High rate aerobic treatment of brewery wastewater using the jet loop reactor

An aerobic Jet Loop Reactor (JLR) activated sludge process of 541. volume was used to investigate its suitability for the treatment of industrial wastewaters, specifically brewery wastewater. A loading rate of 50 kg COD/m3•d was achieved with 97% COD removal for a period of 5 weeks and although the settleability was found to be acceptable non-flocculating motile bacteria caused the effluent to be cloudy and have a high suspended solids concentration in the order of 200–350 mg/l. Investigations into how this loading rate was achievable and its consequences included measurements of oxygen transfer rate, Specific Oxygen Uptake Rate (SOUR), determination of Monod kinetic coefficients and microscopic examination. Oxygen transfer rates were found to be high, with a low energy efficiency possibly due to the small scale of the rig, SOUR values varied between 100–400 mg O2/g VSS•h for F/M ratios of 5–8 kg COD/kg MLVSS•d and the maximum growth rate was found to be 12.2/d with a yield of 0.4 kg VSS produced/kg COD removed. Although the Jet Loop Reactor was found to be a suitable method for pretreating brewery wastewater, an effluent polishing stage before final discharge to a water course would be necessary and it was concluded that further investigations into jet design may increase the oxygen transfer efficiency and quality of effluent.