Remoção físico-química de fósforo de efluentes de sistemas anaeróbios-aeróbios de tratamento de esgoto doméstico.

Abstract

Phosphorus is one of the most important macro nutrients responsible for eutrophication of surface waters. A concentration of 0,03 mg/L indicates an eutrophic condition in a lake. To avoid problems with eutrophication, there is a need to remove phosphorus from effluents produced in sewage treatment plants that are to be discharged into surface waters. In practice, phosphorus can be removed by biological means in aerobic treatment plants if the P/COD ratio is high enough, or by physical chemical treatment, using the fact that several phosphates are poorly soluble. In anaerobic- aerobic plants, the only alternative to produce an effluent with a low P concentration is the application of physical chemical treatment. A bench scale experimental investigation was carried on with the objective to establish the feasibility of physical chemical phosphorus removal in anaerobic-aerobic sewage treatment plants, using both ferric chloride (FeCh) and aluminium sulfate (A^CSO^). The results indicated that the partial removal is feasible, but for a low effluent P concentration a high dosage of either coagulant is required. The results also indicated that ferric chloride is more recommendable because of its low price per mass unit and a less problematic final disposal of the produced sludge.