Introduction of washing wastewater treatment equipment
The wastewater discharged during the production process of the laundry industry contains a large amount of pollutants. The laundry wastewater mainly includes washing wastewater, cleaning wastewater and spin-dry wastewater.
Laundry wastewater has different characteristics: it contains surfactants, sodium tripolyphosphate, carboxymethyl cellulose, oil stains, dust particles, and various microorganisms. The appearance is turbid, with a COD of 300 to 800 mg / l and a pH of 6.5. ~ 7.5, high suspended matter content, generally at 500 ~ 1200mg / l. Phosphate entering the water body will cause eutrophication of the water body. After the surfactant enters the water body, it will cause vivid water and plant poisoning to death. Solubilizes certain micro-pollutants in the water;
In order to ensure the quality of the effluent from the treatment of laundry wastewater, the physical and chemical processes mainly adopt the following measures:
(1) Concentrate the three kinds of wastewater: washing wastewater, cleaning wastewater, and spin-dry wastewater to ensure that the source of wastewater treated by the process is relatively stable.
(2) When the laundry wastewater is discharged into the concentration tank, a grille is added to eliminate short fibers and some suspended matter in the water.
(3) Select a suitable flocculant for flocculation and sedimentation according to the wastewater quality, reduce the chroma, and remove suspended matter and some harmful impurities.
(4) Mechanical filtration of the supernatant liquid after flocculation and sedimentation of wastewater to ensure that the effluent is clear and transparent.
(5) Dosing oxidation, sterilization, and further treatment of mechanically filtered effluent to ensure that the quality of the effluent reaches the quality index for reuse.
(6) After adjusting the pH, enter the fresh water tank for laundry.
1. The number of structures is small and the cost is low.
2. The structure is simple and the combined construction method is conducive to the expansion and transformation of the wastewater treatment plant.
3. Quick processing, and the effluent quality is good after processing.
Choice of treatment process
1. The main characteristic of detergent wastewater is that the main pollutant in wastewater is anionic surfactant LAS. The high concentration of LAS in wastewater has a certain hindrance to the activity and proliferation of microorganisms. Therefore, the biological degradation of such wastewater becomes more difficult. The wastewater is alkaline, and the pH is usually 9-12. In addition, the wastewater lacks nitrogen essential for microbial synthesis. According to the characteristics of sub-class wastewater, it is determined to adopt a process combining physical and chemical and biochemical treatment. Physical and chemical treatment uses coagulation sedimentation, and biochemical treatment uses hydrolytic acidification and contact oxidation.
2. Small sewage treatment stations generally adopt the following biological treatment methods.
A) Biological contact oxidation method. The biological contact oxidation method belongs to the biofilm method. This process is equipped with a new type of elastic three-dimensional filler. It has the advantages of high load, no sludge expansion, small facility size, stable and reliable operation, and convenient management. Ensure that all indicators meet the standards after treatment. The selected packing is easy to repair and replace, with a service life of more than 30 years. Generally applicable to small sewage treatment stations.
B) Conventional activated sludge method, conventional activated sludge method is widely used in large-scale sewage treatment, but because of the low load of conventional sludge method, it is easy to produce sludge expansion, and it is not easy to control and manage, so in recent years, it has been used in small sewage treatment stations. The use of less and less. The SBR method is a relatively advanced activated sludge treatment method developed in recent years. The treatment process integrates aeration tank and sedimentation tank, continuous water inflow, intermittent aeration, and sewage sedimentation and skimming off the supernatant. Become a cycle and start again and again. The SBR method does not have a sedimentation tank, and there is no sludge return equipment. However, the SBR method is intermittent operation and requires multiple processing units. The water inlet and aeration are switched between each other, resulting in more complicated control. In order to ensure the overflow rate, the SBR method has high requirements for the manufacture of decanter equipment, and must be kept in perfection during the production, otherwise it will easily cause the final water quality to be substandard. At present, there is no high-quality decanting equipment in China. The purchase of imported equipment is cumbersome and expensive. At the same time, maintenance costs will be high in the future. The sludge concentration in the SBR method tank is measured by a concentration meter in order to control the amount of excess sludge discharged. At present, the quality of the domestic concentration meter is not sufficient, which makes it difficult to control the sludge discharge. In summary, the biological treatment of this project intends to adopt biological contact oxidation.