The removal of formaldehyde from concentrated synthetic wastewater using O3/MgO/H2O2 process integrated with the biological treatment.
The catalytic advanced oxidation process (CAOP) of O(3)/MgO/H(2)O(2) was integrated with a sequencing batch reactor (SBR) system to completely treat concentrated formaldehyde wastewater, demonstrating that this combination is an effective method for treating such wastewaters. The influence of several operational variables--including pH, MgO powder dosage, and the concentrations of H(2)O(2) and O(3)--was investigated for the O(3)/MgO/H(2)O(2) degradation of a 7000 mg/L formaldehyde wastewater. The optimum conditions were found to be a pH of 8, 5 g/L dose of MgO powder, 0.09 mole/L concentration of H(2)O(2), and 0.153 g/L min dose of O(3). The formaldehyde and COD concentrations were reduced 79% and 65.6%, respectively, in the CAOP for 120 min of reaction time under the optimum condition stated above. The remaining concentrations of formaldehyde and COD were 1500 mg/L and 3200 mg/L, respectively, in the effluent. The degradation of formaldehyde in CAOP was determined to be a first-order reaction with a constant of 0.015/min, and radical oxidation was the predominant degradation mechanism. This effluent was post-treated in SBR system for a total cycle time of 24h. The SBR completely removed the formaldehyde and removed 98% of the COD, reducing the COD concentration to lower than 60 mg/L. Therefore, the integrated O(3)/MgO/H(2)O(2) and SBR process is demonstrated as a promising technology for the complete treatment of wastewater with high concentrations of toxic and inhibitory compounds such as formaldehyde.
Moussavi
Gholamreza
G
Department of Environmental Health, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran. moussavi@modares.ac.ir
Yazdanbakhsh
Ahmadreza
A
Heidarizad
Mahdi
M
D001673:Biodegradation, Environmental; D019149:Bioreactors; D004305:Dose-Response Relationship, Drug; D005557:Formaldehyde / Q000737:chemistry / Q000302:isolation & purification*; D006861:Hydrogen Peroxide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste; D008277:Magnesium Oxide / Q000737:chemistry*; D008956:Models, Chemical; D010100:Oxygen / Q000737:chemistry; D010126:Ozone / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000302:isolation & purification; D018508:Water Purification / Q000379:methods*
D007220:Industrial Waste; D014874:Water Pollutants, Chemical; D005557:Formaldehyde; D008277:Magnesium Oxide; D010126:Ozone; D006861:Hydrogen Peroxide; D010100:Oxygen