Indian Tannery + Leather Processing MEP — CPCB Tannery 2022 + CLRI + LWG Audit + UNIDO

A 1500 hides/day Indian chrome tannery demands ₹183 Cr MEP capex with soaking + liming + chrome tanning + recovery + segregated ETP + sulphide stripping + HW sludge. CPCB Tannery 2022 + CLRI + LWG + USEPA NESHAP YYYY + UNIDO govern. Three failures: chrome recovery < 85 % (medium tanneries at 60-70 % leaving Cr in effluent), Cr-III to Cr-VI conversion in alkaline storage causing EU export rejection, sulphide stripper undersized releasing H2S (Kanpur 2022 fatalities).

Indian tannery + leather processing framework

Indian leather industry (Kanpur + Kolkata + Chennai + Vellore + Ambur + Ranipet + Jalandhar + Agra) — Asias 2nd-largest. Tanning uses chromium (Cr-III + Cr-VI) + sulphide + dyes + finishing chemicals. Standards stack — CPCB Tannery Industry Norms 2022 + CLRI Central Leather Research Institute Standards + IS 581-587 (leather quality) + USEPA NESHAP Subpart YYYY (Tannery) + LWG Leather Working Group Audit Standard 2024 + ZDHC + ICC Indian Council on Chemicals + UNIDO Leather Cleaner Production Manual.

1500 hides/day chrome tannery MEP scope

Three Indian tannery + leather MEP failures

1. Chrome recovery < 85 % — Cr-III in spent tan-liquor at 2500-4000 mg/L. CLRI + UNIDO best practice recovery 85-95 %. Indian medium tanneries achieve 60-70 % = high Cr in final effluent + soil contamination. Specify magnesium oxide precipitation + dissolution + re-use.
2. Cr-VI conversion from Cr-III in finishing — alkaline storage of Cr-III tan-liquor converts to carcinogenic Cr-VI. CLRI mandates pH-controlled storage + monthly Cr-VI test per IS 581. Many Indian tanneries skip + face customer rejection in EU + USA leather export.
3. Sulphide stripping bed-volume under-sized — Na2S in liming effluent at 1500-3000 mg/L. Oxidation to Na2SO4 requires sulphide stripper with 2-hr residence + aeration. Undersized stripper releases H2S into atmosphere (Kanpur 2022 worker fatalities).