Treatment of hemodialysis wastewater by aerobic granular process

• Main Authors: Chih-Hsiang Cheng, 鄭至翔
• Other Authors: 李奇旺
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/36824562524596838889

碩士 === 淡江大學 === 水資源及環境工程學系碩士班 === 101 === Hemodialysis wastewater contains high concentration of ammonia nitrogen (about 60~70 mg/L). It may cause serious water pollution if the wastewater is not properly treated. Literatures showed that aerobic granule process has good stability, maintains high sludge concentration, withstands high organic loadings, and can remove ammonia nitrogen effectively. In this study, aerobic granular process was used to treat hemodialysis wastewater collected from a local clinic. Both aerobic granular process and activated sludge process in the existing activated sludge process were compared side-by-side for removing chemical oxygen demand (COD) and ammonia nitrogen of hemodialysis wastewater. At first, cultivation of aerobic granule using hemodialysis wastewater was conducted in the laboratory to observe granule formation and treated water quality. The result shows that aerobic granule can be cultivated in SBR reactor using hemodialysis wastewater as substrate, having outstanding treatment efficiency. After a three-week operation, aerobic granules were formed in SBR reactor, achieving more than 95% of COD and ammonia nitrogen removal efficiency. Besides, complete oxidation of ammonia nitrogen to nitrate nitrogen was observed in the aerobic granule process. Thereafter, SBR reactor was moved onsite to the clinic and was operated side-by-side with the activated sludge process in the existing wastewater treatment plant. Influent and effluent of SBR reactor and of the existing treatment process were collected and brought back to laboratory regularly for water quality analysis to compare the performance of two systems. No aerobic granules formed during the course of six-month study due to raw water containing sodium hypochlorite, which was used to sterilize medical devices at the end of each business day. Therefore, the onsite SBR reactor was operated as a normal activated sludge system. Less than 85% of COD and ammonia nitrogen removal efficiency was achieved for both systems. Furthermore, the SBR reactor was only capable of oxidizing ammonia nitrogen into nitrite nitrogen, while no ammonia nitrogen removal was observed for the activated sludge process of the existing treatment plant. Comparison of SBR reactor in the laboratory with SBR reactor onsite, this study confirmed that aerobic granule process achieved better nitrification efficiency and produced better treated water quality than activated sludge process.