The first key strategy of industrial pollution prevention is the implementation of good housekeeping measures. This means generally improving the way in which materials, particularly hazardous ones, are purchased, stored, conveyed, handled and used in the industrial facility. Good housekeeping means identifying and reducing leakage and spillage, carrying out regular maintenance of all materials processing equipment, and instituting better inventory controls. A particular prerequisite for good housekeeping is to implement regular waste reduction audits (Box 1).3 These are systematic accounting processes which track materials flows through the process, monitor
A waste reduction audit is a systematic, periodic, internal review of a company's processes and operations with the aim of identifying and providing information about opportunities to reduce wastes. The following six stages can be identified.
1 AUDIT PREPARATION
• prepare and organise the audit team
• advise personnel
• identify management responsibilities
2 MATERIAL BALANCE
• identify processes and construct flow diagrams
• identify process inputs (energy, water, materials)
• identify outputs (products, by-products, waste emissions)
• identify recycle and reuse rates
• derive a preliminary materials balance
• evaluate and refine the materials balance
3 ECONOMIC BALANCE
• identify financial parameters: inputs costs, waste disposal costs, emis sions charges, product revenues and so on
• identify pollution prevention measures: good housekeeping, input substitution, recycling, process change, clean technologies, product reformulation
5 EVALUATE OPPORTUNITIES
• undertake technical, environmental and economic evaluation of waste reduction options
• list and prioritise viable options
6 DESIGN A WASTE REDUCTION STRATEGY
• formulate strategies and measures
• produce timescales for implementation
• identify waste reduction targets the efficiency and proper functioning of the process, and identify opportunities for waste reduction.
Another basic strategy is to implement internal recycling. In many industrial processes there are opportunities to collect materials after they have been used and recycle them for the same or another use within the process. This will reduce material emissions from the process. It will also reduce the need for a continued supply of raw material inputs. Examples of this kind of measure include the recovery and reuse of solvents and acid cleaning baths in electroplating, the recovery and refurbishment of catalysts, and the precipitation and recovery of metals from treatment sludges.
Both internal recycling and good housekeeping measures are examples of simple process modifications. Other process modifications may also contribute to industrial pollution prevention. Some of these other measures are simple. Some are more complex. Examples include: the use of electronic process controls to moderate and optimise material flows; the addition of minor capital investments (such as membranes and filters); and the segregation of waste streams to aid recovery and recycling.
A continuation of the idea of process modification is the implementation of newer, more efficient and cleaner process technologies. These are generally processes which differ from the original in that they possess inherently better material efficiencies or inherently reduced reliance on hazardous materials. Examples of such clean process technologies include: the development of membrane technology to replace electrolysis in the chlorine production industry;4 and the employment of electrolytic (rather than thermal) smelting technologies.
Most of the techniques for industrial pollution prevention which I have described so far relate to improved material efficiency. This was the first of the two principal avenues for preventive environmental management which I have identified. The other avenue was substitution. And input substitution is another important technique for industrial pollution prevention.
Figure 16 illustrates the main idea behind input substitution in industrial processes. Hazardous raw material inputs are replaced with less hazardous materials. This substitution can have a number of different impacts. In the first place, particular hazardous components in the waste streams can be eliminated.5 Next, the products themselves can be less hazardous, because they no longer contain that particular material. Last but not least, there are advantages to be gained in terms of safety in materials handling.
Figure 16 also illustrates the sixth strategy for industrial pollution prevention, that of product reformulation. In the particular example
Figure 16 Industrial pollution prevention—input substitution i(tj| after sut^HuHonl
Figure 16 Industrial pollution prevention—input substitution shown here, the product is reformulated by substituting less hazardous materials for its hazardous components. This reformulation also reduces the hazardous content of the aqueous waste stream. An example of this kind of reformulation is provided by the development of non-CFC-based aerosol sprays. This change means not only that CFCs are eliminated from the manufacturing process, but also that the product itself is less liable to harm the environment. Quite generally, reformulating the product can lead to multiple advantages: reduced material input requirements, fewer hazardous throughputs and emissions from the industrial process, and safer products.
In fact, we can see that the idea of reformulating and redesigning products is a very powerful one which goes a long way beyond simply reducing production process wastes. And we could say that the strategy of redesigning products represents a higher level of prevention because it starts to look even further upstream in the industrial chain—the demand for particular products and services. Ironically, product reformulation has been one of the least favoured options within industrial pollution prevention. This is partly because manufacturers are naturally concerned about loss of product quality. Sometimes, though, product reformulation has had rather dubious results because it has meant the transfer of hazardous substances from the waste stream to the product. Although this has the effect of reducing hazardous wastes from the facility, it clearly increases the hazard associated with the product itself.
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