Study On The Degradation Of Aldehydes Wastewater By Advanced Oxidation Processes And Membrane Bio-reactor (MBR)

Aldehydes are main pollutants in industrial wastewater. For its toxicity to microorganisms, the aldehydes wastewater must be treated by other methods before it comes into activated sludge process. In this paper, advanced oxidation process along with membrane bioreactor (MBR) was investigated in treating formaldehyde and other aldehydes wastewater.It was found that when the formaldehyde concentration was fixed to 5000 mg/L, the optimal parameters of photo-catalytic oxidation were found to be:H2O2=0.28mol/L-0.31 mol/L, TiO2=0.5～1g/L, initial pH=12, with the UV(254nm/10W) in a reaction of 4L. Under these conditions, about 58% TOC removed and 99% formaldehyde removal ratio could be obtained. And The optimal parameters of Fenton oxidation were as follows:the actual dosage of H2O2 was 1.25 times of ideal value, the proportion of H2O2 to Fe2+ was among 10:0.75 to 10:1.25,under these, about 52% TOC removed and 96% formaldehyde removal ratio could obtained.And with photo-Fenton oxidation, the TOC and formaldehyde removal ratio could arrived to 53% and 97%. When the formaldehyde water went into MBR after photo-catalytic oxidation, the optimal parameters of MBR were as follows:MLSS=8000mg/L, DO=2.5mg/L, HRT=16h. Under these,93% COD removal ratio could be obtained. With the treatment of photo-catalytic oxidation, the TOC removal ratio of 3300mg/L acetaldehyde and 2000mg/L glutaraldehyde wastewater could seperately get to 26% and 22%. And the application of photo-catalytic oxidation on the removal of formaldehyde in the production progress of glyphosate was also introduced in the end of the paper.