BIOGAS PRODUCTION FROM WASTE ACTIVATED SLUDGE USING CATTLE DUNG INOCULUMS: EFFECT OF TOTAL SOLID CONTENTS AND KINETICS STUDY
S. Maamri and M. Amrani
Laboratory of Soft Technology, Recovering, and Sustainable Development, Faculty of Science, M’Hamed Bougara University, Boumerdes, Algeria
Waste activated sludge (WAS) resulting from wastewater treatment plants treating carbon and nitrogen pollution by extended aeration processes.
The propose of this study was to enhance the efficiency of digestion of WAS using cattle dung inoculums in semi continuous mode at laboratory scale in (5L) digester. The study was carried out at thermophilic temperature that is 60°C for a retention period of 13days. We studied the effects of total solid (TS) content of sludge on the biogas production, the methane content, the soluble COD reduction, the volatile solid reduction, and the total solid reduction. The biogas produced was collected by water displacement method which was subsequently measured. The digestion of WAS at concentration 35,8 g.L-1 gave the best results. The biogas production reaches 0.283 day-1, and the cumulative biogas production was 17 m3. M-3 at the end of the 13th day of the experiment. This amount of biogas with composition 82.59 % of CH4, and 14.6 % of CO2 is equivalent to 190 KWh of electricity. In this case, the rate of soluble COD reduction was 79.03%. Therefore, it is proposed to establish a kinetic model to predict methane production performance. The first order model based on the availability of substrate as the limiting factor was used to perform the kinetic studies of batch anaerobic digestion system.
The data obtained establish that WAS mixed with cow dung is an effective subtract for biogas production achieving high cumulative biogas yield with stable performance.