How to treat sewage?
According to local conditions, the construction mode and treatment process of combining pollution control and resource utilization, engineering measures and ecological measures, and centralization and decentralization are adopted
Deep in the mountains, the fields dyed green and gurgled out. Wang Xingmo, a villager in Wuling Village, Damu Township, Fuling District, Chongqing, used to water the corn field and need to rely on people to carry water up the mountain. Now he has a water pipe in the field and can open the valve to irrigate.
"It's all recycled water." "Waste water becomes fertilizer, saving money and fertilizing the land," Wang said.
Originally, in October 2021, the Wuling Village domestic sewage resource utilization facility project with a total investment of 2,643,900 yuan was completed, and the domestic sewage after resource treatment became recycled water, which can be poured by villagers. More than 30 mu of corn planted by Wang Xingmo's family relies on reclaimed water for irrigation. He said: "Listening to experts, recycled water is rich in nitrogen and phosphorus, can effectively improve soil fertility, and can save about half of the fertilizer application per mu." Together with the free irrigation of recycled water, my family's total income from planting last year increased by about 30,000 yuan compared with before the project was completed."
The mountains are high and the forests are wild. Wuling Village is located in the deep Wuling Mountains, more than 1700 meters above sea level, an area of 16.5 square kilometers, the population of only 350 people, scattered living in two village groups. If the centralized sewage treatment plant is built in the urban model, the pipe network has a large coverage, the sewage collection is low, and the construction cost is high, which is difficult for the village to afford.
How to find a low-cost, extendable path of rural domestic sewage treatment? In July 2020, Fuling District launched the construction pilot project of rural domestic sewage resource utilization facilities in Wuling Village.
Carrying a backpack, wearing a straw hat and sneakers, Ding Ying, head of the natural ecological protection section of the Fuling District Ecological Environment Bureau, plunged into the mountains and conducted field research in Wuling Village. The notebook is densely written - Wuling village is high in altitude, more than 2,000 summer tourists per day, the resident population is only a few hundred people in the tourism off-season, and the seasonal difference in domestic sewage treatment capacity is large, and there are peaks and troughs.
How to meet dynamic demand? According to the investigation, Fuling District Ecological Environment Bureau planned and designed two kinds of sewage treatment facilities. One is an integrated treatment facility with a capacity of 100 tons per day. After anaerobic treatment, aeration, cement separation and other technical links, the sewage is formed into standard discharge water. The other is the resource treatment facility, the construction cost is low, the daily treatment capacity is 10 tons, the sewage can not be discharged after treatment, but can be used to irrigate the dry land. The four sewage treatment facilities in the village are all started in the tourist peak season, and only the resource treatment facilities are used in the tourist off-season, and the operation and maintenance costs are greatly reduced.
In order to further reduce the operating costs of the facility, Ding Ying and his colleagues selected several sites and finally built the facility at a relatively low elevation in the village, so that the difference in height and height can be used to naturally collect sewage and reduce the electricity consumption of pumping water.
"The key is to treat rural domestic sewage according to local conditions." Ding Ying said that Fuling District has set up a rural domestic sewage resource treatment model of "septic tank effluent - ecological regulation tank water volume - pipeline network extension to crops - intelligent irrigation" by building facilities such as the new rural domestic sewage intelligent ecological control tank. "Villagers no longer have to pick and choose to bring water to the field." Wang Xingmo said.
In July 2019, the Central Agriculture Office, the Ministry of Agriculture and Rural Affairs, the Ministry of Ecology and Environment and other nine departments jointly issued the "Guiding Opinions on Promoting Rural Domestic Sewage treatment" (hereinafter referred to as the "Guiding Opinions"). "According to local conditions, the construction mode and treatment process combining pollution control and resource utilization, engineering measures and ecological measures, centralized and decentralized" and "actively promote low-cost, low energy consumption, easy maintenance and high efficiency sewage treatment technology".
In 2021, Fuling District raised more than 80 million yuan to implement domestic sewage resource utilization facility projects in 78 rural residential areas, serving about 38,000 surrounding population. In 2022, Fuling District will invest 20 million yuan to continue the construction of domestic sewage resource utilization facilities in the remaining 21 rural residential areas, and achieve full coverage of sewage treatment facilities in more than 100 rural residential areas in the district, saving 230,000 cubic meters of irrigation water and more than 70 tons of nitrogen and phosphate fertilizer use annually.
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