Treatment Of Organic Wastewater By Fe(Ⅵ) And Ozone With The Process Intensified By High Gravity Technology

Phenolic wastewater is a refractory wastewater which is widely present in petrochemical industry. Upon tightening requirements for enrionmental protection, the relevant industry has an urgent need for efficient treatment technologies for phenolic wastewater. This thesis thus studied the treatment of phenolic wastewater with ferrate and ozone intensified by the high gravity, combining the advantages of the strong oxidation ability of ozone advanced oxidation processes (AOPs) and potassium ferrate as well as the intensification of mass transfer of the high gravity technology, and a novel process for phenolic wastewater treatment is proposed.At first, this thesis verified that potassium ferrate with advanced oxidation process have better effect with ozone compared with the ferrous ions. The synergetic effects of potassium ferrate and AOPs were studied by a comparison of O3+Fe(Ⅵ) process with O3 process and O3/H2O2+Fe(Ⅵ) process with O3/H2O2 process. It was verified that the treatment effects of O3, O3+Fe(VI), O3/H2O2 and O3/H2O2+Fe(VI) processes in the rotating packed bed (RPB) were better than those in a beaker. The main research conclusions are as follows:(1) Comparision of O3+Fe(VI) process with O3 process for the treatment of phenolic wastewater in the RPB.Potassium ferrate dosage was determined as 0.42 Mm. Phenol and COD removal rate increased with the increase of the initial pH of the solution and gas flow rate, and decreased with liquid flow rate and temperature. Phenol removal rate increased with the increase of rotational speed, but the COD removal rate increased first and dropped then with the increase of rotational speed. The degradation effect of the O3/Fe(VI) process was superior to that of the O3 process.(2) Comparision of O3/H2O2+Fe(VI) process with O3/H2O2 process for the treatment of phenolic wastewater in the RPB.Phenol and COD removal rate increased with the increase of the initial pH of the solution, increased first and dropped then with the increase of gas/liquid ratio and temperature. Phenol removal rate increase with the increased of rotational speed, but the COD removal rate increased first and dropped then with the increase of rotational speed. The degradation effect of the O3/H2O2+Fe(VI) process was superior that of the O3/H2O2 process.(3)The B/C values of the O3/Fe(VI) and O3/H2O2+Fe(VI) processes were higher than those of the O3 and O3/H2O2 processes respectively, which shows that potassium ferrate combined with the AOPs is advantageous for the biochemical treatment of phenolic wastewater. It was also found that the B/C value increased with increasing pH and rotational speed.(4) Phenol removal rate reached 99.81% in a very short reaction time with a potassium ferrate/phenol dosage ratio of 2/5. Compared to other work, this study employed a much higher phenol concentration, lower potassium dosage and short treatment time, which indicates that the high gravity intensification of the synergetic treatment of phenolic wastewater by potassium ferrate and ozone has good effect and high efficiency, providing a promising treatment technology for organic wastewater.