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Chemical and Mechanical Properties of Waste

Chemical Properties of Solid Waste

The chemical properties of solid waste may be characterized in several ways, including:

  • general classes of chemical compounds
  • ultimate analysis
  • proximate analysis
  • flushing point of flash
  • energy content

These chemical properties of solid waste are important in assessing alternative treatment and/or recovery options. Knowledge of the general classes of compounds and there characteristics enables to have a better understating of the behavior of the waste (1992). This section describes only the ultimate analysis, the proximate analysis, the flushing point of ash, and the energy content. These methods are often required when designing a system where waste is used as a fuel.

Ultimate Analysis

An analysis comprises of chemical a mass balance analysis of chemical and thermal possesses. It is an analysis used to ascertain the percentage of each elements present in a waste sample. It frequently involves calculating the percentage of the five primary elements . It is apparent that four elements, carbon, hydrogen, oxygen, and nitrogen, make up the bulk mass of the materials listed. The ash fraction contains both residues from the combustion of the organic matter in the waste and a  percentage of inorganic material. Further analysis of ash is important to determine the percentage of heavy metals that they may pose significant environment problems for the ultimate disposal of the ash.


Proximate Analysis

Proximate analysis is used to evaluate the combustion properties of solid waste and determine the possibility of its use in combustion system. It frequently  involves the determination of moisture content, volatile combustible matter, fixed carbon and ash content. The analysis determines:

  • moisture content-loss moisture when heated to 105′ C
  • volatile combustible matter-loss of weight due to combustion of gases on ignition at 950’C in a covered crucible
  • fixed carbon- residue left when volatile matter is removed
  • ash-weight of residue after combustion in an open crucible.

The mechanical properties  of solid waste are impotent when designing landfills, leachate management system, and ancillary structure. Testes describe in the section on soil testing methods are generally performed to determine the mechanical properties of waste samples collected from landfill sites.

Mechanical Properties of Waste

Strength Parameters

The strength of waste materials are very important parameters for assessing whether building structure would be stable on a waste and established soil environment if there is a possible of such structure being built. It is very difficult to establish relationships among different related parameters because of their drivers nature of waste constituent and their degree of composition. A few test result are reported in Oweies and Khera.

Field Capacity

The field capacity of a waste sample is the fraction of water retried by a waste sample based on the dry weight of the sample. The filed capacity plays an important role in designing leach tea management system. The filed capacity of refuse sample reported by Beaven or Powire range between 60 percent and 141 percent depending on the applied stress.