TOXICITY REDUCTION EVALUATIONS AT TEXTILE MILLS. Introduction

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1 TOXICITY REDUCTION EVALUATIONS AT TEXTILE MILLS John Burke, North Carolina Division of Pollution Prevention and Environmental Assistance, Lexington, NC Introduction The North Carolina Division of Pollution Prevention and Environmental Assistance is a state program that provides non-regulatory and free technical assistance to business and industry on techniques and technologies that can reduce waste generation, improve environmental compliance, and improve industrial competitiveness. Due to the water intensive nature of textile dyeing operations and subsequent volume and constituency of wastewater discharged, DPPEA engineers often work with these facilities on wastewater related issues. As a discharger to the surface water or as a discharger to a municipal treatment system, most of these textile mills have wastewater issues related to meeting typical limits for biological and chemical oxygen demand, metals, total nitrogen, ph, oil and grease, etc.. Occasionally, textile wet processing mills will be presented with compliance issues related to effluent toxicity either in the form of acute or chronic toxicity. Unlike most other wastewater parameters, toxicity can result from any number of and combination of constituents that can be extremely difficult to identify. DPPEA has provided technical assistance to a number of textile operations in identifying and reducing effluent toxicity related issues. This paper discusses the current toxicity regulations in North Carolina and the activities DPPEA promotes for facilities to maintain toxicity compliance. Toxicity Testing Requirements in North Carolina Most all textile mills in North Carolina that have a National Pollutant Discharge Elimination System (NPDES) permit or discharge to a municipality that has an NPDES permit, are affected by the whole effluent toxicity (WET) testing requirement. The WET limits and monitoring requirements are based upon the instream waste concentration (IWC) during conditions of maximum permitted effluent flow and 7Q10 stream flow using the following equation 1. IWC (%) = (Qw/(Qw+Qu)) * 100 Eq (1) Qw = NPDES Maximum permitted flow Qu = Upstream flow during 7Q10 (lowest seven day flow during a ten year period) condition. Depending on the IWC, NPDES holders have to complete either acute or chronic testing of the whole effluent. Chronic testing If the facility's IWC is greater or equal to 0.25 percent the "North Carolina Ceriodaphnia Chronic Effluent Bioassay Procedure" or the " North Carolina Phase II Chronic Whole Effluent Toxicity Test Procedure" is required. The limit will be stated as "there may be no observable inhibition of reproduction or significant mortality" at the effluent concentration equivalent to the facility's IWC with a maximum of permit limit of 90%. If a facility discharges to a receiving stream classified as "High Quality Waters" the limit will be twice the IWC. If the IWC is greater than 45% the limit will be 90% 1. 1

2 The chronic test evaluates mortality and reproduction over a seven-day period. Fresh effluent is added on the 2 nd and 5 th days. Ceriodaphnia dubia is the species required. The water flea can be exposed to the IWC and compared statistical to the control to determine a simple pass/fail at the IWC or the water fleas can be exposed to multiple concentrations of effluent to determine the actual chronic value. Acute Testing If the facility's IWC is less than 0.25 percent, a 24 hour flathead minnow acute "No Significant Mortality" test will be applied. The acute test evaluates mortality over a 24, 48, or 96 hour period. The test requires the use of water fleas, fathead minnows, or mysid shrimp. Pass or failure of the test is based on statistically significant mortality of the organisms exposed to the effluent in comparison to the control organisms. WET Testing Status in NC and Related Issues Permitted facilities are typically required to monitor for toxicity no more than once per quarter. If a facility fails its toxicity testing, it will be required to began testing toxicity once per month until it begans passing. A facility receives a notice of violation (NOV) for each failure and can be fined. Facilities are rarely fined in the initial periods of toxicity failure. Typically, if a facility shows a history of non-compliance with the WET requirement it is asked to enter into a special order by consent (SOC). An SOC specifies several steps the facility must take to resolve the toxicity issue and provides a timeframe in which the facility must resolve this issue. The time is typically a year or longer. Facilities that do not comply with the SOC are more likely to receive fines. Currently there are 11 facilities with toxicity limits that are having ongoing compliance problems in North Carolina. This is 2.5% of the total toxicity limits in the state. Thus, the number of permitted dischargers with toxicity limits that have continuous toxicity issues is relatively low. Despite the relatively low number of compliance issues, those being regulated often criticize WET testing requirements. One major issue is the relationship between WET testing and actual instream toxicity. To help address this issue, The Water Environment Research Foundation funded a study by Tetra Tech to define the relationships between WET testing and instream toxicity. Tetra Tech evaluated WET test, instream assessment data, and other support data for over 300 municipal and industrial wastewater facilities. Studies were accepted into the database if they meet six requirements WET tests used effluent representative of what was discharged; 2. WET test met current EPA QA requirements; 3. WET test were preformed prior to but not more than 1 year before the bioassessment; 4. upstream and downstream bioassessment data were available; 5. stream habitat quality was similar up and downstream of the discharge; and 6. no point or non point sources, other than the discharge of interest, were present between the upstream and downstream site. While the final report on this study is pending, there are some preliminary findings that are of interest for this national debate. First, if WET testing consistently passed current state criteria, there appeared to be a higher likelihood of no instream impairment. Second, among those sites that consistently failed, there was approximately a 50:50 chance of the stream being impaired. Some of those cases where the WET test showed impairment and instream testing showed no impairment could be explained due to the higher flows at that time period. WET testing dilution rates are typically based on the lowest flow over a seven-day period within ten years. 2

3 Internal Proactive Measures for Identifying and Reducing Effluent Toxicants Once a facility is faced with a toxicity issue, identifying the source or sources of toxicity is typically the most difficult part. Because the WET test is evaluating the effect of wastewater constituents on selected organisms and not testing for specific constituents, it does not identify the specific constituents that are causing the problem. Additionally, there can be constituents that are masking other toxic constituents. Thus, if the primary toxicant(s) are identified and dealt with, the facility may still fail WET test due to secondary toxicants. Facilities showing historical problems with toxicity are typically required by the State to complete a toxicity reduction evaluation (TRE). TREs are typically completed by labs and consulting firms. To assist in identifying toxicants, EPA has developed a series of test methods presented in "Methods for Aquatic Toxicity Identification Evaluations: Phases I, II, and II". These methods are typically used during TREs. Phase I and II use tests to narrow the focus to groups of constituents such as those affecting ph, suspended solids, volatile, sublatable, or oxidizable compounds, non-polar organics and metal chelates, oxidants (eg chlorine), cationic metals, and ph dependant toxicants (eg ammonia). Phase III provides procedures for confirming toxicants. While these methods are useful in narrowing the focus on toxicants, these cannot always identify the specific culprits and test methods do not cover all potential groups of toxicants. TREs can be costly and time consuming, but there are many activities that facilities can accomplish that could significantly reduce the time and cost of TRE projects. The following sections discuss activities that DPPEA promotes to help facilities avoid or resolve toxicity compliance issues. Raw Material Screening Program Textile facilities that are not currently having toxicity problems can greatly impact the future occurrence and costs associated with toxicity issues through implementing a raw material screening program. Screening programs take many forms and cover areas ranging from quality issues to environmental issues. In relation to toxicity, a raw material screening program should involve the gathering of toxicity related data that can be used by the facility for determining chemicals with the lowest toxicity impact as well as for use by consultants if toxicity problems arise. During a persistent toxicity issue, most facilities or their consultant will request data from selected suppliers. Many facilities find it difficult to obtain useful and consistent information at this point. By having a continuous screening program in place that requires specific toxicity related data, facilities can persuade suppliers to be more forthcoming as they are marketing their products. A supplier will be much more willing to submit their products to testing requirements when their trying to sell you a new product as opposed to once you are already purchasing that product. Additionally, the more facilities that have testing data requirements the more likely chemical suppliers are to complete those tests as part of their standard procedures. There are various types of data that would prove useful in evaluating chemicals for toxicity impact. The following is a list of tests that are commonly requested by some TRE consultants 3 : 1. Toxicity testing 48-h Daphnid Acute Static Bioassay (OECD Method 202 Part I) 7-d C. dubia Survival and Reproduction (OECD Method 202 Part II) Provides information on the toxicity of a specific chemical that has not been treated. 2. Biodegradability testing 5 Day BOD (OECD Method 301D) 28 Day BOD (OECD Method 301D) Provides information on the treatability of a specific chemical in a biological system. For a 28 day test, chemicals with 80% or more biodegradability should be considered easily 3

4 biodegradable, 50% to 80% moderately biodegradable, and less than 50% difficult to biodegrade 4. The less biodegradable the chemical, the higher the chance that chemical will impact toxicity in the effluent of a biological treatment system (obviously this depends on the toxicity of the chemical in question). 3. Biomass Respiration Inhibition testing Activated Sludge Respiration Inhibition (OECD 209) Provides information on the effect of a specific chemical on the aerobic respiration rate of wastewater treatment plant activated sludge. This testing data can prove extremely useful in preventing the use of highly toxic raw materials. If the facility is evaluating two chemicals that provide roughly the same quality goods at the same costs but one is extremely more toxic than another, having this data would potential prevent the use of a product which can cause significant environment problems down the road. For those personnel who are wearing too many hats to deal with evaluating this type of data, there are programs that provide an environmental impact rating for the chemicals whose data is entered into the program. Aquatox TM, developed by Burlington Research Inc., takes the previous listed testing results and develops an environmental impact ranking. Programs like Aquatox TM could prove extremely useful to help facilities identify problematic chemicals. Facilities should begin a program by targeting the high use raw materials and chemicals. Raw materials and chemicals used in excess of 50 pounds on a given day would be a good starting point. If suppliers are not open to submitting their products to all of the tests listed above, they should at least provide toxicity testing data. Additionally, facilities should not overlook raw materials such as incoming yarn or fabric that can be loaded with chemical additives. Identifying Potential Toxic Effluent Constituents Collecting toxicity related data on incoming raw materials will assist textile operations in avoiding toxicity issues. Unfortunately though, this activity will not eliminate the chance of toxicity issues even if done effectively. This is due to the fact that toxicity can result from a synergistic effect of several chemicals as well as from intermittent use of small quantities of highly toxic chemicals that could be used anywhere from maintenance to water treatment to floor cleaning. The following example outlines a situation where the raw material screening program discussed above may not identify the chemicals that would be contributing to a toxicity issue. There are specific surfactants that are chronically toxic at 1 ppm. A facility may be using five chemicals with this surfactant as part of their constituency. During the raw material screening process, the toxicity data may have shown each chemical product to be mildly toxic because the levels of the surfactant in each were small. When all five chemicals are used in combination, the total loading of that type of surfactant may exceed 1 ppm. Thus, a toxicity issue could result from the combination of chemicals as opposed to any one chemical. Additionally, there are synergistic effects where combination of chemicals can form toxic constituents during reactions with one another. In an effort to help identify some of these cases, DPPEA can work with mills to identify potentially toxic effluent constituents. Those constituent groups that have been most commonly identified as the source of effluent toxicity in textile effluents are dissolved solids (salt), dissolved metals, and surfactants. If a textile facility is beginning to have toxicity issues, during the days of toxicity sampling the facility should also sample for effluent conductivity, MBAS, CTAS, and selected dissolved metal levels. These concentrations of these pollutants should be compared to the toxicity data provided in Tables 1 through 3 or other sources of toxicity data. To effectively compare test concentrations to toxicity data, the dilution rates and in the case of SIUs municipal treatment efficiencies should be considered. In the case of a direct discharger the IWC would be the dilution factor. For an SIU, the IWC of the 4

5 municipality and the percent flow contribution of the SIU to the municipality would be used to determine the dilution factor. Treatment efficiencies for selected pollutants can be obtained from the municipality. Table 1. Chronic Toxicity of Various Salt Ions 5 Parameter Ceriodaphnia dubia Daphnia magna Conductivity (uohms/cm) Sodium (mg/l) Chloride (mg/l) Sulfate (mg/l) Table 2. Daphnia pulex Acute Toxicity and Ceriodaphnia dubia/affinis Chronic Toxicity of Various Surfactants 6,7 Nonionic Surfactant Acute, mg/l Chronic, mg/l Diethanol amid of coconut fatty acid 6 2 Linear alcohol ethoxylate Ethylene oxide-propylene oxide Nonylphenol ethoxylate 6 12 Ethoxylated mercaptan 6 17 Anionic Sodium napthalene sulfonate Sodium diphenyl oxide di sulfonate Sodium lauryl sulfonate Sodium dodecyl benzene sulfonate Sodium alcohol ether sulfonate 6 20 Cationic N alkyl dimethyl benzyl ammonium chloride 7 <1 Benzyl trimethyl ammonium chloride Tallow amine ethoxylate Tallow amine ethoxylate Amphoteric Cocoamphocarboxypropionate

6 Table 3. Water Quality Criteria for Various Metals 8 Criteria Maximum Criteria Continuous Notes Conc., ug/l Conc., ug/l Mercury C Silver 3.4 A,B Chromium IV C Copper A,B Lead A,B Zinc A,B Chromium III A,B Nickel A,B A- Water 100 mg/l B- Dissolved metal concentration C- Total metal concentration If a facility identifies pollutants that appear to exceed toxic levels and could contribute to toxicity issues through this method or a more scientific method preformed by a TRE consultant, the next step would be to install a treatment system or minimize toxicants through source reduction. While installing a treatment technology is often less time consuming for plant personnel, it is much more costly and often results in more future compliance problems do to inadequate operation than does source reduction. In order to reduce toxicants at the source the facility must identify the major sources. Identifying Major Sources of Toxic Constituents After specific effluent constituents have been identified as potential major toxicants, the facility will need to identify the major sources of each toxic constituent. One method to assist in identifying major sources of specific pollutants is to rank the sources based on pounds of pollutant contributed daily. To determine the pounds per day loading, the percent constituency of a selected chemical in a chemical product, the pounds per day usage of that chemical product, and the estimated amount of chemical constituent that enters the effluent is required. Table 4 provides an example of how this ranking would be presented. Chemical Product Table 4 Example Ranking of Major Sources of a Selected Constituent Chemical Constituent Percent Constituency, % Highest Average Usage, lbs/day Percent Loss, % Effluent Loading, lbs/day Scouring agent nonylphenol ethoxylate 25% % Fiber spin finish nonylphenol ethoxylate 6% % Finishing agent nonylphenol ethoxylate 2% % Finishing agent nonylphenol ethoxylate 1% % By ranking the sources, the facility can then focus source reduction efforts on those that are the most significant. Obviously, the most difficult part is determining all the sources that will need to be 6

7 included in this ranking effort. This will require a review of MSDS sheets, additional information on a chemical's constituency provided by chemicals suppliers, information on yarn or fabric additives provided by material suppliers, and information on levels of pollutant in incoming tap water. Major sources of free or dissolved metal sources can vary widely in a textile mill. Often dyestuffs are targeted as the major contributor of metal loading, but these sources of metal are typically bound and do not contribute to the free metal portion and thus do not impact toxicity. Before discarding dyestuffs, facilities should make sure metal constituents are bound and will not contribute to the free or dissolved portion of total metals. Other sources of free metal to investigate include: 1. Incoming tap water; 2. Piping and machinery; 3. Lubricating and hydraulic oils used on dyehouse machinery; 4. Incoming fabrics and yarns; 5. Dye fixing agents; 6. Oxidizing agents; 7. Stripping agents; 8. Anti-microbial agents; 9. Finishing agents (i.e., water repellant, flame retardant, UV inhibitor, latex, etc.); 10. High volume commodity chemicals due to trace metal contaminates contributing a major amount due to volume of usage (i.e. caustic, soda ash, bleach, peroxide, salt, etc.); and 11. Boiler and cooling tower treatment chemicals. As with metals, major sources of surfactants can also vary widely in a textile mill. The following are some chemical product groups that should be reviewed through MSDS sheets as well as contacts with chemical suppliers to determine constituency: 1. Incoming fabric and yarn (part of emulsification package for knitting oils, spinning oils, coning oils, etc); 2. Scouring agents; 3. Machine lubricants and hydraulic oil; 4. Dyeing auxiliaries (i.e., leveling agents, retarding agents, dye assistants) 5. Stripping agents; 6. Finishing agents (i.e., softener, flame retardant, latex, etc.); 7. Boiler and cooling tower treatment chemicals; 8. Anti-microbial agents; 9. Machine and floor cleaning agents; 10. Polymers (water treatment chemicals); and 11. Adhesives. Once a facility has identified the major sources, there are a number of activities the facility can consider for reducing the contribution of the chemical constituents to the effluent. Source Reduction for Toxic Constituents Each individual situation will require unique activities to successfully reduce or eliminate major sources of toxic constituents, but listed below are general discussions of options to pursue. 1. Chemical substitution or reformulation- Work with supplier to find alternatives or modify chemistry of existing product. Effective but can result in other problems due to new chemistry. 7

8 2. Dyehouse formula modifications- Small reductions in required adds of toxic products can reduce effluent loading. Many companies have effectively reduced scouring chemicals, dyeing auxiliaries, and finishing chemicals by as much as 25% without affecting product quality. This often leads to improved effluent while reducing operating costs. 3. Equipment modifications- Investment in more efficient technologies that would reduce chemical usage or losses. While this requires a capitol expense there is a payback in reduced operating costs while treatment technologies typically have no payback at all. 4. Operational modifications- Reuse of bleach baths or finish baths to reduce losses to the effluent and increased attention to control parameters such as time and temperature during dyeing to reduce dye auxiliary requirements. 5. Scheduling modification- Through scheduling light to dark dyeing the need for machine boilout with cleaning agents can be reduceed. Conclusion In most all situations where a facility is having consistent effluent toxicity issues, they will need the services of a TRE consultant to help them address the issue. But, facilities that take a more proactive role through the techniques listed above will more than likely benefit through reduced TRE costs and more expedient resolutions to toxicity issues. References 1. Tedder, Steve. NCDEM Memorandum, October 4, Tedder, Steve. NCDEM Memorandum, October 14, Diamond, Jerry, et. al.. "Defining Relationships Between Whole Effluent Toxicity Testing and Instream Toxicity" NC AWWA/WEA Industrial Wastewater Seminar. September 30, Chemical Product Stewardship Analysis Document. Burlington Research Inc., Burlington NC. 4. Best Management Practices for Pollution Prevention in the Textile Industry. EPA/625/R-96/004. Page Town of Star, TRE Report Burlington Research Inc.. 6. Acute and Chronic Bioassays of Industrial Surfactants, November, Burlington Research Inc.. 7. Collected by Burlington Research Inc. from selected Chemical Manufacturers. 8. EPA. National Recommended Water Quality Criteria. April EPA/