WATER TREATMENT PLANT WASTES MANAGEMENT WITH SPECIAL REFERENCE TO BHANDUP WATER TREATMENT PLANT

Abstract

Advances in technology has laid to a rapid industriali-zation, and with this is increasing the demand for water. To render water safe for human consumption, it is often necessary to treat it, treatment of water produces certain wastes. These wastes contribute to the pollution of water resources. There-fore proper handling and management of these wastes is necessary. These wastes like any other waste has recovery potential. The quantity of wastes from an alum coagulation water treat-ment plant range from 2.5-7 percent, and it is possible to recover water, chemicals, and solids. Municipal Corporation of Greater Bombay has undertaken the construction of 1910 Mld Bhandup water treatment plant. The volume of the waste at the above plant is expected around 38-76 Mld. Since adequate waste management system for the above plant has yet to be evolved. It was therefore decided to study the characteristics of wastes from the Pogaon water treatment plant and to predict characteristics of the waste that would result at the Bhandup water treatment plant. Study reveals that backwash waste water has high initial turbidity (145-520 JTU), suspended solids (236-1236 mg/1), BOD(9-101 mg/1), COD(24-176 mg/1) and MPN count, and also traces of N and P contents, therefore, their direct discharge x. to drinking water lake may not be desirable. It is possible to recover 90-95 percent water and 20 per cent alum from these wastes by recycling the supernatant, which in terms of the Bhandup water treatment plant would mean saving of 25-52 lakhs of rupees per year from water, and 1500 tonnes of alum per year. Study also shows that it is possible to prepare building bricks from the sludge solids and earn a profit of rupees 1.2 lakhs per year, this will also eliminate the problem of sludge solids disposel. Number of alternative for waste treatment were analysed and an economical and efficient waste management system has been proposed, which consists of: • Allow one hour of settling time-using multibottom settlers • Collect supernatant from the backwash waste water and the basin sludge, chlorinate it, if necessary, and recycle it to the plant inlet. • Thicken the sludge, if necessary • put the sludge solids on concrete bottom and porous sides drying beds, add grog to reduce drying period. • Utilize the sludge for brick making. The capital investment on the approach suggested would be recovered in first two years of its operation, and would accrue substantial saving of water, chemicals, and profitable use of solids, and would eliminate lake water pollution.