Treatment of Leather Plant Effluent by Membrane Separation Processes

Abstract

A scheme is proposed for the treatment of the leather plant effluent using membrane based separation processes. The effluent coming out from the various upstream units of the leather plant (except chrome tanning) are combined and a two step pressure driven membrane processes involving nanofiltration (NF) and reverse osmosis (RO) are adopted after a pretreatment consisting of gravity settling, coagulation, and cloth filtration. The entire membrane separation scheme is validated by conducting experiments under a continuous cross flow mode. A detailed parametric study for cross flow experiments is investigated to observe the effects of the operating conditions, i.e., the transmembrane pressure drop and the cross flow velocity on the permeate flux and quality for both NF and RO. Using a combination of osmotic pressure and solution diffusion model for both NF and RO, the effective osmotic pressure coefficient, solute diffusivity, and the solute permeability through the membrane are obtained by optimizing the experimental permeate flux and concentration (in terms of total dissolved solids) values for this complex industrial effluent. The BOD and COD values of the finally treated effluent are well within the permissible limits (in India).

Keywords:

• Leather plant effluent
• membrane
• nanofiltration
• reverse osmosis
• chemical oxygen demand
• conductivity
• total dissolved solids

Acknowledgement

One of the authors (PKB) acknowledges the funding received from the Indo‐French Center for the Promotion of Advanced Research (IFCPAR) in partial support to this work. SD acknowledges the financial support provided by IIT Kharagpur as the submission project under Manufacturing and System Engineering (IIT/SRIC/MSE/2003‐2004/99).