Ecotoxicity assessment of sludge and leaching test eluates of sludge.

Sludge mainly collected from wastewater treatment plants were subjected to chemical and ecotoxicological characterization to provide a preliminary assessment of their suitability for land application. We examined the leachability and toxicity of organic compounds in several industrial wastes and recovered materials such as dewatered sludge through standard leaching tests. Several toxicity tests were performed under standard laboratory conditions using a freshwater alga, a crustacean, and some terrestrial plants. Some eluates showed high toxicity. No correlation was found between the ecotoxicological and chemical characteristics or the sum parameters (TOC, total organic carbon concentration). Further, bioassays are extended to exhibit the toxicity, which can be explained by the presence of organic compounds. In general, the eluates differed in their toxicity profiles and their organic chemical composition. Therefore, chemical analyses are unreliable for quantifying biological effects. The samples can be classified as ecotoxic/hazardous based on the LC/EC(50) (lethal concentration/effective concentration reducing 50% of survival or biological activity) values. It is necessary to know the relative ecotoxicity of the potential leachate from organic sludge waste before landfill in order to predict the environmental impact in the event of leakage from the landfill.