Nitrogen and phosphorus flow analysis from pig farming in Bang Pakong Basin, Eastern Thailand

Material/Substance Flow Analysis, a systematic environmental management method, is applied to assess the current situation of nutrient (nitrogen-N and phosphorus-P) pollution arising from pig farming (including slaughterhouse activities) in Bang Pakong Basin (BPB), Eastern Thailand. This study was conducted by using the present information, based on several reliable sources, for calculations. The results of this study indicate that water supply and animal feed are the main mass inflows to the pig farms totaling 9.86 and 0.61 million tons per year respectively. The key nutrient inflows from animal feed are calculated as approximately 15,000 tons of nitrogen and 3,300 tons of phosphorus per year. All wastewater from pig farming to degrade water quality of the basin is about five million tons per year, which contains 3,250 tons of nitrogen and 1,030 tons of phosphorus per annum. According to this study, three scenarios are set and proposed to reduce the nutrient loads into the receiving water of the basin: 1) if all farms gathered and recycled dung to use as fertilizer and fish feed, this act alone would reduce nitrogen and phosphorus by 11% and 12% respectively; or 2) collecting all wastewater to a treatment system could decrease nitrogen and phosphorus amounts by 14% and 8% respectively; or 3) by combining both scenarios (1+2) the overall reduction for nitrogen would stand at 23% and 18% for phosphorus.