Effluent toxicity testing methods have been well defined, but for the most part, these methods do not attempt to segregate the effects of active ionic concentrations and ion imbalances upon test and species performances. The role of various total dissolved solids in effluents on regulatory compliance has emerged during the last few years and has caused confusion in technical assessment and in permitting and compliance issues. This paper assesses the issue of ionic strength and ion imbalance, provides a brief summary of applicable data, presents several case studies demonstrating successful tools to address toxicity resulting from salinity and ion imbalance, and provides recommendations for regulatory and compliance options to manage discharges with salinity/ion imbalance issues. Effluent toxicity resulting from inorganic ion imbalance and the ion concentration of the effluent is pervasive in permitted discharge from many industrial process and municipal discharges where process streams are concentrated, adjusted, or modified. This paper discusses procedures that use weight-of-evidence approaches to identify ion imbalance toxicity, including direct measurement, predictive toxicity models for freshwater, exchange resins, mock effluents, and ion imbalance toxicity with tolerant/ susceptible text species. Cost-effective waste treatment control options for a facility whose effluent is toxic because of total dissolved solids (TDS) or because of specific ion(s) are scarce at best. Depending on the discharge situation, TDS toxicity may not be viewed with the same level of concern as other, more traditional, toxicants. These discharge situations often do not require the conservative safety factors required by other toxicants. Selection of the alternative regulatory solutions discussed in this paper may be beneficial, especially because they do not require potentially expensive or high-energy-using treatment options that may be ineffective control options. The information presented is intended to provide a better understanding of the role of ion imbalance in aquatic toxicity testing and to provide various recommendations that should be considered in addressing these issues.
Abstract-Effluent toxicity testing methods have been well defined, but for the most part, these methods do not attempt to segregate the effects of active ionic concentrations and ion imbalances upon test and species performances. The role of various total dissolved solids in effluents on regulatory compliance has emerged during the last few years and has caused confusion in technical assessment and in permitting and compliance issues. This paper assesses the issue of ionic strength and ion imbalance, provides a brief summary of applicable data, presents several case studies demonstrating successful tools to address toxicity resulting from salinity and ion imbalance, and provides recommendations for regulatory and compliance options to manage discharges with salinity/ion imbalance issues. Effluent toxicity resulting from inorganic ion imbalance and the ion concentration of the effluent is pervasive in permitted discharge from many industrial process and municipal discharges where process streams are concentrated, adjusted, or modified. This paper discusses procedures that use weight-of-evidence approaches to identify ion imbalance toxicity, including direct measurement, predictive toxicity models for freshwater, exchange resins, mock effluents, and ion imbalance toxicity with tolerant/ susceptible text species. Cost-effective waste treatment control options for a facility whose effluent is toxic because of total dissolved solids (TDS) or because of specific ion(s) are scarce at best. Depending on the discharge situation, TDS toxicity may not be viewed with the same level of concern as other, more traditional, toxicants. These discharge situations often do not require the conservative safety factors required by other toxicants. Selection of the alternative regulatory solutions discussed in this paper may be beneficial, especially because they do not require potentially expensive or high-energy-using treatment options that may be ineffective control options. The information presented is intended to provide a better understanding of the role of ion imbalance in aquatic toxicity testing and to provide various recommendations that should be considered in addressing these issues.
A nine-laboratory round-robin study of the Duphniu mugnu static, acute, effluent toxicity test was conducted to examine inter-and intralaboratory variability in test results. A single effluent sample was split and sent to three government, three commercial and three industrial aquatic laboratories. Each laboratory followed a specifically designed test protocol and reported the number of daphnids immobilized in each of seven effluent test concentrations at 24 h and 48 h of exposure. The mean 48-h EC50 value for all data was 5.3% effluent. The range was 3.5 to 9.1% effluent, so there is a factor of 2.6 between the highest and lowest EC50 values. The pooled within-laboratory standard deviation and coefficient of variation were 0.91 and 1670, respectively. Combined interand intralaboratory estimates of standard deviation and coefficient of variation were 1.8 and 3370, respectively. The results of this study show that Duphniu mugnu effluent toxicity data can be reproduced both within and between laboratories when clearly defined test protocols are employed.
Abstract-Routine National Pollutant Discharge Elimination System (NPDES) cooling-water toxicity tests demonstrated an acute effect on Ceriodaphnia dubia and fathead minnows (Pimephales promelas). Test results were characterized by irregular mortality dose-response curves and a brown filamentous mass on the opercular area of affected fish. Some fish and Ceriodaphnia also became entrapped in filamentous material present on the bottom of the test vessels. Microscopic examination of test fish revealed severe fouling of the oral and branchial cavities with a mixed population of microbes, the major component being a filamentous sheathed bacteria. Treatment of water samples with a 0.45-m membrane filter and/or ultraviolet light sterilizer were effective in eliminating the bacteria and test organism mortalities. Regulatory test procedures were modified to allow filtration of the water prior to testing to eliminate this naturally occurring biological interference in toxicity tests.
Chlorine and chlorine-ammonia compounds have been reported to be toxic to various species of freshwater fish. We have found that the basis of this toxicity in at least one species is the oxidation of hemoglobin to methemoglobin, producing death of the fish due to anoxia.Since the beginning of this century, the chlorination of public water supplies, sewage, and industrial effluents has become a wide-
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