Degradation Of Dyeing Wastewater By Processes Of Ozonation In RSR-BCR

Dyeing wastewater,with a high organic load,is one of the world's major pollution sources and is difficult to degrade.The existing treatment processes of dyeing wastewater need to upgrade to meet the ever-increasing environmental requirements.Due to excellent mass transfer,small equipment volume,and short reaction time,high-gravity technology exhibits application potential in industrial wastewater treatment.In this thesis,rotor-stator reactor(RSR),a novel high-gravity device,was employed in tandem with a traditional bubble column reactor(BCR)to enhance Acid Red 73(AR73)degradation by ozonation in a simulated dyeing wastewater.The O3/RSR,O3/BCR,O3/RSR-BCR,O3/Fe2+/RSR,and O3/Fe2+/RSR-BCR processes were investigated in detail to determine the optimal conditions.A possible degradation mechanism of AR73 in the O3/RSR-BCR process was put forward.Furthermore,an industrial dyeing wastewater was degraded based on the O3/RSR-BCR process.The main conclusions are as follows:1.Treatment of AR73 wastewater was investigated in the O3/RSR,O3/BCR,O3/RSR-BCR processes,and suitable process conditions were proposed.When the RSR rotating speed,liquid flow rate,gas flow rate,O3 concentration,and pH were 1000 rpm,12 L·h-1,60 L·h-1,50 mg·L-1,and 9.25 respectively,AR73 degradation percentage and COD removal percentage in the O3/RSR-BCR process were 96.9%and 29.6%respectively,and they were 68%and 9.8%in the O3/RSR process,90.4%and 30.6%in the O3/BCR process.Due to the excellent mass transfer effect of RSR,AR73 degradation percentage in the O3/RSR-BCR process was significantly higher than that in the O3/BCR process,exhibiting the effect of lowered O3 consumption as well as reduced BCR volume as a result of shorter liquid residence time.2.AR73 wastewater was treated by the O3/Fe2+/RSR,O3/Fe2+/RSR-BCR processes,and suitable process conditions were proposed.When the RSR rotating speed,liquid flow rate,gas flow rate,O3 concentration,pH,and Fe2+concentration were 1000 rpm,12 L·h-1,60 L·h-1,50 mg·L-1,4,and 1 mmol·L-1 respectively,96.7%AR73 degradation percentage and 39%COD removal percentage were achieved in the O3/Fe2+/RSR-BCR process.Compared with the O3/RSR-BCR process,the O3/Fe2+/RSR-BCR process has a higher AR73 treatment capability at lower gas flow rate,O3 concentration and shorter residence time.Especially,the O3/Fe2+/RSR-BCR process can still maintain a good treatment effect under the acidic environments(pH<4).3.Based on UV-vis,GC-MS,HPIC and other analytical methods,possible AR73 degradation pathways were proposed.First,the N=N bond of AR73 was attacked by OH and O3,achieving a high AR73 degradation percentage.And then C-S and C=C were broken and produced SO42-,SO2,aniline,p-phenylenediamine,and naphthalenes,suggesting that low COD removal percentage was due to an incomplete degradation of AR73.4.An industrial dyeing wastewater(aniline compounds as main pollutant)was treated by the O3/RSR-BCR process,and suitable process conditions were proposed.When the RSR rotating speed,liquid flow,gas flow rate,O3 concentration,and pH were 1000 rpm,12 L·h-1,36 L·h-1,50 mg·L-1 and 8.36 respectively,90 PCU wastewater chroma and 97.9%anline compounds degradation percentage were achieved,and the requirement of aniline compounds content<1 mg·L-1 was met.