WASTE Management

Environmental Engineering
WASTE
Core Notes for Module 6 (Elective) of the Course
“Environmental Engineering – Sustainable Development in Coastal Areas”

1.
WASTE Management

The field of waste management is often highly underestimated in its complexity, not only by the community, but by senior officials as well. It is mainly due to this fact that waste management issues are often an afterthought rather than a carefully planned, integrated component of development and services. It needs to fit in with the Constitutional rights of the citizens of the country, as well as the Integrated Development Plan (IDP) of the city. Waste management itself needs to have its own subset of an Integrated Waste Management Plan (IWMP), which will be compulsory on all major metropolitan cities in the near future. It is therefore very important that waste management activities be carefully planned, sometimes over long periods of time, before implementation can occur in order to ensure a successful outcome.

The field of waste management itself is multidisciplinary and encompasses management, financial, environmental, legal, engineering, chemical, biological, logistical, social and entrepreneurial issues.

Waste is defined as “an undesirable or superfluous by-product, emission, residue or remainder of any process or activity, any matter, gaseous, liquid or solid or any combination thereof,…” (Government Gazette, 24 August 1990). A more simplistic definition defines waste as “anything that we have used that is not being reused and has not been absorbed back into nature. It can be solid or liquid and we must find somewhere to put it, or some way to reuse or recycle it.” (Wise up on Waste, 5th Edition, FCA). Wastewater effluents are not defined as waste as they are regulated and controlled by the Water Act (1998). Similarly, radioactive waste is regulated and controlled by the Nuclear Energy Act (Act 92 of 1902) and the Hazardous Substances
Act (Act 15 of 1973). Sewage sludge from sewage works and building rubble contaminated by other waste or not used for fill would fall under the definition of waste.

Waste is divided into two classes in accordance with the risk it poses: General Waste and Hazardous Waste. General waste refers to any waste that does not fall within the definition of Hazardous Waste. This waste does not pose a significant threat to public health and the environment if properly managed. Examples would include domestic (although it may contain small quantities of hazardous substances), commercial, certain industrial wastes and builder’s rubble. General Waste may be disposed of on any landfill that is permitted in terms of the Environment Conservation Act. Hazardous Waste is waste that has the potential, even in low concentrations, to have a significant adverse effect on public health and the environment because of its inherent toxicological, chemical and physical characteristics. Hazardous Waste requires stringent control and management, to prevent harm or damage and hence liabilities. It may only be disposed of on a hazardous waste landfill. A further classification, termed the hazard rating, differentiates between hazardous waste that is fairly or moderately hazardous and one that is extremely hazardous. Hazard Rating 3 (moderate risk) and/or 4 (low risk)
waste and can be disposed of on a landfill site classified as H:h, whereas Hazard Rating 1 (extreme risk) and/or 2 (high risk) waste can only be disposed of on landfill
sites classified as H:H.

General waste landfills are classified in terms of their potential to generate leachate. This ensures that the risk of water pollution from leachate is identified at the earliest opportunity.

Any landfill has the capacity to generate sporadic leachate in excessively wet weather conditions. It is only necessary to install leachate management systems (liners, drains and removal systems) when leachate generation could impact adversely on the environment. Significant leachate generation requires to be managed by means of a proper leachate management system, whereas sporadic leachate, while requiring some management does not warrant a costly leachate management system.

The Climatic Water Balance (B) is defined by the difference between Rainfall in mm of water ( R ) and Evaporation from the soil surface (E). The value of B is calculated for the wet season of the wettest year on record, and then recalculated for drier years. If B is positive for less than one year in five for the years for which data is available, then there should be no leachate generation on account of the climate and
the site would be classified as B- . No leachate management system should thus be necessary. If B is positive for more than one year in five for the years for which data is available, there should be significant leachate generation and the site will be classified as B+. A leachate management system would now be required.

B = R – E
As a rough guide: If R > E, then B = B+ and if R < b =" B-."> 25 and <> 150 and <> 500

A site classified as GLB+ would therefore indicate that the site is a general landfill, receives over 500 tons of waste per day, and requires leachate management due to the climatic balance or moisture content of the waste.

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Sumber:
Core Notes for Module 6 (Elective) of the Course
“Environmental Engineering – Sustainable Development in Coastal Areas”
Cape Peninsula University of Technology (CPUT)
Cape Town, South Africa
2006
Available to Distance Learners on www.dlist-benguela.org