Transcription: Raw sewage is first screened to remove rags, paper and other large objects. It then passes into settling tanks where the organic sludge separates out from the watery effluent. The effluent is pumped into an aeration tank in which oxygen is bubbled through the water and bacteria digest any organic matter. Any remaining sludge settles out and is removed. Finally, the water is treated with chlorine to kill the bacteria before it's discharged into a local river or the sea. The sludge is taken to a digester where more bacteria break down the solids. Once the digested sludge is dried, it can be safe ...
(.mp4)