Aim: to serve as a general guide of the treatment options for hatchery wastewater to reduce contamination of the local environment and the hatcheries themselves. Although new hatchery registration guidelines include the requirement for a wastewater treatment system, there are no standards or discussion of concentrations or types of wastes permissible.

• Installation of hatchery effluent treatment systems is now mandatory in the new governmental hatchery registration rules. Proper treatment and disposal of hatchery discharge will help ensure sustainability of the industry, reduce disease problems within the hatcheries, and help avoid problems with conflicts over water use with other industries and users.
• Currently in Bangladesh, very few hatcheries employ wastewater treatment systems before discharging into the open environment. Waste disposal areas/facilities for all types of hatchery wastes are absent from most hatcheries. Wastewater is neither monitored nor analyzed before or after treatment in all hatcheries. In the case of mortality due to disease, dead animals are disinfected with chemicals and disposed of by various means, but no standards are evident, and thus this is an area for concern.
• Wastewater treatment systems should be used to protect the environment and the hatcheries themselves from hatchery-sourced contamination with biological, pathogen and/or chemical threats. This is particularly crucial where the water is to be discharged to the same location as the abstraction point. Such discharge close to the intake point should be avoided, if possible.
• Biological and pathogen threats can be reduced via particle settlement/filtration followed by passage to chlorination or ozonation tanks.



• Chlorination requires treatment with chlorine (>20 ppm active chlorine for > 60 min or 50 ppm for >30 min or 100–200 ppm for 20 min).
• The chlorine should then be volatilized via aeration (over 2–3 d) or if unavoidable, treatment with sodium thiosulphate (depending upon retention capacity) to avoid discharging it into the environment.
• Alternatively, hatcheries can install concrete or lined settlement tanks (sufficiently large to accept one days’ wastewater) connected to perforated pipe soak-aways dug into the beach to discharge effluents safely – or go through constructed wetlands/mangroves.



• If these facilities are not included in the current hatchery design, efforts should be made to redesign the wastewater systems to comply with regulations, while trying to reduce costs. In view of the large volume of wastewater discharged from hatcheries, recirculation systems should be evaluated for cost efficiency.
• There are a number of water quality parameters that must be monitored in the discharge in order to be effective and comply with the general standards. With the lack of set standards, the Aquaculture Certification Council (ACC) standards for Best Aquaculture Practice (BAP) effluent standards can serve as a guideline (See Table 13).

Table 13. Aquaculture Certification Council (ACC) guidelines for hatchery effluent standards.

• Hatcheries must maintain records of effluent monitoring for future certification efforts.
• However, hatchery personnel must be careful not to create more problems than solutions with the treatment of effluents, since discharge of some chemicals, such as chlorine, formalin, iodine, virucides, antibiotics, etc. may also create problems if they are not first eliminated or allowed to dissipate. Use of such disinfectants must therefore be carefully controlled and excessive use avoided. Toilet wastes should not be discharged into any waterbody without treatment, which should be separated from the treatment of hatchery wastes.
• Care should also be taken to eliminate discharge of saltwater into freshwater bodies surrounding the hatcheries (limit to <550 ppm chloride) to prevent salinization.
• Apart from discharge water, the hatchery will also produce solid wastes that also require proper disposal according to local regulations and laws. All potentially hazardous materials should be properly labeled and stored within the hatchery and disposed of by suitable means, i.e. incineration.
• Shrimp stock (whether broodstock or larvae) that have become infected or died should also be disposed of properly, so as to not contaminate the immediate environment with pathogenic organisms. This should involve suitable chemical disinfection (i.e. with chlorine at >50 ppm for 1 h) of the sick or dead shrimp, often within their own tanks, before burial (with larger shrimp). They should not be discharged into the drainage system/sea unless unavoidable (i.e. with young larvae).
• Construction of wastewater discharge and treatment systems is site specific. However, in general, it is essential to ensure that drainage pipes, canals and treatment tanks are of adequate capacity to handle the maximum predicted flow of discharge water (taking into account the residence time in the treatment tank). Thus, problems with water-logging, back flow and inadequate treatment can be avoided. The use of infiltration pits depends upon the soil, the water table and the relative height of the hatchery above ground water level. If infiltration pits are impractical, direct connection to the receiving body of water can be made through long drainage canals, following treatment.
• Since installation of effluent treatment facilities is onerous for every hatchery, the government could assist in establishing effluent treatment plants that take wastewater from groups of hatcheries via the existing canal systems and treat this wastewater in dedicated plants before returning it to the sea.