Effect of Australian zeolite on methane production and ammonium removal during anaerobic digestion of swine manure. Issue 1 (February 2018) - Wijesinghe, D. Thushari N.
Highlights: Australian zeolite addition increased methane production significantly. Australian zeolite removed substantial amount of ammonium. The anaerobic digestion process was optimized by Australian zeolite. Abstract: Anaerobic digestion is one of the most effective methods for treating swine manure by converting it into green energy, and efficiently reducing methane (CH4 ) emission to the atmosphere. Low C/N ratio of swine manure and the production of high levels of total ammoniacal nitrogen (TAN) during acidogenesis due to the high N contents of swine manure considerably reduce CH4 yield. The reduction of N during anaerobic digestion by the addition of zeolite improves CH4 production and reduces potential environmental threats associated with ammonia (NH3 ) emissions from anaerobic digestion of swine manure. The main objective of this study was to determine the optimum Australian zeolite dose that produces maximum NH4 + recovery at optimum CH4 production. In laboratory experiments, swine manure was treated with natural and sodium zeolites at 0, 10, 40, 70, 100 mg/L and digested anaerobically for 60 days. Natural zeolite at a dose of 40 g/L resulted in the largest increase (29%) in total CH4 yield from swine manure compared to the nil zeolite treatments. The lag phase of digestion was decreased with increasing zeolite doses up to 100 g/L. Natural and sodium zeolites at a dose of 100 g/L reduced NH4 + by 50% and 52% in the media, respectively, compared to the nil zeolite treatments. However, the increases in CH4 yield of natural and sodium zeolites at a dose of 100 g/L were only 10% and 12%, respectively. Variations of cation concentrations in the digesters caused by adding zeolite at different rates might be a reason for variation of biogas and CH4 productions from various rates of zeolites digesters.