Fishery industry wastewater treatment manages the wastewater from fish processing, canning, fish meal production, and aquaculture packaging facilities. This sector is characterized by both high organic load and salt tolerance issues.
In fish wastewater, BOD reaches levels of 1,500-5,000 mg/L, COD 3,000-12,000 mg/L, oil-grease 500-3,000 mg/L, and salinity 5,000-30,000 mg/L (due to the use of seawater). Due to its high protein content, total nitrogen is 200-800 mg/L.
Arsistek fishery sector solutions include a combination of DAF, anaerobic UASB or EGSB, halophilic activated sludge, and odor control unit. Recovered fish oil and protein are utilized as animal feed or fertilizer.
Characteristics of Fish Processing Wastewater
There are 4 main sources of wastewater in fish processing: brine, cutting-cleaning, cooking-evaporation, and equipment-floor washing. The total flow rate is between 5-15 m³ per ton of product.
The most distinct feature of the wastewater is its salinity — in marine fish processing facilities, TDS can reach 30,000 mg/L. This makes standard biological treatment impossible. Halophilic bacteria culture or dilution with fresh water is required.
Due to the high protein content, ammonia release and odor problems are at serious levels. The facility air must be maintained below -50 Pa and treated with a biofilter or chemical washing (scrubber).
Halophilic Biological System
For high salinity, a halophilic (salt-loving) bacterial culture is used. Halobacterium and halophilic Pseudomonas strains operate efficiently at a salinity of 30,000 mg/L.
Adaptation takes 4-8 weeks. The MBR design increases efficiency by providing high MLSS.
Protein and Oil Recovery
The floating material collected by DAF contains 30-50% oil + 20-30% protein. This is separated by centrifugation.
Oil: if it is of fish oil quality, it is used as omega-3 supplement; otherwise, it is used for biodiesel. Protein: it is evaluated as animal feed or organic fertilizer.
Odor Management and Air Quality
Odor management in fish processing facilities is a legal obligation and a source of public complaints. The Regulation on the Control of Odor-Generating Emissions is implemented in Turkey.
A three-layered strategy is followed:
- Source isolation: Wastewater channels are closed, and the balancing tank is not ventilated.
- Air collection: The facility air is maintained at -30 to -50 Pa and collected with an exhaust fan.
- Air treatment: Odor removal of 95%+ is achieved using a biofilter (wood chips + peat) or a chemical scrubber (NaOCl/H2SO4).
Effective odor control targets hydrogen sulfide <0.5 ppm, ammonia <5 ppm.
Advantages of Solutions for the Fishing Industry
Fishing Industry Reference Projects
8 visuals will be added soon — stay tuned for our reference projects and facility photos.
Frequently Asked Questions
Standard bacteria experience osmotic shock above 5,000 mg/L — the cell contents are released and they die. Halophilic cultures have mechanisms that equilibrate intracellular salinity and operate efficiently up to 30,000 mg/L.
Yes. Fish oil obtained from DAF sludge is sold in the range of 200-800 USD/ton. If it is not of food quality, it can be used for biodiesel/soap. The investment cost pays back in 2-3 years.
The facility air is maintained at negative pressure (-30 to -50 Pa) and directed to the biofilter or scrubber. A closed system is used at the sources (sink, channel, tank). This combination reduces odor complaints by over 95%.
Canned wastewater is characterized by pasteurization temperature (hot), low fat, and balanced pH. Fishmeal wastewater stands out with very high COD (15,000+ mg/L), volatile fatty acids, and unpleasant odor. An additional anaerobic stage is required for fishmeal.
Fishery farm wastewater has a lower concentration — COD 200-800 mg/L. However, the volume is large. On-site treatment with RAS (recirculating aquaculture systems) is common. Antibiotic residues should be monitored.
In Turkey, a deep sea discharge pipeline permit is required for marine discharge. In standard discharge, COD must be <250, BOD <50, and TSS <40 mg/L. Stricter limits apply in coastal protection zones.