Design And Research On Lingdong Sewage Treatment Plant In Wafangdian City

With the rapid economic development, living standard of people has been greatly enhanced. Simultaneously urban sewage increased year by year and sewage ingredients became more and more complex. So sewage discharge standards become stricter, which had brought some pressure and challenges to sewage treatment plants. Therefore, it’s important and difficult to select a sewage treatment process which was of stable treatment effect, small footprint, low operating cost, high removal rate of pollutant and advanced control system.In recent years, urban construction and industry of Wafangdian City developed fast and showed strong momentum. Lingdong region, as new planning area surrounding Wafangdian City, developed faster under economic radiation of Wafangdian City, with which industrial wastewater and sewage emissions increased greatly. So construction of Lingdong sewage treatment was necessary to solve water pollution in Lingdong region, which would result in significantly environmental and social benefits. In this paper, natural conditions and water quality of urban sewage for Wafangdian City were explored. Then based on the case of existing sewage treatment, technology selection and engineering design parameters were designed and demonstrated feasibility, so that the effluent quality of wastewater treatment plant could reach emission standards and improve the discharge status of existing sewage. Though the economic evaluation, it is determined that whether economy of sewage treatment plant was in compliance with the economic sewage treatment industry. Details were as follows:(1) Through investigating the natural condition of the region and present situation and planning of existing urban drainage system, results showed that the sewage treatment could achieve perfect treatment effect as long as it was of reasonable process scheme, design parameter and engineering measures.(2) It was determined the A2 O process as a secondary treatment process, microflocculation process as the further wastewater treatment process. Generated sludge was concentrated and mechanical dewatering by gravity and frame filter. Then the treated urban wastewater was disinfected and deodorized by ultraviolet and bio-filter.Finally, according to the process of sewage treatment, the parameters of buildings, electrical, heating, and ventilation were designed properly.(3) Through estimating cost, liquidity and risk analysis, it was concluded that the financial internal rate of return before tax was 5% higher than the industry benchmark yields, the payback period of investment was lower than the standard benchmark payback period of 15 years. the net present value was greater than zero, so it meant the needs of industry requirements.