Physicochemical Processes

In this chapter, the physicochemical processes used in the treatment of aqueous streams such as domestic and industrial wastewaters, drinking water, contaminated groundwater, and aqueous residuals from soil treatment are reviewed.Processes that have their own chapter in the WEF review are not included in this chapter. GENERALDiscussion and development of new approaches for managing liquid waste streams found their place alongside research and application of innovative physicochemical processes.For instance, data from a large number of pulp and paper mills across the U.S. revealed a substantial decrease in environmental discharges during the last 20-25 years, largely as a result of pollution prevention measures by the industry (Das and Jain, 2001).Reduction of organic (i.e., BOD) and sulfur emissions were the most pronounced.Regulatory as well as treatment technology advances such as enzyme bleaching, black liquor gasification, and ethanol production should lead to further reductions over the next decade.Case studies were presented illustrating application of a methodology, developed by DuPont, that identifies waste minimization opportunities in chemical processes (Mulholland and Dyer, 2001).The methodology begins with examining target waste streams and working back to the source of these wastes, while asking questions about waste minimization or elimination at each flow or process node in the system.Another case study of wastewater recovery and reuse, with an emphasis on the total quality management approach, was reported by Orhon et al. (2001) for a knit fabric processing textile plant.