Comparing the Efficiency of MBBR and SBR in Treating Wastewater Containing Formaldehyde

Nowadays formaldehyde is used in many industrial activities such as adhesives, resins and paper producing, pharmaceutics, and also a number of general and commercial activities like some hospital services, dead burial and providing the sanitation of some public places like garrisons. In this research aerobic treatment of formaldehyde in MBBR compared with SBR in the influent COD range between 0 to 2500 mg/L. According to the results, SBR under serial operation was better than MBBR. These results showed the removal efficiency of influent CODs less than 200 mg/L was 100% and for CODs between 200 to 450 mg/L was 90% after 48 hours. In this study, it took 4 days in CODs less than 1500 mg/L and 4 to 6 days in CODs between 1500 to 2500 mg/L for reactors to reach steady state condition. In kinetic study, related coefficients followed Stover-Kincannon second order model. 13C-NMR spectroscopy showed that formaldehyde and urea was converted to N-{[(amino-­carbonyl) amino] methyl} urea. It was determined formaldehyde was polymerized in ordinary temperature and all molecules including carbons were degraded.