OPTIMIZATION OF CASSAVA EFFLUENT BIOMETHANIZATION WITH ASH AS COSUBSTRATE

Abstract

The main objective of this study is to determine the optimal conditions for anaerobic biodigestion of cassava effluents with the ash of cassava peels as co-substrate. To do this, three (03) digesters were used in which were put effluent + ash for digester 1, effluent + ash + cow dung for digester 2 and effluent + ash + urine for digester 3. The physico-chemical parameters (temperature, pH), biochemical parameters (COD and TKN) and the volume of biogas produced were quantified. In each of the reaction media a decrease in values was observed in pH (digester 1: 7.15 to 6.92 digester 2: 7.20 to 5.38 digester 3: 7.00 to 5.28), COD (digester 1: 1.66g/l to 1.16g/l digester 2: 1.81g/l to 1.44g/l digester 3: 1.46g/l to 0.99g/l) and NTK (digester 1: 0.27 g/l to 0.24 g/l digester 2: 0.29 g/l to 0.22 g/l digester 3: 0.25 g/l 0.16 g/l). ¨For the temperature of the media, the recorded values are in the range of mesophilic fermentation (digester 1: 26.66°C, digester 2: 27.97°C and digester 3: 27°C). Regarding gas production, the digesters produced gas from day 1 with 37.463 m3, 37.463 m3 and 69.272 m3 respectively. A significant improvement in the biogas production rate was observed in all digesters. Thus, the ash could be used as a replacement for human urine for pH adjustment of cassava effluents.