2. Material and methods
2.1. Material
The biological samples on which we work are the WAS and Cattle dung.
The simpling of WAS was done in the urban wastewater treatment plants in Boumerdes, Algeria whose it’s retention time in the extended aeration process (sludge age) was 10 days.
Then Cattle dung was obtained from bovine’s cattle farm, they characteristics are shown in table 1. The material has been homogenized in an electric blender.
The samples have been stored at 4°C in a refrigerator until usage.
2.2. Anaerobic digestion
Microorganisms for anaerobic digestion consisted in start of those present in aerobic activated sludge inoculated
with rumen microorganisms of cattle dung.
The reactor for anaerobic digestion had a volume of 5 L and its working
volume of 4.5 L. It was also equipped with gas and sludge sampling ports.
When subtract was added, reactor was purged with helium gas to eliminate air from the reactor.
The mixed sludge was stirred in the digester without oxygen contact. The reactor was incubated at 55 °C and the biogas volume generated was measured by liquid displacement (water, pH 2, NaCl 10%).
2.3. Analysis
Total solid (TS), volatile suspending solid (VS) and Chemical Oxygen Demand (COD) were determined according
to Standard Methods APHA, 1995 [15] Biogas samples were collected using a gas sampling injector and a sample of 100–200 L was used for each run. The biogas composition (CH4+ CO) was determined using a gas chromatograph(GC-HP 5890) equipped with a thermal conductivity detector (TCD) and stainless steel column that 2