Formaldehyde Degradation in Fixed-bed Aerobic Biological Reactor

The development of appropriate technology for treatment of high concentration formaldehyde wastewater prior to discharge into the environment is important to minimize its impact. Therefore, this study investigates the degradation of formaldehyde in a bioreactor. The experimental unit consisted of an up-flow aerobic immobilized biomass (UAIB) reactor with high porosity pumice stone as a fixed bed support. The UAIB reactor was fed with synthetic wastewater, prepared by mixing a solution of molasses with formaldehyde and nutrients. Reactor was tested at different synthetic wastewater concentrations with CODtotal (CODFA+CODmolasses) of 500, 1000 and 1500 mg/l at 24hr hydraulic retention time. The effect of feed composition was tested by changing the ratio of CODtotal/CODFA at 6/1, 5/1, 4/1, 3/1 2/1 and 1/1 to analyze the impact of formaldehyde concentration. The average formaldehyde and COD removal efficiencies obtained in the UAIB were 97.1% and 88%, respectively. The maximum CODT and CF removal efficiency occurred at the CODT/CODF equal to 4/1. Maximum CF removal efficiency was obtained at COD=1000 mg/l. In all cases total organic removal in the reactor in terms of COD was very satisfactory. The effect of toxic shock on the performance of the reactors was examined, and the results proved that the UAIB has good resistance against shock loads. Maximum FA concentration as a threshold of this reactor was 1370 ppm. Formaldehyde inhibitory behavior and its growth kinetics can be correlated well by the simple Haldane’s inhibitory growth kinetics model. Obtained results from this work concluded that the UAIB reactor is suitable for treatment of formaldehyde-containing wastewater, and pumice stone is a suitable media for biofilm support.

کلیدواژه ها:

Biological Treatment ، Pumice Stone ، Aerobic Treatment ، Toxic Biodegradation