Due to the limitations imposed by the level of regional economic development, effective control of rural water environmental pollution is often not achieved. It is estimated that over 8 billion cubic meters of domestic wastewater are generated annually in rural areas across the country, with the majority being directly discharged into water bodies without any treatment, posing a serious threat to groundwater safety. To address the wide distribution, dispersion, and diverse sources of rural domestic wastewater, various treatment technologies have been explored both domestically and internationally, including anaerobic digester water treatment, stabilization pond wastewater treatment, and constructed wetland wastewater treatment. These commonly used technologies have the advantages of one-time investment, convenient installation, and simple maintenance, making them suitable for on-site treatment of small volumes of rural domestic wastewater. However, the effluent quality of most treatment facilities only meets the Class B standard of the pollutant discharge limits specified in the GB18918-2002 "Pollutant Discharge Standards for Urban Sewage Treatment Plants". The combination of integrated wastewater treatment equipment and constructed wetlands has been studied experimentally for the treatment of dispersed rural domestic wastewater.
For decentralized wastewater treatment in rural areas, three main types of technologies and processes are commonly used domestically and internationally. The first type involves miniaturizing traditional secondary biological treatment processes used in urban sewage treatment plants, such as sequencing batch reactor (SBR), oxidation ditch, A/O, A2/O, MBR, etc. From a technical perspective, these technologies and processes are relatively mature and can meet the requirements of wastewater treatment. The second type includes some relatively simple ecological wastewater treatment technologies, such as constructed wetlands, oxidation ponds, and land treatment systems. These technologies have the advantages of simple processes, small investment, low energy consumption, easy maintenance, and environmental friendliness. The third type is anaerobic treatment technology, which has the advantages of simple processes, low energy consumption, low sludge production, low nutrient requirements, and a wide range of adaptability compared to traditional aerobic technologies. Therefore, anaerobic technology has received widespread attention. Anaerobic treatment systems primarily based on anaerobic reactors are low-cost wastewater treatment technologies that can also recover and utilize energy. Many developing countries face severe environmental problems, energy shortages, and inadequate funding, requiring effective, simple, and low-cost technologies. Therefore, anaerobic biotechnology is particularly suitable for China's national conditions. For rural domestic wastewater treatment, organic wastewater from human and animal excreta, crop straw, weeds, leaves, and organic wastewater from agricultural product processing enterprises can be added to anaerobic digesters for simultaneous anaerobic treatment with domestic wastewater. The generated biogas can also be used as energy for bathing and cooking in households. Wastewater anaerobic digestion and biogas production technologies have been effectively promoted and used in some areas of China.
In the treatment process, domestic wastewater enters the collection well through sewage pipelines. Pre-treatment involves using perforated pipe screens to remove solid residues from the wastewater. Submersible lift pumps are installed within the grid chamber, fixed at the bottom of the chamber, to lift the wastewater into the integrated wastewater treatment equipment. The effluent from the equipment enters the constructed wetland system for ecological treatment, where pollutants in the wastewater are filtered, adsorbed by plant roots, decomposed by microorganisms, and absorbed by plants, among other processes, to achieve further treatment.
Adopting appropriate technologies based on local conditions and achieving the principles of "affordability, affordability, and good management" are important considerations. Emphasis should be placed on the aesthetic appearance of the equipment, and comprehensive ecological benefits and environmental aesthetics should also be taken into account as development trends.