<b>Application of activated sludge process followed by physical-chemical processes in the treatment of industrial saline effluent for reuse</b> - doi: 10.4025/actascitechnol.v35i2.13006

Abstract

The treatment of complex effluent with high salinity and sometimes with toxicity rates from a chemical plant is investigated. Two reactors were monitored continuously: control reactor R1 and reactor R2 adapted for saline effluent with 25h-HRT. The adaptation process to saline effluent (0 - 100%) was effective in removing COD and N-NH₄⁺, respectively with 70 and 85% efficiency. After adaptation, the sequence coagulation/flocculation (40 mg L^-1 PAC coagulant and 0.3 mg L^-1 cationic polymer), rapid downflow sand filter (120 m³ m^-2 day) and reverse osmosis to obtain water for reuse was analyzed. Results obtained by coagulation/flocculation and sand filter sequence were satisfactory, mainly with the removal rates of turbidity at 50-65 and 98%, respectively. Average removals of 91, 87, 98 and 98% were obtained for COD, N-NH₄⁺, TOC and Cl^-, respectively, in reverse osmosis, with all parameters below the limits for reuse in cooling towers. However, membrane fouling was detected.