From drain to sea
Wastewater from your home comes from human waste, soaps and detergents. It goes through many stages before it is clean and safe to discharge into the sea, rivers or lakes.
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Preliminary Treatment
Preliminary Treatment
This preliminary treatment stage removes materials which can be easily removed from the raw wastewater before they damage or clog the pumps or downstream treatment processes. Preliminary treatment involves screening to remove papers and plastics as well as fats, oils, grease and grit removal.
Primary Sedimentation
Primary Sedimentation
In this stage wastewater flows through large primary sedimentation tanks with mechanical scrapers. They are used to settle solids by gravity, which are then transferred to the sludge treatment facilities.
Aeration
Aeration
The wastewater then passes through aeration tanks, where organic matter is reduced through a biological process. Chemicals may also be added during this secondary treatment stage to reduce unwanted nutrients like phosphates. These are turned into solids that later settle.
Settlement
Settlement
Following biological treatment in the aeration tanks, the wastewater is then passed through final settlement tanks equipped with mechanical scrapers where the particles settled by gravity are removed.
Sludge Treatment
Sludge Treatment
Sludge extracted throughout the treatment process is used to generate electricity or recycled to the land as fertilizer.
Final Testing
Final Testing
Various process checks and laboratory analysis is undertaken on the final effluent to ensure it has no detrimental effects on the aquatic life or other water users.
