MSW hat mehr als 50 % Anteil an biologisch abbaubaren Stoffen und zählt deshalb ebenfalls zu den “erneuerbaren Energeiequellen”
Landfill is the Past
Incineration is The Present
SynGasGeneration from Waste is the Future
Current situation and development of Waste Management
Over the past years considerable efforts have been put into disposing municipal, industrial and agricultural waste worldwide with minimal effort. According with the principle “out of sight is out of mind” waste was simply dumped on landfill sites or at sea. Only with growing environmental awareness and the increase of environmental movements the attitude has changed and new ways of waste disposal have been attempted. Setting up comprehensive recycling schemes to recover some of the raw materials was one of them:
However, these systems have their limitations and from an economic point of view a total recovery is impossible: there is still rest-waste that needs to be deposited. Because of waste disposal areas in industrialized countries exceeding their capacity limits the remaining quantity of waste is being reduced by incineration. Since the 1970’ies massive incineration plants have been built in all industrial countries and in the meanwhile in developing and newly industrialized countries as well.
Politics and Waste Management
Generally speaking waste disposal worldwide belongs to the responsibility of the Executive implemented by the conditions imposed by the Legislative. Even though waste disposal is a government task it is executed by various organizational forms that vary widely between industrialized and developing countries.
It is characteristic for industrialized countries to contract out waste disposal to the municipality or to private companies. The complete set of tasks (collecting, sorting, depositing, incineration ) is being financed by a long term fee model using various company strategies.
Private sector – – – Profit Maximization
Municipal /Public sector- – – Reducing Expenses/Fees
Despite different objectives both legal forms are interested in an efficient and profitable recovery of the accumulated waste.
Developing and newly industrialized countries
By comparison (with industrialized countries), the recycling rate by incineration in developing and emerging countries is very low. Because of the amount of waste per capita is still lower than in developed countries, an above-average growth of amounts will be expected with growing prosperity. These quantities are always still largely deposited due to (still) missing recovery capacities.
Because in these countries politically overall great efforts are made to improve the standard of living of the population, it is no longer opportune with the now available technologies to not recover raw materials contained in waste.
In addition, the landfills, no matter where they are located, will represent an environmental problem on the long run, which then will burden the next generations.
Today’s policy should therefore be:
- to curb waste volume growth and
- to increase the degree of recyclability through reuse, composting and others, and
- to feed back the currently still not reusable residual amount (R5) into the economic cycle efficiently and with minimal environmental impact.
Due to the ever-growing cost of waste disposal and the increasing environmental risks associated with the sprawling landfills, research is being done to improve the techniques of waste disposal. Goal is to increase the energy efficiency of equipment and systems and to reduce the environmental impact at the same time.
The today dominant technology is incineration in modern waste incinerators. This technology is constantly improved by the manufacturers, so that with the installations of the 4th generation (2.4 KVA) we can speak of State of the art technology.
With further development the following main trends are identifiable:
1. Improvement of combustion technologies
- Optimization of grating
- high quality materials for higher temperatures suitable
2. Flue gas cleaning
- Reduction of energy expenses
- Boost of the degree of cleaning
3. Power generation
- High-temperature steam turbines
Due to technologically driven boundaries the electrical efficiency of most of this modern equipment scores between 20-30%. Moreover, with this technology up to 10% of the initial quantity of the waste remains in the form of ash and slag, which still must be deposited.
The so-called zero-waste movement has the goal to reduce global waste. Its approach is to already use materials in the manufacturing process that can be recycled according to the waste management pyramid. These efforts are sometimes quite successful, but they cannot solve the fundamental problem.
Although thus the amounts of the first four R’s is constantly increasing, both as a result of political requirements as well as technical achievements, the amount of waste to be disposed is still growing worldwide. In the EU, that sure is one of the developed regions, you can see that the currently economically viable recycling rate is at a maximum of 50-70%.
The zero-waste movement remains an unreachable goal yet for a long time, but at least for the next 15-20 years.However, a new method of waste management is going to be explained in more detail. While today’s core technology of waste management is recycling and incineration, the combustion is going to be substituted by syngas generation.
Customer demand for efficiency and sustainability
Municipalities, businesses, agriculture and forestry have a everyday problem of
- law compliant
- efficient and
disposal of waste in their area.
The procedures used must meet the following minimum requirements:
- all national and local environmental conditions
- be as simple as possible
- be so efficient that a positive operating result can be achieved on a long term
- the output must be sellable on the long run
In times of scarce funds, growing environmental regulations and political uncertainty we will have to go new ways to comply with the provisions and the law as well as achieve a break-even or positive operating result. This requires a new perspective on the waste product:
Waste should not be seen as an annoying by-product –but as a tradable material after its treatment and as a resource for profit oriented recycling management.
Types of waste around the world
Worldwide, there are several hundred different types of waste, of which some occur more regionally (E.g., waste from oil sand extraction in Alberta/Ca), some have only marginal importance (E.g. remains of shells from processing almonds in California) or some require special disposal procedures (for example medical radioactive waste).
However, the present study deals only with the waste situation for combustible waste with a focus on municipal solid waste.
Current disposal methods
All waste products, that so far could not be recycled in one form or another, were and are disposed of in the end as follows:
Disposal on landfills
Oldest and currently still most common method
- Long-term effects on air (out-gassing of methane) and groundwater
- High consumption of land in sensitive areas
Dumping at sea
- Has been a common method for a long time especially for the disposal of hazardous waste
- is regulated and prohibited for household waste in the EU by international and national laws (e.g. OSPAR agreement)
- is strictly being monitored by coastal protection, marine and satellites and no longer statistically significant
- Combustion in the free field is still common practice for the disposal of agricultural waste
- Combustion in so-called waste incineration plants, currently the world’s most common method to reduce waste
- Waste incineration in cement production and incineration of sewage sludge in sludge incineration plants
All of these disposal procedures have the stigma that the thus disposed substances only are returned partly or not at all to the energy and material cycles. Thus, valuable raw materials are destroyed and lost.
Composting / Fermentation
Composting of biogenic waste to the later reintroduction into agricultural and horticultural land
- Fermentation of liquid or semi liquid and solid waste in gas tanks for the production of gas, which is then used to produce heat and electricity with gas engines