ABSTRACT
Background: Furfural is a toxic chemical, so, to avoid its effects on humans and the environment, furfural-containing wastewater must be treated with an appropriate method prior to dispose in the environment. In this study, advanced oxidation methods based on ozone was used to removal of various concentrations of furfural in laboratory scale
Material and Methods: This study is an applied research and the required samples was taken in desired times. The effects of single ozonation process [SOP], catalytic ozonation process [COP], and single adsorption on activated carbon [SAP] on furfural removal efficiency in different conditions were studied
Results: In this study, the influence of some important parameters such as pH, activated carbon dosage and reaction time on the efficiency of SOP, SAP and COP was studied. In the case of pH, the results showed that the efficiency of all three processes in very acidic and very alkaline conditions were higher than the other pH. By increasing activated carbon dosages, the removal efficiency was also increased. Finally, the removal efficiency for the processes studied, increased by increasing reaction time
Conclusion: The higher removal efficiency of furfural in acidic conditions can be due to direct and catalytic oxidation of furfural by ozone. Higher efficiency in the alkaline pH may be due to indirect oxidation because of hydroxyl radicals generation. About the effect of reaction time, the removal efficiency of COP indicates that there was a synergistic effect in catalytic ozonation processes. The increase of reaction surfaces available for ozoneactivated carbon-furfural reactions could be the reason of increased efficiency with increasing dosages of activated carbon
ABSTRACT
A conventional treatment to stabilize the excess activated sludge is the aerobic digestion process but due to long aeration time, it requires large equipments as well as high investment cost. Because of high oxidation potential of ozone, sludge ozonation enhances stabilization rate and reduces sludge treatment equipment size and cost. Therefore, in this study, the combination of pretreatment with ozone and aerobic digestion processes were investigated. The experimental set-up consisted of an ozone generator and ozonation reactor with the total volume of 2 L. Removal percentages of TSS, VS, total and soluble COD, HPC, fecal coliform and settable solids were measured in integrated process compared to the single ones. The results of this research indicated that the aerobic digestion of waste activated sludge during 10 days could reduce 38% of volatile solids and thus obtaining the EPA standard. Also, the results of combined ozonation and aerobic digestion revealed that the pre-ozonation at 0.25 g O3/g TS or 0.5 g O3/g TS with 6 or 3 days aeration, respectively, could achieve 38% reduction in VS and hence the requirement set by EPA. Therefore, integration of pre-ozonation with aerobic digestion can significantly reduce the digestion time to attain the standards. The sludge pre-ozonation with low dose of ozone due to solids disintegration can enhance the efficiency of aerobic digestion in waste activated sludge stabilization, and consequently decrease size of equipments, air requirement, investment and probably operation cost