Impact of tumbling on production of biomethane from household waste.

Abstract

This study utilized nine anaerobic digesters (ADs) with individual capacities of 10 l to investigate methane (CH4) gas generation from various waste combinations and operating conditions, employing both non-tumbling and tumbling processes with the aid of the Taguchi method. The experimentation encompassed different varieties of fruit waste (FW), raw vegetable waste (RVW), and mixed cooked waste (MCW) at varying proportions (1:1, 1:1.5, and 1:2) and temperatures (35 °C, 40 °C, and 45 °C), along with multiple feed inputs. Additionally, the study assessed the impact of tumbling, examining durations of 0, 10, and 20 min at a speed of 15 rpm. The results yielded substantial insights, revealing coefficient of determination (R2) values of 94.76% and 98.48% for non-tumbling and tumbling processes, respectively. Under the conditions of 40 °C and a 1:1.5 ratio, the average optimal methane (CH4) gas generation in FW without tumbling was determined to be 37.12%. For RVW and MCW at ratios of 1:1.5 and 1:2, respectively, the estimated CH4 values were 26.7% and 26.68% at a temperature of 35 °C. Comparison between tumbling and non-tumbling conditions demonstrated noteworthy improvements in CH4 gas production. For FW, tumbling for 10 and 20 min resulted in 11% and 6% increases in CH4 gas production, respectively. Tumbling also led to substantial boosts in CH4 gas production for RVW, with 31.1% and 47.9% increases after 10 and 20 min, and for MCW, with 25.7% and 12.2% increases after 10 and 20 min, respectively. Tumbling enhances CH4 gas production in anaerobic digesters, promising for waste-to-energy conversion.