Remoção e recuperação de nutrientes em sistema UASB seguido de LAT e posterior separação de microalgas por FAD

Abstract

The discharge of partially treated effluents with nutrients may cause eutrophication in water bodies. To avoid this process due treatment is necessary to improve the final quality of the effluent to be released. This work presents the treatment of domestic sewage from an Upflow Anaerobic Sludge Blanket (UASB) followed by a high algal rate lagoon (LAT) with subsequent separation of algal biomass by dissolvedair flotation (FAD) operated for one year.The UASB reactor was managed at a flow rate of 1.6 m³/h and a HRT of 10.8 h. The pond was worked at a flow rate of 0.8 m³/h with a HRP of 4.1 days. Inorganic coagulant ferric chloride with a dosage of 40 mg/L and organic flocculant Tanfloc SG with a dosage of 50 mg/L were tested to assist the flotation system. The UASB+LAT system showed an average TKN removal of 61.3 ± 11.2 % and the total phosphorus 32.3 ± 5.5 %. The overall removal observed in the pond and separations tests showed that ferric chloride showed a higher performance in the removal of total phosphorus reaching values of 74.5 ± 7.5 %. On the other hand, Tanfloc SG performed better for the removal of volatile suspended solids and organic matter with up to 88.2 ± 4.3 % and 89.8 ± 4.2 %, respectively.