Definition of domestic sewage:

The so-called domestic sewage refers to the sewage generated by people in their daily lives, mainly including kitchen wastewater, washing wastewater, and discharge wastewater

The hazards of domestic sewage:

1. Pathogen pollution: mainly from urban domestic sewage, hospital sewage, restaurant waste, airports, hotels, residential areas, etc.

2. Organic pollution: The common characteristic of organic matter is that these substances directly enter the water body and are decomposed into simple inorganic substances such as carbon dioxide and water through the biochemical reactions of microorganisms,

3. Total phosphorus and ammonia nitrogen pollution: It is a water pollution phenomenon caused by excessive content of plant nutrients such as nitrogen and phosphorus. Eutrophication of aquatic ecosystems can occur through two pathways of chemical pollutants: one is through an increase in the amount of inorganic nutrients that normally limit plants; Another way is through the increase of organic matter as decomposers.

4. Odor: Odor in domestic sewage is one of the more serious pollution hazards. It not only pollutes the water environment, but also causes inconvenience to residents' lives. There are over 4000 types of foul odors that humans can smell, with dozens of more harmful ones.

5. Acid, alkali, and salt pollution: Acid and alkali pollution cause changes in the pH of water bodies, disrupt their buffering effect, eliminate or inhibit the growth of microorganisms, and hinder the self-cleaning growth of water bodies, which has adverse effects,

6. The hardness of groundwater has increased.

Characteristics of buried domestic sewage treatment equipment:

1. Buried below the surface, the surface above the equipment can be used for greening or other purposes, without the need for building houses, heating, or insulation.
2. The secondary biological contact oxidation treatment process adopts push flow biological contact oxidation, which has a better treatment effect than fully mixed or two-stage series fully mixed biological contact oxidation tanks. And it has a smaller volume than activated sludge tanks, strong adaptability to water quality, good shock load resistance, stable effluent quality, and will not cause sludge expansion. A new type of elastic three-dimensional packing material is used in the pool, with a large specific surface area and easy biofilm formation and detachment by microorganisms. Under the same organic load conditions, it has a high removal rate of organic matter and can improve the solubility of oxygen in the air in water.
3. The biochemical tank adopts the biological contact oxidation method, which has a relatively low volume load of the filling material, and the microorganisms are in their own oxidation stage, resulting in low sludge production. It only takes more than three months (90 days) to discharge the sludge (using fecal trucks to suction or dehydrate into sludge cakes for external transportation).
4. The deodorization method of this buried domestic sewage treatment equipment not only uses conventional high-altitude exhaust, but also includes soil deodorization measures.
5. The entire equipment processing system is equipped with a fully automatic electrical control system and equipment fault alarm system, which operates safely and reliably. Generally, there is no need for dedicated personnel to manage it, and only timely maintenance and upkeep of the equipment is required.

Process flow diagram of buried domestic sewage treatment equipment:

Brief description of domestic sewage treatment process:

Wastewater is collected in the living area and enters the septic tank for initial sedimentation. It then enters the regulating tank through a grid well for uniform mixing. As wastewater may contain some large suspended solids, a grid is installed to remove them before entering the regulating tank. This can effectively reduce the subsequent biological treatment load and prevent large suspended solids from blocking the subsequent treatment equipment.

The wastewater treated by the grid flows automatically into the regulating tank. Anaerobic bacteria are introduced into the regulating tank to acidify and degrade the organic matter in the wastewater. After sedimentation, homogenization, acidification, and degradation in the regulating tank. The pump is lifted into the integrated treatment system of activated sludge method. The biochemical method mainly adopts a series process of acidification hydrolysis aerobic oxidation. The purpose of acidification hydrolysis is to hydrolyze and acidify certain high molecular weight substances and soluble substances with poor biodegradability in the wastewater, degrade them into small molecular weight substances and soluble substances, and create conditions for subsequent aerobic biochemical treatment. The aerobic oxidation process adopts the biological contact oxidation method, which is one of the commonly used aerobic biological treatment methods for large and medium-sized wastewater due to its ease of management, low sludge production, resistance to sludge expansion, and low operating costs. At the same time, the sludge generated by aerobic biochemical treatment is partially refluxed to the facultative biochemical section through the sedimentation tank to increase the microbial content.

After biochemical treatment, the water flows into the sedimentation tank and undergoes solid-liquid separation. After entering the clean water tank and being disinfected, it meets the discharge or reuse standards. Part of the separated sludge flows back into the biochemical system, while the remaining sludge is discharged into the sludge concentration tank.