One, the definition of urban sewage and sewage characteristics
(a), the definition
The urban sewage refers to the urban residents living sewage, institutions, schools, hospitals, commercial services and a variety of public **** facilities drainage, as well as allowed to be discharged into the urban wastewater collection system of industrial wastewater and early rainwater, etc., can be divided into a variety of domestic sewage, industrial wastewater and seepage into the groundwater (rainwater) three parts. Rainwater) three parts. Urban sewage treatment system is the collection, transportation, treatment, regeneration and utilization of sewage of these facilities in a certain way combined into a total.
(ii), characteristics
1. Physical indicators. The physical indicators of water quality in municipal wastewater plants generally include: water temperature , odor, color, redox potential, chromaticity, conductivity and so on.
2. Chemical indicators. Chemical indicators can be divided into four categories: general water quality indicators, such as pH, hardness, alkalinity, residual chlorine, a variety of anions and cations, etc.; organic content indicators, such as biochemical oxygen demand BOD5, chemical oxygen demand CODcr, total oxygen demand TOD, total organic carbon TOC, etc.; plant nutrient indicators, such as ammonia nitrogen, nitrate nitrogen, nitrite nitrogen, phosphate, etc.; toxic indicators, such as petroleum, heavy metals, cyanide, sulfur, etc. toxic substances indicators, such as petroleum, heavy metals, cyanide, sulfide, polycyclic aromatic hydrocarbons, a variety of chlorinated organic compounds and a variety of pesticides and so on. General urban sewage treatment plants need to analyze the chemical indicators are: pH, alkalinity, CODc, BOD5, nitrogen and phosphorus, residual chlorine.
3. Biological indicators. Biological indicators of wastewater are total bacteria, coliforms, various pathogenic microorganisms and viruses. Wastewater treatment plants generally do not detect and control biological indicators of incoming water, but disinfection of treated wastewater before discharge, in order to control the pollution of treated wastewater on the receiving water body.
Two, the development of urban sewage treatment plants
From the 1970s, China began to focus on carrying out the construction of urban sewage treatment facilities. At that time, the urban sewage treatment plant capacity of about 1.73 million m3, sewage is mainly domestic sewage, the proportion of 50%, in addition to petroleum, chemical, paper and other industrial external drainage. To the 80's, tianjin jizhuangzi sewage treatment plant - China's first large-scale urban sewage treatment plant was completed and put into operation opened the curtain of China's urban sewage construction work, provinces and cities have been put into the construction of work, such as Beijing, Shanghai, guangdong, hebei, hubei, zhejiang, jiangsu and so on. During the "Eighth Five-Year Plan" period, the annual sewage treatment volume of China's cities reached 1.749 billion m3, with a treatment rate of 8.69% and a drainage network penetration rate of 64.8% (calculated according to the service area). The number of urban sewage treatment plants reached 169, with 116 secondary biochemical sewage treatment plants.
Three, the study of urban sewage treatment plant construction
(A), urban sewage treatment, the government attaches importance to
The construction of urban sewage treatment facilities by the national government departments at all levels of the importance of the work, are aware of the development of Western countries can not take the "first pollution, and then governance" of the old way, the environmental, economic and social benefits of unity. The unity of environmental, economic and social benefits is the key to sustainable development in China. Recognize that environmental improvement plays an increasingly important role in local investment promotion work. From the implementation of the sustainable development strategy, to energy saving and emission reduction of the national policy, all from the policy level to the town sewage construction work as a long-term, unremitting work to carry out.
1, government-led, leading the construction
Strengthened local governments at all levels of the guiding role, to strengthen the policy orientation, to guide the construction of effective work. With the central government taking the lead, provincial and municipal governments have played a leading role. In the actual work, they adhere to the principle of adapting to local conditions, do not blindly copy ready-made experiences, and study local conditions in depth to explore construction and operation modes that meet local characteristics. Taking the sewage charging system as an example, various places start from improving and strengthening the means of charging, for the standard of levy and the adjustment of levy rate are arrived at after conducting market research. In the use of sewage charges, refine the management norms, strengthen the government supervision and social supervision, and gradually explore another way of operation and management, change the old mode of government financial inputs as the source of funds to maintain the operation of urban sewage treatment plants.
2, the transformation of the way of project investment
The government drew on the construction experience of advanced countries, the introduction of BOT mode of operation. BOT is a way of infrastructure investment, construction and operation, to the agreement between the government and the private sector as a prerequisite for the government to issue concessions to the private sector to allow it to raise funds to build a certain period of time to build a certain infrastructure and management and operation of the facility and its corresponding products and services with a certain amount of money to the private sector. The government issues a concession to the private organization allowing it to raise funds to build a certain infrastructure and to manage and operate the facility and its corresponding products and services for a certain period of time. The risks of the entire process are shared between the government and the private organization. At the end of the concession period, the private organization transfers the facility to a government department as agreed, to be operated and managed by a government-appointed department. This model is a milestone in China's urban sewage treatment construction business.
3, the improvement of urban sewage treatment planning and design
such as the determination of the scale of construction, consider the indicators are mainly the scope of services, the population within the scope of services provided, economic and technological development. In the rapid economic development of the town today, the future level of economic development is also an important indicator to be considered. The more thorough and in-depth the consideration of these elements in the project premise, the less risk will be borne for the future commissioning and operation of the project.
4, the penetration of science and technology
The information management of urban sewage treatment to the digital transformation, the establishment of a **** enjoy the digital information system, the initial realization of the project was completed and the operation of the dynamic management. On the one hand, for the government to grasp the coverage of urban sewage treatment facilities, treatment rates, facility utilization and reduction of pollutants discharge rate and other indicators to provide a convenient, on the other hand, the new information management system for sewage plants to solve the problem of improving the management capacity of the plant to enhance the effect of sewage treatment, to avoid the operation of the randomness, to ensure the implementation of energy conservation and emission reduction in practice.
Four, urban sewage field operation problems
(a), at present, China's central and eastern developed provinces and cities have basically built sewage treatment facilities, most of the small and medium-sized towns have not yet built the relevant sewage treatment facilities. To solve this regional development imbalance will be the "Twelfth Five-Year" period of water pollution control work objectives.
(2), the project before the research work to be scientific and rationalized. In some places in the construction work, before the project research work in form, for the project scale, scope of service, selection of technology, etc. is not based on the actual situation of the local determination, there are high investment costs of the project, the treatment of the load rate is low, resulting in a waste of resources. Small and medium-sized towns have their own characteristics of sewage treatment, should not be copied from other areas of the model, should draw on its useful experience, take the economic, efficient, easy to implement the model.
(C), sludge treatment and disposal facilities are backward. The phenomenon of random transportation and indiscriminate disposal of sludge without dewatering has been greatly improved compared with the early stage of construction, but there still exists the situation that sludge treatment is not stabilized, and the water content of dewatered sludge does not meet the requirements of mixed landfill. The root cause lies in the fact that sludge treatment has not been emphasized, the proportion of investment in some sewage treatment plants is low, and the sludge treatment and disposal facilities that have been built have not been functioning properly. The completion rate and utilization rate of sludge treatment facilities will be an important issue affecting the development of China's urban sewage treatment business.
(E), urban sewage treatment plant operation and management is not high. According to information, the current domestic sewage plant is mainly taken to monitor the software to collect the equipment status signals, summary and output is relatively simple; operators of the management, there is no processing efficiency, operating costs according to the relevant technology, performance appraisal, operating costs are high. In addition, should also improve the sewage plant laboratory and analysis equipment and operating specifications, strengthen the monitoring of water quality, and improve the system's compliance rate.
Fifth, the development trend of urban sewage treatment plants
From the "12th Five-Year Plan" Outline, in the country's "energy-saving and emission reduction" policy to vigorously promote the cause of urban sewage construction will continue to promote. In the future construction tasks, the focus of the work are: nitrogen, phosphorus nutrient removal; industrial wastewater management to the whole process of control changes; the construction of sewage treatment facilities to the centralized treatment model changes; will be proposed more reasonable, more standardized water quality control indicators; accelerate the small and medium-sized towns and cities in the sewage treatment planning and construction work, and so on. Such as the establishment of local government departments as the main responsibility for the system; according to the characteristics of each region, the establishment of sewage charging system in line with the market mode of operation, to maintain the effective operation of sewage treatment facilities; increase the introduction of social capital to encourage more social forces to participate in the construction of China's sewage treatment business.
Sixth, conclusion
The development of urban sewage treatment, directly related to the city, towns and cities of public **** health and safety and improve the quality of human environment. Under the guidance of the national "Tenth Five-Year Plan", the construction of urban sewage treatment facilities in China will start another new pattern.
The above is collected and organized by Zhongda Consulting
For more information about engineering/service/procurement bid writing and production, to improve the bidding rate, you can click on the bottom of the official website of the customer service for free consultation:/#/?source=bdzd