Teacher resources and professional development across the curriculum
Teacher professional development and classroom resources across the curriculum
SewageSolid waste going into landfills has a serious impact on the environment, but it's not our only disposal concern. Wastewater also needs to be managed in order to reduce threats to public health, safety, and the environment. Wastewater can consist of industrial waste, human waste (or sewage), or runoff from rainwater.
All of the wastewater produced by a city eventually ends up in a river, lake, or ocean. On its way, this wastewater flows through a sewage treatment plant. In conventional sewage treatment plants, bacteria remove up to 90 percent of biodegradable organic wastes before the sewage moves to a sedimentation tank, where remaining solids and microorganisms settle as sludge. The sludge is incinerated, dumped in the ocean or a landfill, composted, or used as fertilizer. The remaining wastewater, still containing oxygen-demanding wastes, suspended solids, nitrates, phosphates, and toxic metal compounds, may pass through additional advanced sewage treatment before being discharged to the river, lake, or ocean.
Treating Sewage: A Costly
Besides wastewater from sewage, there is urban runoff: water that flows down streets and into storm drains. In some coastal communities, urban runoff flows untreated into the ocean. When this happens, the runoff also transports contaminants such as gasoline, oil, paint, heavy metals, pesticides, human and animal waste, and trash. These contaminants pose a severe threat to the ocean as an economic, recreational, and biological resource as well as to the community's residents and economy.