Introduction to Process Flow of Sewage Treatment in Canning Factory

As a cannery, a large amount of waste water is generated during the production process. These wastewaters contain high concentrations of organic substances such as oil, protein, and suspended solids. If they are not treated, they will cause serious pollution to the water body and even endanger the survival of organisms if they are directly discharged into the environment. Therefore, it is very necessary to scientifically and rationally treat the wastewater from canning factories.

1. Preliminary treatment
The initial treatment of cannery wastewater generally adopts a combination of physical and chemical treatment. First of all, large particles of impurities and sediments in the wastewater are removed through grids, sedimentation tanks and other equipment. Then, put the waste water into the dispensing pool, add appropriate amount of chemicals, and remove the organic matter in the water through chemical reaction.

2. Biological treatment
The wastewater after preliminary treatment still contains a large amount of organic matter, which needs to be further degraded by biological treatment. Biological treatment generally adopts a combination of aerobic biological treatment and anaerobic biological treatment. Aerobic biological treatment can degrade organic substances in wastewater into carbon dioxide and water, while anaerobic biological treatment can reduce compounds such as sulfide and nitrate in sewage to hydrogen sulfide and ammonia.

3. Secondary precipitation
The sewage after biological treatment still contains many microorganisms, cells and some inorganic substances, and secondary precipitation is required. By adding an appropriate amount of flocculant, the tiny suspended solids in the sewage are gathered together to form a larger sediment, and then separated by sedimentation. This step of treatment can effectively remove suspended solids and colloidal substances in wastewater.

4. Filtration treatment
After secondary sedimentation, the sewage still contains tiny suspended solids and bacteria, which needs further filtration treatment. Generally, a filter plate filter press is used for filtration treatment, and the sewage is filtered through layers of filter media with different particle sizes to remove residual tiny suspended solids and colloids, making the water more clear and transparent.

5. Disinfection treatment
The sewage treated by the above processes has basically met the discharge standards, but in order to ensure safer water quality, it needs to be disinfected. Generally, ultraviolet disinfection or chlorine disinfection is used to kill residual bacteria and viruses to prevent harm to the environment and human body.

In ultraviolet disinfection, ultraviolet lamps are used to irradiate sewage through ultraviolet lamps, and the DNA and RNA of bacteria and viruses will be damaged and lose their vitality. This method has a fast disinfection speed, does not need to add other chemicals, and has little environmental pollution. However, the UV lamp needs to be replaced regularly, and the maintenance cost is high.

Another method of disinfection is chlorine disinfection. This method needs to add chlorine gas during the treatment process, and the chlorine gas and the microorganisms in the sewage will undergo a chemical reaction and be killed. The disinfection effect of this disinfection method is stable and reliable, but chlorine gas itself is a poisonous and harmful gas. If it is not operated properly, it will cause harm to the operator and pollute the environment.

To sum up, disinfection treatment is an essential step in the sewage treatment process and plays an important role in ensuring human health and environmental safety.

6. Reuse processing
Reuse treatment is a viable option in the canning factory wastewater treatment process. Reuse treatment can reprocess the treated sewage to achieve the goal of reuse.

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