Biological treatment of low-biodegradable composite chemical wastewater using upflow anaerobic sludge blanket (UASB) reactor: Process monitoring

Upflow Anaerobic Sludge Blanket (UASB) reactor was investigated for the treatment of low biodegradable composite chemical wastewater, which was complex in nature and has low biodegradability (BOD/COD ratio -0.32), with high concentrations of sulphate and total dissolved inorganic solids (TDIS). After inoculating with slaughterhouse wastewater treating anaerobic sludge, the reactor showed a rapid startup phase. The reactor was operated continuously for 60 days with an actual organic loading rate (OLRactual) of 4.25 kg COD/ m(3)-d accounting for 37 h of detention time in continuous mode without recirculation at a mesophilic temperature of 29 +/- 2 degrees C. At steady state conditions, the reactor resulted in 62% of COD removal efficiency accounting for substrate degradation rate (SDRactual) of 2.6 kg COD/ m(3)-d. The experimental data demonstrated the applicability of UASB system for treating composite chemical wastewater with low biodegradable nature. Introduction of appropriate inoculum to the reactor during startup showed the effective biological treatment of composite wastewater, which is evident from the substrate and sulfate removal data and non-accumulation of VFA concentration in the reactor along with the generation of biogas.