PROCESS INTEGRATION FOR WATER MANAGEMENT IN PULP AND PAPER INDUSTRY

Abstract

The thesis entitled "Process Integration for Water Management in Pulp and Paper Industry" covers different topics related to Process Water Management in a paper mill. Chapter 1 presents need of recycling of process water in the present scenario. Water recycling is a need of the time to ensure sustainable development in Indian industry. Recycling of process water can be beneficial in both the terms i.e. environmentally and economically. This chapter also covers introduction to water pinch technology and membrane filtration technology. The objective of this work is to prepare environmental management plan of pulp and paper mill through minimizing the fresh water consumption and waste water generation by recycling of process water through closed system without/with treatment. Chapter 2 describes the system closure using water pinch technology. Water cascade analysis (WCA) technique was used to identify critical limiting constraint and minimum fresh water requirement for the system. Nearest network algorithm was used to design water network. Water network was designed in two cases, without treatment and after treatment. Water network without treatment was designed for three sections i.e. pulping, bleaching and paper machine section. To design network after treatment, only bleaching section was selected. AOX, COD and TDS was selected as limiting constraints and after the analysis AOX was found to be the critical constraint for bleaching section and for all other sections, COD was found to be the critical limiting constraint. Water network design after treatment was also designed for bleaching and after use of combined permeate, further reduction in pollution load was achieved. ...