l BENEFITS waste treatment.
1.1. Treatment of organic materials.
1.2. treatment of plastics.
1.3. Treatment of glass.
1.4. Treatment of paper and paperboard.
1.5. treatment of metals.
1.6. The tetrabrick.
1.7. wastes.
2. The energy recovery.
2.1. Advantages and disadvantages recovery.
2.2. Other forms of recovery.
3. controlled landfills.
4. Bibliography.
Advantages and disadvantages of recovery.
1. The recovery has a number of advantages: reduction of waste volume by up to 90%.
2. Energy recovery.
3. The ashes are more stable than the starting waste.
The energy recovery from waste is getting energy from combustion. The calorific value of waste is variable, in the case of hydrocarbon plastics is estimated to be comparable that of petroleum products with environmental advantages such as not generate sulfur oxides, causing acid rain. However, the burning of PVC generates a 50% energy than before.
The disadvantages are:
1. The indiscriminate burning of garbage without separation occurs as an effect of certain highly toxic combustion. The presence of PVC in the blend, contributes to the combustion gases hydrochloric acid in the presence of organic matter can cause toxic by-products of dioxins and dibenzofurans.
2. The product of combustion ash containing heavy metals such as cadmium in quantities considered hazardous and should receive special treatment as hazardous waste.
3. As a result of the above two points need to make large investments in technology.
4. If recyclable materials are incinerated in other ways there is a valuable resource consumption.
In response to these problems of incineration technology has developed considerably in recent years to reduce emissions of gases and fumes. Incinerators operate at high temperatures to destroy dioxins and furans, they usually do at 1000 ° C. On the other side and to ensure the composition of gases emitted units incorporating washing and appropriate filters. All therefore governed by a strict both European and national legislation. Several technologies
process: grill, fluidized bed and plasma. The aim of all is to achieve complete combustion and emitted into the atmosphere, only carbon dioxide and water, after having been detained by heavy metals, acid gases and particulates generated during combustion. In all fluidized bed technology can reduce emissions below the limits. Good contact is used in an afterburner combustion of a sand bed heated to 850 º C in the presence of a higher rate to 6% oxygen in a period of at least two seconds.
Recently the company Solvay, the manufacturer of chlorinated products, including PVC, has developed a combustion technology (NEUTREC ®) ensuring the control of the gases emitted into the atmosphere and the recovery of ash generated. The process is based on the addition of sodium bicarbonate dry in the gas stream. And major improvements are achieved with respect to semi-wet processes used previously. The novelty lies in the possibility of separating the residual solids content of heavy metals and organic compounds in the chemical recycling.
gases must be in contact with sodium bicarbonate during two seconds at temperatures above 140 º C to ensure complete neutralization. Then the gases pass through bag filters to retain particles of dust and one for particles of activated carbon to retain heavy metals dioxins and furans.
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