Characteristics of Wastewater and Rice Straw in an Anaerobic Co-Digestion System

บทคัดย่อ

This research investigated the characteristics of wastewater and digested rice straw in a co-digestion system between swine wastewater and rice straw under anaerobic conditions. Effect of rice straw preparation in 3 different types, rice straw cut into 7-8 cm, rice straw cut into 7-8 cm and soaked with NaHO and rice straw without preparation, and effect of different digestion period, 2, 4, 6, 8 and 10 wk, on characteristics of wastewater and digested rice straw were evaluated. The results showed that organic compounds in wastewater and rice straw decomposed via digestion processes occurring in the system. Organic matter and nitrogen in digested wastewater were higher than those in raw wastewater. BOD5, COD and TKN of digested wastewater were 416.6-1,255.3, 1,520.0-2,600.0 and 200.0-308.6 mg/L, respectively in which different rice straw preparation showed effect on organic matter indicating with BOD5and COD of wastewater. The composition analysis of digested rice straw showed that organic matter, nitrogen and phosphorus of the rice straw increased while potassium and C/N ratio decreased. Organic matter, nitrogen, phosphorus, potassium and C/N ratio of digested rice straw were 28.6-346.3 %, 0.68-4.15 %, 0.06-0.48 %, 0.10-0.36 % and 34.4: 1-198.7:1, respectively. The result indicated that different digestion periods showed significant effect on most of characteristics of digested rice straw.