The overall efficiency evaluation of the wastewater treatment plant and gray water reclamation system

• Main Authors: Shou-De Chen, 陳守德
• Other Authors: Yung-Pin Tsai
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/86995869835543357828

碩士 === 國立暨南國際大學 === 土木工程學系 === 97 === The wastewater treatment plant in National Chi Nan University played an important role of prevention and control of regional water pollution. As the more strict regulation of environmental protection and the outdated apparatus of treatment plant, the treatment apparatus designed in the past have already not accorded with the new demand nowadays. The source of water is limited due to the geographical factor. In order to increase the available source of water, promotion of the gray water to retrieve and reuse is necessary. The gray water reclamation system constructed in National Chi Nan University had not suited measures to local conditions, and it resulted in the difficulty of operation. Thus, this study assessed systematically the functionalities of the wastewater treatment plant and the grey water reclamation system to improve the problems of old apparatus and operational deficiency. These two systems were assessed according to the water standard of gray water and further suggested the strategies to improve their efficiencies. There were nine deficiencies in both of the wastewater treatment plant and gray water reclamation systems. The improvement of five problems, including dissolve oxygen control, mechanical agitator of Sequencing Batch Reactor (SBR), sludge thickener, injector system of disinfection unit and reservoir, had already been finished. In addition, the assessment of other problems, including coarse bubble diffuser of SBR, mechanical screener of rainwater collection system, water pipeline of gray water reclamation system and lavatory system in dormitories, had also been finished, but not been improved yet. In the study, residual chlorine concentration was controlled by chlorine measurement instrument instead of conventional fix dose control in disinfection unit. The experimental result showed that Escherichia coli in gray water can be reduced to accord with gray water quality standard while the chlorine residual concentration is maintained at the level of 2-2.5 mgl-1. Because of the reservoir has already faced to eutrophication problem. It is needed to enhance the nitrogen and phosphorus removal of the wastewater treatment plant. In the nitrogen part, 25％ removal efficiencies of nitrate can be improved by controlling the stage time of the SBR process. By using sodium acetic acid as carbon source in anoxic phase can further achieve 30％ removal efficiencies of nitrate. In phosphate part, phosphate can be removed by poly aluminum chloride (PAC). About 100％ removal efficiencies of phosphorus could be achieved when PAC demand was 40 mgl-1,. The total PAC demand is 6 ton/year, and the cost of expenses for PAC is 228,000 NT$/year. The amount of produced chemical sludge is 24 ton/year, and the cost of expenses for treatment and disposal is 96,000 NT$/year.