Abstract
In order to develop a simple operation and low cost denitrification process for swine wastewater, autotrophic denitrification using baffled reactor filled with sulfur powder was investigated. The reactor consisted of five chambers separated with a series of vertical baffles that direct the wastewater under and over the baffles as it passes from the inlet to the outlet. This structure allows wastewater to come into intimate contact with sulfur powder as it passes through the chambers of the reactor. Twenty seven kilogram sulfur powder for soil pH conditioning was filled in a 311L baffled reactor composed of fisheries tank. Swine wastewater after treated with activated sludge plant in a farm was fed to the reactor with hydraulic retention time of 9 to 36 hours. Sodium bicarbonate solution was continuously added to the influent for supplying CO2 to sulfur oxidizing bacteria and neutralize the effluent. Concentration of nitrate nitrogen of influent was approximately 270mg/L. Removal rate of NOx-N after reclamation of denitrifing sulfur oxidizing bacteria was averaged 99.6% in RUN 1 (water temperature 17 to 21°C, NOx-N loading rate 0.2 to 0.3kg/ton-S・d), 77.9% in RUN 2 (water temperature 16 to 21°C, NOx-N loading rate 0.3 to 0.4kg/ton-S・d), and 47.9% in RUN 3 (water temperature 12 to 14°C, NOx-N loading rate 0.6 to 0.8kg/ton-S・d). It was suggested that the baffled reactor filled with sulfur powder was suitable for stable and simple denitrification of swine wastewater.
