Green Chemistry and Industrial Ecology in Waste Management

13 GREEN CHEMISTRY AND INDUSTRIAL ECOLOGY IN WASTE MANAGEMENT 

FIGURE 16.8 Order of effectiveness of waste treatment management options the darkened circles indicate the degree of effectiveness from the most desirable (1) to the least (4). In the figure, POTW refers to a publicly owned treatment works. 

Industrial ecology is all about the efficient use of materials (see Chapter 14, Seetion 14.2). Therefore, by its nature, a system of industrial eeology is also a system of waste reduction and minimization. In reducing the quantities of wastes, it is important to take the broadest possible view. This is because dealing with one waste problem in isolation may simply create another. Early efforts to control air and water pollution resulted in problems from hazardous wastes isolated from industrial operations. 

Many hazardous waste problems can be avoided at early stages by waste reduction (cutting down quantities of wastes from their sources) and waste minimization (utilization of treatment processes that reduce the quantities of wastes requiring ultimate disposal). This section outlines some basic approaches to waste minimization and reduction. 

Modifications of the manufacturing process can yield substantial waste reduction. Some such modifications are of a chemical nature. Changes in chemical reaction conditions can minimize the production of by-product hazardous substances. In some cases, potentially hazardous catalysts, such as those formulated from toxic substances, can be replaced by catalysts that are nonhazardous or that can be recycled rather than discarded. Wastes can be minimized by volume reduction, for example, through dewatering and drying sludge. 

---