Application of the upflow anaerobic sludge bed (UASB) process for treatment of complex wastewaters at low temperatures

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Abstract
The feasibility of the upflow anaerobic sludge bed (UASB) process for the treatment of potato starch wastewater at low ambient temperatures was demonstrated by operating two 5.65‐L reactors at 14°C and 20°C, respectively. The organic space loading rates achieved in these laboratory‐scale reactors were 3 kg COD/m3/day at 14°C and 4‐5 kg COD/m3/day at 20°C. The corresponding sludge loading rates were 0.12 kg COD/kg VSS/day at 14°C and 0.16−0.18 kg COD/kg VSS/day at 20°C.These findings are of considerable practical importance because application of anaerobic treatment at low ambient temperatures will lead to considerable savings in energy needed for operating the process. As compared with various other anaerobic wastewater treatment processes, a granular sludge upflow process represents one of the best options developed so far. Although the overall sludge yield under psychrophilic conditions is slightly higher than under optimal mesophilic conditions, this doesn't seriously hamper the operation of the process. The extra sludge yield, due to accumulation of slowly hydrolyzing substrate ingredients, was 4.75% of the COD input at 14°C and 1.22% of the COD input at 20°C.