Investigation on removal pathways of Di 2-ethyl hexyl phthalate from synthetic municipal wastewater using a submerged membrane bioreactor

Highly hydrophobic Di 2-ethyl hexyl phthalate (DEHP) is one of the most prevalent plasticizers in wastewaters. Since its half-life in biological treatment is around 25 days, it can be used as an efficiency indicator of wastewater treatment plant for the removal of hydrophobic emerging contaminants. In this study, the performance of submerged membrane bioreactor was monitored to understand the effect of DEHP on the growth of aerobic microorganisms. The data showed that the chemical oxygen demand (COD) and ammonia concentration were detected below 10 and 1.0 mg/L, respectively for operating conditions of hydraulic retention time (HRT) = 4 and 6 hr, sludge retention time (SRT) = 140 day and sludge concentration between 11.5 and 15.8 g volatile solid (VS)/L. The removal efficiency of DEHP under these conditions was higher and ranged between 91% and 98%. Results also showed that the removal efficiency of DEHP in biological treatment depended on the concentration of sludge, as adsorption is the main mechanism of its removal. For the submerged membrane bioreactor, the pore size is the pivotal factor for DEHP removal, since it determines the amount of soluble microbial products coming out of the process. Highly assimilated microorganisms increase the biodegradation rate, as 74% of inlet DEHP was biodegraded; however, the concentration of DEHP inside sludge was beyond the discharge limit. Understanding the fate of DEHP in membrane bioreactor, which is one of the most promising and futuristic treatment process could provide replacement for conventional processes to satisfy the future stricter regulations on emerging contaminants.     

生物铁强化膜生物反应器处理印染废水的研究

通过向普通膜生物反应器(MBR)中添加氢氧化铁,驯化成生物铁污泥,形成生物铁膜生物反应器,分析各自对印染废水的处理效果,结果表明,生物铁MBR对COD的去除效果更好,去除率提高10%左右,但水力停留时间的长短对COD的去除效率影响不是很明显;通过改变泥龄观察处理效果,结果表明,生物铁MBR可以在较长泥龄的条件下运行而处理效果不会受到影响,比普通MBR排放更少的污泥,能达到污泥减量化;同时生物铁污泥絮体的形成为硝化细菌提供了良好的生存环境,使得对氨氮的去除效率比较稳定。试验说明:生物铁污泥的强化生化与物化作用可以加强系统整体的稳定性。     

阴极电极面积和膜面积对H型MFCs产电能力的影响

以生活污水为底物,碳棒作电极,构建H型瓶式微生物燃料电池(microbial fuel cells,MFCs),研究了阴极电极面积和膜面积对电池产电能力的影响.阳极以厌氧污泥作接种体,两室分隔物使用阳离子交换膜(cation exchange membrane,CEM),阳极不使用中介体,阴极使用无催化剂的普通碳电极....     

Influence and mechanism of N-(3-oxooxtanoyl)-L-homoserine lactone (C8-oxo-HSL) on biofilm behaviors at early stage

N-acyl-homoserines quenching, enzymatic quenching of bacterial quorum sensing, has recently applied to mitigate biofilm in membrane bioreactor. However, the effect of AHLs on the behavior of biofilm formation is still sparse. In this study, Pseudomonas aeruginosa biofilm was formed on ultra-filtration membrane under a series of N-(3-oxooxtanoyl)-L-homoserine lactone (C₈-oxo-HSL) concentrations. Diffusing C₈-oxo-HSL increased the growth rate of cells on biofilm where the concentration of C₈-oxo-HSL was over 10^-7 g/L. The C₈-oxo-HSL gradient had no observable influence on cell density and extracellular polymeric substances of biofilm with over 10^-7 g/L C₈-oxo-HSL. Surprisingly, 10^-11-10^-8 g/L of C₈-oxo-HSL had no effect on cell growth in liquid culture. The cell analysis demonstrated that the quorum sensing system might enhance the growth of neighboring cells in contact with surfaces into biofilm and may influence the structure and organization of biofilm.     

膜生物反应器处理高浓度含酚废水研究

将膜生物反应器(MBR)用于高浓度含酚废水的处理中,探讨了进水中苯酚浓度、水力停留时间和污泥浓度对膜生物反应器处理含酚废水效果的影响。实验结果表明:经过42d驯化后,可以在高浓度含酚废水中正常运行,MBR系统对COD和氨氮的去除率分别可达98%和80.6%。当苯酚浓度为134mg/L时,处理的最佳水力停留时间为3h,最佳污泥浓度(MLSS)为7367mg/L。     

季铵盐壳聚糖膜对水体中十二烷基苯磺酸钠吸附的研究

以壳聚糖为原料,制备季铵盐壳聚糖膜(QCSM)吸附剂,研究吸附剂对十二烷基苯磺酸钠(SDBS)的吸附性能,考察了溶液pH值、吸附时间、浓度和温度的影响。结果表明,吸附适宜条件的为:pH 4.0,吸附时间120 min,吸附过程可以很好地用准二级动力学方程描述,吸附等温线用Langmuir方程的拟合效果优于Freundlich和Tempkin方程。在热力学研究表中,ΔG0<0,ΔH0>0,ΔS0>0,表明此吸附过程是自发、吸热和熵增加的过程。     

A novel method to synthesize polyaluminum chloride with a membrane reactor

Al13 or Alb is usually regarded as the most efficient species of polyaluminum chloride(PAC), the performance flocculant for water treatment. This paper was intended to report a new method to synthesize PAC with high content Alb, by using the membrane reactor. NaOH solutions were managed to permeate slowly through the micropores of ultrafiltration membrane into AlCl3 solutions under the suitable transmembrane pressure(TMP). Meanwhile NaOH drops size was limited to nano-scale, resulting in dramatical reduction of the characteristic diffusion time and great increment of contact interface between the strong base and AI ions in solution to favor the formation of Al(OH)4^-, the precursor of AI,3, so few precipitates and much Alb are produced. When the initial concentration of AlCl3/NaOH is 0.40/2.0 (mol/L), MWCO = 10000, TMP = 0.0085 MPa, T= 305 K and B(molar ratio of OH^-/Al^3 ) = 2.25, the quantity of Alb attains about 80%. The results of ^27Al-NMR determination showed that the Al13 content is equal to Alb content. And our PAC product has shown better flocculation effects than the commercial product.     

Methanation and chemolitrophic nitrogen removal by an anaerobic membrane bioreactor coupled partial nitrification and Anammox

● Efficient carbon methanation and nitrogen removal was achieved in AnMBR-PN/A system. ● AOB outcompeted NOB in PN section by limiting aeration and shortening SRT. ● The moderate residual organic matter of PN section triggered PD in anammox unit. ● AnAOB located at the bottom of UASB played an important role in nitrogen removal. An AnMBR-PN/A system was developed for mainstream sewage treatment. To verify the efficient methanation and subsequent chemolitrophic nitrogen removal, a long-term experiment and analysis of microbial activity were carried out. AnMBR performance was less affected by the change of hydraulic retention time (HRT), which could provide a stable influent for subsequent PN/A units. The COD removal efficiency of AnMBR was > 93% during the experiment, 85.5% of COD could be recovered in form of CH₄. With the HRT of PN/A being shortened from 10 to 6 h, nitrogen removal efficiency (NRE) of PN/A increased from 60.5% to 80.4%, but decreased to 68.8% when the HRT_PN/A further decreased to 4 h. Microbial analysis revealed that the highest specific ammonia oxidation activity (SAOA) and the ratio of SAOA to specific nitrate oxidation activity (SNOA) provide stable NO₂⁻-N/NH₄⁺-N for anammox, and anammox bacteria (mainly identified as Candidatus Brocadia) enriched at the bottom of Anammox-UASB might play an important role in nitrogen removal. In addition, the decrease of COD in Anammox-UASB indicated partial denitrification occurred, which jointly promoted nitrogen removal with anammox.     

无矩阵迭代法在膜结构风振耦合分析中的应用

提出在采用浸入物体法(IOM)对膜结构和空气流体建模时,可以采用带有预定条件的无矩阵Newton-Krylov迭代算法求解浸入物体法,并引入了预定条件矩阵。将提出的无矩阵迭代方法应用于一双坡型膜结构的风振耦合分析中,得出了结构的风压和风速分布,并对带有预定条件和不带预定条件的无矩阵迭代算法进行了对比。结果表明,将带有预定条件的无矩阵迭代算法应用于膜结构风振的耦合分析中,可以得到准确结果,并使计算效率大大提高。     

膜分离技术治理糠醛废水

糠醛生产废水中含1—2.5％的乙酸,若废水外排,会造成大量损失且污染环境.通过30—80对膜组装的400×800mm电渗析器中试操作,回收了浓度为20％的乙酸,再经萃取、精馏工艺得到工业一级乙酸.治理后的废水含酸量为0.02—0.05％,可安全排放及回用.中试技术指标优于小试,重现良好.