T/CAQI 323-2023 Method for Identifying Toxic Substances in Wastewater

Scope

Main technical content: Wastewater toxicity identification and evaluation (TIE) refers to the use of a series of model organisms and standardized testing methods, with survival and growth development as the test endpoints, to determine the comprehensive toxicity of wastewater. By combining toxicity testing with physical and chemical treatment, the components of toxic substances in wastewater can be identified. It typically includes three stages: (I) Toxicant characteristics, (II) Toxicant identification, and (III) Toxicant confirmation (Figure 1). For toxicant characteristics, a series of physical and chemical treatments are applied to water samples, including pH adjustment, aeration, filtration, solid-phase extraction, and the addition of EDTA and Na2S2O3. Gradient pH adjustment is also used. By comparing the toxicity changes of the water samples before and after various treatments, the physicochemical characteristics of the toxicants can be determined, and the types of toxicants can be identified. For toxicant identification, suitable separation techniques are used to separate toxic and non-toxic substances, thereby reducing the number of compounds to be analyzed. At the same time, analytical techniques are used to identify specific toxic substances in the wastewater. For toxicant confirmation, mass balance methods, correlation analysis methods, symptom observation methods, biological sensitivity tests, suspected toxicant addition tests, or suspected toxicant removal tests are used to confirm whether the suspected toxicants identified in the second stage are indeed the main toxicants causing the toxicity of the wastewater.

Development Information

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