The Study Of Reducing Excess Sludge Production By Metabolic Uncoupler-TCS (3,3',4',5-tetrachlorosalicylanilide)

Activated sludge process is a method of wastewater treatment that is used most extensively in the world , with a great deal of advantages such as high efficiency ,fine effluent quality, well reliability of operation. But excess sluge production is highly. The construction capital and operating cost of the excess sludge treatment and disposal facilities are all very highly. Meanwhile, the excess sludge also causes new environmental pollution.Therefore, the most effective method of solving the problem of excess sludge is to reduce the production of the excess sludge to maximum in the course of wastewater treatment. Of the various kinds of technology of reducing production of excess sludge, utilization of uncoupler may be the most prospective, because it needn't increase the extra treatment facilities, and it is convenient to run.Among the uncouplers used for reducing excess sludge production currently, TCS is more gently and environmentally sound. In this study ,TCS (3, 3′ , 4′ , 5 — tetrachlorosalicylanilide )has been used. Eight batch reactors filled with activated sludge were operated in a batch mode in parallel. Batch experiments were carried out for 3 h .In each test, the initial MLSS concentration was kept at 2000mg/L, while the initial COD concentration was 1000mg/L. The effective concentration of TCS was 0.6 and 1.4mg/L, the Y_obs was reduced by 37.7% and 51.0% respectively. The COD removal efficiencieswere obviously reduced with concentration of TCS ranging form 0.4-1.0 mg/L. The COD removal efficiencies were reduced by 2.3% and 17.6% respectively. In this study, the model for growth yield under uncoupler-presence conditions was validated by experimental data that was adapted to high conventional S_o/X_o conditions. Y_obs. is thefunction of C_TCS/X₀. The energy uncoupling coefficient(E_u) was further validated byexperimental data. Four batch experimens were carried out for 30 days. It is apparent that the COD removal efficiencies were not affected by the presence of TCS even when its concentration is 1.2 mg/L. The sludge settleablity is gently affected by the presence of TCS during the 30 days operation in this study.