RANDALL K. DRAZBA, P.E.

Transcription

1 TOXCTY REDUCTON EVALUATON BY RANDALL K. DRAZBA, P.E. of Floyd Browne Associates, nc. Marion, Ohio Presented at ndiana Water Pollution Control Association ndianapolis, ndiana August 7, 1990

2 NTRODUCTON BACKGROUND Under the regulatory emphasis of the Clean Water Act (CWA), water pollution control activities in the United States focused on the conventional pollutants of biochemical oxygen demand (BOD), oil and grease, total suspended solids (TSS), ph, and others. Efforts to control toxic pollutants increased as a result of a 1976 consent decree between the Natural Resources Defense Council and the United States Environmental Protection Agency (USEPA). The consent decree and subsequent adoption of the 1977 Federal Clean Water Act Amendment produced a shift toward the control of toxic pollutants as well as conventional pollutants in order to produce an effluent that is not detrimental to aquatic life and/or human health. TOXCTY REDUCTON EVALUATON DEFNTON OF TRE A basic toxicity reduction evaluation (TRE) is an investigation of the effect of toxicity resulting from a complex mixture of multiple toxics to protect the ecosystem. The TRE is also referred to as toxicity identification and reduction evaluation. The TRE is a detailed procedure which combines toxicity testing and specific chemical analyses to determine what agents are causing effluent toxicity and which treatment methods will reduce effluent toxicity. A TRE is generally mandated by the regulatory agency when an entity fails to comply with the biomonitoring limits in their NPDES Permit. The procedure for conducting an industrial TRE is somewhat different from a municipal TRE. n this overview of a TRE we will confine our discussion to the municipal TRE.

3 DEFNTON OF TOXCTY A toxin is defined as a poison. A toxic substance is a substance that can cause an adverse health effect on living organisms. The severity of the effect depends on several variables including: (1) route of exposure, (2) time or length of exposure, (3) strength or concentration of the toxin, (4) ambient exposure conditions (temperatures, humidity, and ventilation), and (5) condition of the exposed organism (age, physical condition, etc.). For example, many compounds such as zinc, copper, potassium, selenium, and manganese are relatively harmless in our daily life, and in fact, are essential for good health and if included in small quantities in a balanced diet. However these substances can be highly toxic at high concentrations. Toxicity as it applies more specifically to biomonitoring and TRE's will be discussed later. As stated previously, water quality-based permits and the TRE use sensitive bioassays or biomonitoring (referred to as toxicity tests) to define the degree of toxicity of a wastewater discharge. Biomonitoring is the application of biological techniques to determine the ability of an organism to live when exposed to an effluent, effects on reproduction capabilities, suppressed growth, and the presence of tumors, mutations, loss of mobility, etc. WATER QUALTY - BASED PERMT LMTATONS The national "Policy for the Development of Water Quality-Based Permit Limitations for Toxic Pollutants" was published in early 1984, and is implemented by a Technical Support Document which was issued in This policy uses sensitive bioassays (biomonitoring) to indicate toxicity of wastewater effluents to the ecosystem. This approach also employs increasingly sensitive chemical analysis to detect the discharge of specific

4 toxic PO lutants in wastewater. The water qual ty-based toxics control process is defined in a diagram on Plate 1. An inspection of this diagram reveals that the water quality-based approach to establish permit requirements generally includes the following procedure: 1. Define water quality goals. 2. Prioritize streams or other bodies of water for achieving these goals. 3. Generate data through stream studies. a. Specific chemical analyses. b. Biomonitoring. 4. Determine limiting parameters (i.e. critical flow, fate modeling and mixing), and calculate wasteload allocation. 5. Define wastewater discharge characteristics. 6. Develop permit limitations. a. Evaluate toxicity reduction. b. Final permit with monitoring requirements. As NPDES Permits are being renewed or updated, the regulatory agencies are adding biomonitoring limitations to wastewater discharges. The State of ndiana is currently issuing biomoni toring limits only to "major" wastewater discharges. Entities generally classified as "major" discharges include POTW's with flow rates in excess of 1 mgd or certain industrial wastewater discharges which are classified as "major" as a result of an evaluated formula which includes wastewater flow, stream flow, type of manufacturing process, and etc.

5 OVERVEW OF THE WATER QUALTY-BASED TOXCS CONTROL PROCESS FLOYD BROWNE ASSOCATES, NC, CUNSULTNG ENGNEER MARUN, UHU PLATE 1 Define water quality goals Set permlt limits directly Prioritize streams, lakes & other bodies of water Generate data Screen for individual chemicals Collect definitive data for specific chemlcais Evaluate exposure and calculate wasteload allocation luent f,ef Screen for effluent toxicity Collect definitive data for toxicity Define required discharge characteristics Derive permit requirements Evaluate Toxicity Reduction Final permit with monitoring requirements

6 r., TRE PROCEDURE A flow diagram which defines the procedure for conducting a TRE for a municipal POTW is shown on Plate 2. The first step is the gathering of information and acquisition of analytical data pertaining to effluent toxicity. This information and/or data may include the following: 1. Operation and performance of the POTW a. Plant design data. b. Discharge monitoring reports. 2. Data from POW'S pretreatment program a. ndustrial waste survey application. b. Local limits compliance reports. POTW PERFORMANCE EVALUATON PURPOSE AND OBJECTVE After acquiring information and data on the POW, a POW performance evaluation is completed to determine if operational deficiencies may be allowing partially or untreated wastewater to pass-through the POW. This phase of the TRE is shown on Plate 3. ncomplete removal of conventional pollutants may be a source of part or all of effluent toxicity and it is the objective of this phase of study to determine if plant operation improvements or treatment process modifications could eliminate effluent toxicity. n this evaluation the POW'S major unit processes are reviewed using wastewater characterization data and process operating data to assure that conventional pollutant treatment deficiencies are not a source of toxicity. PHASE TE An optional Phase Toxicity dentification Evaluation (TE) could be completed at this time to verify the results of the performance evaluation in relation to the types of compounds causing effluent toxicity. For example,

7 POTW Performance Eva1 uat ion nformation and Data Acquisition v TE No Yes Yes * Conventional Pollutant Treatability Tests 1 No No 1 Yes TS E-Ti er 1 Y W e s 1 Toxicity Control Selection 4 * Toxicity Control m lementation and Fol P ow-up Monitoring TRE FLOW DAGRAM FOR POTW FLUYD BROWNE ASSOCATES, NC, CONSULT1 NG ENGNEER MARON, OHO PLATE 2

8 POTW PLANT PERFORMANCE EVALUATON FLOYD BRUVNE ASSOCATES, NC, CONSULTNG ENGNEER MAiZUN, UHD PLATE 3 nformation and Data Acquisition - J + TE Phase Toxicity Characterization Data Base on POW Operation and Performance. Backg rou nd-historical nformation. Discharge Permits. Process Control Data. Biological Treatment nhibition. Chlorination Problems. Treatment Bypasses. Process Sidestream Discharges. Sludge Toxicity. Toxicity or Toxics Pass-Through No Yes No Toxicity Control Selection

9 the POW performance evaluation would determine if incomplete treatment such as excess ammonia or routine operations such as over-chlorination are causing effluent toxicity. TE Phase testing includes the following characterization steps: 1. Filtration to determine if excess suspended solids is a source of toxicity. 2. Adjustment of ph to shift the equilibrium concentration of ammonia between its toxic form (NH3) and its relatively nontoxic form (NH4). 3. Reduction of oxidants by adding a reducing agent such as sodium thiosulfate determines if wastewater oxidants such as total residual chlorination are causing toxicity. TREATABLTY STUDES The results of the operation and performance review and the Phase TE tests may conclude that improvements in conventional pollutant removal would eliminate effluent toxicity. Using data from these previous studies a treatability study would be performed. These treatability studies could range from a simple laboratory study of the effect of removal of total chlorine residual on toxicity reduction to a pilot scale test of a biological treatment process. Specific chemical analyses and toxicity tests would be monitored throughout the treatability study to demonstrate the success for toxicity reduction. Results of the treatability study would be used to modify existing POTW processes or to design new process additions to the POW. TOXCTY DENTFCATON EVALUATON DEFNTON OF TE f there are no apparent operational problems, then the TRE may proceed to TE testing after the presence of toxicity has been established. The

10 purpose of the TE is to identify the compound(s) causing effluent toxicity by relating the physical/chemical characteristics of the wastewater to the toxicological characteristics. This is accomplished in three TE phases: 1. Phase - Characterize the toxic wastewater components. 2. Phase 1 - dentify the toxicants of concern. 3. Phase Confirm the suspected toxicants. The TE procedure is shown on Plate 4. The toxicological characteristics are generally determined using acute toxicity tests to indicate the presence of toxicity as the wastewater is physically and/or chemically fractionated. Phase TE tests are conducted using minimal quality assurance (no duplications, etc.) in an effort to collect as much data as quickly and as inexpensively as possible. ACUTE AND CHRONC TOXCTY Acute toxicity is defined by USEPA as a stimulus severe enough to rapidly induce a response: in toxicity tests, a response observed within 96 hours (generally 48 hours) is typically considered acute. refers to a "short" test period rather mortality rate. Therefore, acute USEPA also defines chronic toxicity as a stimulus that lingers for a relatively long period of time, often one-tenth of a life span of the test species or more. Chronic tests are generally run over a 96 hour period. Chronic means long but should be considered a relative term depending on the life span of an organism. The units of expression of toxicity are toxic unit acute (TU,) and toxic unit chronic (TU,) which are respectively the acute effect at the end of the acute exposure period or the unacceptable effect on the test organism by the end of the chronic exposure period.

11 ... Phase TE-Toxicity Characterization. nitial Baseline Toxicity. ph Adjustment. Aeration. Filtration. Ci8 Solid Phase Extraction/Elution. Oxidant Reduction. EDTA Chelation. Graduated ph No Phase 1 TE-Specific Chemical Analyses Phase 111 TE-Confirmation Procedures Toxicity Control Control Evaluation TOXCTY DENTFCATON EVALUATON FLUYD BRUWNE ASSUCATES, NC, CONSULTNG ENGNEER MARUN, OHO ni ATT A

12 SELECTNG TEST ORGANSMS The test organisms are selected in Phase of a TE. As the sensitivities of organisms vary in toxicity tests, USEPA recommends that more than one species be used in the early phases of the TE procedure. Test species generally used for TE toxicity tests are Ceriodaphnia dubia (waterfleas) and pimephales promelas (fathead minnow). TE PROCEDURE Phase Toxicity characterization uses several bench-top -reatment steps to separate the wastewater into basic fractions prior to performing toxicity tests to define the cause(s) of toxicity. The following list describes the Phase tests: 1. nitial "baseline" toxicity determines the baseline toxicity by use of an acute toxicity test on a whole wastewater sample. 2. Aeration determines if toxicity is associated with volatile or oxidizable compounds. 3. Filtration reveals if toxicity is caused by particulate or soluble 4. components. Aeration with ph adjustment determines toxicity associated with volatility, such as ammonia or hydrogen sulfide. 5. Oxidant toxicity may be caused by the presence of wastewater oxidants such as total residual chlorine. This is determined by analyzing for toxicity after the wastewater is mixed with a reducing agent such as sodium thiosulfate.

13 6. Cationic metals such as cadmium, iron, lead, zinc, etc. may be the source of toxicity and this is determined through graduated sodium ethylenediaminetetracetic acid (EDTA) addition to the wastewater which changes the solubility of the metals. This test is followed by toxicity testing. 7. c18 solid phase extraction determines toxicity of selective non- polar organic compounds such as benzene, toluene, etc. that are soluble in solvents and have essentially no ionic charge. f these tests are insufficient to define or characterize the source(s) of toxicity there are other procedures such as ion exchange, activated carbon, etc., which may be used to identify the cause of toxicity. Phase 1 Phase 1 of the TE procedure is a toxicity identification stage in which specific chemical analyses are conducted in parallel with toxicity tests to further evaluate the probable cause or causes of toxicity. n Phase 1 tests, additional procedures are used to separate the wastewater into more specific compounds. These procedures include the following tests: 1. Reverse phase HPLC column tests as a follow-up to the c18 Solid Phase Extraction to further separate non-polar toxicants into more narrow fractions. The HPLC method is used in conjunction with gas chromatography/mass spectrometry (GC/MS) to identify specific organic toxicants. 2. Equitoxic solution test or zeolite resin test which can be used to identify ammonia toxicity. 3. Atomic absorption or nductively Coupled Plasma (CP) Spectrometry to determine which cationic metals are causing toxicity.

14 Phase 11 Phase 11 of the TE is the the toxicity confirmation procedure in which the toxic compounds identified in Phase 1 are further studied using the following approaches: 1. Observation of test organisms symptoms. 2. Additional species toxicity testing. 3. Correlation of toxicity and toxicant concentration from multiple samples. Once the evaluation procedures in the TE have been completed, the probable causes of toxicity have been identified. Subsequent steps of the TRE are to investigate the sources of toxicity and to determine to prevent the discharge of toxicity compounds to the POTW or modifications to the municipal wastewater treatment plant to provide for the removal of toxicity before discharge. TOXCTY SOURCE EVALUATON DEFNTON The next phase of the TRE is toxicity source evaluation or TSE. The TSE is a two tiered evaluation which includes sampling of wastewater direct from industrial discharges or sampling major sewer interceptors in Tier. Tier 1 confirms the suspected toxic sources identified in Tier. TER TSE A diagram of TER, the TSE procedure is shown on Plate 5. The TSE phase is facilitated by referring to pretreatment program data or TE results which may indicate which sewer users are discharging potentially toxic compounds. f no industrial users appear to be the source of the toxicity, then sewer line sampling will be necessary to track toxic sources through a process of elimination of segments of the collection system.

15 Resultsof TE Chemical4 ecific nvestigation o P Selected Point Discharges or Collection System Y Refract0 Toxicity Assessmen of Selected Point Discharges or Collection System nformation and Data Acquisition Pretreatment Program Review L Tier : TSE Yes No POW n-plant Control Eva1 uation Toxicity Control Selection TER 1 TOXCTY SOURCE EVALUATON FLOYD BROWNE ASSOCATES, NC. CUNSULT NG ENGNEER MARON, nt A T T UHD r

16 Refractory toxicity tracking is necessary when results from the TE only identifies a broad class rather than a specific toxic compound. Refractory toxicity tracking may also be required where there exists a variety of toxic substances in industrial discharges to the sewer system and their occurrence is highly variable. Source tracking in TER of the TSE may be accomplished using specific chemical analyses or toxicity tests. f results of the TE phase has identified effluent toxics, then specific chemical analyses may be used to trace the problem to the responsible sewer discharger. f a limited number of industrial users discharge to the POTW then referring to data from the pretreatment program data may expedite the source investigation. f results of the TE Phase fails to identify specific toxicants, then toxicity tests will be needed to trace the problem to the responsible sewer discharger. Toxicity test tracking is complicated by the fact that sewer samples must be subjected to the same level of biological treatment as provided by the POTW for its influent wagtewaters. Treating sewer samples in aerobic batch bioreactors and then testing the resulting effluents for toxicity is known as refractory toxicity assessment. TER 1 TSE After tracking the identified toxicant to the responsible sewer users the TRE proceeds to TER 1 of the TSE to confirm the source of toxic discharge. TER 1 TSE phase of the TRE is shown on Plate 6. Based upon results of TER of the TSE, potentially toxic sewer users are identified and their discharges are sampled and analyzed using the TER 1 refractory toxicity assessment. TER 1 assessment differs from that of TER in the following respects:

17 Test Wastewater Selected from Tier : TSE Sludge Refractory Toxicity Assessment. ndustrial Wastewater Dilution Series. ndustrial User (U) Wastewater Spiked into Primary Effluent. Primary Effluent Control. Synthetic Sewage Control. Use POW Acclimated Biomass (if toxic also use nontoxic biomass). Use Same F/M as POW Test Batch Effluents Toxicity Pass-Throug h. Toxicity Test nhibition Testing. Oxygen Uptake. COD Uptake cific Sources and Nature of oxicity/l nterfe re nce + Toxicity Control Selection 1 TER U TOXCTY SOURCE EVALUATON FLOYD BRUWNE ASSUCATES, NC, CONSULTNG ENGNEER MARON, UHD P ATF F,

18 1. A series of wastewater dilutions are reviewed to determine the pollutant concentration at which toxicity pass-through occurs. 2. Optimal control tests may be conducted to compare relative levels of refractory toxicity and inhibition effects. 3. TE Phase tests of bioreactor batch effluent to indicate the components of the refractory toxicity. f the pretreatment program data has not been reviewed up to this point, then this data should be reviewed to confirm that the discharger is using the identified toxicant as a part of their production operations. The POW may then require industrial users to conduct a TRE to reduce or eliminate the toxicity of their discharge. POTW N-PLANT CONTROL EVALUATON DEFNTON AND OBJECTVE As shown of Plate 7 the POTW in-plant control evaluation begins with a typical engineering evaluation of selected treatment alternatives applied in this situation to reduce or completely eliminate toxicity from the POTW discharge. Alternatives that are to be evaluated are selected from a consideration of data gathered in the POTW.Plant Performance Evaluation and TE investigations using best professional judgment. f the engineering evaluation determines that modifying or expanding the POTW is feasible, then a treatability study is conducted. TREATABLTY STUDY Following the evaluation a bench scale or pilot scale treatability test is conducted to determine toxicity removal effectiveness and unusual operating characteristics. Acute or chronic toxicity tests and toxic specific chemical analyses are used to monitor the effectiveness of the treatment system for toxicity reduction. Test data from the treatability study will also provide

19 POTW N-PLANT CONTROL EVALUATON FLOYD BRUUNE ASSOCATES, NC. CONSULTNG ENGNEER MARON, UHCi D ATC 7.Sludge Bench Scale or Pilot Scale Treatability Test Test Modification of Existing Process or Evaluate Additional Process / Effluent - No (Optional) Phase Toxicity Characterizatlon Toxicity Control Selection

20 the design basis for modifying and/or expanding the POW processes. f the engineering evaluation determines that modifying the POTW is not cost effective then pretreatment control alternatives of toxicity reduction by the responsible sewer user(s) may be preferred to in-plant control. TOXCTY CONTROL SELECTON Toxicity control selection involves the evaluation of potential control alternatives and selection of the most appropriate alternative based on technical and cost considerations. This evaluation is conducted by reviewing data collected during various phases of the TRE. The selection of an in-plant control alternative over a pretreatment control alternative must be made in accordance with the following considerations: 1. Technical and economical feasibility of POTW treatment modifications. 2. Quality of the pretreatment data on sewer users who discharge refractory toxicity. 3. TE data and TSE data sufficient to unquestionably identify the NTRODUCTON source(s) of toxicity. TOXCTY CONTROL MPLEMENTATON After the alternatives for toxicity control have been evaluated the final phase of the TRE, toxicity control implementation, may begin. MPLEMENTATON From results of previous steps a toxics control implementation plan or report is developed. The plan should present the results of the TRE and include a description of alternatives for controlling or reducing toxicity to allowable levels. The plan should provide the design basis for in-plant control alternatives and should include construction cost estimates, operation

21 and maintenance costs, and the time required for design, construction and start-up and obtain a steady-state of operation. For source control options the selected pretreatment alternative should be described with an explanation of the basis of selection, present a technical justification for local limits and a methodology for monitoring industrial users. f pretreatment regulations are to modified, the needed revisions should be described in this report. CONFRMATON MONTORNG After the in-plant control modifications or toxicity pretreatment control systems have been constructed and placed into steady-state operation, effluent toxicity monitoring should be performed on the POTW effluent. The purpose of this final toxicity monitoring step is to confirm that toxicity has been reduced to acceptable levels and that the TRE objectives have been met. CONCLUSON n 1987 FBA performed a TRE for the City of York, Pennsylvania to determine the source of several toxic organic compounds that were passing through the POW to the discharge into Codorus Creek. Since these specific compounds were identified by Pennsylvania Department of Environmental Resources (PADER) as the toxicants, the specific chemical analyses procedure was used in toxicity source evaluation to determine the sources of the toxic discharges. FBA is currently working on two Alternative Justification studies for two clients in Ohio. The Alternative Justification Procedure is a program that the State of Ohio has established for POTW's to request variances from proposed effluent limits developed from the water quality-based toxic control process. These studies include the application of specific chemical analyses,

22 bioassays and biological stream studies to verify wasteload applications that were calculated by the regulatory agency in deriving the permit limitations.

23 REFERENCES 1. Bishop, D.F., "Toxicits Reduct ion in MuniciDal Waste water Treatment Plant," presented at the Annual Water Pollution Federation Conference at Philadelphia, Pennsylvania, October 8-9, United States Environmental Protection Agency, "Methods for Aquatic Toxicity dentification Evaluations," National Effluent Toxicity Assessment Center, Cincinnati, Ohio, September United States Environmental Protection Agency, "Toxicity Reduction Evaluation Protocol for Municipal Wastewater Treatment Plants," Office of Research and Development, Cincinnati, Ohio, April United States Environmental Protection Agency, "Wastewater Treatment Plant Toxicity Evaluation, Reduction and Control," Center for Environmental Research nformation, Cincinnati, Ohio, Volumes and 11, November 1989.

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