Performance evaluation of a bottom liner incorporated up-flow anaerobic sludge blanket reactor start-up for food waste

Abstract

A bottom biofilter liner incorporated up-flow anaerobic sludge blanket reactor was designed, developed, and evaluated for food wastes over 47 days. It was operated as a semi-batch setup with intermittent up-flow circulation (very infrequent) to simulate the start-up with phosphate, Ca(OH)2, and fresh cow dung. Volatile solids (VS), volatile suspended solids (VSS), salinity, pH, biochemical oxygen demand, chemical oxygen demand, and phosphate were monitored. An analytical procedure was developed by summing up total VSS over the lapse time from t = 0 for the operational period which gave overall reaction rate of v and the total cumulative values of VS as substrate S for applying Michaelis–Menten kinetics for optimizing and predicting reactor performance. At ideal operating conditions, pH ranged from 5.69 at the bottom to 7.9 at top stratum. The salinity at the bottom stratum reduced from 8.8 to 0.5 ‰, indicating excellent performance of the liner. There are two ways of analysing phase behaviour and applying Lineweaver Burk plot, one gave Michaelis–Menten kinetic parameters of vm=44.25 g/L/day and Km=76.02 g/L for 4th phase and vm=86.96 g/L/day and Km=66.26 g/L for 5th phase. Non-competitive inhibitions can be identified between these phases, thus best to arrest recirculation after 21 days and continuous feeding from then on.