CPCB Source Document
Schedule VI, Environment (Protection) Rules 1986 — General Effluent Standards; CPCB COINDS for Seafood Processing
Authority: CPCB under Environment (Protection) Act 1986 · Also subject to CRZ Notification 2019 for coastal units
View effluent standards on cpcb.nic.in ↗CPCB website links may change — search "seafood processing effluent" on cpcb.nic.in if the link is broken.
Scope: Seafood Processing Sub-Sectors
India is one of the world's largest seafood exporters, processing fish, shrimp, squid, crab, and other marine products. The main seafood processing sub-sectors generating regulated wastewater are:
- Shrimp processing: Peeling, de-heading, de-veining, cooking, freezing of shrimp (prawns) — generates high-protein, shell-fragment-rich wastewater with strong odour.
- Fish processing and canning: Filleting, evisceration, cooking, and canning of fish — generates blood-contaminated washwater, high in BOD, suspended solids, and fat.
- Fish meal and fish oil plants: Cooking and pressing whole fish to extract oil and concentrate protein — generates very high-BOD press water (stick water) and cooking condensates.
- Squid and cephalopod processing: Generates ink-contaminated wastewater with very high COD.
- Seafood export processing zones (EPZs): Large integrated facilities processing shrimp and fish for export — high water consumption, large ETP requirements.
CPCB Pollution Category
Seafood processing plants are categorised as:
- Red category: Large processing plants (>5 MT/day output), fish meal plants, and integrated export processing units — full consent and ETP required with monthly monitoring.
- Orange category: Medium-scale processors, coastal cold storage units with processing — Consent to Operate and ETP required.
- Green category: Small artisanal fish cleaning units — minimal regulatory obligations.
Effluent Characteristics of Seafood Processing Wastewater
Seafood processing effluent characteristics:
- BOD: 500–3,000 mg/L — from dissolved proteins, blood, fat, and organic fragments.
- COD: 1,000–6,000 mg/L — higher than BOD due to resistant proteins and lipids.
- Suspended solids: 300–1,500 mg/L — fish scales, shell fragments, viscera particles.
- Oil & grease: 100–500 mg/L — fish oil from fatty species (sardines, mackerel).
- Ammonia: 20–150 mg/L — from protein decomposition and trimethylamine oxidation.
- Salt (chlorides): Elevated if seafood is washed with brine or salt is used in processing — affects biological treatment if above 4,000 mg/L.
CPCB Discharge Standards
| Parameter | Inland Surface Water | Coastal / Tidal Water |
|---|---|---|
| pH | 6.5–8.5 | 6.0–8.5 |
| BOD (5-day, 20°C) | ≤ 30 mg/L | ≤ 100 mg/L |
| COD | ≤ 250 mg/L | ≤ 400 mg/L |
| Total Suspended Solids | ≤ 100 mg/L | ≤ 100 mg/L |
| Oil & Grease | ≤ 10 mg/L | ≤ 20 mg/L |
| Ammoniacal Nitrogen | ≤ 50 mg/L | ≤ 50 mg/L |
| Total Coliforms | ≤ 1000 MPN/100 mL | ≤ 1000 MPN/100 mL |
ETP Configuration for Seafood Plants
Recommended ETP for seafood processing plants:
- Fine screening: Rotary drum screen or vibrating screen — removes shell fragments, fish scales, and solid particles to protect downstream equipment.
- DAF (Dissolved Air Flotation): With coagulant (alum or polyaluminium chloride) — removes 80–90% of suspended protein, fat, and fine solids. The float (protein-rich sludge) is processed into fish meal.
- Equalisation: Buffers variable load between processing shifts and idle periods.
- Aerobic biological treatment: SBR or activated sludge — 12–24 hour HRT achieves BOD ≤ 30 mg/L.
- Ammonia control: Biological nitrification in the aeration tank, or ammonia stripping before biological treatment for high-ammonia streams.
- Disinfection: UV or chlorination before discharge near bathing beaches or recreational water bodies.
Coastal Discharge and CRZ Considerations
Seafood processing plants in CRZ areas face additional requirements:
- The CRZ Notification 2019 restricts industrial activities within specified distances from the high tide line (HTL) — from 50 m to 500 m depending on CRZ category.
- Discharge of any untreated effluent to tidal creeks, estuaries, or sea is prohibited — even for coastal processors.
- Environmental Clearance from SEIAA is required for processing plants above specified capacity in CRZ areas.
- Coastal discharge standards (slightly more lenient than inland standards for BOD) apply where discharge is to open sea via a long outfall pipe meeting minimum dilution requirements.
Odour Control
Seafood processing plants generate intense odour — primarily from trimethylamine (TMA, "fishy" smell), hydrogen sulphide, and volatile fatty acids from protein decomposition. Key odour control measures:
- Rapid cleanup of spills and solid waste — solids on the plant floor are the primary odour source.
- Covered equalization tanks with biofilter exhaust treatment.
- Refrigerated processing areas to slow decomposition.
- Chemical masking or neutralisation at exhaust vents — permanganate-based scrubbers for TMA.
- Plant siting with minimum setback from residential areas as per SPCB guidelines.
By-Product Recovery from ETP
DAF float from seafood ETPs is protein and lipid-rich — representing a recoverable resource:
- Fish meal: DAF float from shrimp and fish processing can be dried and pelletised into high-protein fish meal — valuable aquaculture and poultry feed ingredient.
- Fish oil: Fish fat recovered from the DAF float can be extracted and sold as crude fish oil for aquaculture or industrial use.
- Organic fertiliser: Composted ETP sludge is a nitrogen-rich organic fertiliser approved for aquaculture pond fertilisation and crop production in several states.
- Biogas: Anaerobic digestion of seafood ETP sludge produces biogas for process heat — attractive for fish meal plants that require significant heat energy.
Need Help with Seafood Plant ETP Design?
Spans Envirotech designs ETPs for seafood export processors, fish meal plants, and coastal processing units — including odour control and fish meal recovery from DAF float.
Contact us: bd@spans.co.in · +91-98100 00233
Frequently Asked Questions
What are the CPCB effluent limits for seafood processing?
CPCB prescribes BOD ≤ 30 mg/L, COD ≤ 250 mg/L, TSS ≤ 100 mg/L, oil & grease ≤ 10 mg/L, and ammoniacal nitrogen ≤ 50 mg/L for seafood processing effluent discharged to inland surface water. For coastal discharges, CRZ notifications and state coastal zone management plans also apply.
Why is seafood processing wastewater difficult to treat?
Seafood processing wastewater contains high concentrations of proteins, fats, blood, and viscera — which decompose rapidly and produce extremely offensive odours (trimethylamine, hydrogen sulphide). The effluent is also variable in flow (processing season vs. off-season) and can contain salt from seafood washing. High-strength wastewater (BOD 500–3,000 mg/L) requires effective primary treatment to prevent odour problems and overload of downstream biological systems.
Are seafood processing plants near the coast subject to special rules?
Yes. Seafood processing plants in Coastal Regulation Zones (CRZ) are subject to the CRZ Notification 2019 in addition to Water Act consent requirements. Discharge to the sea or tidal water bodies must meet coastal discharge standards. Some coastal states also have specific notifications for seafood export processing zones (EPZs) with enhanced environmental monitoring requirements.
What is the best treatment technology for shrimp processing wastewater?
Dissolved Air Flotation (DAF) is the most effective primary treatment for shrimp processing wastewater — it removes 70–90% of suspended proteins, fats, and shell fragments. Secondary biological treatment (activated sludge or SBR) then removes remaining BOD to ≤ 30 mg/L. The DAF float (protein-rich seafood sludge) can be processed into fish meal or fertiliser.
Is seafood processing sludge hazardous waste?
No — seafood processing ETP sludge is typically non-hazardous organic material (proteins, fats, shell fragments). It is amenable to composting, anaerobic digestion, or processing into fish meal / organic fertiliser. Some states allow direct land application of composted seafood sludge for agricultural use.
This article summarises CPCB norms for seafood processing effluent for informational purposes. Always verify current standards with your State Pollution Control Board and coastal zone authority.