Formaldehyde removal from wastewater and air by using UV, ferrate(Ⅵ) and UV/ferrate(Ⅵ)

摘要

Formaldehyde removal from an air stream absorbed into a water stream in a packed bed continuously and then removed by employing a combination of UV and ferrate(Ⅵ) as a highly-powerful oxidant in a continuous stirred tank. In addition, the removal of formaldehyde from water was investigated in both batch and continuous modes. The results of the study performed on formaldehyde-contaminated water treatment can be used for both air and water treatment process design. The primary objective of this study is to compare the performance of using UV and ferrate(Ⅵ) individually with that of using UV/ ferrate(Ⅵ) simultaneously to remove formaldehyde from both air and water. Moreover, the effects of several factors such as pH, ferrate(Vl) concentration and temperature on formaldehyde removal from water using ferrate(Ⅵ) method were evaluated. The results of the current study in batch condition showed that the best initial pH and ferrate(Ⅵ) concentration to obtain the highest formaldehyde removal are 2 and 1 mg/l, respectively. The results of this part of research also reveal that temperatures rise from 25 ℃ to 50 ℃ increases formaldehyde removal from 69% to 97%; however, further increase in temperature has an adverse effect on removal efficiency. The combination of UV and ferrate(Ⅵ) enhances formaldehyde removal efficiency to very close to 100% within 35 min. In continuous air stream treatment, maximum formaldehyde removal of 94% was obtained by using a packed bed scrubber with gas over liquid flow rates ratio of 1.28 m~3/m~3. Although the results of this study shows that ferrate(Ⅵ) method for removal of formaldehyde can be considered as a promising alternative for both water and air treatment, further economic studies are required for this process to be commercialized.