Biofertilizer production from agriculture and livestock wastes by temperature-phased anaerobic digestion (TPAD)

• Main Authors: Chuang, Wei-Lun, 莊維倫
• Other Authors: Lin, Jih-Gaw
• Format: Others
• Language: en_US
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/28195824707492372167

碩士 === 國立交通大學 === 環境工程系所 === 101 === This study combined with temperature-phased anaerobic digestion (TPAD) and the concept of anaerobic co-digestion to treat agriculture and live stock wastes (pig manure and rice straw) and investigated the performances of TPAD system, anaerobic bioenergy production as well as biofertilizer production. Pig manure (PM) and rice straw (RS) are the main this type waste in Taiwan and the amount and strength compared to other agro-wastes are much high. In general, single source waste treated with anaerobic digestion often has poor reactor performances or microbial inhibition problems and results in a limitation of anaerobic treatment; co-digestion with two or more different sources wastes can effectively improve anaerobic performances and reduce operational problems. TPAD system, which includes the first thermophilic stage and the second mesophilic stage reactors, takes the thermophilic stage to improve the system performance, volatile solid (VS) removal, producing a large amount of biogas as well as pathogens elimination; while the mesophilic stage is responsible for polishing thermophilc effluent and strengthening the stability of whole system. Because the problem of laboratory equipments in this study caused a considerable impact in overall accumulation periods, the maximum VS concentration was 20 g VS/L in this research to avoid occurring obstruction problem. The data of pseudo-steady-state conditions showed that two ratios of PM and RS (PM:RS=80:20 and 90:10) could meet the Class A biosolids for the specifications of the VS removal and pathogens reduction. Organic nitrogen in the substrate was converted to ammonium, however organic phosphorus in the effluent sludge slightly increased after digesting. From the result of heavy metals, the concentrations of copper and zinc were much higher than other metals and exceeded Taiwanese standards for liquid fertilizers, moreover the concentrations of chromium and nickel were also likely to exceed the standards, indicating both the ratios of PM and RS in this study didn’t yet reach the optimum ratio.