| With the raise of awareness in water protection and overall rural-urban development, and due to the widely-built water treatment facilities, the quality of the water in rural areas has been ameliorated tremendously. Currently, the treatment of waste water collected from large cities, towns and large settlements is apparently more effective than that of waste water collected from dispersing peasant households.As the only municipality in the south-west of China, Chongqing has fixed features of big cities, big villages and big reservoirs. In 2007, Chongqing was listed to be one of the comprehensive reform pilot areas of the national rural-urban overall development which, since, has become a national developmental priority. In 2009, Chongqing was granted with exclusive privileges stipulated in the No.3 file from the State Council. One core of the file is environment protection. In reality, villages scatter in the hilly areas in Chongqing far and wide, so does the waste water, hence the difficulty of collective treatment. Despite the attainments (due to a number of major water treatment project, namely, the eco-family project based on the loan from the World Bank, the Cleaning project in the rural areas in Chongqing, and the project of building beautiful villages) of collective treatment for waste water and the emerge of innovative techniques, in recent years, many managerial and technical problems are still open to resolutions.With the waste water(from single household, small, middle to large household) being the subject, this dissertation first discusses the current situations, the positions, and the managerial and technical problems of the decentralized water treatment in Chongqing, by collecting data, referring literature, interviewing farmers, sampling in field trip and statistical analysis. Then, it sheds a light on the influence that the farmers’awareness to protect the environment has on the eventual effect of water treatment. Also, using different models and methods, it establishes a list of evaluation standards with which the suitability of techniques of different scales is assessed. Most importantly, this dissertation makes a recommendation for choice of water treatment and introduces an insight into the solutions to the managerial and technical problems in water treatment.The conclusion from the research as followed:(1) The quantification of the degree of peasant households being decentralized is established. The average dispersing coefficence is 0.55. The higher the rate, the more decentralized the peasant households, the more difficult the collection of waste water and the more the needs of waste water treatment.(2) The average coverage of water treatment facilities in Chongqing is 87.29%. In Jiangbei District (99.46%), Nan’an District (98.23%), Shapingba District (96.94%), Bishan District (90.97%), the coverage rate is higher than 90%.(3) The population range that a single water treatment facility can satisfy is 3.90～11.00/per facility, with the average being 6.5. The range of hydraulic loading is from 0.26～1.80m3 per facility, with the average being 0.59. The range of occupied area is 2.62 to 6.11m2 per facility, with the average being 3.37. As the population famers increases in an area, the three indexes of a water treatment facility incline remarkably.(4) The decentralized water treatments in the rural areas in Chongqing include septic-tank, biogas digester, anaerobic-aerobic integrated reactors, the anaerobic pond -plants, anaerobic biological filter, anaerobic - ecological purification ditch, anaerobic -shortcut nitrification, the anaerobic - existes oxidation, anaerobic - clarification pool, hydrolysis acidification - adsorption filtration, hydrolysis acidification - contact oxidation, anaerobic - artificial wetland, the aeration oxidation - adsorption filtration etc. 13 types of facilities. Septic-tank and biogas digesters are in the majority of single and small facilities. Anaerobic - artificial wetlands are in the majority of Middle and big household facilities.(5) Established 7 standards for the suitability of decentralized water treatment techniques. They are the remove rate of COD, the remove rate of NH4+, construction cost, operation cost, land occupation, convenience of techniques. Based on the results from different analytical levels and considering the requirements for treatment scale and quality of water produced, it’s recommended that Septic tanks and biogas digester for single household, anaerobic - flower-stand wetlands and anaerobic - existes oxidation for middle household and anaerobic - artificial wetland and the integration of anaerobic aerobic reactor for big household.(6) The main problems of the decentralized water treatment in the rural areas in Chongqing are the households being scattered, the collective rate of waste water being low, the daily change rate of the quantity of waste water being large, the design volume of waste water treatment being overly large, the pattern of the waste water treatment being unreasonable, the financial condition of the government being poor; allocation of responsibilities being obscure, following management, policies, regulations and standards not being in place and the awareness of water conservation being low. Given these problems, it’s crucial to enact regulations accordingly and reinforce the water treatment so as to promise a sustainable development of water treatment.In light of the diversity in the eco conditions in the rural areas in Chongqing and the economical gaps between different social classes, time is still essential to the exploration of waste water treatment. The feasibility of the water treatment techniques and omission quantities recommended in this dissertation is still open to verification on larger statistical samples. |
PDF Full Text Request