Effect of Co-digestion in the Anaerobic Digestion of Sugarcane Effluents

Abstract

This study focused on the optimal conditions for the biodigestion of sugarcane effluents from Sucrivoire Zuenoula located in the southwest of Côte d’Ivoire. Thus, four experimental digesters were fed as follows: 1) sugarcane effluent ; 2) effluent + bagasse ash; 3) effluent + cow dung; 4) effluent + ash + cow dung. The results showed that the digesters operated in a mesophilic manner with temperatures ranging from 28.83 to 29.37 °C and an alkaline pH varying from 6.93 to 7.70. Regarding COD, it decreased in all digesters from 665.7 to 590.9 mg/L for D1; D2: 670.7 to 580.4 mg/L; D3: 2188.9 to 801.3 mg/L; D4: 1551.9 to 890.9 mg/L. As for TKN, it slightly decreased in all digesters (D1 : 79.17 to 60.45 mg/L D2: 670.7 to 580.4 mg/L; D3: 2188.9 to 801.3 mg/L; D4: 1551.9 to 890.9 mg/L). As for TKN, it slightly decreased across all digesters (D1: 79.17 to 60.45 mg/L; D2: 77.98 to 57.7 mg/L; D3: 558 to 220.1 mg/L; D4: 260.12 to 190.45 mg/L). For the volume of gas produced, it is significantly higher in digesters 2, 3, and 4 (0.018; 0.013; 0.058 m3) than in digester 1 (0.0062 m3). The flammability test of the produced gas is positive after 7 days in digester 2, after 6 days in digester 3, and after 4 days of operation in digester 4; the flammability test is negative in digester 1. Overall, the results of the study show that the co-digestion of sugarcane effluents with bagasse ash and cow dung is necessary for optimizing the biomethanization process.