We use water for drinking, bathing, washing dishes, watering plants for home and agricultural use and other daily activities. In order for water to become acceptable for human use, the water must be purified to the point where the concentration of the contaminants in the water is reduced to a level that is not harmful at all to humans and animals.
Water is channeled into various catch areas such as sewage treatment plants for sewage, and storm catch basins for storm water. The treatment of the two types of water can be altogether different as they carry different pollutants.
Sewage waters mainly have to be treated to rid the waters of microorganisms such as e-Coli, bacteria that is normally found in feces. Solid materials are created from sludge which is thickened and ultimately used to place into landfills.
The liquid part of the sewage treatment is divided up into primary, secondary and tertiary treatment.
The primary treatment involves the sedimentation of the water where roughly 30 to 50 per cent of the suspended materials in the water is removed, then extracted by a biological treatment called secondary treatment.
The semi-liquid is then fed on a regular basis into an aerated tank where the organics of the material is broken down further to the point where there is a clear effluent. This is then trickled through trickling filters and over a biological media, which washes out further bacteria.
Tertiary treatment is a step further when more is needed, such as getting phosphorous out of the water, and other elements such as nitrogen.
The primary method for the treatment of waste water is to simply store the water in large tanks or ponds, and let the natural process of sedimentation and settling take its course. It is not at all practical to run this water through municipal water treatment plants due to the huge volumes of water that is generated by storms.
Evaporation takes in this particular environment and process, and some of the water can be recaptured here, the the natural filtration and natural biological process are the best methods to reclaim the water that is runoff from storms in general.