Anaerobic treatment of an apple processing wastewater

The new generation of anaerobic digestion systems provide a high level of performance under optimal conditions (~ 37°C). However, in practice many influents will be at lower temperatures - heating of digesters presents problems, particularly in developing countries where technical backup is limited. This paper reports on a study of the treatment of a low/medium strength apple juicing waste in an upflow anaerobic sludge blanket reactor (UASB) at temperatures Less than optimal (25°C and 30°C). Maximum loading rates of approximately 12 and 16 kg COD m−3 d−1 were attained at 25°C and 30°C, respectively, for Influent concentrations in the range 2500 to 5000 rag COD ℓ−1. The comparative treatment capacity is In accord with the reported temperature sensitivity of mesophilic anaerobic processes. Formation of pelletised (granular) sludge enabled high upflow velocities and low hydraulic retention times.