Combination of chemical coagulation, photo-Fenton oxidation and biodegradation for the treatment of vinasse from sugar cane ethanol distillery.

The post-treatment of biodigested sugarcane vinasse was envisaged in the present study following three different approaches: i) coagulation/flocculation – Approach 1; ii) combination of coagulation/flocculation with photo-Fenton reaction – Approach 2; iii) coagulation/flocculation followed by biological degradation and photo-Fenton reaction – Approach 3. The coagulation/flocculation per se provided a slight increase in effluent's biodegradability, a decrease in toxicity and turbidity, and provided moderate removals of total organic carbon (TOC), biochemical oxygen demand (BOD 5 ) and chemical oxygen demand (COD). The operating costs associated with chemicals consumption are low (5.7 R$/m 3 ≈ 1.4 €/m 3 ). The second and third treatment approaches allowed to reach a nontoxic effluent, improved the biodegradability and led to similar high global organics removal efficiencies. The combined treatment consisting of coagulation/flocculation plus photo-Fenton oxidation (Approach 2) revealed to be a promising solution for treating this wastewater, in order to be recirculated into the high rate anaerobic reactor. Additionally, this solution provides smaller costs (84.9 R$/m 3 ≈ 20.2 €/m 3 ) associated with chemicals and energy consumption, which are however very high. Nonetheless, this cost can be reduced by about 40% if solar radiation is used in the photo-Fenton process. [ABSTRACT FROM AUTHOR]