Cultus Lake Park Sanitary Sewer Infrastructure Assessment

Fraser Valley Regional DistrictCultus Lake Sanitary Sewer Infrastructure Assessment – Final ReportFigure 3: Activated Sludge Process SchematicConventional activated sludge is an aerobic biological process for treatment of domesticwastewater. The process utilizes microorganisms to feed on available organic matters inthe wastewater. The microorganisms responsible for treatment are maintained insuspension at a certain concentration. The microorganisms use the available organicmatters as food source to maintain its life sustaining process such as energyreproduction, growth…etc. In conventional activated sludge method, the wastewater isintroduced to an aeration tank where air is provided as an oxygen source to keep themicroorganisms alive and in suspension. After, the aeration tank, the liquid flows bygravity to a secondary clarifier tank where the microbial suspension is settled to thebottom. The settled biomass is returned back to the aeration tank (return sludge) tocontinue degradation of organic matters in the tank. A portion of the biomass (wastesludge) has to be removed periodically as the process produces excess biomass. Controlof the process is achieved by maintain certain biomass concentration in the aeration tank.Project No. 30825 – September, 2012 Page 13