Effect of powdered activated carbon on Chinese traditional medicine wastewater treatment in submerged membrane bioreactor with electronic control backwashing

Chinese traditional medicine wastewater, rich in macromolecule and easy to foam in aerobic biodegradation such as Glycosides, was treated by two identical bench-scale aerobic submerged membrane bioreactors （SMBRs） operated in parallel under the same feed, equipped with the same electronic control backwashing device. One was used as the control SMBR （CSMBR） while the other was dosed with powdered activated carbon （PAC） （PAC-amended SMBR, PSMBR）. The backwashing interval was 5 min. One suction period was about 90 min by adjusting preestablished backwashing vacuum and pump frequency. The average flux of CSMBR during a steady periodic state of 24 d （576 h） was 5.87 L/h with average hydraulic residence time （HRT） of 5.97 h and that of PSMBR during a steady periodic state of 30 d （720 h） was 5.85 L/h with average HRT of 5.99 h. The average total chemical oxygen demand （COD） removal efficiency of CSMBR was 89.29% with average organic loading rate （OLR） at 4.16 kg COD/（m^3.d） while that of PSMBR was 89.79% with average OLR at 5.50 kg COD/（m^3.d）. COD concentration in the effluent of both SMBRs achieved the second level of the general wastewater effluent standard GB8978-1996 for the raw medicine material industry （300 mg/L）. Hence, SMBR with electronic control backwashing was a viable process for medium-strength Chinese traditional medicine wastewater treatment. Moreover, the increasing rates of preestablished backwashing vacuum, pump frequency, and vacuum and flux loss caused by mixed liquor in PSMBR all lagged compared to those in CSMBR; thus the actual operating time of the PSMBR system without membrane cleaning was extended by up to 1.25 times in contrast with the CSMBR system, and the average total COD removal efficiency of PSMBR was enhanced with higher average OLR.

Zeolite powder addition to improve the performance of submerged gravitation-filtration membrane bioreactor

In this study, the effect of zeolite powder addition on submerged membrane bioreactor （SMBR） on membrane permeability, and the removals for COD, NH3-N, TN were investigated. Through the parallel operation of control and test systems, it was found that the zeolite powder addition could alleviate the ultra-filtration membrane fouling and enhance the membrane permeability. On the basis of experimental investigations, a concept of ＂protection coating layer＂ was proposed to illustrate the phenomenon of UF membrane fouling. In addition, the removal for COD in test system was more stable, a little higher compared to the control system. Due to the combination of nitrification and ion exchange, a more excellent removal for NH3-N in test system was obtained regardless of influent NH3-N loading rate. It was also found that a mean 25% higher TN removal took place in the test system, and ion exchange and simultaneous nitrification and de-nitrification were analyzed to be main factors. During the stable operation period, the SOURs of test zeolite powder added sludge and control activated sludge were measured to be 75 mgO2/（gMLVSS, h） and 24 mgO2/（gMLVSS, h） respectively, it meant that the zeolite powder addition could enhance the microorganism activity significantly.

A pilot scale anoxic/oxic membrane bioreactor(A/O MBR) for woolen mill dyeing wastewater treatment

A pilot scale(10 m 3/d) anoxic/oxic membrane bioreactor(A/O MBR) was tested for dyeing wastewater treatment of woolen mill without wasting sludge in 125 days operation. Results showed that the effluent quality was excellent, i.e. effluent COD less than 25 mg/L, BOD 5 under 5 mg/L, turbidity lower than 0 65 NTU, and colour less than 30 DT, and met with the reuse water standard of China. The removal rates of COD, BOD 5, colour, and turbidity were 92 4%, 98 4%, 74% and 98 9%, respectively. Constant flux operation mode was carried out in this study, and backwash was effective for reducing membrane fouling and maintaining constant flux. Membrane fouling had heavy impact on energy consumption. More attention should be paid on pipe selection and design for the sidestream MBR system, too.

Dynamic membrane bioreactor performance enhancement by powdered activated carbon addition:Evaluation of sludge morphological,aggregative and microbial properties

The effects of powdered activated carbon(PAC) addition on sludge morphological, aggregative and microbial properties in a dynamic membrane bioreactor(DMBR) were investigated to explore the enhancement mechanism of pollutants removal and filtration performance. Sludge properties were analyzed through various analytical measurements. The results showed that the improved sludge aggregation ability and the evolution of microbial communities affected sludge morphology in PAC-DMBR, as evidenced by the formation of large, regularly shaped and strengthened sludge flocs. The modifications of sludge characteristics promoted the formation process and filtration flux of the dynamic membrane(DM) layer. Additionally, PAC addition did not exert very significant influence on the propagation of eukaryotes(protists and metazoans)and microbial metabolic activity. High-throughput pyrosequencing results indicated that adding PAC improved the bacterial diversity in activated sludge, as PAC addition brought about additional microenvironment in the form of biological PAC(BPAC), which promoted the enrichment of Acinetobacter(13.9%), Comamonas(2.9%), Flavobacterium(0.31%) and Pseudomonas(0.62%), all contributing to sludge flocs formation and several(such as Acinetobacter) capable of biodegrading relatively complex organics. Therefore, PAC addition could favorably modify sludge properties from various aspects and thus enhance the DMBR performance.

Techno-economic characteristics of wastewater treatment plants retrofitted from the conventional activated sludge process to the membrane bioreactor process

While a growing number of wastewater treatment plants(WWTPs)are being retrofitted from the conventional activated sludge(CAS)process to the membrane bioreactor(MBR)process,the debate on the techno-economy of MBR vs.CAS has continued and calls for a thorough assessment based on techno-economic valuation.In this study,we analyzed the operating data of 20 large-scale WWTPs(capacity≥10000 m^(3)/d)and compared their techno-economy before and after the retrofitting from CAS to MBR.Through cost-benefit analysis,we evaluated the net profit by subtracting the operating cost from the environmental benefit(estimated by the shadow price of pollutant removal and water reclamation).After the retrofitting,the removal rate of pollutants increased(e.g.,from 89.0%to 93.3%on average for NH3-N),the average energy consumption increased from 0.40 to 0.57 kWh/m^(3),but the operating cost did not increase significantly.The average marginal environmental benefit increased remarkably(from 0.47 to 0.66 CNY/g for NH3-N removal),leading to an increase in the average net profit from 19.4 to 24.4 CNY/mJ.We further scored the technical efficiencies via data envelopment analysis based on non-radial directional distance functions.After the retrofitting,the relative cost efficiency increased from 0.70 to 0.73(the theoretical maximum is 1),while the relative energy efficiency did not change significantly.The techno-economy is closely related to the effluent standard adopted,particularly when truncating the extra benefit of pollutant removal beyond the standard in economic modeling.The modeling results suggested that MBR is more profitable than CAS given stricter effluent standards.

PAC更新率对PAC-MBR耦合处理效能及污泥特性的影响

粉末活性炭(PAC)的定期回收和补充是混合膜生物反应器(PAC-MBR)稳定运行所必需的。研究探索了不同PAC更新率对PAC-MBR中污泥过滤特性和微生物群落的影响,创新性地提出通过PAC更新来提高微生物活性,以达到提高出水效能并减缓膜污染的效果。结果表明:PAC更新对CODCr和氮的去除没有显著影响;随着PAC更新率的增加,可溶性微生物产物逐渐降低,胞外聚合物浓度逐渐增加。PAC的更新能够降低MBR系统膜污染,同时提高过滤效率。微生物活性与PAC的更新率呈正相关规律。此外,由高通量测序可知由于添加新鲜的PAC,Proteobacteria(变形菌属)、Bacteroidetes(拟杆菌属)及Nitrospira(硝化螺旋菌属)的丰度增加,保证污染物的去除,同时Proteobacteria及Bacteroidetes造成的膜污染减少。最佳PAC更新率为1.67%,能够有效缓解膜污染并增强优势细菌结构。在推动PAC-MBR广泛应用方面,PAC更新被认为是一种有前景的方法。

MBR／PAC组合工艺处理污水厂尾水的中试研究

在MBR中试的基础上,向MBR反应器中投加40 g/L粉末活性炭(PAC)构成MBR/PAC组合工艺并处理污水厂尾水。试验结果表明:MBR/PAC系统的出水BOD5≤4 mg/L、COD≤18 mg/L、氨氮≤0.3 mg/L、浊度≤0.2 NTU,处理效果优于MBR系统。PAC能吸附并降解易引起膜污染的有机物,有效降低了膜污染,减缓了过膜压力的增长趋势,保护了膜组件,并且运行效果良好。通过气洗和反冲洗能很好地维持膜的透过性能,离线清洗可基本恢复膜的透过性能。

AS-SMBR与BPAC-SMBR运行特性的比较研究

在完全相同的进水和操作条件下,考察了添加粉末活性炭(PAC)的生物活性炭浸没膜生物反应器(BPAC-SMBR)与常规的活性污泥浸没膜生物反应器(AS-SMBR)的运行特性。研究比较了2类反应器在长期运行条件下的膜通透性和活性污泥混合液特性,并就ρ(PAC)对膜过滤阻力的影响及2个体系的抗冲击负荷能力进行了分析。结果表明BPAC-SMBR的过滤性能要优于AS-SMBR,其主要原因来自于反应器内活性污泥混合液特性的差异;随着ρ(PAC)的提高,膜过滤阻力的降低幅度依次减小;与AS-SMBR相比,BPAC-SMBR具有更强的抗冲击负荷能力。

PAC投加量对MBR混合液性质及膜污染的影响

比较了1g/L及2g/L的PAC投加量对膜生物反应器中混合液性质及膜污染速率的差异。发现两系统上清液COD差距不明显,说明1g/L的PAC投加量已足以吸附小分子的有机物。当PAC从1g/L增至2g/L时,从微生物絮体中提取的多糖平均值分别为:14.92mg/g MLSS、15.38mg/g MLSS;蛋白质平均值分别为18.82mg/g MLSS、17.58 mg/g MLSS;且膜丝内部累积的多糖和蛋白质含量基本相同。当PAC投加量为2g/L时,部分破碎的PAC颗粒会进入膜孔内部,引起不可逆污染。

PAC—MBR组合工艺处理焦化废水的试验研究

采用PAC—MBR组合工艺处理焦化废水，考察了该工艺对COD、NH3-N和浊度的去除效果。结果表明，在水温〉25℃、DO〉3mg／L、pH值为7～8的条件下，组合工艺对COD和NH3-N的去除效果较好，去除率分别大于86．8％和98％，出水COD约为80mg／L，NH3-N基本在10mg／L以下，分别达到了《污水综合排放标准》（GB8978-1996）的二级和一级标准；出水浊度〈10NTU，出水水质较为稳定。

PAC-MBR组合工艺处理城市污水厂出水的研究

采用平板式膜生物反应器(MBR)工艺处理城市污水处理厂的出水,考察投加粉末活性炭(PAC)对处理效果、膜污染和污泥特性的影响.结果表明,系统在很低的有机负荷(MLSS可承受的TOC负荷为0.014 kg/(kg.d))下有机物去除率大于60%,NH4+-N去除率大于95%,浊度去除率约为92%,可维持30 d左右.平行实验显示,投加PAC极大地提高了系统对有机物的去除率,而对NH4+-N和浊度的去除无显著影响;投加PAC能有效减缓膜生物反应器中的膜污染,使膜污染缓慢发展阶段的历时时间延长了一倍多,并使膜过滤污泥的凝胶极化阻力和总阻力分别减小40.5%和17.4%;另外投加PAC改变了污泥特性,是使系统性能提高的主要原因.

生物陶粒柱-PAC-MBR系统处理饮用水研究

利用生物陶粒柱和粉末活性炭结合膜生物反应器处理饮用水,研究表明,该预处理工艺不仅解决了膜生物反应器氨氮去除不力的弱点,避免了亚硝酸盐的积累,而且极大地降低了膜生物反应器的有机负荷.生物陶粒柱-PAC-MBR系统高锰酸盐指数平均去除率为76.97%,氨氮和亚硝酸盐的平均去除率分别达到了95.50%和99.15%;而预处理工艺还可以减轻浓差极化,延缓膜污染,在试验过程中形成的膜孔阻力和滤饼阻力之和比没有预处理的膜生物反应器中超滤膜下降了72%.

投加粉末炭对SMBR过滤性能的影响

在相同的进水和运行条件下 ,考察和比较了生物活性炭—膜生物反应体系 (BPAC—SMBR)与常规的活性污泥—膜生物反应体系 (AS—SMBR)的膜过滤特性 ,并就粉末活性炭 (PAC)对通量改善的相关机理进行了探讨。结果表明 ,添加 1.2g/L的PAC可明显改善SMBR的过滤性能。与AS—SMBR相比 ,BPAC—SMBR的临界通量可提高 32 % ;相同恒通量下的长期运行结果也表明BPAC—SMBR透膜压力的升高更为缓慢 ,其稳定运行周期可达到AS—SMBR的 1.8倍 ;BPAC—SM BR的膜过滤总阻力比AS—SMBR的低约 4 4% ,其差别主要来自于滤饼阻力的减少。此外 ,还分析了混合液粘度。

PAC/MBR用于微污染地表水处理的中试研究

采用投加粉末活性炭(PAC)的膜生物反应器(MBR)组合工艺-PAC/MBR处理微污染地表水。中试结果表明,该工艺出水水质稳定,稳定运行期间出水浊度、CODMn和氨氮分别保证在0.3NTU、1.9mg·L-1和0.2mg·L-1以下,达到生活饮用水卫生标准的要求。膜表面生物活性炭(BAC)滤层具有良好的抗压性,出水通量呈阶梯式下降,防止了持续性的大幅度衰减。混合液中悬浮态PAC和生物活性炭能吸附大部分胞外聚合物(EPS),降低溶解态胞外聚合物含量,有利于减缓膜污染。

炭载体MBR处理低碳、氮比生活污水效能研究

为使膜生物反应器工艺在取得高质量出水的同时能更有效地延缓膜污染,从而延长膜的工作周期和使用寿命,向生物反应器中一次性投加了1500 mg/L的粉末活性炭(PAC),同时该膜生物反应器采用恒温(30℃)、恒定膜通量(7 L/(m^2·h))和间歇抽吸(开10min,停3min)的方式连续运行120 d．结果表明,PAC的加入使活性污泥中的一部分微生物以PAC作为载体形成生物膜,从而在膜生物反应器中形成了以生物膜和活性污泥2种形式构成的新的生态系统,大大提高了膜生物反应器的污水处理效果．由于PAC的加入,改善了膜表面滤饼层的水力特性,从而减小了膜过滤阻力,有效延缓了膜污染．

MBR中微生物代谢产物对膜污染的影响及其调控方法的研究进展

膜生物反应器(Membrane bio-reactor,MBR)作为一种高效实用的新型污水处理与回用技术,近年来得到了广泛的理论研究与工程应用,而膜污染问题一直是限制MBR发展和应用的一个瓶颈。分析了微生物代谢产物对膜污染的影响,并从调控微生物代谢产物减缓膜污染的方法入手,综述了投加粉末活性炭(PAC)、混凝剂与絮凝剂,以及通入臭氧对污泥混合液的理化性质影响的研究现状。虽然目前的研究取得了一定的进展,但在投加试剂的反应机理、相关性分析等方面仍存在着许多的不足。

多介质过滤-活性碳过滤-MBR工艺深度处理城市中水回用火电厂工业用水研究

针对湛江某火电厂升级现有地下水深度处理工艺以实现深度处理中水的要求,研究通过增加活性炭-膜生物反应器（MBR）单元去除水中的溶解性痕量有机物,进一步降低水中的SS、微生物及降解水中残余难降解有机物含量,使出水满足反渗透系统进水要求。结果表明,MBR出水平均浊度为0.43 NTU,浊度平均去除率为81%,能满足反渗透进水水质对浊度的要求（〈1 NTU）;COD去除率平均约为30%,最高可达66%;出水NH3-N的质量浓度低于5 mg/L,最高去除率为90%;出水p H为7.25～7.5。活性炭吸附可去除一部分的难降解有机物及氨氮,每日进行气水联合反冲洗有利于延长活性碳使用寿命。MBR稳定去除浊度及细菌总数,但需要额外添加碳源维持系统稳定运行。

A/O-MBR-臭氧-活性炭工艺处理混合污水的试验研究

建立水解-好氧膜生物-臭氧-活性炭组合工艺处理工业和生活的混合污水.试验结果表明,在不同的进水流量下,生物处理工艺对COD、氨氮(NH3-N)、总氮(TN)、总磷(TP)、SS和色度均有稳定的处理效果.单纯活性炭吸附、臭氧氧化和臭氧-活性炭组合工艺处理可进一步降低生化出水的COD浓度.组合工艺的出水水质满足GB18918-2002的一级B标准.

PAC/MBR与MBR工艺处理微污染水源水的效能对比研究

对PAC/MBR和MBR工艺处理微污染水源水的效能进行对比研究。结果表明,PAC/MBR对CODMn、UV254具有更好的去除效果,在浊度、氨氮的去除上,PAC/MBR没有明显优势。通过检测混合液中EPS的含量、分析膜出水通量的变化趋势,可以发现PAC的加入,增强了反应器内的生物活性,改变了系统混合液中EPS的形态及含量,改善了膜出水通量。说明PAC有助于减缓膜污染,提高系统的稳定性。

PAC-MBR组合工艺处理城市污水

采用PAC-MBR组合工艺处理城市污水,考察了该工艺对COD、NH4+-N和浊度的去除效果,试验结果表明,在水温>26℃、DO>4.5mg/L及pH为6～9的条件下,组合工艺对COD、NH4+-N和浊度的去除效果较好,平均去除率分别达到88%、98%和98%以上,高于单独MBR工艺和常规工艺。出水COD约为22mg/L,NH4+-N<1mg/L,浊度<1NTU,水质优于中国建设部生活杂用水水质标准(CJ25.1-89)。已污染的膜可通过水反冲洗、水-酸洗、水-碱洗使膜通量恢复至新膜的43%、81%、89%。