Waste Treatment in the Process Industries - Chapter 11 pptx

Agricultural pesticide use in the United States averaged 1.2 billionpounds of ingredient in 1997, and was associated with expenditures exceeding $11.9 billion.This use involved over 20,7

to modern society can be summarized by a statement made by Norman E Borlaug, the 1970Nobel Peace Prize winner: “Let’s get our priorities in perspective We must feed ourselves andprotect ourselves against the health hazards of the world To do that, we must have agriculturalchemicals Without them, the world population will starve” [1].

However, the widespread use of pesticides has also caused significant environmentalpollution problems Examples of these include the biological concentration of persistentpesticides (e.g., DDT) in food chains and contamination of surface and groundwater used fordrinking sources Because they can affect living organisms, pesticides are highly regulated in theUnited States to ensure that their use will be safe for humans and the environment Recently, theNational Research Council’s Committee on the Future Role of Pesticides in U.S Agricultureconducted a comprehensive study and concluded that although they can cause environmentalproblems, chemical pesticides will continue to play a role in pest management for theforeseeable future In many situations, the benefits of pesticide use are high relative to risks orthere are no practical alternatives [2]

This chapter deals with the characterization, environmental regulations, and treatment anddisposal of liquid wastes generated from the pesticide industry

The pesticide industry is an important part of the economy Worldwide and U.S pesticide sales

in 1990 were expected to reach more than $20 billion and $6 billion, respectively (ChemicalWeek, January 3, 1990) Usually the highest usage of pesticides is in agriculture, accounting forabout 80% of production [3] Agricultural pesticide use in the United States averaged 1.2 billionpounds of ingredient in 1997, and was associated with expenditures exceeding $11.9 billion.This use involved over 20,700 products and more than 890 active ingredients [2] Household andgarden pesticide uses are other significant markets The United States constituted about 40% of

499

the world market for household pesticides, with annual sales exceeding $1 billion in 2002 [4].China is the second largest national market with over $580 million of household insecticidespurchased each year [5] The United States also dominates the world market for gardenpesticides with sales of over $1.5 billion per year The United Kingdom is a distant second withsales of $155 million [5].

Pesticides are classified according to the pests they control Table 1 lists the variouspesticides and other classes of chemical compounds not commonly considered pesticidesbut included among the pesticides as defined by U.S federal and state laws [1] The four mostwidely used types of pesticides are: (a) insecticides, (b) herbicides, (c) fungicides, and(d) rodenticides [6]

The major components of the pesticide industry include manufacturing and formulation/packaging [7] During manufacture, specific technical grade chemicals are made Formulating/packaging plants blend these chemicals with other active or inactive ingredients to achieve theendproducts’ desired effects, and then package the finished pesticides into marketablecontainers A brief overview of these sectors of the industry follows

Table 1 Pesticide Classes and Their Uses

Larvicide Kills larvae (usually mosquito)

Molluscicide Kills snails and slugs (may include oysters, clams, mussels)

Pediculicide Kills lice (head, body, crab)

Predicide Kills predators (coyotes, usually)

Chemicals classed as pesticides not bearing the -cide suffix:

Chemosterilant Sterilizes insects or pest vertebrates (birds, rodents)

Disinfectant Destroys or inactivates harmful microorganisms

Growth regulator Stimulates or retards growth of plants or insects

Pheromone Attracts insects or vertebrates

Repellent Repels insects, mites and ticks, or pest vertebrates

(dogs, rabbits, deer, birds)

Source: Ref 1

11.2.1 Pesticide Manufacturing

presents the geographical locations of these plants [7] Specific pesticide manufacturingoperations are usually unique and are characteristic only of a given facility

Almost all pesticides are organic compounds that contain active ingredients for specificapplications Based on 500 individual pesticides of commercial importance and perhaps as many

as 34,000 distinct major formulated products, pesticide products can be divided into six majorgroups [8]:

Plants that manufacture pesticides with active ingredients use diverse manufacturingprocesses, including synthesis, separation, recovery, purification, and product finishing such asdrying [9]

Chemical synthesis can include chlorination, alkylation, nitration, and many othersubstitution reactions Separation processes include filtration, decantation, extraction, andcentrifugation Recovery and purification are used to reclaim solvents or excess reactants as well

as to purify intermediates and final products Evaporation and distillation are common recoveryand purification processes Product finishing may involve blending, dilution, pelletizing,packaging, and canning Examples of production facilities for three groups of pesticides follow

Halogenated Aliphatic Acids

Figure 2 shows a simplified process flow diagram for halogenated aliphatic acid productionfacilities [8] Halogenated aliphatic acids include chlorinated aliphatic acids and their salts, forexample, TCA, Dalapon, and Fenac herbicides Chlorinated aliphatic acids can be prepared bynitric acid oxidation of chloral (TCA) or by direct chlorination of the acid The acids can be sold

as mono- or dichloro acids, or neutralized to an aqueous solution with caustic soda Theneutralized solution is generally fed to a dryer from which the powdered product is packaged

As shown on Figure 2, wastewaters potentially produced during the manufacture ofhalogenated aliphatic acids include the following:

Nitro Compounds

This family of organonitrogen pesticides includes the nitrophenols and their salts, for example,

commercial process for the production of a dinitroaniline herbicide [8] In this example, achloroaromatic is charged to a nitrator with cyclic acid and fuming nitric acid The crude product

is then cooled to settle out spent acid, which can be recovered and recycled Oxides of nitrogen

Figure 1 Geographical distribution of major pesticide manufacturers in the United States Most of the plants are located in the eastern half of the continent(from Ref 7).

Figure 2 General process flow diagram for halogerated aliphatic acid production facilities Major processes for pesticide production,including chlorination, cooling, crystallization, centrifying, and drying The salt of the pesticide is produced by another route (from Ref 8).

Figure 3 General process flow diagram for nitro-type pesticides Major processes for pesticide production are mononitration, dinitration, filtration, amination, filtering,

are vented and caustic scrubbed The mononitrated product is then charged continuously toanother nitrator containing 100% sulfuric acid and fuming nitric acid at an elevated temperature.The dinitro product is then cooled and filtered (the spent acid liquor is recoverable), thecake is washed with water, and the resulting washwater is sent to the wastewater treatment plant.The dinitro compound is then dissolved in an appropriate solvent and added to the aminationreactor with water and soda ash An amine is then reacted with the dinitro compound The crudeproduct is passed through a filter press and decanter and finally vacuum distilled The saltwaterlayer from the decanter is discharged for treatment The solvent fraction can be recycled to thereactor, and vacuum exhausts are caustic scrubbed Still bottoms are generally incinerated.Wastewaters potentially generated during the manufacture of the nitro family of pesticidesinclude the following:

Metallo-Organic Pesticides

Metallo-organic active ingredients mean organic active ingredients containing one or more

a general process flow diagram for arsenic-type metallo-organic pesticide production [8].Monosodium acid methanearsenate (MSMA) is the most widely produced organoarsenicherbicide in this group

The first step of the process is performed in a separate, dedicated building The drums ofarsenic trioxide are opened in an air-evacuated chamber and automatically dumped into 50%caustic soda A dust collection system is used The drums are carefully washed with water, thewashwater is added to the reaction mixture, and the drums are crushed and sold as scrap metal.The intermediate sodium arsenite is obtained as a 25% solution and is stored in large tanks prior

to further reaction In the next step, the 25% sodium arsenite is treated with methyl chloride toproduce the disodium salt DSMA (disodium methanearsenate, hexahydrate) This DSMA can besold as a herbicide; however, it is more generally converted to MSMA, which has morefavorable application properties [8]

To obtain MSMA, the DSMA solution is partially acidified with sulfuric acid and theresulting solution concentrated by evaporation As the aqueous solution is being concentrated, amixture of sodium sulfate and sodium chloride precipitates out (about 0.5 kg per 100 kg of activeingredient) These salts are a troublesome disposal problem because they are contaminated witharsenic The salts are removed by centrifugation, washed in a multistage, countercurrent washingcycle, and then disposed of in an approved landfill

Methanol, a side product of methyl chloride hydrolysis, can be recovered and reused Inaddition, recovered water is recycled The products are formulated on site as solutions and areshipped in 1 to 30 gallon containers

Wastewaters that can be generated from the production of these pesticides include thefollowing:

Figure 4 General process flow diagram for arsenic-type metallo-organic production Sodium arsenate is formed in the first reactor, disodiummethanearsenate (DSMA) in the second reactor; DSMA is purified as a product or further changed to monosodium methanearsenate (MSMA) byacidification and purified (from Ref 8) Wong

In the United States, there are more than a thousand pesticide formulating/packagingplants covering a broad range of formulations [7] Many small firms have only one productregistration, and produce only a few hundred pounds of formulated pesticides each year.However, USEPA [7] identified one plant operating in the range of 100 million pounds offormulated product per year The approximate production distribution of formulators/packagers

is presented in Table 2 [7]

The most important unit operations involved in formulation are dry mixing and grinding ofsolids, dissolving solids, and blending [8] Formulation systems are virtually all batch-mixingoperations The units may be completely enclosed within a building or may be in the open,depending primarily on the geographical location of the plant Production units representative ofthe liquid and solid formulation/packaging equipment in use as well as wastewater generationare described in the following

Liquid Formulation Units

pesticide is usually stored in its original shipping container in the warehouse section of the plant.When this material is received in bulk, however, it is transferred to holding tanks for storage.Batch-mixing tanks are frequently open-top vessels with a standard agitator and may ormay not be equipped with a heating/cooling system When solid technical grade material isused, a melt tank is used before this solid material is added to the mix tank Solvents are normallystored in bulk tanks and are either metered into the mix tank or are determined by measuring thetank level Necessary blending agents (emulsifiers, synergists, etc.) are added directly From themix tank, the formulated material is frequently pumped to a holding tank before being put intocontainers for shipment Before packaging, many liquid formulations must be filtered byconventional cartridge filters or equivalent polishing filters

Air pollution control equipment used on liquid formulation units typically involvesexhaust systems at all potential sources of emission Storage and holding tanks, mix tanks, and

Table 2 Formulator/Packager Production

Figure 5 Liquid formulation unit Technical grade pesticide products are blended with solvents and emulsifiers or

other agents in a mix tank Formulated products are filtered before packaging (from Ref 8)

container-filling lines are normally provided with an exhaust connection or hood to remove anyvapors The exhaust from the system normally discharges to a scrubber system or to theatmosphere.

Dry Formulation Units

Dry products can include dusts, powders, and granules Dusts and powders are manufactured bymixing technical grade material with the appropriate inert carrier and grinding the mixture toobtain the correct particle size Several rotary or ribbon blender-type mixers mix the product

Figure 6shows a typical dry formulation unit for pesticides [8]

Baghouse systems efficiently control particulate emissions from grinding and blendingprocesses Vents from feed hoppers, crushers, pulverizers, blenders, mills, and cyclones aretypically routed to baghouses for product recovery This method is preferable to using wetscrubbers However, even scrubber effluent can be largely eliminated by recirculation.Granules are formulated in systems similar to the mixing sections of dust plants Theactive ingredient is adsorbed onto a sized, granular carrier such as clay or a botanical material.This is accomplished in various capacity mixers that generally resemble cement mixers If thetechnical grade material is a liquid, it can be sprayed directly onto the granules Solid material isusually melted or dissolved in a solvent to provide adequate dispersion on the granules.Screening to remove fines is the last step prior to intermediate storage before packaging

Packaging and Storage

Packaging the finished pesticide into a marketable container is the last operation conducted at aformulation plant This operation is usually carried out in conventional filling and packagingunits By moving from one unit to another, the same liquid filling line is frequently used to fillproducts from several formulation units Packages of almost every size and type are used,including 1, 2, and 5 gallon cans, 30 and 55 gallon drums, glass bottles, bags, cartons, and plasticjugs

Aerosol products (for home use) undergo leak testing in a heated water bath to complywith U.S Department of Transportation regulations This water bath also serves as a qualitycontrol checkpoint for leaks Bath water must be kept clean for inspection

Generally, onsite storage is minimized The storage facility is often a building completelyseparate from the formulation and filling operation or is at least located in the same buildingbut separate from the formulation units to avoid contamination and other problems Technicalgrade material, except for bulk shipments, is usually stored in a special section of the productstorage area

The major source of contaminated wastewater from formulation plants is equipmentcleanup Formulation lines, including filling equipment, must be cleaned periodically to preventcross-contamination of product Sometimes equipment is washed with formula solvent andrinsed with water Hence, this waste may contain pesticide ingredients as well as solvents.

Figure 6 Dry formulation unit Technical grade products are ground and mixed with appropriate inertmaterials; the premixed material is further blended with more inert materials and wetting agents in severalsteps to obtain the correct particle size (from Ref 8)

For housekeeping purposes, most formulators clean buildings that house formulation units

on a routine basis Prior to washdown, as much dust, dirt, and so on as possible is swept andvacuumed The washdown wastewater, which generally contains pesticide ingredients, isnormally contained within the building and is disposed of in whatever manner is used for othercontaminated wastewater

A few formulation plants process used pesticide drums so they can be sold to a drumreconditioner or reused by the formulator for appropriate products, or simply to decontaminatethe drums before they are disposed of Drum-washing procedures range from a single rinse with

a small volume of caustic solution or water to complete decontamination and reconditioningprocesses Hence, drum-washing wastewater usually contains caustic solution as well as washedpesticide ingredients in the drums

Water-scrubbing devices are often used to control emission to the air Most of thesedevices generate wastewater streams that are potentially contaminated with pesticideingredients Although the quantity of water in the system is high – about 20 gallons per

1000 cfm – water consumption is kept low by a recycle – sludge removal system

Natural runoff at formulating/packaging plants, if not properly handled, can become amajor factor in the operation of wastewater systems simply because of the relatively high flowand because normal plant wastewater volumes are generally extremely low Isolation of runofffrom contaminated process areas or wastewaters, however, eliminates its potential for becomingsignificantly contaminated with pesticide ingredients Hence, the content of area runoff depends

on the degree of weather protection and area isolation Modern stormwater pollution preventionregulations in the United States have virtually eliminated this pollution source

Most of the larger formulation plants have some type of control laboratory on site.Wastewater from the control laboratories relative to the production operations can range from

an insignificantly small, slightly contaminated stream to a rather concentrated source ofcontamination In many cases, this stream can be discharged into the sanitary sewer Larger,more highly contaminated streams, however, must be treated along with other contaminatedwastewaters

Wastewater Flows

Based on survey results from individual plants, USEPA determined the amount of flow per unit

of pesticide production (gal/1000 lb) and the amount of flow (million gallons per day, or MGD)

at these plants

Figure 7 presents a probability plot of the flow ratio (gal/1000 lb) for 269 of the 327pesticide process areas for which data were available [7] Significant information in thisfigure shows that 11% of all pesticide processes have no flow, 50% of all pesticide processeshave flows equal to or less than 1000 gal/1000 lb, and 84% have flows equal to or less than

4500 gal/1000 lb

Figure 8presents a probability plot of pesticide wastewater flows (MGD) at individualplants [7] This figure shows that 50% of all plants have flows less than 0.01 MGD, and thatvirtually all plants (98%) have flows less than 1.0 MGD

Wastewater Constituents

Because of the nature of pesticides and their components, wastewaters generated frommanufacturing plants usually contain toxic (e.g., toxic priority pollutants as defined by USEPA)and conventional pollutants Based on the results of the surveys and process evaluations, USEPAdetermined the pollutants or groups of pollutants likely to be present in raw wastewater fromthese facilities The agency also selected raw waste loads for these pollutants in order to designtreatment and control technologies The approach taken was to design for the removal of

presents the summary of these raw waste load design levels [7]

The pollutants or groups of pollutants likely to be present in raw wastewater includevolatile aromatics, halomethanes, cyanides, haloethers, phenols, polynuclear aromatics, heavy

Figure 7 Probability plot of pesticide product flow ratios Of pesticide production processes, 11% have

no flow, 50% have flows less than 1000 gal/1000 lb; 84% have flows less than 4500 gal/1000 lb (fromRef 7)

metals, chlorinated ethanes and ethylenes, nitrosamines, phthalates, dichloropropane anddichloropropene, pesticides, dienes, TCDD, and other common constituents such as BOD, COD,and TSS The sources and significance of these pollutants are briefly discussed [7].

Volatile Aromatics

Benzene and its derivatives are used widely throughout the chemical industry as solvents andraw materials Mono-, di-, and trichlorobenzenes are used directly as pesticides for theirinsecticidal and fungicidal properties Benzene, toluene, and chlorobenzene are used as rawmaterials in the synthesis of at least 15 pesticides, although their main use is as a carrier solvent

in 76 processes Additional priority pollutant aromatics and chlorinated aromatics exist asimpurities or as reaction byproducts because of the reactions of the basic raw materials andsolvent compounds

Halomethanes

Halomethanes, including methylene chloride, chloroform, and carbon tetrachloride (di-, tri-, andtetrachloromethane, respectively), are used mainly as raw materials and solvents inapproximately 28 pesticide processes Bromomethanes can be expected in at least fivepesticides as raw materials, byproducts, or impurities and in the case of methyl bromide, canfunction as a fumigant

Figure 8 Probability plot of pesticide product wastewater flows Of pesticide manufacturing plants, 50%have flows less than 0.01 MGD; 98% have flows less than 1.0 MGD (from Ref 7)

Cyanide is a known or suspected pollutant in approximately 24 pesticide processes The primaryraw materials that favor the generation of cyanides as either byproducts or impurities arecyanamides, cyanates, thiocyanates, and cyanuric chloride Cyanuric chloride is usedexclusively in the manufacture of triazine pesticides

Haloethers

Five compounds classified as priority pollutants contain an ether moiety and halogen atomsattached to the aryl and alkyl groups Five pesticides are suspected to contain at least onecompound from this class Bis(2-chloroethyl) ether (BCEE) is used as a raw material in twopesticides; BCEE itself functions as a fungicide or bactericide in certain applications In theother three pesticides, the ethers are suspected to be present as raw material impurities

Detected pesticidewastewaters atdesign levela(%)

methylphenols (cresols) These compounds may be found throughout the pesticide industry asraw materials, impurities in raw materials, or as byproducts of reactions using relatedcompounds such as chlorobenzenes The presence of nitrated phenols is expected in sixpesticides Methylated phenols are not expected to be significant because they are not used asraw materials, but they may appear as impurities of reaction from one pesticide because of using4-methylthio-m-cresol as a raw material.

Polynuclear Aromatics

Seventeen priority pollutant compounds can be classified as polynuclear aromatics (PNA).These compounds consist of two or more benzene rings that share a pair of carbon atoms.They are all derived from coal tar, with naphthalene being the largest constituent Naphthalenederivatives such as alpha-naphthylamine and alpha-naphthol are used in some pesticide pro-cesses; therefore, naphthalene is by far the most prevalent PNA priority pollutant in the industry.Acenaphthene, anthracene, fluorene, fluoranthene, and phenathrene are found as raw materialimpurities Acenaphthene is found in one pesticide process as a raw material The remaining tenPNAs are not suspected to be present in pesticide processes

Heavy Metals

In the pesticide industry, metals are used principally as catalysts or as raw materials that areincorporated into the active ingredients, for example, metallo-organic pesticides Prioritypollutant metals commonly incorporated into metallo-organic pesticides include arsenic,cadmium, copper, and mercury For metals not incorporated into the active ingredients, copper isfound or suspected in wastewaters from at least eight pesticides, where it is used as a rawmaterial or catalyst; zinc becomes part of the technical grade pesticide in seven processes; andmercury is used as a catalyst in one pesticide process Nonpriority pollutant metals such asmanganese and tin are also used in pesticide processes

Chlorinated Ethanes and Ethylenes

The chlorinated ethanes and ethylenes are used as solvents, cleaning agents, and intermediates.Vinyl chloride (chloroethylene) is used in the production of plastic polyvinyl chloride (PVC)

In the pesticide industry, approximately 23 products are suspected to contain a member of thisgroup of priority pollutants The main pollutants include 1,2-dichloroethane, which is used as asolvent in seven pesticides and tetrachloroethylene, which is used as a solvent in two pesticides

Nitrosamines

the nitrogen of an aromatic or aliphatic secondary amine N-nitrosodi-N-propylamine is asuspected reaction byproduct from the nitrosation of di-N-propylamine Two pesticides aresuspected to contain some form of nitrosamines

Phthalates

Phthalate esters are used widely as plasticizers in commercial polymers and plastic endproductssuch as PVC One phthalate classified as a priority pollutant is suspected to be present in threepesticide processes Dimethyl phthalate is known to be a raw material in two products

Dichloropropane and Dichloropropene

1,3-Dichloropropene is a raw material in one pesticide 1,3-Dichloropropene and the combinedpollutants 1,2-dichloropropane-1, 3-dichloropropene are pesticide products as well as prioritypollutants and function as insecticidal fumigants

Priority Pollutant Pesticides

There are only 18 priority pollutants commonly classified as pesticides Only two are still inproduction: heptachlor and chlordane Aldrin, dieldrin, and endrin aldehyde are suspected asreaction byproducts in the endrin process Heptachlor epoxide occurs as a reaction byproduct inboth chlordane and heptachlor manufacturing DDD, DDE, and DDT can occur as a reactionbyproduct in the manufacture of endosulfan

Dienes

Four manufactured pesticides and two pesticides currently not manufactured use a prioritypollutant diene as a raw material The basic material for all six pesticides is hexa-chlorocyclopentadiene (HCCPD) The priority pollutant hexachlorobutadiene is suspected to bepresent in the pesticide wastewater because it is a byproduct of HCCPD synthesis and is used as

a solvent in manufacturing mirex

TCDD

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is believed to be a byproduct in chemicalprocessing generated by a halophenol or chlorobenzene starting material An intermediatereaction will occur at an elevated temperature (equal to or greater than 1608C), an alkalinecondition, or in the presence of a free halogen The end reaction results in either direct dioxin,intermediate dioxin, or predioxin formation that will ultimately form dibenzo-p-dioxins [10].TCDD is suspected in wastewaters from pesticide manufacture that uses such raw materials as2,4,5-trichlorophenol (2,4,5-T) and 1,2,4,5-tetra-chlorobenzene, which are characteristic ofTCDD precursors A TCDD level as high as 111 mg/L has been found in drums of waste fromthe production of the pesticide 2,4,5-T

Other Pollutants

The pesticide industry routinely monitors conventional and nonconventional pollutants inmanufacturing wastewaters According to the USEPA surveys [7], chemical oxygen demand(COD) concentrations ranged from 14.0 mg/L to 1,220,000 mg/L; Total organic carbon (TOC)ranged from 53.2 mg/L to 79,800 mg/L; biochemical oxygen demand (BOD) ranged fromnondetected to 60,000 mg/L; and total suspended solids (TSS) ranged from 2.0 mg/L to

4090 mg/L Many other pollutants can be present in pesticide wastewaters that are not unique tothis industry, including pollutants such as ammonia, oil and grease, fluoride, and inorganic salts.Nonpriority pollutant pesticides would naturally occur in their manufacturing wastewaters due

to imperfect separations

Washing and cleaning operations provide the principal sources of wastewater in formulating andpackaging operations Because these primary sources are associated with cleanup of spills, leaks,

area washdowns, and stormwater runoff, there is apparently no basis from which to correlate thepollutants generated to the product made.

According to USEPA’s survey [8] of 71 pesticide formulating/packaging plants, 59reported no generation of wastewater For the plants that generated wastewater, neither the rate

of production nor the type of product formulated had a direct bearing on the quality or quantity

of wastewater generated The three largest plants of a major pesticide formulator each generatedless than 5800 gal/day Other plants generated from 5 to 1000 gal/day The average flowsgenerated in formulating/packaging plants were between 50 and 1000 gal/day [11]

The pollutants contained in the wastewaters are expected to be similar to those frommanufacturing facilities Pesticides and solvents are the principal pollutants of concern.Although their volumes are small, the wastewaters from pesticide formulating/packaging plantscould be highly contaminated and toxic

Many federal and state regulations govern the registration, manufacture, transportation, sale,use, and disposal of pesticides in the United States Pesticides are regulated by the USEPAprimarily under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and theFederal Food, Drug, and Cosmetic Act (FDCA) The FIFRA requires pesticides to be registered

by USEPA and authorizes the agency to prescribe conditions for their use The FDCA requiresthe agency to establish maximum acceptable levels of pesticide residues in foods Thetransportation of hazardous pesticides is regulated by the Hazardous Materials TransportationAct (HMTA) In addition, certain states such as California and Florida aggressively enforce theirown pesticide laws

The disposal of pesticides and pesticide wastes is regulated by the Clean Air Act (CAA),the Clean Water Act (CWA), the Resource Conservation and Recovery Act (RCRA), and theComprehensive Environmental Response, Compensation, and Liability Act (CERCLA) Thissection deals with the regulations for liquid waste disposal, which is mainly under the CWA.However, when the waste is disposed of as a hazardous waste, it is regulated by the RCRA

The U.S Congress enacted the Federal Water Pollution Control Act (FWPCA) in 1972 The actwas significantly amended in 1977 and has since become known as the CWA It was againamended by the Water Quality Act of 1987 The CWA applies to all industries that generatewastewater discharges Some of its provisions are particularly applicable to the pesticideindustry

Effluent Guidelines for Pesticides

Under Section 304 of the CWA, USEPA was required to establish “effluent guidelines” for anumber of different industrial categories by specifying the effluent limits that must be met

by dischargers in each category Two types of standards were required for each industry:(a) effluent limitations that require the application of the best practicable control technology(BPT) currently available, and (b) effluent limitations that require application of the bestavailable technology (BAT)

Effluent limitations reflecting BPT currently available for the pesticide manufacturing andformulating industrial category were promulgated by USEPA on April 25, 1978 (43 Federal

Regulation 17,785, 1978) The pesticide industry was divided into three subcategories under theBPT regulations: (a) organic pesticide chemicals manufacturing, (b) metallo-organic pesticidechemical manufacturing, and (c) pesticide chemicals formulating and packaging.

For the first subcategory, the rules limit the number of pounds or kilograms of COD, BOD,TSS, and pesticide chemicals that a plant may discharge during any 1 day or any 30 consecutivedays Table 4 presents the BPT effluent limitations for the organic pesticide chemicalsmanufacturing subcategory (40 CFR pt 455) For the second and third subcategories, theregulations permit “no discharges of process wastewater pollutants into navigable waters.” TheBPT regulations are based on pesticide removal by hydrolysis or adsorption followed bybiological treatment [3]

The USEPA issued BAT regulations for the pesticide industry in October 1985 (50 FederalRegulation 40701, 1985) However, four chemical companies and three chemical tradeorganizations challenged these regulations in Chemical Specialties Manufacturers Association

vs EPA, No 86-8024 (11th Cir July 25, 1986), modified (11th Cir August 29, 1986) As aresult, the agency voluntarily withdrew its regulations and, on remand by the Eleventh Circuit,agreed to initiate a new round of rule making on the pesticide industry standards (51 FederalRegulation 44,911, 1986) The new regulations were later proposed by USEPA in 1992 [12] andfinalized in 1996 (61 FR 57551, No 6, 1996) All of the updated effluent guidelines andstandards for the pesticide manufacturing and formulation industries are included in 40 CFR Part

455 – Pesticide Chemicals

Pretreatment Standards for Pesticides

Section 306(b) of the CWA requires USEPA to promulgate pretreatment standardsapplicable to the introduction of wastes from industry and other nondomestic sources intopublicly owned treatment works (POTWs) USEPA issued the General Pretreatment Regulations

on June 26, 1978, and amended these regulations several times in the following years (40 CFR

Average of daily valuesfor 30 consecutive daysshall not exceed

BPT, best practicable control technology currently available.

Note: For COD, BOD 5 , and TSS, metric units: Kilogram/1,000 kg of total organic active ingredients.

English units: Pound/1,000 lb of total organic active ingredients For organic pesticide – metric units:

Kilogram/1,000 kg of organic pesticide chemicals English units: Pound/1,000 lb of organic pesticide

chemicals.

Register 50690) The main concern for this subcategory is the discharge of priority pollutants

maximum monthly discharge limitations With the exception of cyanide and lead, all the prioritypollutants are organic compounds Presently there are no pretreatment standards for the metallo-organic pesticide chemicals manufacturing subcategory The pretreatment standard for thepesticide chemicals formulating and packaging subcategory is no discharge of processwastewater pollutants to POTWs (40 CFR Part 455.46)

The general pretreatment regulations prohibit an industry or nondomestic source fromintroducing pollutants that will pass through or interfere with the operation or performance ofPOTWs [40 CFR Section 403.5(a)] In addition, the CWA requires USEPA to establish

“categorical” pretreatment standards, which apply to existing or new industrial users in specificcategories (40 CFR Section 403.6) The discharge of wastewater from the pesticide industry toPOTWs will also be subject to the general discharge prohibitions against “pass through” and

“interference” with the POTWs These pretreatment requirements are usually enforced byPOTWs, with approved pretreatment programs As an example, Table 5 shows the general

Table 5 Industrial Waste Pretreatment Limits for a Publicly Owned

Treatment Works

Toxic substance

Maximum allowableconcentration (mg/L)

Chlorinated hydrocarbons including, but not

limited to, pesticides, herbicides, algaecides

industrial effluent limits established by the City of San Jose, CA (San Jose Municipal Code,1988).

Toxic Pollutant Effluent Standards

Section 307 of the CWA requires USEPA to maintain and publish a list of toxic (priority)pollutants, to establish effluent limitations for the BAT economically achievable for control ofsuch pollutants, and to designate the category or categories of sources to which the effluentstandards shall apply [3] Effluent standards have been promulgated for the following toxicpollutants: aldrin/dieldrin; DDT, DDD, and DDE; endrin; toxaphene; benzidine; and PCBs (40CFR 129.4) These standards, which may be incorporated into National Pollutant DischargeElimination System (NPDES) permits, limit or prohibit the discharge of process wastes or otherdischarge from manufacturing processes into navigable waters For example, any discharge ofaldrin or dieldrin is prohibited for all manufacturers (40 CFR 129.100(b)(3))

Water Quality-Based Limitations

In the United States, as control of conventional pollutants has been significantly achieved,increased emphasis is being placed on reduction of toxic pollutants The USEPA has developed awater quality-based approach to achieve water quality where treatment control-based dischargelimits have proved to be insufficient [13]

The procedures for establishing effluent limitations for point sources discharging to awater quality-based segment generally involves the use of some type of mathematical model orallocation procedure to apportion the allowable loading of a particular toxicant to each discharge

in the segment These allocations are generally made by the state regulatory agency andreviewed, revised, and approved by the USEPA in accordance with Section 303 of the CWA

To control the discharge of toxic pollutants in accordance with Section 304(1) of theCWA, state and regional regulatory agencies may also establish general effluent limitations for aparticular water body For example, Table 6 shows the discharge limits for toxic pollutants

Table 6 Effluent Limitations for Selected Toxic Pollutants

for Discharge to Surface Waters (All Values in mg/L)

Daily averageShallow water Deep water