Effect of Starting pH on the Produced Methane from Dairy Wastewater in Thermophilic Phase

The experimental study was undertaken in order to evaluate the effects of the initial pH on the anaerobic digestion of dairy waste. The biodegradability tests were carried out in a series of reactor of 400ml of volume with four arrangements of the initial pH (pH= 4; 5.5; 7; and 9.5) in thermophilic phase (T = 55 degrees C). The dairy wastewater was the only source of organic carbon. After the incubation period (50 days), the result show that the height efficiency of removal COD (about de 90.8 %) was obtained for initial pH = 7, allowed by Reactor of pH=9.5 79.64 %; pH=5.5 63.75 % and finally pH=4 (49.11%). Concerning the produced biogas it volume was: 163ml, 1000ml, 2000ml and 1500ml for pH= 4; 5.5; 7 and 9.5 respectively. However the produced of CH4 for pH=4 is negligible, for the pH=5.5 and pH=9.5 is slightly over 50 % and 75 % respectively compared to the production of the test pH=7 It can be concluded that dairy waste degradation in anaerobic process can happen optimum on range neutral pH.