The United Nations Environment Programme developed in 1991 the following CP definition that is still commonly used:
“CP is the continuous application of an integrated preventative environmental strategy to processes, products and services to increase efficiency and reduce risks to humans and the environment”.
Several complementary CP techniques or practices are possible, ranging from low or even no cost solutions to high investment, advanced clean technologies. A common distinction for CP implementation in developing countries is:
- Good Housekeeping: appropriate provisions to prevent leaks and spills and to achieve proper, standardized operation and maintenance procedures and practices;
- Input Material Change: replacement of hazardous or non-renewable inputs by less hazardous or renewable materials or by materials with a longer service life-time;
- Better Process Control: modification of the working procedures, machine instructions and process record keeping for operating the processes at higher efficiency and lower rates of waste and emission generation;
- Equipment Modification: modification of the production equipment so as to run the processes at higher efficiency and lower rates of waste and emission generation;
- Technology Change: replacement of the technology, processing sequence and/or synthesis pathway in order to minimize the rates of waste and emission generation during production;
- On-Site Recovery/Reuse: reuse of the wasted materials in the same process or for another useful application within the company;
- Production of Useful By-Products: transformation of previously discarded wastes into materials that can be reused or recycled for another application outside the company; and
- Product Modification: modification of product characteristics in order to minimize the environmental impacts of the product during or after its use (disposal) or to minimize the environmental impacts of its production.