Activated sludge process (ASP) systems use electricity to blow air into raw, unsettled sewage. This smashes the solids to develop a biological 'soup'. Aeration allows the naturally occurring bacteria in waste to digest any organic content, reducing the overall pollutant level. ASP sewage treatment plants don’t have a primary settlement chamber, which means less frequent emptying and fewer unwanted odours.
Once the sewage has been aerated for long enough, excess liquid is discharged into a clarification chamber, where live bacteria settle to the bottom. Dead bacteria rise to the top, leaving clean water in the middle – which can then be discharged safely into either a watercourse, drainage field or soakaway.
FILTRE TIL NEDSÆNKET BELUFTNING
In a submerged aeration filter, a primary settlement chamber holds solid material. This is where anaerobic digestion by bacteria takes place. Clarified water then passes into a second chamber containing a submerged media – and here, the water is treated to remove dissolved constituents by aerobic bacteria, supported by diffused air. This process ensures that full treatment is achieved before the material flows to a final settlement chamber. The final, treated wastewater is discharged to the drainage field, watercourse or soakaway.