Case Studies-Thailand Seafood Processing Wastewater Treatment Plant Project

Current status and requirements of wastewater to be treated

The seafood deep processing industry is expanding continuously, Thai Union was founded in 1977 and is the world's largest canned tuna producer. This production line generates a large amount of wastewater during the cleaning and slaughtering of tuna, with high levels of TSS, BOD, COD, oil and grease, and algae.. As a result, it becomes more difficult and costly to treat this wastewater.

Thailand is one of the top seafood exporting countries globally, and as it continues to improve the quality and processing capabilities of seafood products, it inevitably produces a large volume of wastewater. The wastewater mainly comes from washing fish, and it contains oil, fish skin, fish mince, fish offal, thawing sewage, and other suspended wastes, such as animal oils. The project's leading water inlet and outlet indicators are as follows:

The seafood processing plant purchased a dissolved air flotation system from Yosun Environmental Protection for the primary treatment of seafood processing wastewater. The on-site installation photos are as follows:

Wastewater treatment process

The fish washing wastewater first flows into the regulating tank for water quality and quantity homogenization, and then is pumped to the flocculation sedimentation device for flocculation reaction. The effluent enters the flotation tank for further removal of grease, suspended solids and COD, and coagulants are added to enhance the flotation effect.

The flotation effluent enters the aerobic tank for removal of ammonia nitrogen and BOD, and then enters the aeration tank to degrade organic pollutants, thereby further reducing COD and BOD. After the effluent from the aeration tank flows into the secondary sedimentation for mud and water separation, the effluent enters the lifting tank, is pumped into the existing filter and enters the intermediate water tank, and enters the reverse osmosis treatment from the intermediate water tank and is discharged after meeting the standards. The reverse osmosis concentrated water returns to the regulating tank for secondary treatment. Part of the activated sludge discharged from the secondary sedimentation tank is returned to the anoxic tank for denitrification reaction. The remaining sludge is discharged to the sludge concentration tank for concentration treatment. The sludge residue produced by the sedimentation tank and flotation is also discharged into the sludge tank, and the dry sludge is transported for treatment after being dehydrated by the sludge dewatering machine.

The wastewater generated during the deep processing of seafood is composed of a complex mixture of components. Depending on the specific characteristics of the wastewater and the desired treatment outcomes, suitable combinations of treatment processes can be selected. It is important to ensure that resources are used efficiently during the treatment process to minimize the environmental impact of wastewater discharge.