A large amount of wastewater is generated during the food processing process, with high levels of organic matter and suspended solids in the water, which is prone to decay and deterioration of water quality. If discharged directly without treatment, it will cause harm to human health and the environment. It must be treated and qualified before discharge. So what are the steps for treating COD wastewater in food processing? Let's take a look together!

Food wastewater treatment process:

(1) Preprocessing

Pre treatment is the key to the effective operation of the entire system. Solid suspended solids (SS) in slaughter wastewater are high and prone to corrosion, and must be intercepted in a timely manner. On the one hand, it can prevent blockage of subsequent pipeline equipment, and on the other hand, timely cleaning can prevent suspended organic matter from dissolving into the wastewater and becoming soluble organic matter, leading to an increase in COD and BOD concentrations in the wastewater.

There are two main methods for pre-treatment: air flotation and screening. Air flotation is mainly used in treatment stations with low wastewater volume, but its disadvantages include complex equipment, difficult management, high operating costs, and poor conditions. Screening is mainly used for the pretreatment of slaughter wastewater with large amounts of wastewater. Easy management and stable operation.

(2) Acid hydrolysis or anaerobic

The organic compounds in wastewater are mainly proteins and fats, which belong to large molecule long-chain organic compounds and are difficult to be directly utilized by general aerobic bacteria. In their biodegradation process, they are generally decomposed into small molecule organic compounds such as amino acids and carbohydrates through the action of enzymes before being directly utilized by aerobic bacteria. The complete anaerobic process is divided into two stages: acidification hydrolysis and the production of alkanes, which produce methane and a large amount of odor. Therefore, anaerobic processes are less commonly used.

(3) Activated sludge or direct contact oxidation

To meet the first level discharge standard for organic wastewater, aerobic biological treatment process is the most commonly used, effective, and cost-effective process. Aerobic biological processes include activated sludge process and contact oxidation process, which have large quantities. The activated sludge process is a traditional and mature treatment method, but its disadvantage is that microorganisms are in a suspended state. Contact oxidation is a type of biofilm that is not yet mature. The disadvantage is that the aeration tank requires the installation of biological packing as a carrier for the organisms, which is relatively expensive. The effect of the secondary sedimentation tank is poor, but the advantage is that there is no need for sludge reflux.

(4) Chemical oxidation method

After pretreatment and anaerobic aerobic process, the water quality has been greatly improved, and most of it can be discharged in a qualified manner. Except for COD slightly exceeding the standard, chemical agents can be added to assist in removal, enhance the effect, and discharge in a qualified manner.

This article is organized by food wastewater treatment equipment and does not represent the views of this website.