Osmotic bioreactor combined with reverse osmosis and UV/H2O2 to treat wastewater containing pharmaceuticals and produce high quality reuse water

Abstract

The objective of this Thesis was to evaluate the processes of osmotic membrane bioreactor (OMBR), reverse osmosis (RO) and advanced oxidation with ultraviolet and hydrogen peroxide (UV/H2O2) for the treatment of synthetic wastewater, aiming removal of pharmaceuticals and production of reuse water. The combination of OMBR and RO is essential when the goal is to reuse water, since OMBR alone generates only diluted draw solution (DS). In this work, potassium pyrophosphate salt (K4P2O7) was used as DS, and RO was employed to reconcentrate the DS. The RO permeate corresponded to the reuse water. The results showed that, by using K4P2O7, low reverse salt permeability (0.05 LMH) was obtained while maintaining the biological activity in the bioreactor, measured in terms of oxygen uptake rate. Reuse water had concentrations of nitrite, nitrate and the pharmaceuticals sulfamethoxazole, carbamazepine and diclofenac 4, 10, 74, 6 and 4 times lower, respectively, than those found in RO permeate after a conventional MBR, and there was no water flux decline in the RO employed after OMBR. It was demonstrated experimentally that permeation of pharmaceuticals from the bioreactor to the DS occurs at considerable levels, reaching concentrations in the range of µg.L-1 after 72h of continuous operation. A UV dose of 816 mJ.cm-2 with H2O2 of 30 mg.L-1 removed more than 91% of all pharmaceuticals accumulated in the DS. These results demonstrate the technical feasibility of the combined process. In terms of economic feasibility, the minimum cost of reused water was USD 1.23 per m³ of water produced.