Proper waste management is a necessity for today's civilization. The volume and complexity of the waste streams generated by people, industry, and agriculture require that waste be handled using environmentally sound, economically viable methods, recovering and reusing as much of the material as possible. The impacts of poor waste management on human health and the environment become more apparent every day. The environmental impacts of many of the new chemicals used by today's civilization, at all levels, are not fully understood, promoting a great deal of concern and often speculation.
Urban areas generate large volumes of waste in several categories that have attracted attention in recent years. Municipal Solid Waste (MSW) or garbage is the largest stream. This material has been mostly disposed of in western societies by moving it to dumps or the ocean, and now to landfills which contain the waste to prevent the spread of disease and odor from the surface and protect surface and ground water by liners and runoff collection. The high cost of landfill siting and construction has promoted an increase in recycling and other methods of disposal such as incineration and composting. In the south, up to 25% of the material going to the landfill has been yard trimmings and diverting this material to compost sites has been done in a number of localities.
The solids from Municipal Waste Water Treatment Plants are one of the most recyclable and controversial materials generated by urban societies. Many cities have recycled their Biosolids after proper treatment for decades without incident. Agriculture and horticulture have benefited from this practice as the material rebuilds soil organic matter lost to cultivation and replaces the normally used manufactured nutrients with recycled organic ones.
Industry also produces large volumes of wastes or residuals (depending on how they are treated) that require handling. Materials that are specifically listed as hazardous or are classified as hazardous due to pH or other characteristic must be handled appropriately. However, many industrial residues can be used as soil amendments or as ingredients in other processes. A common industrial residue is lime, which has many uses in agriculture, sanitation, and road construction. Other residues contain phosphorous, potassium, or minor plant nutrients. Beneficial reuse of these residues may reduce costs to both the generator and the user while preventing the environmental threat created by large concentrations of any material in one place.
The primary processing of agricultural and forest harvests can also generate large volumes of residues. Many of these materials are organic in nature and can be land applied or composted. Waste to energy practices employed by some of these processors generates ash, which may contain usable amounts of lime or phosphorous and usable trace element concentrations.
The manures generated by animal production are currently receiving a great deal of attention both nationally and locally. While the manures generated by animal production have historically been returned to the soil to improve its fertility, the concentration of large numbers of confined animals and increasing urban encroachment of agricultural areas have created both manure and odor management concerns. When more manure is generated than can be safely applied to the soil, waste treatment technologies must be modified or upgraded. Excess manure applications can lead to bacteria, organic matter and nutrients entering surface and shallow ground waters and reducing their usability. Improperly operated storage ponds used for collection and storage and poorly operated lagoons used for collection, storage and treatment are subject to odor problems and can overflow following heavy rains. The proper disposal of the incidental mortality inherent in animal production must also be done in a manner to protect health and the environment.