Industrial Waste Composts: Toxicity Tests and Decomposition Studies under Laboratory Conditions.

Abstract

Enzyme industrial wastes viz. multiple effect evaporator salts, primary sludge, filter press feed were evaluated for their phytotoxic effects under laboratory conditions to understand their potential to use as a nutrient medium for supporting plant growth. It was found that the industrial waste-water extract recorded lower contents of essential nutrients and the presence of heavy metals viz. Ni and Cd. Germination studies revealed the inhibitory effects of industrial waste-water extracts on percentage and rate of seed germination and length of plumule and radicle. None of the seeds germinated in MEES: water extract and seed germination of tomato as indexed by rate 6.11 in PS: water extract exhibited the inhibitory effect by primary sludge on seeds. The length of radicle (5.79) and plumule (4.94) was relatively lesser in PS: water extract to that of FPF: water extract and control. The incubation study carried out in the laboratory conditions to understand the rate of decomposition of urban solid waste alone and three different industrial waste-composts prepared by combining urban solid waste with enzyme industrial wastes viz. multiple effect evaporator salts, primary sludge, filter press feed revealed that the carbon-di-oxide evolved was higher in incubating urban solid waste-multiple effect evaporator salts exhibiting a higher rate of decomposition due to the presence of more easily degradable compounds. This was 6.10 mg CO2 100 gc-1 day-1 on the 50th day of incubation in urban solid waste-multiple effect evaporator salts and 2.60 mg CO2 100 gc-1 day-1 in incubating urban solid waste alone at the 50th day of incubation. The cumulative CO2 evolved ranged from 32.27 mg CO2 100 gc-1in urban solid waste alone to 89.48 mg CO2 100 gc-1 in urban solid waste+ multiple effect evaporator salts on the 50th day of incubation.