TASK 4

Sewage usually dangerous for the nature, so we need a process before the sewage can be disposed freely to the river going to the sea. “Fresh sewage” from the sewer was collected in the settling tank. In this tank, particles heavier than water fall to the bottom of the tank, then it will be removed and burned. The polluted water that its solids have been removed was pumped through the pipes to the surface where there’s a filter. The polluted water comes out from the sprinkler so the water can be spread over the filter’s surface. The filter consists of several layers of stones and microorganisms. Polluted water will flow through those series of layers and was collected under the filter. The result of this process is purified water which is safe to be disposed in the river or sea.