aulenbach, D.B., P.C. Town, and M. Chilson. 1970. Treatment of laun-
dromat wastes, Part I.Proceedings, 25th Industrial Waste Conference.
Purdue University, Lafayette, Ind. (May 5–7).

Aulenbach, D.B., M. Chilson, and P.C. Town. 1971. Treatment of
Laundromat Wastes, Part II.Proceedings, 26th Industrial Waste
Conference. Purdue University, Lafayette, Inc. (May 4–6).
Burns and Roe, Inc. 1971. Process design manual for suspensed solids
removal.Environmental Protection Agency Technology Transfer.
Flynn, J.M. and B. Andres. 1963. Launderette waste treatment processes.
J.W.P.C.F.,35:783.
Great Lakes–Upper Mississippi River Board of State Sanitary Engineers.
1968. Recommended standards for sewage works.
©1999 CRC Press LLC
8.2
REMOVING ORGANIC CONTAMINANTS
Aldehydes
Aldehydes have several properties important to water pol-
lution control. Saturated aldehydes are readily biodegraded
and represent a rapid oxygen demand on the ecosystem,
whereas unsaturated aldehydes can inhibit biological treat-
ment systems at low concentrations. Aldehyde volatility
makes losses through air stripping an important consider-
ation.
BIOLOGICAL OXIDATION
Aldehyde amenability to biodegradation is indicated by
high biochemical oxygen demand (BOD) levels reported
by several investigators. At a low test concentration,
formaldehyde, acetaldehyde, butyraldehyde, crotonalde-
hyde, furfural, and benzaldehyde all exhibited substantial
biooxidation (Heukelekian and Rand 1955; Lamb and
Jenkins 1952). An olefinic linkage in the
␣
,

␤
position usu-
ally renders the material inhibitory (Stack 1957). The lev-
els inhibitory to unacclimated microorganisms for acrolein,
methacrolein and crotonaldehyde were 1.5, 3.5, and 14
mg. per liter (mg/l), respectively, whereas levels for ac-
etaldehyde, propionaldehyde and butyraldehyde were 500
mg/l or above. Formaldehyde was inhibitory at 85 mg/l.
Bacteria can develop adaptive enzymes to allow bio-
logical oxidation of many potentially inhibitory aldehydes
to proceed at high influent levels. Stabilization by accli-
mated organisms of several organic compounds typical of
petrochemical wastes has been investigated (Hatfield
1957). For organisms acclimated to 500 mg/l formalde-
hyde, approximately 3 hr aeration time was required to
bring the effluent concentration to zero. However, efflu-
ent organic concentration after this interval was still high,
indicating oxidation to formic acid or Cannizzaro dismu-
tation to methanol and formic acid. Eight to ten hr of aer-
ation were required for the effluent BOD to approach zero.
Removals of acetaldehyde (measured as BOD) were from
an initial concentration of 430 to 35 mg/l after a 5 hr aer-
ation time. Propionaldehyde removals were from 410–25
mg/l after five hr. The oxidation pattern of paraformalde-
hyde, the polymer of formaldehyde, resembled its precur-
sor.
Data collected through Warburg respirometer studies
using seed sludges from three waste treatment plants
(Gerhold and Malaney 1966) showed that aldehydes were
oxidized to an extent second only to corresponding pri-

mary alcohols. Only formaldehyde exhibited toxicity to all
three sludges. Branching in the carbon chain increased re-
sistance to biooxidation.
AIR STRIPPING
Kinetic data for air stripping of propionaldehyde, bu-
tyraldehyde, and valeraldehyde have been presented
(Gaudy, Engelbrecht and Turner 1961). Removal of pro-
pionaldehyde in model units at 25°C followed first-order
reaction kinetics; removals calculated from residual alde-
hyde and residual chemical oxygen demand (COD) analy-
ses were parallel, indicating that no oxidation of the acid
occurred. However, at 40°C stripping was not described
by first-order kinetics, and propionaldehyde oxidation to
less volatile propionic acid was apparent when removals
measured as COD were less than those measured as alde-
hyde.
Stripping of butyraldehyde and valeraldehyde at 25°C
did not follow first-order kinetics, indicating oxidation of
aldehyde to acid may also be occurring. Removals after
an 8 hr aeration time at 25°C and an air flow of 900
ml/min/l, were 85% for propionaldehyde and butyralde-
hyde, and 98% for valeraldehyde. In a biological system
all three removal mechanisms would exist: biological ox-
idation and synthesis, air stripping, and air oxidation. The
magnitude of each means would depend primarily on the
activity of the bacterial culture and the degree of gas-liq-
uid contact.
CARBON ADSORPTION
Aldehydes, due to their low molecular weight and hy-
drophilic nature, are not readily adsorbed onto activated

carbon. Typical data from Freudlich isotherm tests of ad-
sorbability at various carbon dosage levels are presented
in Table 8.2.1. On a relative basis, aldehydes were less
amenable to adsorption than comparable undissociated or-
ganic acids but were more amenable than alcohols (Giusti
1971). However, none of the low molecular weight, po-
lar, highly volatile materials were readily adsorbed.
Cellulose Pulp
All pulp mill effluents contain wood extractives, a highly
diverse, ill-defined chemical group that varies widely ac-
cording to wood species and origin. Chemical pulping
wastes also contain hydrolyzed hemicelluloses and lignin,
solubilized during cooking. Since various pulp processes
vary considerably in mill design and operation, effluents
are extremely diverse.
WASTEWATER VOLUME
Problems arise due to the tremendous volumes discharged
(Table 8.2.2). Newer installations recycle process waters.
Much market pulp is bleached, with bleach plant dis-
charges as large as those from pulping. Since mills with
500–1000 ton/day capacity are not uncommon, volumes
discharged at a single point may be abnormally high.
EFFLUENT CHARACTERISTICS
Pulp effluents usually have an abnormal pH, a variable
loading of suspended fibrous solids, and an appreciable
oxygen demand (Table 8.2.2). Older mills may have even
heavier loadings. Kraft pulping produces alkaline wastes,
©1999 CRC Press LLC
TABLE 8.2.1CARBON ADSORPTION OF
ALDEHYDES

Aldehyde Removal
from 1000 mg/l
Solution at 5 gm/l
Carbon Dose
Equilibrium
Loading mg/g Removal
Carbon Level, %
Formaldehyde 19 9
Acetaldehyde 22 12
Propionaldehyde 57 28
Butyraldehyde 106 53
Acrolein 61 31
Crotonaldehyde 92 46
Benzaldehyde 188 94
Paraldehyde 148 74
TABLE 8.2.2EFFLUENT CHARACTERISTICS OF CELLULOSE PULPING WASTES
a
Water Volume BOD
5
a
Suspended Solids
Unit Process U.S. gal/ton pH lb/ton lb/ton
Hydraulic debarking 500–10,000 4.6–8.0 5–20 30–50
Groundwood 6,500–10,000 6.0–6.5 10–40 15–80
Neutral sulfite
semichemical pulping
(with recovery) 3,000–20,000 6.5–8.5 30–60 Ͻ10
Kraft pulping 6,000–20,000 7.5–10.0 10–50 Ͻ20
Sulfite pulping
(no recovery) 20,000–30,000 2.5–3.5 550–750 150–200

Sulfite pulping
(with recovery) 20,000–30,000 2.5–4.0 50–100 40–60
Bleaching 20,000–40,000 2.0–5.0 10–25 14–25
a
Oxygen consumed at 20°C during a 5-day incubation with acclimated microorganisms.
whereas sulfite pulping and bleaching plant wastes are
acidic. Chemical recovery is essential in keeping oxygen-
depleting materials low. Large calcium bisulfite mill efflu-
ents may have oxygen demands equivalent to 2,000,000
or 3,000,000 people. Effluents display some toxicity to
aquatic fauna, albeit of a low order. Neutral and higher
pH value effluents are darkly colored, which is aestheti-
cally undesirable and inhibits photosynthesis. In smaller
streams, fish downstream from pulp mill outfalls can have
tainted flesh. Odor and taste imparted to receiving waters
can also interfere with the subsequent use of the stream
for drinking water. Wind and wave action can create foam
on receiving waters, and inorganic salt content may pre-
vent use in irrigation.
METHODS OF TREATMENT
No process can alleviate all pulping effluent problems.
Abnormal pH is neutralized with slaked lime, calcium car-
bonate or sodium hydroxide, since integrated pulping ef-
fluents are usually acidic (Laws and Burns 1960; Charles
and Decker 1970). Settling removes suspended solids ex-
cept for some mechanically ground “fines.”
All microbiological oxidation systems reduce pulp ef-
fluent oxygen demand, but concurrent removal of acute
toxicity is not related to operating parameters for these
systems. Microbiological treatment may not completely

remove substances responsible for tainting fish flesh or
causing odor, foam, and taste in drinking water.
Microbiological treatment does not remove color, how-
ever color bodies can be precipitated by massive lime treat-
ment (EPA 1970).
RESEARCH PROBLEMS
Originally, pulping waste treatments were the same as
those used in domestic sewage treatment. Problems arise
with pulping effluents because of their variable nature. In
short-term microbiological oxidation systems, sludge re-
cycling difficulties may occur. Biologists emphasize the
need to remove sublethal toxicity, however the responsi-
ble chemical entities are largely unknown, and means of
measurement are lacking. Massive lime treatment has tech-
nical and economic limitations, and specific information
concerning unresolved problems is lacking. Thus, a con-
siderable impetus exists for in-process changes or new
processes to minimize current wastewater problems.
Food Processing Wastes
Water is absolutely necessary in food processing. Through
conservation and reuse, liquid waste is reduced, cutting the
pollution load. The National Canners Association has set
four conditions governing the use of reclaimed waters in
contact with food products:
1.the water must be free of microorganisms of public
health significance
2.the water must contain no chemicals in concentrations
toxic or otherwise harmful to man
3.the water must be free of any materials or compounds
that could impart discoloration, off-flavor or odors to

the product or otherwise adversely affect quality
4.the water appearance and content must be aesthically
acceptable
WATER REUSE
Historically, water reuse was given little consideration.
Water is relatively abundant in nature and reuse was con-
sidered hazardous due to bacterial contamination.
Contamination potential (Figure 8.2.1) shows that, in
washing fruit, unless 40% of the water is exchanged each
hour, the growth rate of bacteriological organisms be-
comes extremely high. To overcome this, other means of
control such as chlorination must be used. The importance
of chlorination in maintaining satisfactory sanitary condi-
tions is graphically shown in Figure 8.2.2. When chlori-
nation was discontinued, the bacterial count more than
doubled. As soon as chlorination resumed, bacterial counts
were again brought under control.
Water conservation can be achieved through counter-
flow reuse systems. Figure 8.2.3 outlines a counterflow sys-
tem for reuse of water in a pea cannery. At the upper right,
fresh water is used for the final product wash before the
peas are canned. From this point, the water is reused and
carried back in successive stages for each preceding wash-
ing and fluming (the transport of the fruits by flowing wa-
ter in an open channel) operation. As the water flows coun-
©1999 CRC Press LLC
FIG. 8.2.1Effect of rate of water replacement on growth of
mesophilic bacteria at 90°F.
tercurrent to the product, the washing and fluming water
becomes more contaminated; therefore, it is extremely im-

portant to add chlorine. At each stage, sufficient chlorine
should be added to satisfy the chlorine demand of the or-
ganic matter in the water.
WATER CONSERVATION
Recently, it was determined that adding citric acid to con-
trol the pH of fruit fluming waters reduced water use with-
out increasing bacteria. A pH of 4 (Figure 8.2.4) will main-
tain optimum conditions with cut fruit, such as peaches.
The system not only reduces the total water volume and
therefore the amount of wastewater discharged, but also
increases product yield due to decreased solids loss from
sugar and acids leaching. Consequently, total organic pol-
lutants in the wastewater are reduced. Flavor and color of
the canned fruit are also improved because of better solu-
ble solid retention.
Closed loop systems, such as the hydrostatic cooker-
cooler for canned product, are another conservation
method. The water is reused continuously, with fresh
makeup water added only to offset minor losses from evap-
oration. Closed loop systems not only conserve water but
also reclaim much heat and can result in significant eco-
nomic savings.
It is not the intent of this section to describe the enor-
mous array of concepts and ramifications used in the food
processing industry to reduce water and waste loads while
maintaining product quality. Many factors determine the
final effectiveness of proper water use. For example, toma-
toes spray-washed on a roller belt where they are turned
are almost twice as clean as the same tomatoes washed on
a belt of wire mesh construction. In another example,

warm water is approximately 40% more effective in re-
moving contaminants than the same volume of cold wa-
ter.
There is a delicate balance between water conservation
and sanitation, with no straightforward or simple formula
for the least water use. Each process must be evaluated
with the equipment used to arrive at a satisfactory proce-
dure for water use, chlorination, and other factors, such
as detergents.
ELIMINATION OF WATER USE
Eliminating water in certain operations eliminates atten-
dant wastewater treatment problems. Wherever possible,
food should be handled by either a mechanical belt or
pneumatic dry conveying system. If possible, the food
should be cooled in an air system. Recent studies by the
National Canners Association in comparing hot air
blanching of vegetables with conventional hot water
blanching show that both product and environmental
quality were improved by using air. Blanching, used to de-
activate enzymes, produces a very strong liquid waste. For
©1999 CRC Press LLC
FIG. 8.2.2Effect of chlorine concentration on bacterial counts
in reused water. A. Chlorine concentration; B. Bacterial counts.
FIG. 8.2.3Four-stage counterflow system in a pea cannery. A.
First use of water; B. Second use of water; C. Third use of wa-
ter; D. Fourth use of water; E. Concentrated chlorine water.
FIG. 8.2.4Effect of pH control on bacterial cell growth.
pea processing, this small volume of wastewater is esti-
mated to be responsible for 50% of the entire wasteload
BOD; for corn, 60%; and for beets with peelings, 80%.

Preliminary results show a reduced pollution load (Table
8.2.3), while improving product nutrients, vitamins, and
mineral content.
WASTEWATER TREATMENT
Preprocessing
Proper management of food processing wastes requires
consideration of individual operations from harvest
through waste disposal as integrated subunits of the total
process. Every effort should be made to eliminate wastes
and to avoid bringing wastes from the farm into the pro-
cessing plant. Where possible, preprocessing should occur
in the field, returning the organic materials to the land. In
the processing plant, wastewater volume and strength
should be reduced at each step. This principle applies to
all food processing wastes, including fruit, vegetables, meat
and poultry, and dairy.
Waste segregation within a plant is important in opti-
mizing the least-cost approach to treatment. In a typical
brewery (Figure 8.2.5), where 3% of the flow contains
59% of the BOD, it is less expensive to treat this small
flow separately than to mix it with the entire plant waste
flow. This is effective when a plant treats its own wastes
or releases waste to a municipality with surcharges for
high-strength waste.
Food processing wastes are amenable to biological
treatment, and they frequently provide nutrients essential
to efficient biological treatment. Although various waste
treatment methods are available to the food processor
(Figure 8.2.6) there is no simple guide for the most prac-
tical and economical method.

Lagoons and Land Disposal Systems
Since food wastes contain suspended and soluble organic
contaminants, they are readily treated in lagoons and land
disposal systems. The lagoons may be complete storage
ponds, frequently used by seasonal processors for waste
containment. In four to six months, the waste is stabilized,
with up to 90% BOD reduction. If large lagoon acreage
is available, aerobic conditions are maintained by limiting
organic loadings to less than 100 lb of BOD per acre per
day. When extremely strong wastes are encountered, a
combination of anaerobic and aerobic lagoons provides an
excellent means of treatment on less land, since the anaer-
obic system may reduce BOD from 60% to 90%, reduc-
ing the aerobic lagoon acreage required to achieve desired
effluent quality.
Anaerobic lagoons are odorous and require an artificial
or natural cover. In meat products, the high grease con-
tent forms a natural cover. Aerobic lagoons can also cause
odors if overloaded and lacking sufficient dissolved oxy-
gen. Various mechanical aeration methods have reduced
required lagoon acreage, but these increase power costs.
Land disposal can be achieved by flooding; however,
the most efficient means is conventional farm spray irri-
gation equipment. Sandy soil with a high infiltration rate
offers no surface runoff, and no discharge to a receiving
stream. Recently, an overland flow technique has been de-
veloped as an equivalent of tertiary treatment.
©1999 CRC Press LLC
TABLE 8.2.3HOT AIR VS HOT WATER BLANCHING
Blanching Wastewater COD Produced SS Produced

Product System gal/ton lb/ton lb/ton
Green peas Hot water 1,000.0 32.70 1.42
Green peas Hot air 0.018 Not measured Not measured
Green beans Hot water 1,710.0 4.70 0.11
Green beans Hot air 0.25 0.002 0.0002
Corn on the cob Hot water 1,223.0 4.70 0.041
Corn on the cob Hot air 0.013 5.6 ϫ10
Ϫ5
1 ϫ10
Ϫ6
Red beets Hot water 1,333.0 4.11 0.16
Red beets Hot air 0.089 0.001 7.4 ϫ10
Ϫ6
Spinach Hot water 1,430.0 2.6 3 ϫ10
Ϫ1
Spinach Hot air 3.6 ϫ10
Ϫ2
3.0 ϫ10
Ϫ4
3 ϫ10
Ϫ
7
FIG. 8.2.5Source and relative strength of brewery wastes
Canning Wastes
The canning industry uses an estimated 50 billion gal of
water per year to process one billion cases of food. Liquid
waste is normally screened as a first step in any treatment
process. Solids from these screens can be trucked away as
garbage or collected in a by-products recovery program.
Food product washing is the greatest source of liquid

waste. The water used is normally reclaimed in a coun-
terflow system, with a final discharge high in soluble or-
ganic matter and containing suspended solids—much of it
inorganic—from the soil. Other wastes come from peeling
operations. The amount of suspended matter varies with
the type of peeling. The type of peeler—steam, lye, or abra-
sive—has an effect on the nature of the waste generated.
Normal practices utilize large volumes of water to wash
away loosened peelings, creating tremendous suspended
and organic loads in the waste stream. Lye peeling also
generates wastewater with markedly high caustic alkaline
concentrations. Equipment for dry lye peeling of fruits and
vegetables removes the lye peelings in a semidry state so
that solids can be handled separately without liquid con-
tamination.
Raw foods are blanched to expel air and gases from
vegetables; to whiten, soften, and precook beans and rice;
to inactivate enzymes that cause undesirable flavor and
color changes; and to prepare products for easy filling into
cans. Little fresh water is added during blanching (8-hr
shift), therefore the organic material concentration be-
©1999 CRC Press LLC
FIG. 8.2.6 Wastewater treatment maze (for organic waste from food processing industries). The diagram illustrates the many op-
tions open to solving waste treatment problems. The best route through the maze is suggested by an engineering study and report.
Such a report discloses possible treatment methods, anticipated influent properties, effluent requirements and costs. Most important,
the report serves as a mutually agreed-upon criterion with regulatory agencies. Designing a waste treatment system should not be
considered without such a study and report.
comes high due to leaching of sugars, starches, and other
soluble materials. Although low in volume, blanch water
is highly concentrated and frequently represents the largest

load of soluble wastes in the entire food processing oper-
ation. The amount of dissolved and colloidal organic mat-
ter varies, depending on the equipment used.
The last major source of liquid wastes is the washing
of equipment, utensils, and cookers, as well as washing of
floors and food preparation areas. This wastewater may
contain a large concentration of caustic, increasing the pH
above the level experienced during food processing.
After cooking, the cans are cooled, which requires a
large volume of water. The cooling water is clean and
warm and should be reused for washing.
Meat and Poultry Wastes
Feed lot, stockyard, and poultry receiving area wastes con-
sist primarily of manure, unconsumed feed, feathers, and
straw, together with common dirt and drain water.
Pollution can be reduced if solid wastes are not diluted by
water.
In killing operations blood must be collected separately
and prevented from entering sewer or waste treatment sys-
tems, since blood has an extremely high waste strength of
about 100,000 ppm BOD. In poultry plants, various
processes must be isolated to avoid cross-contamination
from live birds or wastes of previous operations. As the
bird goes through the plant on shackles, feathers are re-
moved and flumed away. A major incision is made, en-
trails and major organs are pulled out, and inedible vis-
cera are discarded in a flowaway flume system. The lungs
and other material remaining in the carcass are removed
by vacuum suction.
Flowaway systems (for feathers, entrails and offal) cre-

ate an increased organic load, and it is desirable to use a
dry conveying system. Most plants use the flowaway sys-
tem as a more convenient and nuisance-free operation.
After the offal flowaway leaves the area, it must be
screened in order to remove solids. These solids and wastes
from other operations are then sent to a rendering plant
where they are utilized in making chicken feed.
Meat packing houses generate a strong waste. These
wastes are amenable to treatment, as are poultry wastes.
Before releasing processing wastewaters into city sewers or
private waste treatment systems, screening and grease re-
moval should be provided to recover solids for by-prod-
uct use. Removal of large solids and free floating grease is
also important to avoid clogging sewer lines and fouling
biological treatment systems.
Dairy Wastes
Among waste generating operations in the dairy industry
are receiving stations, bottling plants, creameries, ice cream
plants, cheese plants, and condensed and dried milk prod-
uct plants. Wastes include separated milk, buttermilk, or
whey, as well as occasional batches of sour milk. Diverse
methods are being explored for reclamation and concen-
tration of materials, such as reverse osmosis for whey.
Unfortunately, there is no simple economical method to
reclaim and utilize these materials as byproducts.
Indiscriminate dumping of these materials into sewers
should be avoided, and where possible these extremely
strong wastes should be treated separately or eliminated
by hauling.
Milk wastes are normally treated in municipal plants,

since most dairies are located in communities. The wastes
are amenable to biological treatment, and screening is com-
monly provided; grit removal is sometimes necessary, as
well.
Solid Waste Disposal
Most solid wastes from food processing are generated in
processing raw materials. Some materials, such as pack-
aging, faulty or damaged containers, office or warehouse
papers, and refuse from laboratories, should be kept sep-
arate from the food solids. Solid food waste is produced
in growing and harvesting raw crops, in food processing,
and by the retailer and consumer.
Many food processing operations are seasonal and gen-
erate large quantities of organic solid wastes in a short
time. The putrescible nature of the wastes requires quick
handling in utilization or disposal. Land disposal opera-
tions—by far the most common method of disposal—must
be rigidly controlled to prevent odor production and fly
breeding. It is apparent that the food processing industry
must recycle and recover more of its by-products.
Utilization of food processing waste as animal feed is a
widely used method of disposal. In some areas, seafood
canning waste is pressed into fish meal for animal feed or
into fertilizer material. Tomatoes are pressed and dehy-
drated for use as dog food and cattle food. Pea vines, corn-
cobs, and corn husks are also used as feed. Citrus peel
waste may be pressed for molasses, which may then be
processed, dried, and sold as cattle feed. Certain types of
pits and nutshells have been converted to charcoal.
Other possibilities exist, such as producing alcohol from

fruit wastes and composting fruit waste solids, but usually
it is much cheaper to dump, landfill, spread on the land,
or discharge at sea than to attempt reclamation. There does
not appear to be much chance of a change in this area un-
less prevailing economic conditions can be altered through
new legal restrictions or some form of subsidy program.
Hydrocarbons
A bulk oil handling terminal stores and tranships petro-
leum products, petrochemicals, animal fats, greases and
food grade vegetable oils. In addition they often accept
and dispose of ballast wastewaters from marine tankers
©1999 CRC Press LLC
that deliver to the terminal or pick up cargo for tranship-
ment. A biological treatment system is appropriate because
of the wide range of physical and chemical characteristics
of the various types of oils and petrochemicals; mechani-
cal and/or chemical means of separation and neutraliza-
tion are too expensive to install and operate.
The equipment used in the system includes (1) a col-
lection system for the wastewater flow; (2) an API sepa-
rator; (3) a high-rate oxidation pond (or “aerated lagoon”)
with a 150,000 gal capacity; (4) a secondary settling or
“polishing pond” with a capacity of 450,000 gal; (5) a re-
circulation system; and (6) an 800,000 gal storage tank
for ship ballast holding and for surge flow equalization.
DESIGN BASIS
Biological treatment was chosen because some oils float,
some sink, some are “soluble,” and some saponifiable.
Thus, a broad-spectrum treatment was required. No mu-
nicipal sewerage system was available, therefore the efflu-

ent had to meet waterway discharge requirements. This
specified effluent concentration limits (mg/l): including bi-
ological oxygen demand (BOD) of 20 or less; hexane sol-
ubles of 15 or less; suspended solids of not over 25; and
a pH range of 6 to 10. In addition, effluent had to be sub-
stantially color free. Influent characteristics were as fol-
lows:
Average daily flow 20 gpm
Average BOD 400 ppm
Average hexane solubles 300 ppm
Average suspended solids 100 ppm
Average pH range 5 to 12
Maximum aeration requirements were calculated to pro-
vide (1) sufficient flexibility to vary input air in response
to extreme pollutant load variations; and (2) excess hy-
draulic mixing capacity to increase suspended solids oxi-
dation and reduce the volume of sludge accumulating in
the system.
The use of 3–5 hp floating aerators provides a total
available oxygen transfer rate of 7.5 lb oxygen per lb of
BOD, according to the manufacturer. Under most termi-
nal operating conditions, only two aerators were required
to provide 95% BOD removal. Sludge accumulation was
below 350 lb wet sludge (7 lb dry) per day. The system
has never had an odor problem.
A recirculating system was established for peak waste
loads in oil handling terminal operations (Figure 8.2.7).
The 800,000 gal ballast tank gives an additional ten days
of holding time for recirculation when pollutant loadings
far exceed design capacity.

OPERATIONAL HISTORY
The BOD of the high-rate oxidation pond (“small pond”)
at startup was 2420 ppm (mg/l), and the hexane soluble
content was 2040 mg/l. Both ponds were covered with
about 6 in of floating oil and grease (see Figure 8.2.8 for
the rate of stabilization).
The system was set on a recirculation rate of 50 gpm.
Three days later, when the pH showed no further erratic
swings, dried bacterial cultures (special species of sapro-
phytic and facultative bacteria that consume oil) were
added to create a biomass specifically for oil and grease
reduction. The initial dosage was 5 lb, followed by 1 lb/day
addition for 14 days. After this initiation, the system was
©1999 CRC Press LLC
FIG. 8.2.7Bulk oil-handling terminal waste treatment system.
FIG. 8.2.8BOD reduction in ponds as a function of time after startup. (BOD is usually 50% of ODI.)
maintained by the addition of Aslb of the dried culture
three times a week. Figure 8.2.9 illustrates initial reduc-
tion of the hexane soluble content and continuing control
since the beginning of plant operation.
The effectiveness of a biological treatment to control
oily wastewater is also shown in Figure 8.2.10 where the-
oretical and actual performances are compared.
Pesticides
Since pesticides enter the aquatic environment in runoff
from agricultural areas as well as from point sources, con-
trol must be based on a multiphased approach:
1.Controlled application in minimum quantities over ar-
eas where specifically needed
2.Degradation in soil and watercourses

3.Removal at plants producing potable water
4.Treatment of wastes from pesticide handling facilities
and sewered areas
The various mechanisms for removing pesticides entering
the environment are discussed in this section as outlined
in Table 8.2.4, and the chemical structures of the pesti-
cides are shown in Figure 8.2.11.
PESTICIDE REMOVAL IN NATURAL
AQUATIC SYSTEMS
Pesticide occurrence in surface waters can be traced to sev-
eral sources: agricultural runoff, industrial discharge, pur-
poseful application, cleaning of contaminated equipment,
and accidental spillage. Chlorinated hydrocarbons in aque-
ous solutions are readily adsorbed by clay materials. After
adsorption, small fractions of some pesticides are gradu-
ally desorbed into the overlying water where the pesticide
concentration is maintained at a dynamic equilibrium level.
Drainage of clay-bearing waters from agricultural areas
represents a continuous supply of pesticides to the aque-
ous solution. Desorption rates are not significantly affected
by pH, temperature, salt and organic levels (Huang 1971).
The introduction of many new pesticides in recent years
has created the need for reliable evaluation of the effects
on the aquatic biota. The model ecosystem for these eval-
uations consists of glass aquaria arranged in a sloping soil-
air-water interface (Metcalf, Sangha and Kapoor 1971). A
food chain of plant and animal organisms, compatible with
the environmental conditions simulated in the aquarium,
is chosen for following radiolabeled DDT (labeled in the
aryl rings with C

14
) and methoxychlor. Average data pre-
sented in Table 8.2.5 show a 13,000-fold increase in con-
©1999 CRC Press LLC
FIG. 8.2.9Polishing pond performance from startup. A ϭini-
tial BOD of 2420 ppm (at startup ODI roughly equals BOD;
later BOD is stabilized at 50 percent ODI for this waste); B ϭ
FIG. 8.2.10Theoretical vs actual performance. A. Rate of pol-
lutant addition reducers; B. Standard theoretical curve for rate of
pollutant reduction by biological treatment systems; C. Curve dis-
tortion due to exceptional load condition. System gave 97% re-
duction in 30 days.
centration of carbon-14 in the fish over the concentration
in water. The DDE metabolite of DDT was largely re-
sponsible for the undesirable accumulations in animal tis-
sue noted.
In studies with tritium-labeled methoxychlor, accumu-
lations of the pure compound and its degradation prod-
ucts in fish were of the order of 0.01 those for DDT
(Metcalf, Sangha and Kapoor 1971). The presence of sev-
eral degradation products and the relatively low accumu-
lations in most organisms revealed the environmentally
degradable nature of methoxychlor.
The organophosphate insecticides were less persistent
in the aquatic environment than were the organochloride
compounds (Graetz, et al. 1970). Depending on environ-
mental conditions, degradation is by chemical or microbi-
ological means, or both. Chemical degradation involves
hydrolysis of the ester linkages. Hydrolysis can be either
acid-catalyzed, e.g., ciodrin, or base-catalyzed, e.g.,

malathion. Microbial degradation can be by hydrolysis or
oxidation. Partial degradation is often the case, although
for diazinon, chemical hydrolysis of the thiophosphate
linkage attached to the heterocyclic ring results in 2-iso-
propyl-4-methyl-6-hydroxypyrimidine, which is degraded
rapidly by soil microorganisms. Among the orthophos-
phates, parathion is one of the most resistant to chemical
hydrolysis, but microbial degradation to aminoparathion
can proceed.
©1999 CRC Press LLC
TABLE 8.2.4 PESTICIDE REMOVAL ORIENTATION
Removal Method Applicability
Adsorption onto clay and precipitates Soils and clay-bearing watercourses
Water treatment coagulation processes
Controlled self-destruction Soil and watercourses
Degradation by biological systems Soil at point of pesticide application
Watercourses receiving runoff
containing pesticides
Waste treatment system at pesticide
handling facility
Chemical oxidation Water and wastewater treatment
systems
Activated carbon adsorption Water and wastewater treatment
systems
Membrane separation Water and wastewater treatment
systems
Incineration Concentrated residue disposal
FIG. 8.2.11 Chemical structures of key pesticides. A.
Chlordane; B. 2,4-D; C. DDT; D. Dieldrin; E. DNOCHP: F.
DNOSBP; G. Endrin; H. Heptachlor; I. Lindane; J. Parathion;

K. Sevin; L. Silvex; M. 2,4,5-T; N. Toxaphene.
TABLE 8.2.5 DISTRIBUTION OF DDT IN MODEL
ECOSYSTEM
Distribution
Water Snail Fish
Total Carbon-14
Content, mg. per
liter 0.003 20 38
Distribution, %
as DDT
a
53131
as DDE
b
74756
as DDD
c
81112
as polar metabolites 74 7 1
Unclassified 6 4 0
a
DDT, Dichlorodiphenyltrichloroethane
b
DDE, Dichlorodiphenyldichloroethylene
c
DDD, Dichlorodiphenyldichloroethane
Standard biochemical oxygen demand tests involving
glucose incubation with a carbaryl insecticide, Sevin, indi-
cate no inhibition of bacterial oxidation of glucose up to
a Sevin concentration of 100 mg/l. In fact, Sevin was bioox-

idized to a considerable extent at this level; oxidation was
enhanced after a period of acclimatization.
BIODEGRADABLE REPLACEMENT AND
CONTROLLED SELF-DESTRUCTION
Biodegradable substitutes have been developed for some
hard pesticides. One approach is to substitute aromatic
chlorine atoms in the DDT molecule (Anon., Chemical
Week 109:36 1971). The new compounds reportedly do
not build up in animal tissue and concentrate at higher
levels in the food chain.
A mildly acid reduction by zinc will speed degradation
of DDT and other pesticides in natural systems (EPA
1970). A copper catalyst speeds up the reduction. Effective
degradation of DDT to bis(p-chlorophenyl) ethane appears
possible in soil by using micron-sized particles of the re-
ductant in close proximity to the DDT. Thin, slowly sol-
uble wax or silyl coatings on the reductant can delay the
reaction. A second technique for delayed reaction involves
controlled air oxidation to sulfur to produce the required
acidity. Effective degradation of DDT in aqueous systems
was also achieved using reduction techniques. The proce-
dure was reported effective in substantially degrading
dieldrin, endrin, aldrin, chlordane, toxaphene, Kelthane,
methoxychlor, Perthane and lindane.
BIOLOGICAL TREATMENT PROCESSES
The waste flow from a parathion production unit under-
goes activated sludge treatment (Coley and Stutz 1966)
with a residence time of 7–10 days, providing nearly com-
plete breakdown of parathion and paranitrophenol as well
as over 95% reduction in organic matter as measured by

chemical oxygen demand (COD).
Studies were also conducted in designing a wastewater
treatment facility for production of organic phosphorus
pesticides (Lue-Hing and Brady 1968). Although treata-
bility studies showed the waste to be biodegradable, shock
loads caused stresses at up to 6000 mg/l solids.
Consequently, a two-stage activated sludge system was
chosen in which the first stage is a dispensable, low-solids,
detoxification unit. Removal of dissolved organic matter
measured as biochemical oxygen demand was 90–98% in
the pilot plant.
The oxidation of Sevin carbaryl insecticide by an acti-
vated sludge culture is depicted in Figure 8.2.12. No ad-
verse effects on bacteria, protozoa and rotifers were noted.
Biological degradation studies (Leigh 1969) of lindane in-
dicated no significant removal of this pesticide from mi-
crobial activity following 28 days of acclimatization in sta-
tically aerated cultures. Removals in unseeded controls
(reference samples) were approximately 46% while bio-
logical removals averaged only 41%. The biodegradabil-
ity of heptachlor could not be deduced from similar stud-
ies because analyses of aqueous solutions of this pesticide
indicated partial degradation to 1-hydroxyl chlordene and
an undetermined compound. Removals of as high as
99.4% were attained within four days for heptachlor, but
volatilization losses were considered significant.
The degradation of chlorinated hydrocarbon pesticides
was studied under anaerobic conditions (Hill and McCarty
1966) such as lake and stream bottoms, lagoon treatment
systems, and digestion systems. Lindane and DDT were

rapidly decomposed, the latter to DDE which degraded
more slowly. Heptachlor and endrin also formed inter-
mediate degradation products within short periods. The
rate of decomposition of aldrin was similar to that for
DDD; only slight degradation of heptachlor epoxide oc-
curred, and dieldrin remained unchanged. Anaerobic con-
ditions were more favorable than aerobic conditions for
pesticide degradation. Sorption of chlorinated hydrocar-
bon pesticides was found to be greater on algae than on
bentonite or fine sand; the process was partially reversible
and the degree of sorption was inversely related to the sol-
ubility of the pesticide.
Lindane was degraded anaerobically in pure culture;
only 0.5% of the lindane present after 1hr incubation was
found in the reaction mixture after 27hr incubation
(MacRae, Raghu and Bautista 1969). The covalently
linked chlorine of the lindane molecule was released. A de-
tected intermediate product reached a maximum level af-
ter about 4hr incubation and diminished to undetectable
levels after 27hr incubation.
©1999 CRC Press LLC
FIG. 8.2.12Oxidation of Sevin carbaryl insecticide by accli-
mated bacteria.
CHEMICAL FLOCCULATION AND
OXIDATION
Since pesticides are used mainly in unsewered agricultural
areas, they reach lakes and streams without passing
through treatment facilities. Consequently, ease of removal
in conventional water supply treatment processes (when
water is withdrawn for processing to produce potable wa-

ter) is important. A study used pilot water supply treat-
ment plants to evaluate conventional and auxilliary treat-
ment process effectiveness in removing pesticides from
natural surface water (Robeck, Dostal, Cohen and Kreiss
1965). The results showed that each part of the water
treatment plant had some potential for reducing certain
pesticides. The effectiveness of the standard process of co-
agulation and filtration is shown in Table 8.2.6. Removals
ranged from 98% for DDT to less than 10% for lindane.
The only pesticide affected significantly by the application
of chlorine or potassium permanganate (1–5 mg/l) was
parathion, 75% of which was oxidized to paroxon, a more
toxic material. At high dosages, ozone (10–38 mg/l) re-
duced chlorinated hydrocarbons; by-products of unknown
toxicity were formed.
In full-scale evaluations (Nicholson, Grzenda and
Teasley 1968), the standard processing steps of coagula-
tion, settling, rapid sand filtration, and chlorination were
successful in reducing DDT and DDE levels but not
toxaphene and lindane levels. Side tests with a 25-
␮
filter
removed DDT and DDE more effectively than toxaphene
and lindane, indicating that the latter materials were trans-
ported in solution.
Chemical degradability of frequently used chlorinated
hydrocarbon insecticides has also been investigated (Leigh
1969). Lindane and endrin were not removed by either
chlorine or potassium permanganate at oxidant dosages
ranging from 48 to 61 mg/l, contact times of 48 hr and a

wide range of pH values. Heptachlor was removed by
KMnO
4
to the extent of 88% with only slight variation
due to pH adjustment. Heptachlor and DDT were both
partially removed by chlorine, and DDT was partially re-
moved by KMnO
4
with slightly higher removals at lower
pH levels. Maximum removals by potassium persulfate,
attained only for lindane and DDT, were 9.4% and
18.5%, respectively, at higher pH values.
Several physical and chemical treatments for removing
the herbicide 2,4-D and its ester derivatives from natural
waters have also been investigated (Aly and Faust 1965).
Chemical coagulation of 1 mg/l solutions by 100 mg/l alu-
minum sulfate showed no promise with the herbicides and
derivatives studied. Activated carbon studies indicated car-
bon requirements for reducing 2,4-D concentrations from
1 to 0.1 mg/l were 31 mg/l for sodium salt, 14 mg/l for
isopropyl ester, 15 mg/l for butyl ester and 16 mg/l for
isooctyl ester. Potassium permanganate dosed at 3 mg/l
did not oxidize 1 mg/l of these same compounds. However,
0.98 mg/l of 2,4-DCP was completely oxidized by 1.25
mg/l KMnO
4
in 15 min. Ion exchange studies indicated
that strongly basic anion-exchange resins more effectively
removed the compounds studied than cation exchange
resins.

Strong oxidants to degrade chlorinated hydrocarbon
pesticides (Buescher, Dougherty and Skrinde 1964) have
also been studied. Preliminary studies with lindane and
aldrin showed negligible removals with hydrogen perox-
ide and sodium peroxide at 40 mg/l dosages and four-hr
contact times. Chlorination had negligible effects on lin-
dane, but completely oxidized aldrin, while potassium per-
manganate (KMnO
4
) oxidized lindane to approximately
12% and aldrin, fully. Further studies of potassium per-
manganate added in varying doses from 6 to 40 mg/l to
lindane solution indicated that the excessive time and ox-
idant dosages required for removals greater than 40%
made this treatment unfeasible. Complete removal for
aldrin could be attained in 15 min at 1 mg/l dosage of
KMnO
4
.
Due to the relatively small fraction of ozone in the air
stream used for ozonation, pesticide removals from air
stripping were measured, as well as removals from oxida-
tion. Up to 75% of lindane was removed by ozonation,
whereas aeration alone had no measurable effect. Dieldrin
and aldrin were completely removed almost at once, but
aeration studies also showed fairly rapid removals.
ACTIVATED CARBON ADSORPTION
Considerable data on the adsorption of several pesticides
and related nitrophenols on activated carbon have been
reported (Weber and Gould 1966). Carbon loadings of

40–53% indicate economic feasibility for removal of trace
quantities of these persistent compounds. Rate and
Langmuir equilibrium constants for the pesticides are
shown in Table 8.2.7. The quantity of pesticide adsorbed
per gm of carbon at complete monolayer coverage of the
carbon surface (X
m
values) indicates high ultimate carbon
loadings. B
Ϫ1
values, which relate to energies of adsorp-
tion, indicate that relatively high residual concentrations
©1999 CRC Press LLC
TABLE 8.2.6REMOVAL OF PESTICIDES IN WATER
TREATMENT PLANT OPERATIONS
Removal, percent
Pesticide Coagulation-
Carbon Slurry
(10 ppb dosage) Filtration 5 ppm 20 ppm
Lindane Ͻ10 30 80
Endrin 35 80 94
Dieldrin 55 75 92
2,4,5-T Ester 65 80 95
Parathion 80 Ͼ99 Ͼ99
DDT 98 Not Not
Tested Tested
are required for all but parathion to attain saturation ca-
pacity.
Additional studies (Dedrick and Beckman 1967) indi-
cate that adsorption of 2,4-dichlorophenoxyacetic acid

(2,4-D) can be correlated by both the Freundlich and the
Langmuir isotherms; however, two sets of correlating con-
stants are required for each of the low and high concen-
tration ranges. No significant differences in carbon ca-
pacities were noted between granular and powdered
carbon. Carbon loadings of approximately 60% by weight
of the herbicide were attained at liquid concentrations
95% of saturation, or about 740 mg/l.
Carbon adsorption studies using a slurry approach
showed parathion to be most amenable and lindane least
amenable (Table 8.2.6) to removal by activated carbon.
Use of a granular bed at 0.5 gpm/cu ft resulted in almost
complete removal of all pesticides.
REVERSE OSMOSIS
Specific chemical permeation through a cellulose acetate
membrane has also been reported (Hindin, Bennett and
Narayanan 1969). The membranes were immersed in wa-
ter at 82°C for 30 min prior to use. At a pressure differ-
ential of 100 atm, a temperature of 25°C, flux rates on
the order of 15 gal/sq ft/day, and feed concentrations of
about 500 mg/l, reduction of lindane was 73% while DDT
and TDE (DDD) were rejected above 99%. High reduc-
tions were obtained for those chemical species existing
primarily in the colloidal, aggregate, micelle, or macro-
molecular form. If the chemical species existed both as an
aggregate in dispersion and as a discrete molecule in true
solution where vapor pressure of the discrete molecule in
true solution was appreciably greater than that of water,
the range of reduction was 50–80%. Where discrete mol-
ecules more volatile than water were tested, range of re-

ductions was 14–40%.
INCINERATION
Along with deep-well injection, incineration of concen-
trated pesticide waste is an alternative to treatment and
disposal in surface waters. Solid wastes are burned in a ro-
tary kiln or other incinerator at 1600°–2200°F (Anon.
Chemical Week 108:37 1971). Afterburners can be used
to reach temperatures of 2800°F. A scrubber is used to
clean exhaust gases.
RESEARCH TRENDS
Since outlawing DDT and other pesticides that build up
in the foodchain seems imminent in many developed ar-
eas, replacements must be found, or there will be a re-
crudescence of health problems. For example, malaria and
Venezuelan equine encephalomyelitis resurge in areas
where mosquito control is lax or mosquitos become re-
sistant to the pesticides used. In the case of mosquito con-
trol, malathion and propoxur are recommended as re-
placements for DDT as resistance grows (Anon. Chemical
Week 109:36 1971). Although fenitrothion, iodofenphos,
phenothoate and Landrin show promise, all are more ex-
pensive and less effective than DDT.
Until suitable replacements are developed, much re-
mains to be done in the realm of pesticide removal from
waters—both prior to discharge of wastewater and in
treating water for human use. Although the literature on
the effects and measurement of pesticides is voluminous,
articles on removal techniques for pesticides are relatively
few.
Phenol

Although phenol (C
6
H
5
OH) has been detected in decay-
ing organic matter and animal urine, its presence in a sur-
face stream is attributed to industrial pollution. Petroleum
refineries, coke plants, and resin plants are major indus-
©1999 CRC Press LLC
TABLE 8.2.7 CARBON ADSORPTION CONSTANTS FOR ORGANIC PESTICIDES
Relative Rate
Constant Limiting Monolayer b
Ϫ
1
(relates to
(␮moles/g)
2
Carbon Loading (X
m
), energy of adsorbtion)
per hr
ϫ
10
Ϫ
4
mg per g mg/l
2,4-D 1.44 387 2.32
2,4,5-T 1.00 448 1.71
Silvex 0.71 464 1.86
DNOSBP 1.35 444 1.39

DNOCHP 1.12 500 1.81
Sevin 1.64 — —
Parathion 1.49 530 0.24
Note 1: Experimental Conditions: C
0
ϭ 10
␮
moles per liter, 0.273 mm. Columbia carbon, 25°C
Note 2: Symbols relate to Langmuir isotherm: x ϭ
ᎏ
1
X
ϩ
m
b
b
C
C
ᎏ
(Reprinted with permission, from I.C. MacRae, K. Raghu, and E.M. Bautista, 1969, Nature 221:859.
trial phenolic waste sources. Phenolic compounds and their
derivatives are used in coatings, solvents, plastics, explo-
sives, fertilizer, textiles, pharmaceuticals, soap, and dyes.
Treatment methods for phenol removal include bio-
logical (activated sludge, trickling filter, oxidation pond,
and lagoon); chemical oxidation (air, chlorine, chlorine
dioxide, ozone, and hydrogen peroxide); physical (acti-
vated carbon adsorption, solvent extraction, and ion ex-
change); and physicochemical (incineration and electrolytic
oxidation).

SOLVENT EXTRACTION
For wastewaters containing high phenol concentrations,
solvent extraction reduces the phenol to acceptable levels.
Occasionally, recovered phenol is reused in the manufac-
turing process or solid as a by-product. In solvent extrac-
tion, two immiscible or partially soluble liquids are
brought into contact for transfer of one or more compo-
nents. Using a solvent such as benzene, phenol can be ex-
tracted from the wastewater. The extracted phenol is then
washed out with caustic to form the sodium salt, and the
benzene is reused. In the petroleum industry, light catalytic
cracking oils are used as extractors, and in the coking in-
dustry, coke oven light oils are used as extractors. Process
efficiency depends on solvent choice and system design.
BIOLOGICAL TREATMENT
The microorganisms capable of degrading phenol are
highly specialized and require a controlled, stable envi-
ronment. Under ideal conditions several weeks are required
to develop the proper biological sludge. The efficiency of
an acclimated biological system treating phenolic wastes
depends strongly on temperature, pH, nutrients (nitrogen,
phosphorus, minerals), oxygen concentration, phenol con-
centration, and other organics concentrations in the waste-
water.
To degrade phenol, the microorganism population must
be stable. Fluctuation in any of the preceding variables
shifts the balance of this population, reducing system effi-
ciency and possibly killing the biological organisms.
Optimum phenol removal occurs at neutral pH (7.0), 70°F
and constant phenol concentration.

Biological methods of phenol removal include activated
sludge, trickling filters, oxidation ponds, and lagoons.
Efficiency ranges from 65–90% removal, depending on the
ability of the particular wastewater treatment system to
control the process variables listed. Activated sludge, trick-
ling filters, and oxidation ponds are all capable of high
phenol removal if properly designed and operated; how-
ever, the trickling filter process is regarded as being more
capable of withstanding slug loads without loss of perfor-
mance. Lagoons for treating phenolic wastes are designed
to avoid overflow, with evaporation and seepage used to
balance the influent flow. This method is less desirable,
due to the possibility of ground water pollution, odor, and
overflows from rainfall.
Frequently, phenolic wastes are diluted with sanitary
wastes and treated at the local municipal plant (Muller
and Covertry 1968). Combined municipal-industrial treat-
ment buffers the dilution and provides an ample supply of
nutrients and microorganisms should the system be upset.
Phenolic wastewaters should be neutralized prior to dis-
charge to the municipal sewer system.
CARBON ADSORPTION
Activated carbon in the powdered and granular forms is
used to remove phenolic tastes and odors from drinking
water supplies. In wastewater treatment applications,
where phenol content is considerably greater than in
potable water applications and the flow is continuous,
granular carbon systems are more economical.
Depending on the concentration of phenol and other
organic compounds in the wastewater, activated carbon

will adsorb from 10 to 25 lb of phenol per 100 lb of car-
bon. This capacity can be determined from isotherm and
column test data. In general, phenol adsorption improves
as the pH decreases.
Adsorption at high pH is poor, since phenolate salt
forms and is difficult to adsorb. This is an advantage in
applications where phenol recovery is worthwhile. The
phenol is adsorbed at the low pH and reclaimed as sodium
salt by chemical regeneration, using hot caustic. If the phe-
nolate cannot be reused, regenerant disposal is a problem.
Also, if quantities of other organic substances are present
in the waste stream, they too will be adsorbed. These or-
ganic compounds may not be desorbed during caustic re-
generation, which will decrease the phenol capacity of the
carbon upon subsequent regeneration. If chemical regen-
eration does not sufficiently recover the phenol capacity
of the carbon, thermal reactivation will be required.
Figure 8.2.13 is a flow diagram of a granular carbon
system for phenol removal employing chemical regenera-
tion and phenol recovery. Pretreatment consists of acidifi-
cation to pH 4.2 to precipitate the suspended solids and
clarify the overflow. The phenol content of the feedstream
ranges from 400 to 2500 mg/l, and the effluent objective
is less than 1 mg/l phenol (Gould and Taylor 1969).
CHEMICAL OXIDATION
Air, chlorine, ozone, and other chemical oxidizing agents
are used to destroy phenol, which is first converted to hy-
droquinone and then to quinone. Additional oxidation de-
stroys the aromatic ring, forming organic acids and even-
tually carbon dioxide and water (Eisenhauer 1968).

Air is an inexpensive oxidizing agent but reactions are
slow. Phenol can be completely decomposed by chlorina-
©1999 CRC Press LLC
tion at pH 7.7, provided that the stoichiometric amount
of chlorine is added. This is accomplished in water treat-
ment plants by superchlorination. The major portion of
the chlorine applied consumes other organic compounds
and destroys ammonia. Approximately 42 parts of chlo-
rine per part of phenol are required (Ohio River Valley
Sanitation Commission 1951).
Ozonation effectively oxidizes phenol. However, the
initial cost of producing ozone is high. Ammonia does not
interfere in ozonation, and approximately 5.8 parts of
ozone are required per part of phenol (Ohio River Valley
Sanitation Commission 1951).
Starch
Starch wastes are produced by food processing operations,
including starch manufacturing from corn, potatoes, and
wheat. The wastes are essentially carbohydrates with a
high oxygen demand.
BIOLOGICAL TREATMENT
Starch wastes respond to biological treatment using trick-
ling filters, aerated lagoons, or activated sludge processes.
Waste pH should be adjusted to between 6.0 and 9.0, sus-
pended solids should be removed and, if necessary, nutri-
ents should be added to maintain a BOD-nitrogen-phos-
phorous ratio of 100 to 5 to 1.
Starch is almost completely oxidized biologically, pro-
vided that the loading is maintained within the limits of
the biological activity. If an activated sludge process is used,

it is important to maintain an F to M (BOD to mixed
liquor suspended solids) ratio of less than 0.3 (per day) to
minimize propagation of filamentous organisms that in-
terfere with solids separation.
Oxygen Requirements
In activated sludge operations it is necessary to supply oxy-
gen to sustain the process and to provide intimate mixing
and contact of activated sludge with the organic matter
and nutrients. (A low-speed turbine-type surface aerator is
shown in Figure 8.2.14.) Oxygen requirements depend on
BOD removal and on process loading. The oxygen re-
quirement is expressed by equation 8.2(1):
lb of oxygen required per lb BOD removed
ϭA ϩ
΂
B ϫ
΃
8.2(1)
In equation 8.2(1), “A” is related to the oxygen require-
ment for synthesis of new cells, and “B” is related to the
oxygen requirement for respiration. The value of “A”
ranges from 0.35 to 0.55, and “B” ranges from 0.05 to
lb mixed liquor volatile suspended solids
ᎏᎏᎏᎏᎏ
lb BOD applied per day
©1999 CRC Press LLC
FIG. 8.2.13Granular carbon systems for phenol removal
FIG. 8.2.14Low-speed surface aerator installation
©1999 CRC Press LLC
TABLE 8.2.8 COMPOSITION OF WASTES FROM A SYNTHETIC FIBER FINISH MILL

BOD
Total solids BOD avg. % OWF
b
pH range range, ppm ppm avg
a
Rayon processing
Scour and dye 8.2–9.0 1.012–5.572 2,832 5.7
Salt take-off 6.8–6.9 3.388–7.256 58 0.1
Waterproof — — 960 1.9
Acetate processing
Scour and dye 8.3–8.5 1.534–2.022 2,000 5.0
Scour and bleach 8.9–9.6 766–946 750 1.8
(Estimated) (Estimated)
First rinse 7.0–9.1 108–188 Peroxide
Second rinse 6.8–7.3 80–88 Contained 0.0
peroxide
Nylon processing
Scour 9.3–12.6 1.492–2.278 1,360 3.4
First rinse 8.2–10.7 150–954 90 0.2
Second rinse 6.5–8.2 106–932 25 0.1
Dye 7.8–9.0 , 318–1,016 368 0.9
Last rinse 7.3–7.6 106–134 11 0.0
Waterproof — — 450 1.1
Orlon processing
First scour 9.5–10.0 1.350–2.470 2,190 6.6
First rinse 6.4–8.7 102–294 109 0.4
First dye 2.2–6.5 , 170–1.950 175 0.5
Second rinse 4.1–6.5 116–300 42 0.1
Second dye 1.3–1.7 , 130–3.002 995 3.0
Second scour 5.9–7.7 , 612–1.824 688 2.0

Third rinse 6.3–7.4 82–152 50 0.2
Waterproof 3.7–4.3 , 896–2.318 2,110 6.3
Dacron processing
(Estimated from OWF concentations as listed)
Scour — — 650
Dyes
o-phenylphenol (10% OWF) — — 6,000 18.0
benzoic acid (40% OWF) — — 27,000 81.0
salicylic acid (40% OWF) — — 24,000 72.0
phenylmethylcarbinol (30%
OWF) — — 19,000 57.0
monochlorobenzene (40%
OWF) — — 480 1.4
From Masselli, Masselli, and Burford. A simplification of textile waste survey and treatment. New England Interstate Water Pollution Control Commission.
a
% on weight of fiber, a weight percentage based on dried cloth weight.
b
OWF, weight percentage based on dried cloth.
0.10. As a general rule, one lb of oxygen is required per
lb of BOD removed under conventional activated sludge
operations with an F to M ratio of 0.3 to 0.5. For aero-
bic digestion with an F to M ratio of 0.1, approximately
1.5 lb of oxygen are required per pound of BOD removed.
Sludge Production
In the activated sludge process, soluble organic matter is
converted to suspended solids in the form of bacterial cells.
The amount of sludge produced is a function of process
loading and of BOD removal. Sludge production can be
expressed within practical limits by equation 8.2(2):
ϭ A Ϫ

΂
B ϫ
΃
8.2(2)
lb mixed liquor volatile suspended solids
ᎏᎏᎏᎏᎏ
lb BOD applied per day
lb of volatile suspended solids produced
ᎏᎏᎏᎏᎏ
lb BOD removed
The value of “A” varies from 0.4 to 0.9, and the value of
“B” from 0.01 to 0.1, depending on the waste being
treated. An approximate expression for sludge production
in many treatment applications is given in equation 8.2(3):
ϭ0.75 Ϫ
΂
0.05 ϫ
΃
8.2(3)
Based on conventional activated sludge operations, be-
tween 0.5 and 0.6 lb of excess sludge are produced per lb
of BOD removed. With aerobic digestion, approximately
0.2 lb of excess sludge are produced per lb of BOD re-
moved.
Aerobically digestedsludge can be dewatered on vac-
uum filters with loadings of approximately 1 lb/sq ft/hr.
Dewatering excess sludge from conventional activated
sludge operations requires a heat treatment for sludge con-
ditioning or a heavy dosage of conditioning chemicals to
form a filter cake that will dewater and separate from a

filter cloth.
Textile Industry Wastes
Textile industry wastes are categorized by their source.
Man-made fibers constitute approximately 80% of the
lb mixed liquor volatile suspended solids
ᎏᎏᎏᎏᎏ
lb BOD applied per day
lb volatile suspended solids produced
ᎏᎏᎏᎏ
lb BOD removed
fibers used. Table 8.2.8 lists wastewater compositions from
synthetic fiber finish mills, and Table 8.2.9 reflects per-
formance data of the various treatment methods in re-
ducing BOD, SS, color, grease, and alkalinity.
In textile wastes the suspended solids concentration is
minute, the BOD range can attain 3000 ppm, and color
can sometimes reach as high as 3000 APHA color units.
Electroflocculation removes most color by electrolytically
inducing flotation and collection of foam. Thereafter, bi-
ological or chemical oxidation can be utilized to polish the
effluent and reduce the BOD to 25—virtually eliminating
color. Such textile mill effluent is of sufficient quality to
be recycled and reused.
Viruses and Bacteria
Bacteria and viruses are removed or killed by disinfection
and sterilization. Disinfection destroys all harmful mi-
croorganisms, while sterilization kills all living organisms.
Disinfection of drinking water protects public health by
preventing microorganism growth in the pipelines.
Disinfection of wastewater treatment effluents protects

marine life. Sterilization provides water suitable for med-
ical and pharmaceutical use. Numerous disinfection and
sterilization techniques are available, and Tables 8.2.10
and 8.2.11 compare the effectiveness, advantages, and dis-
advantages.
©1999 CRC Press LLC
TABLE 8.2.9TREATMENT PROCESS REMOVAL EFFICIENCIES
Normal reduction %
Treatment Suspended
method BOD Grease Color Alkalinity Solids
Grease recovery
Acid cracking 20–30 40–50 0 0 0–50
Centrifuge 20–30 24–45 0 0 40–50
Evaporation 95 95 0 0
Screening 0–10 0 0 0 20
Sedimentation 30–50 80–90 10–50 10–20 50–65
Flotation 30–50 95–98 10–20 10–20 50–65
Chemical coagulation
CaCl
2
40–70 — — — 80–95
Lime ϩCaCl
2
60 97 — — 80–95
CO
2
ϩCaCl
2
15–25 — — — 80–95
Alum 20–56 — 75

Copperas 20
H
2
SO
4
ϩalum 21–83
Urea ϩalum 32–65
H
2
SO
4
ϩFeCl
2
59–84
FeSO
4
50–80
Activated sludge 85–90 0–15 10–30 10–30 90–95
Trickling filtration 80–85 0–10 10–30 10–30 90–95
Lagoons 0–85 0–10 10–30 10–20 30–70
Reprinted, from FWPCA. 1967. The cost of clean water, vol. III. Industrial Waste Profile, No. 4. Textile Mill
Products.September.