CPCB Source Document
Schedule VI, Environment (Protection) Rules 1986 — General Effluent Standards; CPCB Guidelines for Paint and Ink Industries; HWM Rules 2016 — Schedule I (Solvent Waste Categories)
Authority: CPCB under Environment (Protection) Act 1986 · Applicable to printing ink manufacturers, pigment processors, and large commercial printing operations
View effluent standards on cpcb.nic.in ↗CPCB website links may change — search "ink effluent standards" on cpcb.nic.in if the link is broken.
Printing Ink Industry Sub-Sectors
The printing ink industry includes manufacturers of printing inks and related products, as well as large commercial printing operations:
- Offset ink manufacturers: Paste inks for lithographic offset printing — contain pigments (carbon black, phthalocyanines, azo pigments) in vegetable oil and petroleum-based varnish. Water usage: modest; effluent from equipment cleaning and pigment dispersion.
- Gravure and flexo ink manufacturers: Liquid inks using toluene, ethyl acetate, IPA, or water as carriers — significant solvent use; effluent includes solvent-contaminated wash water and pigment dispersions.
- Water-based and UV/EB ink manufacturers: Aqueous acrylic, polyurethane, or radiation-curable formulations — lower VOC emissions and simpler wastewater (no organic solvents) but still contain pigments and photoinitiators.
- Pigment manufacturers for inks: Organic and inorganic pigment synthesis — azo pigments, phthalocyanines, quinacridones; generates process effluent from filter washing and synthesis reactions with colour and heavy metals.
- Large commercial printing plants: Gravure publication printing, flexible packaging printing — use large volumes of solvent-based inks; significant solvent recovery systems and wastewater treatment required.
CPCB Pollution Category
Ink manufacturing units are typically Orange category under CPCB — they generate moderate effluent volumes with pigment, solvent, and resin contamination. Units with significant heavy metal pigment use or large solvent consumption may be directed to Red category by the SPCB. Pigment synthesis plants are generally Red category due to chemical synthesis wastewater.
Wastewater Sources and Characteristics
Key wastewater streams and their characteristics:
- Equipment wash water: BOD 500–5,000 mg/L; high colour from pigments; suspended solids 500–3,000 mg/L from undissolved pigment. pH variable depending on ink type (alkaline for water-based, near-neutral for solvent-based).
- Pigment dispersion wash water: Contains finely ground pigment, dispersant (sodium polyacrylate, lecithin), and wetting agents. High colour, low biodegradability.
- Solvent-contaminated water (gravure/flexo): Water contaminated with toluene, ethyl acetate from solvent recovery condensers — requires stripping before biological treatment.
- Laboratory waste: Low volume but may contain trace amounts of all pigments, solvents, and test chemicals used in quality control.
CPCB Discharge Standards
| 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 |
| Lead (Pb) | ≤ 0.1 mg/L | ≤ 1 mg/L |
| Hexavalent Chromium | ≤ 0.1 mg/L | ≤ 0.1 mg/L |
| Total Chromium | ≤ 2 mg/L | ≤ 2 mg/L |
| Cadmium (Cd) | ≤ 2 mg/L | ≤ 2 mg/L |
| Copper (Cu) | ≤ 3 mg/L | ≤ 3 mg/L |
Heavy Metal Management
Heavy metal management is critical for ink plants using inorganic pigments:
- Chemical precipitation: Raise pH to 9–10 using lime or caustic soda — precipitates lead, chromium, cadmium, and copper as metal hydroxides. Flocculate with polyelectrolyte and settle in clarifier. Filter press dewaters the metal-containing sludge.
- Hexavalent chromium reduction: If Cr(VI) is present (from chrome pigments), reduce to Cr(III) at pH 2–3 using sodium metabisulphite before precipitation. Cr(VI) is carcinogenic and cannot be directly precipitated.
- Sludge classification: Filter cake from heavy metal precipitation is Hazardous Waste under HWM Rules (Schedule II, Category 14 — heavy metal sludge). Must be disposed at authorised TSDF or stabilised with cement before landfill.
- Lead-free pigment transition: Modern ink formulations increasingly substitute lead chrome yellow with organic alternatives (diarylide yellow, benzimidazolone). Ink manufacturers transitioning to lead-free formulations see significant ETP simplification and hazardous waste reduction.
Solvent Waste and VOC Control
Solvent waste management and VOC control for gravure/flexo ink plants:
- On-site solvent recovery: Spent toluene and ethyl acetate from ink wash and cylinder cleaning are collected and distilled in batch stills (capacity 200–2,000 litres per batch). Recovery rates: toluene 60–80%, ethyl acetate 50–70%. Recovered solvent is reused in ink manufacture, reducing raw material cost.
- Solvent condensate treatment: Distillation condensers produce water contaminated with residual solvent (typically 100–500 mg/L organic solvent). This stream requires steam stripping or activated carbon treatment before ETP.
- Press house ventilation: Gravure press rooms exhaust toluene-laden air — thermal oxidiser or carbon adsorption unit required to meet ambient air quality standards (toluene NAAQ standard: 200 µg/m³ annual average).
- Transition to water-based inks: Many flexible packaging printers in India are switching from toluene-based to water-based inks under CPCB pressure and customer sustainability demands. Water-based press wash goes directly to ETP without stripping.
ETP Configuration for Ink Plants
ETP configuration for a typical ink manufacturing plant:
- Collection tank with coarse screen — removes pigment lumps and packaging contamination
- pH adjustment — raise to 9–10 for heavy metal precipitation (where applicable)
- Coagulation-flocculation (alum + polyelectrolyte) — removes pigment, resins, and emulsified colour
- Filter press — dewaters pigment/metal sludge (hazardous waste output)
- Equalization tank — buffers load from batch production cycles
- Biological treatment (SBR or activated sludge) — degrades residual BOD from resins and surfactants
- Activated carbon polishing — removes residual colour and trace solvents
Compliance and Hazardous Waste Requirements
Compliance and hazardous waste requirements for ink manufacturers:
- Consent to Operate from State PCB — with ETP design and hazardous waste authorisation as conditions.
- HWM Rules 2016 authorisation for generation, storage, and disposal of: spent solvents (Category 1), heavy metal sludge (Category 14), contaminated packaging (Category 33).
- Annual hazardous waste return to SPCB — reporting quantities generated, stored, transported, and disposed.
- Monthly NABL-accredited effluent monitoring for all consent parameters including heavy metals.
- For solvent-heavy operations: Air (Prevention and Control of Pollution) Act consent for stack emissions from thermal oxidiser and distillation still.
Need ETP Design for Ink or Pigment Plants?
Spans Envirotech designs ETPs for printing ink manufacturers, pigment processors, and commercial printing plants — including coagulation-flocculation for colour removal, heavy metal precipitation, and solvent-contaminated wastewater treatment.
Contact us: bd@spans.co.in · +91-98100 00233
Frequently Asked Questions
What CPCB category are printing ink manufacturers?
Printing ink manufacturers are Orange category under CPCB's industry categorisation — they generate moderate volumes of effluent containing heavy metal pigments (lead, chromium, cadmium in older formulations), solvents, and resins. Large ink manufacturers (above 500 tonnes/year output) with significant wastewater generation may be Red category at SPCB discretion. Commercial printing units (offset, gravure, flexo presses) are typically Green category — they use water-based or UV-cured inks with minimal wastewater — unless they are large-volume operations with significant solvent use.
What are the main wastewater streams from ink manufacturing?
Main wastewater streams from ink manufacturing: (1) Equipment wash water — residual ink from mixing vessels, bead mills, and filling lines washed with water or solvent. This is the largest volume stream with high pigment loading, BOD from resins, and potentially heavy metals; (2) Pigment processing water — from pigment synthesis or flushing operations; (3) Laboratory wash water — from quality control testing; (4) Floor washings — spillage cleanup. Solvent-based ink plants generate solvent-contaminated wash water requiring steam stripping or activated carbon treatment before biological treatment.
Which heavy metals are regulated in ink effluent under CPCB?
CPCB's general Schedule VI standards apply heavy metal limits to ink industry effluent — particularly: Lead (Pb) ≤ 0.1 mg/L (lead-based pigments like chrome yellow, red lead are now largely phased out but still used in some industrial ink formulations), Chromium (Cr) ≤ 2 mg/L total, ≤ 0.1 mg/L hexavalent (chrome green, chrome oxide pigments), Cadmium (Cd) ≤ 2 mg/L (cadmium yellows/reds — restricted in food-contact printing), Copper (Cu) ≤ 3 mg/L (phthalocyanine blue/green pigments leave trace copper), Zinc (Zn) ≤ 15 mg/L. Treatment: chemical precipitation at pH 9–10 removes most heavy metals as hydroxides.
How is solvent waste managed from gravure and flexo printing?
Gravure and flexo printing use solvent-based inks (toluene, ethyl acetate, IPA) requiring solvent waste management: (1) Solvent recovery by distillation — spent toluene and ethyl acetate from ink wash are distilled on-site for reuse (40–60% recovery typical); (2) Residual solvent-contaminated water — steam stripped to remove residual VOCs below 10 mg/L before ETP; (3) Spent solvent sludge — classified as Hazardous Waste under HWM Rules, requiring authorised disposal or co-processing. Water-based inkjet, UV-cured, and water-washable flexo inks are increasingly adopted to eliminate solvent waste streams entirely.
What ETP is required for an ink manufacturing plant?
ETP for an ink manufacturing plant typically includes: (1) Collection pit and screen — removal of pigment agglomerates and packaging material; (2) pH adjustment tank — ink wash water is often alkaline (pH 9–12 for water-based inks) or acidic (pH 3–5 for acid dye inks); (3) Coagulation-flocculation — alum or FeCl₃ coagulates pigment particles and emulsified resins; removal of colour and heavy metals; (4) Filter press — dewaters the pigment-containing sludge (which is hazardous waste); (5) Biological treatment (SBR or activated sludge) — for residual BOD from resins and surfactants; (6) Activated carbon polishing — for residual colour and trace solvents.
This article summarises CPCB norms for printing ink industry effluent for informational purposes. Always verify current standards with your State Pollution Control Board.