Onsite anaerobic treatment of tomato plant waste as a renewable source of energy and biofertilizer under desert conditions

Crop residues, such as toxic tomato plant wastes, often cause environmental and economic burdens. Anaerobic digestion of these residues, which contain hardly biodegradable lignocellulosic content and low C/N (~10), was not thoroughly studied or practiced. This study investigated the impacts of temperature and particle size on anaerobic degradation performance of tomato plant waste in both laboratory and field scales (the latter was studied for one year under desert conditions). The highest batch degradation rate was observed for the smallest particles <0.15 mm and highest temperature (35 °C). In the field reactor, 89 % of the organic carbon was recovered as biogas containing 62 % CH4. The average biogas yield was 0.55 m3/kg-VS. The digestor supernatant contained N and P of 657 mg/L and 76 mg/L, respectively, mostly as ammonia and soluble reactive-P. Onsite anaerobic digestion of tomato plant waste can efficiently reduce pollution burden, produce biogas, and recover nutrients under desert conditions.