CPCB Source Document
CPCB Comprehensive Industry Document — Rubber Industry; Schedule VI, Environment (Protection) Rules 1986
Authority: CPCB under Environment (Protection) Act 1986 · Applicable to natural and synthetic rubber processing and rubber goods manufacturing
View effluent standards on cpcb.nic.in ↗CPCB website links may change — search "rubber industry effluent" on cpcb.nic.in if the link is broken.
Sub-Sectors of the Rubber Industry and Their Effluent Profiles
India's rubber industry spans several distinct sub-sectors with different effluent profiles:
- Natural rubber processing (latex): Concentrated in Kerala — field latex is collected and processed into ribbed smoked sheets (RSS), pale crepe, or latex concentrate. This generates the most challenging rubber effluent — high BOD, ammonia, and volatile fatty acids (VFAs).
- Synthetic rubber plants: Manufacture SBR (Styrene Butadiene Rubber), NBR, and other elastomers from petroleum feedstocks — effluent contains organic solvents, emulsifiers, and residual monomers.
- Tyre manufacturing: High water users for cooling and process — effluent contains rubber particles, zinc compounds, carbon black, and process chemicals.
- Rubber goods manufacturing: Moulded products, footwear, conveyor belts — generates moderately contaminated washwater with rubber residues, sulphur, zinc, and mould release agents.
CPCB Pollution Category for Rubber Units
CPCB categorises rubber industry units as:
- Red: Natural latex processing units, synthetic rubber plants, tyre manufacturers, and large rubber goods units — most significant wastewater generators; full consent and ETP required.
- Orange: Medium-scale rubber goods manufacturers — Consent to Operate and ETP required.
- Green: Small rubber goods workshops with minimal wastewater — lighter compliance.
Effluent Characteristics: Natural Latex vs. Synthetic Rubber
The two main wastewater types have very different characteristics:
- Natural latex processing effluent: BOD 3,000–10,000 mg/L; COD 6,000–20,000 mg/L; ammonia 50–200 mg/L (from ammoniacal latex); high VFAs causing intense sour odour; suspended rubber particles 500–2,000 mg/L; pH 4–5 (acidic due to acetic acid coagulation).
- Tyre and synthetic rubber effluent: BOD 300–1,500 mg/L; COD 600–3,000 mg/L; zinc 5–20 mg/L; sulphide 10–50 mg/L (from vulcanisation); carbon black suspended solids; petroleum hydrocarbons from lubricants.
CPCB Discharge Standards for Rubber Industry
| Parameter | Inland Surface Water | Public Sewer |
|---|---|---|
| pH | 6.5–8.5 | 5.5–9.0 |
| BOD (5-day, 20°C) | ≤ 30 mg/L | ≤ 350 mg/L |
| COD | ≤ 250 mg/L | ≤ 600 mg/L |
| Total Suspended Solids | ≤ 100 mg/L | ≤ 600 mg/L |
| Ammonia (as N) | ≤ 50 mg/L | — |
| Sulphide | ≤ 2 mg/L | ≤ 5 mg/L |
| Zinc (as Zn) | ≤ 5 mg/L | ≤ 15 mg/L |
| Oil & Grease | ≤ 10 mg/L | ≤ 20 mg/L |
| Total Chromium | ≤ 2 mg/L | ≤ 2 mg/L |
Treatment Train for Natural Latex Wastewater
Natural latex processing effluent requires a multi-stage treatment train:
- pH adjustment: Lime dosing to raise pH from 4–5 to 6.5–7.0 before anaerobic treatment — essential for stable anaerobic digestion.
- Anaerobic treatment: Covered anaerobic lagoon or UASB reactor — reduces BOD by 80–90% and suppresses odour by containing VFA fermentation. Biogas collected can be used for process heating.
- Ammonia stripping: Air stripping column or biological nitrification to reduce ammonia from 100–200 mg/L to ≤ 50 mg/L.
- Aerobic polishing: Activated sludge or SBR to reduce BOD from ~500 mg/L to <30 mg/L.
- Settling and filtration: Removes rubber particles and biological solids.
Treatment for Synthetic Rubber and Tyre Manufacturing
Tyre and synthetic rubber plant effluent treatment:
- Sulphide pre-treatment: Alkaline chlorination or air oxidation to destroy sulphide before biological treatment — sulphide is toxic to biological systems above 200 mg/L.
- Zinc removal: Chemical precipitation at alkaline pH (9.5–10) — zinc hydroxide precipitates and is removed in a clarifier. The zinc-bearing sludge is hazardous waste requiring TSDF disposal.
- Carbon black removal: Coagulation/flocculation and sedimentation removes suspended carbon black particles.
- Biological treatment: Aerobic activated sludge reduces remaining BOD/COD to consent limits.
Odour Control: A Key Challenge
Natural latex processing plants in Kerala and other rubber-growing regions have faced significant community complaints about odour from VFAs — primarily acetic acid, propionic acid, and butyric acid formed during latex coagulation and processing. Key odour control measures:
- Covered anaerobic treatment tanks with biogas collection
- Minimising storage time of coagulated latex before processing
- Chemical deodorisation with potassium permanganate or ozone at ETP inlet
- Biofilters on air vents from covered ETP units
- Minimum 500m setback from residential areas recommended by CPCB
Compliance and Consent Requirements
Red category rubber units must maintain:
- Consent to Establish and Consent to Operate from the State PCB.
- Monthly NABL-accredited third-party effluent analysis covering all consent parameters.
- Hazardous waste authorisation for zinc sludge (tyre/rubber goods units) — with TSDF disposal documentation.
- OCEMS at final discharge point for large Red category units as directed by State PCB.
- Annual environment statement under EP Rules 1993.
Need Help with Rubber Industry ETP Design?
Spans Envirotech designs ETPs for natural latex processors, tyre manufacturers, and rubber goods plants — including odour control systems and hazardous waste management.
Contact us: bd@spans.co.in · +91-98100 00233
Frequently Asked Questions
What are the key pollutants in rubber industry wastewater?
Rubber industry wastewater — particularly from natural latex processing — contains high concentrations of volatile fatty acids (VFAs), ammonia (from latex preservation with ammonia), BOD from rubber solids, sulphides (from sulphur vulcanisation), and suspended rubber particles. Zinc compounds used as vulcanisation accelerators are also present in rubber goods manufacturing effluent.
What BOD and COD limits apply to rubber processing effluent?
CPCB prescribes BOD ≤ 30 mg/L and COD ≤ 250 mg/L for rubber processing effluent discharged to inland surface water. Raw latex processing effluent has BOD of 3,000–10,000 mg/L — requiring effective anaerobic pre-treatment followed by aerobic polishing to meet these standards.
Is the rubber industry Red or Orange category under CPCB?
Large rubber processing units (natural rubber sheets, latex concentrates, tyre cord fabric) are Red category. Tyre manufacturers and synthetic rubber plants are also Red category due to their high water consumption and complex effluent. Small rubber goods manufacturing units (moulded parts, footwear) are typically Orange category.
What treatment works best for natural latex processing wastewater?
Natural latex processing effluent responds well to extended anaerobic treatment in covered lagoons or UASB reactors, which reduces BOD by 80–90% and controls odour from VFA fermentation. Aerobic polishing (activated sludge or SBR) then brings BOD down to ≤ 30 mg/L. Ammonia stripping or biological nitrification is needed to control the high ammonia from latex preservation chemicals.
What sulphide limits apply to rubber industry effluent?
CPCB prescribes a sulphide limit of ≤ 2 mg/L for rubber industry effluent to surface water. Sulphides arise from sulphur-based vulcanisation accelerators used in tyre and rubber goods manufacturing. Sulphide removal requires chemical oxidation (aeration, chlorination) or alkaline chlorination before biological treatment.
This article summarises CPCB norms for rubber industry effluent for informational purposes. Always verify current standards with your State Pollution Control Board.