Tannery and Chrome Chemicals Manufacturing Sector

Abatement Technology

The salient features of the treatment system at CLC, Bantala are:

  • Maximum Raw Hide Processing capacity : 1000 Ton/day
  • Estimated Waste Water Generation  :  30 MLD
  • Raw hide processing capacity: 1.333kg/day/sq.m land
  • Water consumption : 30 KLD/ T of raw hide
  • Water discharge: 28 KLD/T of raw hide

To treat the waste water, a Common Effluent Treatment Plant having 6 Modules with total effluent handling capacity of 30 MLD (each a module of 5 MLD capacity) was proposed to be installed. Before discharging to the CETP,installation of on-site preliminary treatment plant at individual tanneries were also proposed. The present status is given below:

  • No. of modules of CETP in operation : 4
  • Total Capacity of 4 modules of CETP : 20 ML

 Effluent Transportation System
There are 9 Zones in the Leather Complex having 6 nos EPS for carrying the effluent from the tanneries to the CETP. The waste water transportation network is of approximately 22 km.  The following table gives distribution of effluent to different EPS (Effluent Pumping Station) from different zones:

 

Zone EPS
1 Partly to EPS 1 & Partly to EPS 5
2 Partly to EPS 1 & Partly to EPS 3
3 Partly to EPS 1 & Partly to EPS 2
4 EPS 2
5 Partly to EPS 1 & Partly to EPS 2
6 EPS 3
7 EPS 2
8 EPS 4
9 EPS 7

Effluent flows to collection wells in 6 EPS by gravity. Diameter of pipeline of ETS network varies from 200mm-630mm. 

On-site Pretreatment Facility  installed at individual Tanneries

 The major objectives of on-site treatment are  

Removal of coarse materials, grit in order to blueuce clogging and siltation problem in waste water transportation network of approx. 22 kmSeparate collection of chromium containing effluent in order to enable the recovery and reuse of chromium and also to blueuce chromium concentration in the wastewater 

The main components of Pretreatment Plant for beam house liquor i.e. non-chromium bearing effluent comprises of:

i) Collection Tank        

ii) Overhead Sedimentation Tank       

iii) Sludge Drying Bed


 

Collection tank with aeration system for preliminary treatment of individual tannery unit.

 

 

Sedimentation tank of a preliminary treatment plant of individual tannery unit

 

 


Reaction tank of chrome recovery unit (CRU) of individual tannery

 

 

 

 Inside of reaction tank of CRU system of individual tanner

 


           i) Collection Tank
           ii) Reaction Tank
           iii) Recovery Tank   
Common Effluent Treatment Plant (CETP)

Effluent from individual tanneries are collected in six nos. of collection wells and from these wells effluent is pumped to the CETP. Each module consists of the following successive components :

  •      Equalisation Tank
  •      Flash Mixer
  •      Flocculation Tank   
  •      Primary Clarifier
  •      Aeration Tank
  •      Secondary Clarifier
  •      Sludge Holding Tank
  •      Filter Press 

 
  

Primary clarifier of a module of CETP

 

Aeration tank of a module of CETP 

 


Inlet to aeration tank of a module of CETP where effluent from primary clarifier and activated sludge from secondary clarifier are mixed.

 

 

 

Secondary clarifier of a module of CETP

Common Chrome Recovery Unit

Two modules of CCRU each of 120 M3  per day  capacity have been installed, presently approximately   25 M3   chrome liquor is  being treated in the CCRU.