The efficiency of UASB reactor treating dairy effluent at diferent organic loading rates

In this research it was evaluated the performance of a laboratory scale UASB reactor (Upflow Anaerobic Sludge Blanket) treating a simulated dairy wastewater. In order to obtain the same concentration of an ordinary dairy, in terms of COD substrate, it was carried out the dilution of type B pasteurized milk with drinking water at a mean concentration of 2,500 mg.L-1, similar to a dairy wastewater without milk serum. During 205 days of operation the reactor was evaluated considering the efficiency related to the organic loading rate, which varied according to the hydraulic detention time applied. The UASB reactor was operated at different hydraulic retention times, of about 12, 20, 18 and 16 hours. The initial (start-up) biological organic loading rate was about 0,054 kg DBO. kg TVS-1.d(-1). The observed removal efficiencies of organic matter in terms of COD (Chemical Oxygen Demand), were about 24, 43, 52 and 39%, whereas, the removal of TS (total solids) were about 22, 22, 17 and 17%, concerning to the respectively application of hydraulic detention times. The best results related to the removal of organic matter were obtained with the hydraulic retention time (HRT) of 20 and 18 hours. Under the applied temperature, the volumetric loading rate and hydraulic retention time, the reactor demonstrated good condition of buffering and efficiency.