Waste management

WASTE TREATMENT

Currently, the by far most important thermal process is waste incineration. In modern waste management waste, incineration is used to treat nonrecyclable and nonreusable materials in a manner that results in:

* Making inert any hazard waste residues while minimizing the emissions into the air and water.
* Destroying organic contaminants and concentrating inorganiccontaminants.
* Minimizing the quantity of waste requiring disposal, especially its volume.
* Recovering the waste’s heat value to conserve energy resources.
* Transforming the residues into usable secondary products to conserve raw materials and resources (resource cycle)

The above ranking is based on economic priorities. Any optimally operating hazardous waste facility that expectsto retain its operating permit in the future has to be particularly cognizant of the first three factors. In addition, it should be apparent that a residual waste treatment process must be able to operate on a large scale, in order to ensure a minimum degree of disposal options.

The most important principle is the inertization of the waste residue, which includes the contaminant destruction andcontaminant concentration. Inert is understood to mean a pollution-neutral effect on the environment. If the processes discussed below fall short of meeting this criterion, then they are not suitable for waste residue treatment. This makes the principle of inertization the most important criterion for the selection of an appropriate technology.

This also applies, although less stringently, tothe criterion of volume reduction. If a treatment process does not result in a significant waste volume reduction, then the technology is only of limited use.

The next two criteria, energy recovery and the production of marketable secondary raw materials are only of secondary importance. However, these criteria can influence and simplify the choice of processes for inertization and volumereduction (secondary criteria).

In addition to the two primary criteria and the two secondary criteria, as well as the availability of the treatment technology, the following factors should also be considered:

* Operational safety
* Capital investment needs
* Space requirements
* Realistic or feasible throughput

In the pyrolysis process, for example, organic wastes are thermallydecomposed in the absence of air and converted into storable, energy-containing products. The pyrolysis of residual MSW (discards) is currently in the developmental phase because there are numerous unresolved problems. However, the use of pyrolysis in combination with high temperature combustion such as the sulfur combustion facility of the KWU, Germany, has become marketable.

Hydration ispredominantly used for the treatment and utilization of refinery waste and occasionally for scrap plastic. A pilot project operated at the VEBA company facility in Bottrop, Northrhine-Westphalia, is currently using hydration for the treatment of 200 000 t/y of refinery wastes and scrap plastic.

Drying processes are used primarily for the treatment of sewage sludges.

4.1 Incinerators for MSW andCommercial Waste

In Germany, there are currently 48 incinerators being used for the incineration of nine million tons (30% of the total waste disposed of in the Old Federal States) of municipal and commercial waste annually. These facilities serve approximately 21 million German residents. All wastes are processed in facilities with thermal recovery. None of the currently operating facilitiesare located in the New Federal States.

The percentage of energy generated by waste incinerators intended to replace primary energy sources, is relatively minor at 0.46%.

However, compared internationally, Germany is the leader with respect to energy recovery from waste. In 1980, only about 13% of all MSW in the EU was incinerated in facilities for energy recovery.

The current generation...