 The addition of the powdered activated carbon stabilizes biological systems against upsets and shock loading, controls color and odor, and may reduce disposal costs while removing soluble organics.In an aerobic treatment system, influent first enters an aeration tank where the powdered carbon is added, making up a portion of mixed liquor suspended solids.Once the aeration is completed, the treated wastewater and the carbon-biomass slurry are allowed to settle.