Application Study Of Reclamation Of Wastewater By Using Combined MBR And Ozonation

This increasing urbanization has resulted in an uneven distribution of populationand water, imposing unprecedented pressures on limited water supplies. During mostof the20th century, wastewater treatment emphasized pollution abatement, publichealth protection, and prevention of environmental degradation through removal ofbiodegradable material, nutrients, and pathogens. However, over the past few decades,people have recognized the potential for recovering water from wastewater. Integratedmembrane process is the main process for wastewater reclamation. This studysystematically investigated the MBR process optimization with mathematicalmodeling, membrane fouling formation and control and advanced treatment of MBReffluent with ozonation for color removal in practical process.Firstly, BioWinTMsoftware was used to build a process model of MBR, whichwas corrected with monthly average data under stable operating status. And thenprediction analysis was performed with corrected model. We used the modified Morseclassification screening method to analyze the partial sensitivity in order to get theMBR process optimization strategy under complex operating conditions: almost allwater indicators had high sensitivity with SRT, indicating that the SRT was the mostcrucial operating condition of MBR process, and the sludge discharge should beevaluated with BioWin to avoid water quality deterioration; due to the high MLSS inMBR, effluent COD was not sensitive to all operating conditions except SRT,reflecting that MBR had a good and stable performance in COD removal; effluent TPwas sensitive to SRT, AA reflux ratio and OA reflux ratio, which could be selected asoperating parameters for controlling TP concentration under non-steady influentquality; TN was sensitive to SRT and DO and medially sensitive to AA reflux ratioand OA reflux ratio. Therefore, SRT and DO could be selected as operatingparameters for controlling TP concentration under non-steady influent quality.The EEM, HPSEC and ATR-FTIR analysis indicated that the organic foulantscausing PVDF membrane were mainly composed by protein (PN) and polysaccharide(PA) with MW of10kDa~100kDa and humic acid (HA) with MW of100Da~10kDa.In addition, the concentration of protein accounted for65%of whole organic portion,and protein ratio in whole organic portion increased with time. HA accounted for11%,and the concentration of PA was very limited. Meanwhile, the ratio of SMP and HA reduced from14.94%to9.29%and from19.45%to11.98%in the longterm running.For the MBR under shortterm operation, the foulant could be effectively removed bymaintainability cleaning, making rapid recovery of membrane flux, while doublecleaning process was ineffective to improve membrane of MBR operating for a longtime (more than500days).Decoloration and stability by ozonation was studied in municipal wastewaterreusing treatment process. The results show that ozonation can effectively removesurface color and ture color. In the process of simulating a natural situation, The truecolor of water samples with different dosage of ozonation had no significant changeafter22day. The surface color value of water samples with ozonation dosage of0、2、4、6mg/L increased gradually from20、11、6、5to36、35、25、2612day before,However the surface color value increased rapidly after12day and value became126、322、355、559at22day. The surface color value of water samples with ozonationdosage of8、10mg/L increased rapidly with low range at last4days. The resultswhich could provide theoretical basis to production show that the chroma of waterchange caused by algae growing. Higher dosage of ozonation not only can keep thechroma stability but also prolong time of surface color changing. Ozonation dosage of8mg/L was recommended in Municipal Wastewater Reusing Treatment Process.