Emissions, waste reduction methods

Methods of waste reduction, waste reuse and recycling are the preferred options when managing waste. There are many environmental benefits that can be derived from the use of these methods. They reduce or prevent green house gas emissions, reduce the release of pollutants, conserve resources, save energy and reduce the demand for waste treatment technology and landfill space. Therefore it is advisable that these methods be adopted and incorporated as part of the waste management plan. This chapter will highlight the use of clays in such processes. 

Chemical Volume Reduction Incineration has been the method commonly used to reduce the volume of wastes chemically. One of the most attractive features of the incineration process is that it can be used to reduce the original volume of combustible sohd wastes by 80 to 90 percent. The technology of incineration has advanced since 1960 with many mass burn facihties now have two or more combustors with capacities of 1000 tons per day of refuse per unit. However, regiila-tions of metal and dioxin emissions have resulted in higher costs and operating complexity. 

As air pollution management moves forward, economics has a major role in reducing pollution. Multimedia considerations are forcing a blend of traditional emission reduction approaches and innovative methods for waste minimization. These efforts are directed toward full cost accounting of the life cycle of products and residuals from the manufacturing, use, and ultimate disposal of materials. 

The waste materials produced during the primary production of aluminum are fluoride compounds. Fluoride compounds are principally produced during the reduction process. One reason that prebaked anodes are favored is that the closure of the pots during smelting facilitates the capture of fluoride emissions, although many modern smelters use other methods to capture and recycle fluorides and other emissions. 

A variety of factors and methods were used to evaluate and rank the twelve options. For example, the study team considered the reduction in relative risk to human health achieved by different options. Generally, an option s effectiveness in reducing health risks was evaluated by calculating its effect on exposure to benzene emissions. The study team selected benzene emissions as an indicator because benzene can be found in all waste media (air, water, groundwater, and surface water) and poses a known threat to human health. 

A third emission reduction choice is to remain with the existing front end process, which continues to produce a sulfur dioxide-containing waste gas stream, and move to some system which can effectively remove the sulfur dioxide from this waste gas before it is discharged. Many methods are available, each with features which may make one more attractive than the others for the specific sulfur dioxide removal requirements (Table 3.8). Some of the selection factors to be considered are the waste gas volumes and sulfur dioxide concentrations which have to be treated and the degree of sulfur dioxide removal required. It should be remembered that the trend is toward a continued decrease in allowable discharges. The type of sulfur dioxide capture product which is produced by the process and the overall cost are also factors. Any by-product credit which may be available to offset process costs could also influence the decision. Finally, the type of treated gas discharge required for the operation (i.e., warm or ambient temperature, moist or dry, etc.), also has to be taken into account. Chemical details of the processes of Table 3.8 are outlined below. 

Flaring (burning) of waste hydrocarbon streams has been routine practice from the earliest days of the oil and chemical industry because it is the safest disposal method. When CO2 emission reduction... 

---