Monitoring and testing of sewage and wastewater quality has become the basis and guarantee for sewage and wastewater treatment. In order to help relevant users learn and understand the latest technology of sewage and wastewater quality monitoring and the role of related instruments in it, talk about their views on the current status of sewage and wastewater quality monitoring in China.
In 2018, the national sewage treatment plants increased by 14.6% year-on-year, and the growth rate increased significantly. The number of urban drainage pipelines nationwide increased to 683,000 kilometers, a year-on-year growth rate of 8.4%. According to an average annual compound growth rate of 7.9% from 2009 to 2018, the length of drainage pipelines will exceed 700,000 kilometers in 2019. With the support of government policies, the sewage treatment industry has developed well in recent years, and the sewage treatment capacity has continued to increase. Data from the National Bureau of Statistics show that in 2018, the daily treatment capacity of urban sewage in my country has reached 181 million cubic meters, an increase of 6.5% over the same period last year.
The change from "scale growth" to "improvement of quality and efficiency" is the development focus and policy direction of my country's sewage treatment industry. The gradual improvement of sewage treatment laws, regulations and industry standards has promoted the overall improvement of sewage treatment production and supply capacity and the continuous upgrading of sewage treatment technology: the implementation of the "Urban Sewage Treatment Plant Pollutant Discharge Standard" has promoted a new round of urban sewage treatment facilities. Upgrading and reforming promoted the further improvement of sewage nitrogen and phosphorus removal technology. The release of the "Three-year Action Plan for Improving the Quality and Efficiency of Urban Sewage Treatment (2019-2021)" has promoted the technological upgrading of sewage treatment plants and the construction of drainage pipe networks. The core of wastewater treatment is the pipeline network. The current water environment problems in my country are mostly concentrated in the drainage system of the pipe network. The core problem caused by the imperfect construction of the drainage pipe network system is the poor efficiency of pollutant reduction caused by the low concentration of influent water of the sewage treatment plant. How to further monitor the water quantity and quality of the drainage network and early warning is one of the future development trends.
The demand for systematic and integrated sewage treatment is increasing, especially for the collection and treatment of scattered sewage in rural areas. The integration of plant and network, the combination of construction and operation and maintenance has become a development trend.
At present, China’s sewage treatment industry is mainly based on BOT (Build-Operate-Transfer: An agreement is reached between the government and private organizations, and the government issues a concession to the private organization, allowing them to raise funds to build a certain infrastructure and manage and operate it within a certain period of time. The facility and its corresponding products and services)/TOT (Transfer-Operate-Transfer: The government or state-owned enterprise transfers the property rights or management rights of the project for a certain period of time to the investor for compensation, and the investor conducts operation and management; the investor is within the agreed period After the contract expires, the investor returns the project to the government department or the original enterprise), the franchise model introduces social capital, and the traditional business model is shifted to the development path of privatization. The degree of privatization not enough. I believe that the development of the sewage treatment industry requires more participation of social capital. Actively deepening the market-oriented reform of the sewage treatment industry, and introducing a wide range of capital is one of the future investment directions. The combination of PPP, EPC, EPC+O and other investment, construction, and operation and maintenance modes will also accelerate the pace of marketization of water assets.
From the perspective of technologies related to sewage monitoring, the current conventional water quality parameter monitoring technology is relatively mature, and both foreign and domestic technologies have reached a high level. The difference lies in the accumulation of experience in the instrument industry, which is reflected in the long-term stable operation of the instrument, the completeness of the plan, detailed processing, and ease of operation. At present, the difficulty of water quality monitoring lies in the following: ① The instrument has poor adaptability and high requirements for the installation environment, especially for wet chemical instruments, which require better pre-treatment in areas with high debris content such as pipe networks or cement sand entering the plant. The processing process can ensure the normal operation of the instrument. At the same time, because the storage of reagents requires a certain temperature, there are also certain requirements for the installation point and environment; ②The maintenance frequency of the wet chemical method instrument is high, and maintenance work such as regular pipeline inspection, reagent replacement, and cuvette cleaning is required. The investment of a lot of manpower and material resources has affected the reliability of the instrument to some extent; ③The stability and accuracy of the electrode method instrument need to be further improved.
In addition to conventional water quality parameter testing, online monitoring of discharge outlet TOC, comprehensive toxicity of discharged water quality and E. coli are also indicators of concern.