WASTE COLLECTION AND RECYCLING
Urban refuse collection is organized in different ways in different parts of the world. In some countries it is run by municipalities, in others it is provided by private operators. Where a municipality-run waste collection is a service, the same city might build and operate its own power-from-waste plant. Under these circumstances the composition of the waste can be readily assessed and con- trolled if necessary.
Often, however, waste collection is carried out by private companies. The waste that these companies provides will vary in quality. In some cases it will contain the whole range of waste, but in others it will have been sorted to remove the more valuable material. Some countries now require that glass, metal, plastic, and paper be recycled. This too will affect the quality of the MSW available.
Inevitably the quality of waste will vary by season. Economic factors are also important. Waste will be poorer in a recession than in a boom. Local variations can also be significant. Richer neighborhoods tend to produce better- quality waste than poorer neighborhoods. This has led to the suggestion that the quality of waste for a power-from-waste plant might be maintained by collecting only from prosperous areas of a city.
Whatever the strategy, knowledge of the waste, its source, and its variations will form a necessary part of the management of a waste-to-energy plant. That information can only be gained with practical experience, by analysis of waste collected by the contractor that will provide waste for the plant. Even with this knowledge, it may be impossible to maintain an adequate energy content in the waste throughout the year. Then the only solution may be to add some higher energy–content fuel to the waste. Biomass waste from local sources will often be the most economical solution in this situation.
Recycling is becoming an important part of municipal waste handling. This is partly a result of legislation such as that in the European Union and partly a matter of economics. World Bank figures have suggested that the global market for scrap metal and waste paper from municipal waste is worth $30 billion each year and the total waste management market may be valued at $400 billion annually. Even so, there is a long way to go before global waste management achieves adequate levels of recycling and reuse of material. However, the sorting of waste for recycling means that the best combustible waste that remains can also be separated, which can be valuable for a power-from-waste plant. Sorting can also help with production of RDF.