TREATMENT OF COMBINED WASTE WATER BY ACTIVATED SLUDGE PROCESS

Selvabharathi. G, S. Adishkumar, G.Ginni, S.Devi

Abstract: Combined discharge of domestic and tannery waste waters into streams or surface bodies has been witnessed in Vellore district in Tamil Nadu, India where the tannery processes are carried out at small-scale units. In the present study, an attempt has been made to evaluate the treatability of combined domestic and tannery waste waters using lab-scale activated sludge reactor under extended aeration. Studies on the efficiency of the activated sludge reactors were carried out by varying the solids retention time of 8, 12 and 16 days with a various hydraulic retention time of 15, 20, 25 and 30 h with an organic loading rate varying from 1.61 to 3.32 kg COD/ m 3 / day . The results showed that at the end of 30 h HRT at 16 days SRT with a lower F/M ratio of 0.08 kg BOD/kg MLSS, the maximum reduction of COD was observed to be from 2020 to 175 mg/L. From the bio-kinetic parameters estimation studies, the values of kinetic coefficients are obtained such as the half velocity substrate concentration (Ks), maximum specific growth rate (µmax), yield coefficient (Y) , maximum substrate utilization rate (k) and decay coefficient (Kd) as 122 mg/L, 0.224 day-1 , 0.539 mg MLSS/mg COD, 0.416 day-1 and 0.088 day-1 . The study reveals that the combined domestic and tannery waste water is amenable for treatment using ASP, with treatment efficiency as high as 91% and the bio-kinetics arrived at better stability of the system and enhanced microbial activities at longer HRT and SRT. Also the design values suggest that the extended aeration system is the appropriate activated sludge treatment process for combined domestic and tannery waste water treatment.

Keywords: Advanced Oxidation Process, Activated Sludge Process, Hydraulic Retention Time and Solid Retention Time

DOI: https://doi.org/10.15623/ijret.2016.0530010