The world today is faced with a lot of different waste problems. One major problem is how to get rid of the waste safely so that it does not disrupted the environment or hurt people or animals. The major problem for the United States is waste water, the amount, and the cost of treatment and disposal.The United States treats over 1 billion tons of waste a year. How do we treat that much waste.One way it to send the waste water into a treatment plant ran by the state or county. The water contains solid particles, which mixed with the untreated water is called sludge. The sludge contains solid particles, like wood, dead animals, and trash that could cause problems later on, so they filter out all this stuff and send it to a land field. The system relies on gravity to move the sewage to the treatment plant. If the plant is built above ground 3 aerator pumps pump the sewage into the settling tanks. From there gravity pulls in toward the river. The first step in the actual treatment is mixing all the stuff up, releasing the gases and exposing the sewage to air. This process is was smells so bad. It releases hydrogen sulfide, which smells like rotten eggs. From here the sewage enters long concrete tanks. Each tank is divided into two sections. In the first, air is pumped through the water. As the organic matter starts to decay, it needs oxygen. The aeration stages supplies it with this oxygen. The bubbles lets grit settle out. The grit is pumped out of the tanks and taken to the landfills.The water then enters its stage of sedimentation. Here the Sludge settles out and is pumped out of the tanks. Some of the water is removed for a stepped called thickening and then the sludge is sent into large tanks called digesters.As the sludge settles to the bottom, the lighter materials float to the surface. This is called "scum" This can include anything from grease and oil, to plastics and soaps. Slow moving rakes remove the scum off the water su...
