ASSESSMENT OF ENVIRONMENTAL CONTAMINATION POTENTIAL OF DISTILLERY EFFLUENT USING PLANT AND ANIMAL BIO ASSAYS

摘要

Toxic effects of spent wash and crop field soil irrigated with it (hereafter referred to as distillery soil) were examined on 6 species of plants (2 cereals and 4 aquatic macrophytes) and 3 animals (cladoceran, fish and albino mice) by short-term bioassays using end point growth responses and mortality respectively Seedling emergence was found nil (rice) to low (wheat = 30-40%) in distillery soil, but increased (48-00%) proportionately alongwith their vigor after mixing garden soil. In contrast to distillery soil, toxic effects of even cent percent soil leachate were nil on seed germination while meager (10-15%) on seedling vigor in both the cereals. Spent wash, however, decreased germination and seedling vigor in both rice (germination = 5-100%; vigor = 2-100%) and wheat (germination = 0-64%; vigor = nil-93%) with an increase in its concentration, though vigor was greater (43%) than control in wheat at 10%. Among aquatic macrophytes, free-floating species (Lemna aequinoctialis and Spirodela polyrrhiza) were found to be more sensitive than the submerged (Ceratophyllum demersum and Hydrilla verticillata) for spent wash; Lemna being the most sensitive species. During a detailed study, sensitivity of different test organisms to spent wash (in terms of their EC/ LC_(50) values) was in the order of: Daphnia (EC_(50)= 0.68%) > Gambusia affinis (LC_(50) = 1.31%) > Lemna (EC_(50) = 0.8-6.97%) indicating water flea to be the most sensitive test organism. The toxicity of soil leachate was, however, very low to these test organisms (Gambusia: LC_(50)= 12.1%; Lemna. EC_(50) = 46 5-278%) as also noted for cereals. The spent wash exposure not only decreased RBC counts (58-69%) in fish but also altered their morphology (77-97%). Both food (7-14%) and water (27-45%) intake of albino mice (male) declined in soil leachate treatments (5-20%) alongwith their body (8-17%) and reproductive organ weights (4-63%), except that of prostrate gland weight increasing between 12% and 37%. The sperm counts (78-89%) and their motility (14-23%) also decreased in leachate treatments. Higher toxicity of spent wash may be ascribed to its greater conductivity (32.7mS), COD (54,900ppm) and chlorides (62,00ppm) than the soil leachate (EC = 3.56mS; COD = 2290ppm; chlorides = 220ppm).