Anaerobic treatment of a medium strength industrial wastewater at low-temperature and short hydraulic retention time: A pilot-scale experience

摘要

The aim of this work was to evaluate the performance of a pilot-scale upflow anaerobic sludge blanket (UASB) reactor during the treatment of cereal-processing industry wastewater under low-temperature conditions (17 °C) for more than 300 days. The applied organic loading rate (OLR _(appl)) was gradually increased from 4 to 6 and 8 kg COD _(sol)/m~3d by increasing the influent soluble chemical oxygen demand (COD_(sol)), while keeping the hydraulic retention time constant (5.2 h). The removal efficiency was high (82 to 92%) and slightly decreased after increasing the influent COD_(sol) and the OLR_(appl). The highest removed organic loading rate (OLR_(rem)) was reached when the UASB reactor was operated at 8 kg COD_(sol)/m~3d and it was two times higher than that obtained for an OLR_(appl) of 4 kg COD _(sol)/m~3d. Some disturbances were observed during the experimentation. The formation of biogas pockets in the sludge bed significantly complicated the biogas production quantification, but did not affect the reactor performance. The volatile fatty acids in the effluent were low, but increased as the OLR_(appl) increased, which caused an increment of the effluent COD_(sol). Anaerobic treatment at low temperaturewas a good option for the biological pre-treatment of cereal processing industry wastewater.