Influence of the organic volumetric loading rate on soluble chemical oxygen demand removal in a down‐flow fixed‐bed reactor treating abattoir wastewater

Abstract

AbstractA laboratory‐scale anaerobic down‐flow fixed‐bed reactor, operating at 35°C, was used to treat abattoir wastewater at input soluble chemical oxygen demand (COD) levels ranging from 4·7 to 28·7 g sm−3 and volumetric organic loading rates ranging from 2·5 to 25 g COD dm −3 day −1. Start up of the reactor was achieved within 35 days using a regime that include stepped increases in input COD and methanol substitution. The effects of the organic volumetric loading rates on soluble (COD) (SCOD) removal were studied at four feed SCOD concentrations between 4·7 and 28‐7 g dm−3. An exponential dependency of the organic volumetric loading rate with the SCOD removal was observed in the range of loading studied, with variation between 1 and 12 g COD sm−3 day −1 Further increases of the organic loading rates has smaller effects on SCOD removal. A pseudo first‐order kinetic model was used to obtain the gross removal coefficients, the values of which were virtually independent of the feed COD concentration at 6·9 to 7·3 g COD dm −3 day −1. The methane yield coefficient decreased slightly from 0·34 to 0·31 dm 3 g −1 COD when the feed SCOD concentration was increased from 4·7 to 28·7 g dm −3.