Tiếng Việt
中文 (中国)
Vietnam’s aquaculture industry is growing strongly and making a significant contribution to the national economy. Behind the impressive figures, however, lie real challenges: water pollution caused by untreated wastewater. Farms and businesses face rising operating costs, disease risks, ever stricter legal compliance requirements and the threat of damage to their brand reputation. Aquaculture businesses need a breakthrough solution that is effective and sustainable.
NGO International is proud to offer electrochemical technology for aquaculture wastewater treatment – a new step towards green development for the industry.
1. Composition of aquaculture wastewater.
In Vietnam, besides farming in cages, rafts and net enclosures, pond farming is extremely common and has developed in many localities across the country. The main species farmed today are freshwater fish, giant freshwater prawns, black tiger shrimp and others.
With the rapid growth of aquaculture in recent years, large volumes of aquaculture wastewater from many farming operations are not treated thoroughly, creating a risk of pollution for water sources in general and ponds and lakes in particular, with considerable impact on aquatic life and people.
Aquaculture wastewater in general, and wastewater from fish and shrimp ponds in particular, usually has high concentrations of COD, BOD, nitrogen and harmful microorganisms, because of organic matter from excess feed, the biological products used in farming and the waste of the farmed animals themselves.
Characteristics of fish farming wastewater:
- Wastewater from fish ponds is polluted mainly by organic matter from excess feed. In practice, fish absorb only about 17% of the feed, while the remainder (about 83%) mixes into the water and becomes decomposing organic matter. Faeces and other waste then settle on the pond bottom, so COD, BOD, nitrogen and pathogenic microorganisms are all high. If this wastewater is discharged into the environment, it causes the receiving water body to become enriched with sediment or leads to algal blooms. The wastewater also contains residual chemicals (for example antibiotics used for fish) that must be treated.
Characteristics of shrimp farming wastewater:
- Wastewater from shrimp farming contains large amounts of nitrogen, phosphorus and other nutrients, causing hypereutrophication, along with increased primary productivity and blooms of bacteria. The presence of carbonic compounds and organic matter reduces dissolved oxygen and raises BOD, COD, hydrogen sulfide, ammonia and methane levels in natural water bodies. Another problem caused by shrimp farming is sludge deposition in nearby areas, such as mangrove forests and stagnant water. Most of the substances in shrimp pond water settle to the bottom, which is a hazard to the shrimp and to the farming operation itself. This sludge layer is highly toxic and oxygen-deficient, and contains many harmful substances such as ammonia and sulfuric compounds….
Table 1: Typical pollution parameters and estimated concentrations in aquaculture wastewater (for reference)
| No. | Pollution parameter | Unit | Estimated concentration in SHRIMP farming wastewater (intensive/super-intensive) | Estimated concentration in FISH farming wastewater (freshwater, intensive) | Main source / Impact |
| 1 | pH | – | 7.0 – 8.5 | 6.5 – 8.5 | Respiration of aquatic animals, organic decomposition, algal photosynthesis. Affects aquatic life and the efficiency of treatment processes. |
| 2 | Total suspended solids (TSS) | mg/L | 50 – 300 (can be much higher when siphoning the pond bottom) | 30 – 200 (can be higher when siphoning the pond bottom) | Excess feed, faeces, dead algae, pond bottom sludge. Makes the water turbid, reduces light penetration and causes siltation of the receiving water body. |
| 3 | Chemical oxygen demand (COD) | mg/L | 80 – 500 (even >1000) | 60 – 300 | Organic matter (from excess feed and faeces), dead microorganisms. Indicates the total amount of organic and inorganic matter that can be chemically oxidised. |
| 4 | Biochemical oxygen demand (BOD₅) | mg/L | 40 – 250 | 30 – 150 | Readily biodegradable organic matter. Depletes dissolved oxygen in the water and affects aquatic life. |
| 5 | Total nitrogen (TN) | mg N/L | 10 – 100 (mainly organic nitrogen and ammonium) | 5 – 50 | Protein in excess feed, faeces and excreta. Contributes to eutrophication. |
| 6 | Ammonium (NH₄⁺-N / NH₃-N) | mg N/L | 1 – 30 (NH₃ is highly toxic to shrimp) | 0.5 – 15 | Protein decomposition and excreta of aquatic animals. The NH₃ form is highly toxic and affects respiration, growth and survival rate. |
| 7 | Nitrite (NO₂⁻-N) | mg N/L | 0.1 – 5 (highly toxic to shrimp) | 0.05 – 2 | Intermediate product of ammonium nitrification. Highly toxic; causes “brown blood” disease in fish and shrimp. |
| 8 | Nitrate (NO₃⁻-N) | mg N/L | 1 – 20 | 0.5 – 15 | End product of nitrification. Less toxic than ammonium and nitrite, but high concentrations still contribute to eutrophication. |
| 9 | Total phosphorus (TP) | mg P/L | 1 – 15 | 0.5 – 10 | Excess feed and faeces. Main cause of eutrophication and algal blooms. |
| 10 | Mineral oil and grease (if present) | mg/L | < 5 (usually low unless there is an incident) | < 5 (usually low unless there is an incident) | Contamination from pump and equipment oil. Forms a film on the water surface and hinders gas exchange. |
| 11 | Total coliforms | MPN/100mL or CFU/100mL | 10³ – 10⁶ | 10³ – 10⁵ | Faeces and organic waste. Indicates the level of microbial pollution and a potential risk of pathogens (Vibrio, E. coli, Salmonella…). |
| 12 | Salinity | ppt (‰) | 5 – 35 (depending on the farming area and shrimp species) | 0 – 0.5 (for freshwater fish) | Characteristic of brackish/saline shrimp farming environments. Affects the choice of treatment technology. |
| 13 | Sulfide (S²⁻) | mg/L | 0.1 – 2 (especially in pond bottom sludge) | < 0.5 (usually lower than in shrimp farming) | Anaerobic decomposition of sulfur-containing organic matter. Highly toxic; causes a rotten-egg smell and inhibits respiration of aquatic animals. |
2. Aquaculture wastewater treatment solution using electrocatalytic reaction technology
2.1. Key advantages of electrocatalytic reaction technology
Electrocatalytic technology system
- Treats wastewater directly in the farming pond or lake without affecting the fish and shrimp
- Pond and lake water is treated continuously through the electrolytic catalytic reactor and reused immediately, saving water and the cost of periodic water changes
- Simple equipment operation; only periodic cleaning is needed
- Detoxifies harmful wastes such as ammonia (NH3) and nitrite (NO2-) so that aquatic animals live in clean, healthy water
- Breaks down proteins and nutrients, lowering the overall level of organic matter in the water
- Helps shorten the start-up time of tanks/ponds (nitrogen cycle) and prevents new tank/pond syndrome
- Reduces unpleasant odours from pond water
- Improves water clarity
- Supports longer life, higher density and greater weight of shrimp and fish farmed in tanks, thereby improving the economic efficiency of aquaculture.
2.2. Operating principle of the seafood processing wastewater treatment technology
Electrocatalytic technology is used for seafood wastewater with high concentrations of salt, organic matter, sulfur compounds, heavy metal ions, acids and alkalis… The technology relies on oxidation by hydroxyl (OH) free radicals, which react very strongly within a short time. Most organic waste passing through the system is quickly broken down by oxidation into carbon dioxide, water and smaller organic and inorganic ions.
With its many outstanding economic benefits for farmers, together with an optimised design, simple operation and low cost, the aquaculture wastewater treatment solution using electrocatalytic reaction technology, introduced and developed by NGO, helps treat the pollutants in seafood wastewater effectively and ensures that treated water meets QCVN 40:2025/BTNMT – National technical regulation on industrial wastewater (which also applies to aquaculture wastewater)
3. Featured project
A 5-hectare shrimp farm in Bac Lieu was struggling with heavily polluted pond water: ammonia (NH₃) was constantly above 2 mg/L, COD above 150 mg/L, and the shrimp mortality rate from intestinal disease and environmental stress was high. After NGO International installed a recirculating wastewater treatment system using electrochemical technology:
- Results:
- NH₃ concentration fell below 0.5 mg/L.
- COD concentration fell below 50 mg/L.
- Water change frequency fell by more than 70%.
- Shrimp survival rate rose by 25%.
- Effluent quality consistently met the discharge regulations applicable to the farm
- Operating costs (electricity, labour, chemicals) fell significantly.
Treating shrimp pond wastewater used to be a real headache. Since we installed NGO International’s electrochemical system, water quality has clearly improved. The shrimp grow fast and healthy, and we no longer worry about unexpected disease outbreaks. Above all, we save a great deal on water changes and chemicals. NGO’s technical team is very professional and dedicated.”
– Mr V.V.H., owner of a high-tech shrimp farm in Bac Lieu
4. Frequently asked questions
It is a method that uses electric current to trigger chemical reactions (oxidation, coagulation) that remove pollutants from wastewater, and is particularly effective for COD, ammonium and nitrite.
Electrochemical treatment is faster and more effective on hard-to-degrade substances, uses few or no chemicals, produces less sludge, is easier to automate and takes up less space.
The initial investment may be equal to or slightly higher than some simple traditional solutions, but operating costs are lower and the long-term economic benefit is clearly higher. NGO International will advise a solution that fits your budget.
Yes. Treated water meets QCVN 01-80:2011/BNNPTNT or other sector standards and can be fully reused for farming ponds, saving a significant amount of water.
We offer a clear warranty policy for the entire system and equipment, together with 24/7 technical support and periodic maintenance to keep the system operating at its best.
See more: https://ngoenvironment.com/en/wastewater-treatment.html
https://shopngoenvironment.com/product-category/san-pham-cong-nghiep/
For advice on wastewater treatment solutions for aquaculture businesses, contact us on +84 24 7300 0890 or email office@8ngo.com
Talk to an NGO engineer
Free survey and consultation. Send us your wastewater type (industrial or domestic), flow rate (m³/day), influent analysis results if available and required effluent quality; an NGO engineer will propose a suitable technology and a realistic quotation.
Offices in Hanoi and Ho Chi Minh City · +84 24 7300 0890 · office@8ngo.com
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