Toxicity identification evaluation of landfill leachate using fish, prawn and seed plant

The first phase of toxicity identification evaluation (TIE) method comprised of physic-chemical fractionation steps of pH adjustment, pH adjustment followed by filtration, aeration, extraction with solid phase C18 column (SPE), oxidant reduction with sodium thiosulphate and EDTA chelation was conducted to characterize the toxicants of a Malaysian landfill leachate. The battery of organisms test chosen were freshwater fish (Rasbora sumatrana), freshwater prawn (Macrobrachium lanchesteri) and tomato seed (Lycoperson esculentum). Toxicity reductions at each step were comparable for all test organisms. The major toxicants present in the leachate were found to be mostly basic in nature and precipitable under acidic conditions as well as containing non-polar organic compounds. A small reduction in toxicity was observed when leachate was treated with sodium thiosulphate in oxidant reduction test indicating the presence of oxidizers. The EDTA chelating step did not significantly reduce toxicity in the test organisms suggesting insignificant level of (toxic) metals.