Hi Vinod,
I'm not sure what kind of effluents you're testing, but I would expect the most significant changes in mechanical soil properties would be caused by chlorides, sulfates, alkalinity, organic matter, and high or low pH. It's going to depend a lot on the soil, too - low pH effluent is not going to have much effect on sand or silt, but it could on a calcareous soil.
I would not run the tests with effluent. I would instead prepare varying concentrations of the specific contaminant I wanted to study, and test them against distilled water.
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Richard Ammel P.E., M.ASCE
Engineer
EBH & Associates
Great Bend KS
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