Vietnam is one of the countries with high seafood export volume over the world with quality products such as pangasius, basa fish, shrimp, and other mollusks such as squid, octopus, etc. This shows the growing speed of the industry, as well as a large economic contribution to the country. That leads to increased wastewater, causing serious consequences for the environment and human health if they do not treat properly. So what are the characteristics of seafood processing wastewater and how should people be treated before being discharged into the environment?
1. Source of production wastewater.
To export goods to other countries, businesses and factories must process seafood through many different stages to create products, there will be various levels of contamination in each period. The principal wastewater sources are raw material processing, seafood processing, slaughtering, etc.
Thereby, we see that the amount of wastewater from the seafood processing industry is huge in a year. Therefore, if people do not handle it properly, it can cause serious consequences.
2. Characteristics of wastewater from the seafood processing industry.
Aquatic processing wastewater contains most of the components are proteins, fats, organic substances, and suspended solids… derived from producing, cleaning machinery and equipment as well as coloration, smell…. However, wastewater has the following main characteristics:
The high concentration of organic waste in wastewater is mainly carbohydrates, proteins, fats…from main materials such as fish, bones… These substances are easily decomposed in water to create intermediate products due to the breakdown of unsaturated fatty acids, causing high BOD, COD content as well as reducing the dissolved oxygen concentration in water, affecting the growth of shrimp and fish. Moreover, it inhibits the cleaning ability of water sources, leading to a quality reducing of water quality for domestic and industrial purposes.
High suspended solids (TSS) is also one of the characteristics of wastewater because it contains aquatic debris and sand that are carried along in process of preparing raw materials and cleaning equipment, affecting the photosynthesis process of wastewater algae, making the water turbid or colored. This process takes place for a long time, anaerobic decomposition will occur, creating H2S, CO2, CH4, polluting water sources as well as affecting aquatic life. In addition, there are negative effects such as sedimentation of the river, impeding the circulation of water and ships.
High concentrations of Nitrogen and Phosphorus in wastewater from the processing and preliminary processing of aquatic products cause uncontrolled algae growth and to a limited extent, the algae will die, decomposition causes oxygen deficiency leading to dead water bodies. Therefore, it will affect the photosynthesis of lower fauna as well as water quality, aquaculture, tourism, and water supply.
The fishy smell comes from H2S, NH3 gas generated from the decomposition of aquatic products in wastewater due to the decomposition of compounds such as Protid and fatty acids. These substances will cause negative effects on human health if wastewater is not treated properly. In addition, NH3 can kill aquatic life if the content ranges from 1.2 to 3 mg/l.
3. Seafood processing wastewater treatment solution.
Currently, there are many methods to treat aquatic product processing wastewater such as chemical method, microbiological method, mechanical method. However, the microbiological method is the most optimal solution for businesses. Because, adding anaerobic microorganisms, anaerobic microorganisms, aerobic microorganisms will bring many quick effects as well as being environmentally friendly
• UASB tank:
Wastewater is transferred from the conditioning tank to the UASB tank through suspended anaerobic sludge layers, to treat organic compounds with high concentrations of pollution. Here, the phosphorus component in wastewater is removed with the help of anaerobic microbial groups, to promote the ability to decompose complex organic compounds into basic substances such as CO2, CH4, H2S, NH3… according to the following reaction:
Organic matter + Anaerobic microorganisms => CO2 + CH4 + H2S + New biomass…
In addition, the concentration of BOD and COD decreased from 60-80% in wastewater. In addition, it is recommended to add BioFix 114 microorganisms to increase the number of microorganisms to support the formation of methane and other products in the hydrolysis, acetate, and acidification stages.
• Anoxide tank
Wastewater in this tank has anaerobic to help the process treatment: phosphorus and nitrogen removal more thoroughly through the Nitrate and Phosphoril stages. For microorganisms to have maximum contact with the substrates and avoid sedimentation, a stirring device is arranged in the tank to increase efficiency.
The nitrification process takes place as follows: Pseudomonas and Clostridium bacteria will participate in the reduction of nitrate and nitrite to nitrogen, which escapes from the water and flies out in a chain:
NO3– → NO2– → NO → N2O (g) → N2
When restarting the system, it is necessary to add Biofix Ammonia microorganisms to promote nitrogen treatment in anoxic tanks.
In the aerobic process, it is necessary to have enough oxygen to provide for microorganisms working as well as maintain the suspended state of the activated sludge, so air is supplied to the Aerotank tank through the air blower. . Here, organic substances are converted into water and carbonic … creating good conditions for microorganisms to contact the substances to be treated.
In addition to breaking down organic substances to create new cells, microorganisms also perform endogenous respiration to produce energy according to the equation:
C5H7NO2 + 5O2 → 5CO2 + 2H2O + NH3 + H