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Urban Wastewater Management

Water Waste Treatment Process


Water Waste Treatment Process:


Step 1: Sanitary Sewer

Step 2: Grit Chamber

Step 3: Primary Treatment 

Step 4: Aeration Tanks 

Step 5: Secondary Treatment Tank


The image above shows the layout of a typical treatment works. Ideally, wastewater treatment in a municipal treatment works involves four stages: preliminary, primary, secondary and tertiary treatment. There are two end products from the treatment process; sludge solids and liquid effluent. The treatment process reduces the effluent so that it will not adversely affect the quality of the receiving waters.


Preliminary treatment takes large solids and floating debris from the raw wastewater.

Primary treatment separates the smaller solids.

Secondary treatment uses micro-organisms to remove the biodegradable or organic waste.

Tertiary treatment includes nutrient removal and filtration. 

Urban Waste Water Treatment Directive


Urban wastewater can be described as a mixture of domestic and industrial wastewater and run-off rain water. The level of treatment wastewaters receive depends on the size of population served. In urban areas wastewater from homes and industry is carried off by a network of pipes and pump stations to a municipal treatment plant. This treatment of the sewage (the contaminated wastewater) involves primary, secondary and tertiary treatment:


  1. solids are separated from the wastewater

  2. dissolved biological matter is converted to solid mass using micro-organisms

  3. solids are then neutralised and reused or discarded

  4. treated wastewater is discharged to receiving waters

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