Partial treatment of bread oven sewage
In most cities in China, sewage treatment plants with centralized bread ovens have not yet been built. For the enterprise drainage pipe network without a sewage treatment plant, the domestic sewage and production sewage discharged indoors are required to be discharged after partial treatment. Although some cities have sewage treatment plants, some sewage treatments require partial treatment in advance. The local treatment structures generally include a septic tank, a degreasing tank, a sedimentation tank, a cooling pool, a disinfection tank, and the like. For the surface sugar food factory, the septic tank can be used for treating the domestic sewage, and the degreasing tank can be used for the treatment of the high-oil production sewage.
Septic tank: Indoor domestic sewage contains a lot of organic impurities such as feces, paper scraps, and pathogen eggs. After the domestic sewage is discharged, it is discharged into the septic tank and discharged into the urban pipe network after staying in the pool for several hours. About 50-60% of the organic pollutants in the sewage are deposited at the bottom of the pool and become sludge. The sludge stays in the pool for several months. Under the condition of anoxic conditions, part of the hydrolyzed liquefaction is discharged with the sewage by means of the biochemical action of the anaerobic bacteria, and a part of it is vaporized into biogas, carbon dioxide, hydrogen sulfide, etc. by the drainage system. The ventilation ducts are drained; the rest are stable high-fertilizer organics that can be used regularly for agricultural fertilizers. After the sewage is treated in the septic tank, the content of bacteria, parasites and viruses can be reduced by 25 to 75%.
The septic tank can be a rectangular or circular tank, which can be made of brick or reinforced concrete. In order to reduce the contact time of sewage and sludge, it is convenient to clear the sludge, and the pool is often divided into two or three compartments.
The septic tank is usually located on the side of the back of the bread oven building, close to the sewage outlet pipe. The wall of the pool shall be no less than 5 meters from the outer wall of the building. There should be a sanitary protection distance of not less than 30 meters between the septic tank and the water source (well).