Often, when solid waste is mentioned, the first environmental effects that come to mind are the aesthetic deterioration, nasty smell and the consumption of land used for disposal. Households often produce general waste such as food waste, containers for chemicals, electric equipment, paper, boxes and so forth while industries produce a whole range of waste such as biological, chemical, general, and hazardous waste. Hospitals also often produce biological and medical waste. The proper disposal of waste reduces the environmental impact. Unfortunately, not all waste is properly disposed of, affecting the environment. The awful smell from both legal and illegal disposal sites are an air quality concern and impact on people’s wellbeing.
There are many different disposal methods for waste, including incineration, landfill disposal and illegal dumping. The following three disposal methods have different air quality impacts, as mentioned below:
Incineration (Thermal Treatment)
Incineration is a combustion process where waste is burned in a combustion plant. This is usually a two-step process where the waste is first burned and later the residual volatile gases are burned. The process is usually applied for medical and biological waste to avoid viruses and diseases spreading during disposal. The process emits particulate matter which may cause respiratory problems, dioxins and furans which may lead to skin disorders, liver problems, impairment of the immune system, the endocrine system and reproductive functions and affects the developing of the nervous system. A whole host of other air pollutants may emerge depending on the substance incinerated.
A landfill is an engineered pit in which solid waste is filled into and enclosed. The downside to the process is that it creates an anaerobic environment that allow microbes to disintegrate the carbon and sulphur-based waste and create methane gas, hydrogen sulphide and carbon monoxide. Hydrogen sulphide has a rotten egg like smell, and it is explosive and poisonous, while methane is an explosive greenhouse gas that may negatively affect global climate change. Carbon monoxide is created by incomplete oxidation and is poisonous. Other gases associated with landfills include ammonia, sulphides, hydrogen and carbon dioxide. Improper management of a landfill can result in gases moving from one site to another, like into neighbouring communities for example. Although gases may effectively be managed in a landfill, escaping gases through pores may still create a hazard. Landfills are mostly designated and owned by municipalities that survey and locate them at appropriate areas, adequate for potential waste produced by residents, and at suitable locations thereby preventing the effects of the landfill to the surrounding areas. Some landfills are lined to contain seepages that may contaminate groundwater resources.
Illegal dumping is the disposal of waste in areas not designated for that particular purpose. The air quality impact by the illegal disposal of waste is dependent on the magnitude of the illegal dumping site as well as the contents being disposed of in the area. Large dumping sites create anaerobic conditions in the lower levels where the waste is covered up, thereby creating poisonous and explosive gases like a landfill. In the upper waste, the conditions are aerobic meaning that the carbon-based compounds will be fully oxidised. Where illegal dumping is done on wetlands and watercourses, reactions of wastes and water may create bigger issues that could ultimately pollute the water resource as well as the air quality.
With all the air quality impacts mentioned above, the movement of air pollutants from the sources to the receiving environments is a function of wind speed and direction. Furthermore, although pollutants may exit the sources in high concentrations, dilution may occur through chemical reactions, mixing caused by air turbulences and the mixing through the depth as the pollutants moves downstream. While chemical reactions can reduce concentrations, chemical reactions can form more lethal gases in the air.