Leather/Skin/Hide Processing Industry - Environmental Clearance

Leather / Skin / Hide Processing Industry (Tannery)VOCsCH 4ETP Sludge Dewatering SystemETP Anaerobic LagoonsFinishing OperationsETP Anaerobic Lagoonscontaining less than 30 % solids maygenerate especially strong odors Ventilate tannery areas and controlexhaust from odorous areas (e.g., wherewastewater sludge is thickened anddewatered), through use of a biofilterand / or a wet scrubber with acid, alkali,or oxidantSource: Draft report of the Expert Committee on Odor Pollution and its Control, July 2007, CPCB3.3.3 Solid wasteSolid waste includes salt from raw skin / hide dusting; raw skin / hide trimmings; hairfrom the liming / dehairing process, which may contain lime and sulfides; and fleshingfrom raw skins / hides. Other solid waste from tannery industry includes wet-blueshavings, containing Cr 2 O 3 ; wet-blue trimming, which is generated from finishingprocesses and contains Chromium oxide (CrO), syntans, and dye; and buffing dust, whichalso contains CrO, syntans, and dye. The reducing characteristics of tannery sludgestabilize Cr(III) with respect to Cr(VI), due to the presence of organic matter and sulfides.Prevention and control measures for solid waste include the following:Reduce inputs of process agents (particularly precipitation agents in wastewatertreatment) to the extent practically applicableSegregate different waste / residue fractions to facilitate recovery and re-use (e.g., tomanufacture pet toys, pet food, leather fiberboard)Recycle sludge as compost / soil conditioner or in anaerobic digestions for energygeneration. Process sludge may be used for composting / agriculture after appropriateassessment for contaminants and potential impacts to soil and groundwaterFleshings could be degraded through bio-methanation process – CLRI research findingsare encouraging.3.3.4 Hazardous materialsTanning and leather finishing processes involve the use of a variety of hazardouschemicals. Guidance on the management of hazardous materials, including handling,storage, and transportation, shall be adopted as provided in the General EHS Guidelines.3.4 Cleaner Technologies, Minimization, and Recycling / Reuse Options3.4.1 Cleaner technologies in leather processingThe International Union of Environment (IUE) Commission understands that cleanertechnology can be defined as the environmentally and economically best practicabletechnology (BATNEEC, best available technology not entailing excessive cost). Cleantechnology may be defined in terms of minimum environmental impact, towards whichthe industry is striving.Cleaner technologies and waste minimization in leather processing based on the IUECommission report for world leather sector are listed as follows:TGM for Tanneries August 20103-13