Key Questions
What is an effluent treatment plant (ETP)?
An effluent treatment plant (ETP) treats industrial wastewater until it meets discharge standards. Navbharat Water ETPs run from 5 KLD to 5 MLD and bring inlet BOD of up to 5,000 mg/L down to CPCB norms of BOD 30 mg/L or less and COD 250 mg/L or less.
Manufacturing, processing and chemical industries produce high-strength wastewater carrying BOD, COD, heavy metals and suspended solids far beyond municipal standards. An ETP removes these in three engineered stages. Primary treatment screens out gross solids, equalises flow and uses coagulation, flocculation and clarifiers to remove 60–80% of suspended solids and 30–40% of BOD. Secondary treatment uses extended aeration, SBR or MBBR biology to remove dissolved organics, with the process chosen by industry, since textile ETPs need different organisms than food-processing ETPs. Tertiary polishing with sand filtration, activated carbon or advanced oxidation brings the outlet to CPCB norms, with TSS at 100 mg/L or less. Treated water can then be reused in cooling towers or landscaping. Power consumption is 0.4–1.2 kWh/m³, and every system is process-designed for the worst-case inlet load rather than the average.
How do I size an ETP for my plant?
ETP sizing needs three inputs: average daily flow in KLD, a peak flow multiplier of typically 1.5–2 times the average, and inlet quality parameters such as BOD, COD, TSS, pH and heavy metals. Navbharat Water gathers this data through a free pre-design audit.
Industrial discharge fluctuates with shifts, batch processes and cleaning cycles, so equalisation tanks are sized to buffer flow and load variations before biological treatment. The biological stage then needs enough hydraulic retention time, 12–24 hours for an SBR, to reduce organics consistently. Inlet chemistry decides the rest of the train: high-strength distillery or pharmaceutical effluent with BOD up to 5,000 mg/L is handled through extended aeration or SBR stages, while textile effluent needs ozonation or Fenton advanced oxidation to reach the colour limit of 400 Hazen units. Sludge handling must be sized too. Filter press dewatering produces sludge at 20–30% dry solids, cutting disposal volume by over 70% compared with wet sludge handling. In a 250 KLD pharmaceutical ETP in Pune, outlet COD stayed at or below 200 mg/L against an MPCB consent limit of 250, and sludge volume fell 40% versus the previous system.
Which laws govern industrial effluent discharge in India?
Industrial effluent discharge is governed by the Water (Prevention and Control of Pollution) Act, 1974 and Schedule VI of the Environment (Protection) Rules, 1986. CPCB general standards set BOD at 30 mg/L or less and COD at 250 mg/L or less, and State PCBs often impose stricter consent conditions.
CPCB sets the national baseline, while State PCB consent conditions are industry-specific and frequently tighter, from MPCB in Maharashtra to GPCB in Gujarat and TNPCB in Tamil Nadu. Operating without a correctly sized, functional ETP exposes a plant to show-cause notices, production shutdowns and criminal liability under the Water Act. Navbharat Water designs every ETP to the tighter of the central and state limits, which leaves compliance headroom if norms change. Compliance is also a documentation exercise. Navbharat Water supplies the annual environmental statement and the test reports your EHS team needs, and Annual Maintenance Contracts cover daily checks, weekly instrument calibration, monthly diffuser cleaning and quarterly overhauls, with emergency response within 24 hours. Hazardous sludge containing heavy metals or pharmaceutical residues is sent to CPCB-authorised Treatment, Storage and Disposal Facilities, while non-hazardous sludge goes to authorised composting or landfill.
