In recent years, China has been continuously promoting the construction of "beautiful countryside" and integrating ecological civilization into the entire process of rural construction. The issue of sewage discharge and treatment in rural areas has also continuously attracted people's attention. Due to the much lower coverage of rural sewage treatment compared to urban areas, untreated rural domestic sewage is directly discharged, seriously affecting the quality of rural water environment and even the health and safety of rural residents. The rural sewage discharge system has different characteristics from urban areas:

l. The drainage points are relatively scattered in space

2. There are significant fluctuations in drainage volume and water quality over time

3. Inadequate drainage infrastructure and weak economic strength

Therefore, when selecting a rural biological sewage treatment system, attention should be paid to adapting to high impact loads, simplifying the process as much as possible, reducing treatment energy consumption and management difficulties, and at the same time, preventing secondary pollution as much as possible while meeting water quality standards.

Based on these requirements, the following treatment processes have been selected for rural domestic sewage treatment:

(1) Land treatment

The rapid infiltration treatment system using sand for infiltration is a commonly used technology for rural sewage land treatment. By filling the sand with smaller particle size filter media, pollutants are removed and purified during the infiltration process through the interception effect of sand and the biofilm treatment grown on the filter media.

Land treatment is a process with good results, low investment, and low operating costs, but it is not suitable for use in areas with tight land use and high environmental requirements due to its large land occupation, easy generation of odors, breeding of mosquitoes and flies, pollution of surrounding soil and groundwater, and secondary pollution.

(2) Artificial wetland

Artificial wetland wastewater treatment technology is a treatment method that purifies pollutants in wastewater by controlling the discharge of wastewater onto soil and land with aquatic plants, utilizing an ecosystem composed of soil microorganisms plants.

Compared with land treatment, artificial wetlands transfer the sewage treatment site from the land to the water surface and wetlands, so the occupation of land surface is relatively small. Plants planted in wetlands can also obtain certain economic or landscape benefits through harvesting. But the problem of secondary pollution still exists.

(3) Biological contact oxidation method

The biological contact oxidation method is an improved evolution from the contact aeration method based on the biological filter. By filling the oxidation tank with fillers and immersing all the fillers in sewage, aeration and oxygenation are carried out to ensure full contact between oxygen, sewage, and fillers. Microorganisms adhering and growing on the fillers can effectively remove pollutants from the sewage.

The biological contact oxidation method has the advantages of high volumetric load, short residence time, good organic matter removal effect, simple operation and management, and small footprint. However, the system cost and processing energy consumption are relatively high, and the fillers are prone to clogging.

(4) Multiphase cyclic processing

The multiphase circulation sewage treatment process is an improved technology based on the biological contact oxidation process. An umbrella shaped aeration device is installed on the upper part of the biological contact oxidation tank to circulate solid, liquid, and gas phases for sufficient contact.

According to the improvement measures of multiphase circulation sewage treatment process, the filling material is washed with a certain strength through the circulation effect to prevent blockage, the oxygen utilization effect is good, and the effluent quality is improved. The aeration facility is set at the top, which is easy to maintain and repair.

This article is compiled by domestic sewage treatment equipment and does not represent the views of this website.