Dairy Wastewater Treatment Plant (ETP)
High-performance effluent treatment for milk processing, cheese, paneer, butter, and dairy co-operative plants. DAF + MBBR/SBR + optional ZLD — designed for CPCB & SPCB compliance.
Overview
Why Dairy Wastewater Is Uniquely Challenging
Dairy plants — milk processing, UHT, cheese, paneer, butter, ghee, ice cream, and dairy co-operatives — generate effluent with some of the highest organic loads in the food industry. BOD concentrations of 1,500–6,000 mg/L are typical, spiking to 10,000+ mg/L during CIP (clean-in-place) discharge events.
Milk is a nutrient-rich food — and when milk solids, fats, lactose, and proteins enter the wastewater stream, they create an extremely high biological oxygen demand. Without proper primary treatment (DAF for fat removal) before biological treatment, conventional activated sludge or MBBR systems become overloaded, leading to regulatory non-compliance.
Flow variability is another challenge. Production peaks, CIP discharges, product changeovers, and seasonal flush volumes create hydraulic and organic load surges that must be buffered through adequate equalization tank capacity before downstream treatment.
Spans Envirotech has designed and commissioned dairy ETPs for major Indian dairy producers including facilities associated with Amul, Mother Dairy, Heritage Foods, and Hatsun Agro product groups — bringing decades of sector-specific process knowledge to every project.
Key Pollutants in Dairy Effluent
| Parameter | Typical Range | Source |
|---|---|---|
| BOD (Biochemical Oxygen Demand) | 1,500–6,000 mg/L | From lactose, proteins, milk fats |
| COD (Chemical Oxygen Demand) | 2,000–10,000 mg/L | Total oxidisable organic matter |
| TSS (Total Suspended Solids) | 200–2,000 mg/L | Milk solids, curds, proteins |
| Fats, Oils & Grease (FOG) | 50–500 mg/L | Cream, butter fat, processing oils |
| Lactose | 1,000–5,000 mg/L | Highly biodegradable milk sugar |
| pH | 4.0–10.0 | Wide range due to CIP chemicals (acid/caustic) |
| Nitrogen (as TKN) | 30–100 mg/L | From proteins, casein, whey |
* Values are indicative ranges. Actual values depend on plant type, production mix, and CIP frequency.
Process
Spans' Dairy ETP Treatment Train
Our proven process for dairy wastewater treatment — from raw effluent to discharge-quality or recyclable water.
Screening
Bar screens and rotary drum screens remove coarse solids, packaging fragments, and milk curd chunks from the raw effluent.
Equalization
Buffer tank (4–8 hours HRT) homogenises flow and organic load, dampening variability from CIP cycles and shift changes.
DAF (Dissolved Air Flotation)
Pressurised recycled water releases microbubbles that float fat, oil, proteins, and suspended solids to the surface for skimming. Achieves 60–80% BOD reduction in primary stage.
Biological Treatment (MBBR/SBR)
MBBR or SBR systems biodegrade remaining BOD/COD using suspended and attached-growth activated sludge. Achieves BOD <50 mg/L post-secondary.
Secondary Clarification
Settling tank separates biological sludge from treated effluent. Sludge is recycled to maintain biomass and excess sludge is dewatered.
Polishing & Disinfection
Sand filtration, activated carbon filtration, and chlorination/UV polishes effluent to BOD <30 mg/L, COD <250 mg/L for CPCB discharge compliance.
ZLD (Optional)
For zero discharge mandates, RO followed by Multi-Effect Evaporator (MEE) or MVR concentrates reject to crystallisable solids, enabling complete water recycling.
Technologies
Technologies Used in Dairy ETP
DAF (Dissolved Air Flotation)
Primary treatment removing 60–80% of fats, oils, and suspended solids
Explore →MBBR Technology
Robust biological treatment handling variable organic loads
Explore →SBR (Sequencing Batch Reactor)
Flexible batch biological treatment ideal for variable dairy flows
Explore →MBR (Membrane Bioreactor)
High-quality effluent for reuse applications in process water
Explore →ZLD — Zero Liquid Discharge
Complete water recycling using RO + MEE/MVR evaporation
Explore →Evaporation Systems
Multi-Effect Evaporators and MVR for ZLD concentrate handling
Explore →Compliance
CPCB / SPCB Standards for Dairy Effluent
Under CPCB General Standards (Environment Protection Act, 1986 — Schedule VI), dairy effluent discharged to inland surface waters must meet:
- BOD ≤ 30 mg/L (many state SPCBs require ≤ 20 mg/L)
- COD ≤ 250 mg/L
- TSS ≤ 100 mg/L
- pH 6.0 – 8.5
- Oil & Grease ≤ 10 mg/L
Dairy units classified as Red Category industries in 17 water-stressed states must implement Zero Liquid Discharge (ZLD), ensuring no treated effluent is discharged — all water is recycled back to the process.
Treatment Outcomes Achieved
FAQ
Frequently Asked Questions
Why is dairy wastewater difficult to treat?
Dairy effluent has BOD of 1,500–6,000 mg/L with high fats, proteins, and lactose — along with wide flow variability from CIP cycles and shift changes. This demands equalization, effective DAF fat removal, and robust biological treatment capable of handling shock loads.
What treatment process is used for dairy effluent?
Typical process: screening → equalization → pH correction → DAF (fat removal) → MBBR or SBR (biological treatment) → secondary clarification → polishing → disinfection → ZLD (if required). DAF is the critical first stage for dairy applications.
What are CPCB standards for dairy effluent discharge?
BOD ≤30 mg/L, COD ≤250 mg/L, TSS ≤100 mg/L, pH 6.0–8.5, Oil & Grease ≤10 mg/L. Many state SPCBs require BOD ≤20 mg/L. ZLD is mandated for Red Category dairy units in 17 water-stressed states.
Can dairy wastewater be reused?
Yes. With UF + RO tertiary treatment, dairy effluent can be polished for process water reuse (boiler feed, cooling water, CIP pre-rinse), reducing freshwater intake by 40–60%. ZLD systems achieve complete water recycling.
What ETP capacity does a dairy plant need?
Dairy plants typically generate 1.5–3 litres of effluent per litre of milk processed. A 100,000 LPD dairy may need a 150–300 KLD ETP. Accurate sizing requires an effluent audit measuring flow, BOD, COD, and fat content.
Get a Dairy ETP Design Proposal
Share your dairy plant capacity, location, and current effluent situation — our engineers will provide a technology recommendation and indicative cost estimate within 5 working days.