Impact Of Wastewater And Stormwater
Solids within wastewater and stormwater both form sediments and could eventually clog streams, drains, and rivers. Grease particles form scum and are aesthetically undesirable. A nutrients N and P cause eutrophication of water bodies, along with lakes and slow moving waters affected to a greater degree than faster flowing waters. Within the former the algae that are fertilised through the nutrients settle as sediment while they decay. The sediment acts as a store of nutrients and regularly releases the nutrients to the water column, therefore the cycle of bloom and decay of the algae is intensified. In the previously stages of eutrophication, aquatic life is made more abundant, since fish, for instance, graze on the algae. Along With too high a concentration of algae, a decaying alga contribute to BOD and the water is deoxygenated. Therefore wastewater, that has been treated to reduce BOD but still high in nutrients, could still have a significant impact on the receiving water. Some algae generate toxins that could be harmful to bird life and irritate skins coming within contact with the water. Eutrophic water adds to the cost of water treatment, while the water is used for drinking reasons.
Other pollutants in wastewater and stormwater are heavy metals and probable toxic and household hazardous substances. Heavy metals involve copper, zinc, cadmium, chromium nickel, and lead. The content and concentration are dependent on the pipe materials employed to convey household- cleaning agents used, drinking water, and for stormwater the kind of materials used for roofing and guttering. In high sufficient concentrations, these heavy metals are toxic to plants, bacteria, and animals, and to people. Toxic materials might also be disposed along with household wastewater. Those could be medicines, pesticides and herbicides, that are no longer used, excess solvents, paints and another household chemical. These substances could corrode sewer pipes and seriously affect operation of treatment plants. That will also limit the potential of water reuse, and, thus, should not be disposed along with household wastewater.
Spills of chemicals, particulates from motor vehicle exhaust and deposition of atmospheric pollutants could similarly contaminate stormwater. Those pollutants will affect downstream receiving waters and treatment systems if the stormwater is treated. Wastewater and contaminated stormwater could contaminate groundwater. This is by infiltration of the wastewater or stormwater by the soil to unconfined groundwater aquifer. Soil could filter some pollutants, but soluble pollutants (e.g. nutrients and heavy metals) and extremely small particles (e.g. virus) travel along with the water to the groundwater aquifer.
Heavy storm events could cause flooding. The effects of flooding could be severe. Water levels within drain, stream and rivers rise considerably and the flow of water could erode soils and embankments. Sediments, which have been deposited in quiescent stretches of a stream, can be resuspended and transported additionally downstream. In urban areas water picks up litter and solid wastes within its path as well as other diffuse pollution sources, and spread these in the downstream flooded areas. Aquatic environments and water-fowl habitats could be destroyed, and these may take a few times to recover. The amenity value of these, as well as recreational lakes, is thus degraded. Engineered structures, like as culvert and bridges, and could be choked along with wastes and debris, causing more widespread flooded fields.