Occurrence and removal of organic micropollutants in the treatment of landfill leachate by combined anaerobic-membrane bioreactor technology

Organic micropollutants,with high toxicity and environmental concern,are present in the landfill leachate at much lower levels than total organic constituents (chemical oxygen demand (COD),biochemical oxygen demand (BOD),or total organic carbon (TOC)),and few has been known for their behaviors in different treatment processes.In this study,occurrence and removal of 17 organochlorine pesticides (OCPs),16 polycyclic aromatic hydrocarbons (PAHs),and technical 4-nonylphenol (4-NP) in landfill leachate in a comb...

Anaerobic Membrane Bioreactors (AnMBR) for Wastewater Treatment

This paper focuses on the recent research in the development of anaerobic membrane bioreactors in wastewater treatment. Anaerobic wastewater treatment technology is gaining increasing attention due to its capacity to convert wastewater BODs to usable biogas with relatively low energy consumption. The anaerobic membrane bioreactor (AnMBR), which is a combination of the anaerobic biological wastewater treatment process and membrane filtration, represents a recent development in the high-rate anaerobic bioreactors. This paper reviews applications and performances of AnMBR and the membrane filtration behaviour in AnMBRs.

An in-situ biochar-enhanced anaerobic membrane bioreactor for swine wastewater treatment under various organic loading rates

A biochar-assisted anaerobic membrane bioreactor(BC-AnMBR)was conducted to evaluate the performance in treating swine wastewater with different organic loading rates(OLR)ranging from 0.38 to 1.13 kg-COD/(m3.d).Results indicated that adding spent coffee grounds biochar(SCG-BC)improved the organic removal efficiency compared to the conventional AnMBR,with an overall COD removal rate of>95.01%.Meanwhile,methane production of up to 0.22 LCH4/gCOD with an improvement of 45.45%was achieved under a high OLR of 1.13 kg-COD/(m3.d).Furthermore,the transmembrane pressure(TMP)in the BC-AnMBR system was stable at 4.5 kPa,and no irreversible membrane fouling occurred within 125 days.Microbial community analysis revealed that the addition of SCG-BC increased the relative abundance of autotrophic methanogenic archaea,particularly Methanosarcina(from 0.11%to 11.16%)and Methanothrix(from 16.34%to 24.05%).More importantly,Desulfobacterota and Firmicutes phylum with direct interspecific electron transfer(DIET)capabilities were also enriched with autotrophic methanogens.Analysis of the electron transfer pathway showed that the concentration of c-type cytochromes increased by 38.60%in the presence of SCGBC,and thus facilitated the establishment of DIET and maintained high activity of the elec-tron transfer system even at high OLR.In short,the BC-AnMBR system performs well under various OLR conditions and is stable in the recovery energy system for swine wastewater.

Achieving simultaneous removal of carbon and nitrogen by an integrated process of anaerobic membrane bioreactor and flow-through biofilm reactor

In this study,a combined system consisting of an anaerobic membrane bioreactor(AnMBR)and flow-through biofilm reactor/CANON(FTBR/CANON)was developed to simultaneously remove carbon and nitrogen from synthetic livestock wastewater.The average removal efficiencies of total nitrogen(TN)were 64.2 and 76.4%with influent ammonium(NH4+-N)concentrations of approximately 200 and 500 mg/L,respectively.The COD removal efficiencies were higher than 98.0%during the entire operation.Mass balance analysis showed that COD and TN were mainly removed by the AnMBR and FTBR/CANON,respectively.The anammox process was the main nitrogen removal pathway in the combined system,with a contribution of over 80%.High functional bacterial activity was observed in the combined system.Particularly,an increase in the NH4+-N concentration considerably improved the anammox activity of the biofilm in the FTBR/CANON.16S rRNA high-throughput sequencing revealed that Methanosaeta,Candidatus Methanofastidiosum,and Methanobacterium were the dominant methanogens in the AnMBR granular sludge.In the CANON biofilm,Nitrosomonas and Candidatus Kuenenia were identified as aerobic and anaerobic ammonium-oxidizing bacteria,respectively.In summary,this study proposes a combined AnMBR and FTBR/CANON process targeting COD and nitrogen removal,and provides a potential alternative for treating high-strength wastewater.

Anaerobic-aerobic processes for the treatment of textile dyeing wastewater containing three commercial reactive azo dyes:Effect of number of stages and bioreactor type

In this study,the effect of number of stages and bioreactor type on the removal performance of a sequential anaerobic-aerobic process employing activated sludge for the treatment of a simulated textile dyeing wastewater containing three commercial reactive azo dyes was considered.Two stage processes performed better than one stage ones,both in terms of overall organic and color removal,as well as the higher contribution of anaerobic stage to the overall removal performance,thereby making them a more energy efficient option.The employment of a moving bed sequencing batch biofilm reactor,which uses both suspended and attached biomass,for the implementation of the anaerobic stage of the process,was compared with a sequencing batch reactor that only employs suspended biomass.The results showed that,although there was no meaningful difference in biomass concentration between the two bioreactors,the latter reactor had better performance in terms of chemical oxygen demand(COD)removal efficiency and rate and color removal rate.Further exploratory tests revealed a difference between the roles of suspended and attached bacterial populations,with the former yielding better color removal whilst the latter had better COD removal performance.The sequential anaerobic–aerobic process,employing an aerobic membrane bioreactor in the aerobic stage resulted in COD and color removal of 77.1±7.9%and 79.9±1.5%,respectively.The incomplete COD and color removal was attributed to the presence of soluble microbial products in the effluent and the autoxidation of dye reduction metabolites,respectively.Also,aerobic partial mineralization of the dye reduction metabolites,was experimentally observed.

Start-up and contaminants removal characteristics of aerobic granules-membrane bioreactor at low temperature

In order to understand the effect of low temperature on the formation process of aerobic granules and contaminants removal characteristics,the aerobic granules-membrane bioreactor (AGS-MBR) has been started up and operated at low temperature using the carbon resource of sodium acetate. Aerobic granules cultivated in AGS-MBR possess smooth surface and compact structure in morphology as well as better settling property and higher biomass after 38 days. The average parameters of aerobic granules are: diameter 3. 1 mm,wet density 1. 041 g/mL,sludge volume index 42. 35 mL/g and settling velocity 20. 6 - 45. 2 cm/min. During the start-up of AGS-MBR,the respectively average contaminants removal efficiencies at low temperature are 91. 9% for chemical oxygen demand (COD) ,89. 2% for NH4 + -N and 86. 3% for PO43- -P,and the overgrowth of filamentous bacteria has been well controlled. In addition,the hollow fiber microfiltration (MF) membrane fouling is light and the regime membrane layer is capable of enhancing membrane filtration as well as the average growth of trans-membrane pressure (TMP) is 1. 07 kPa/d. Compared with the conventional cultivation of aerobic granules,the sludge granulation time significantly decreases from 73 days to 38 days by the application of microfiltration membrane at low temperature.

Comparison of membrane fouling during short-term filtration of aerobic granular sludge and activated sludge

Aerobic granular sludge was cultivated adopting internal-circulate sequencing batch airlift reactor. The contradistinctive experiment about short-term membrane fouling between aerobic granular sludge system and activated sludge system were investigated. The membrane foulants was also characterized by Fourier transform infrared （FTIR） spectroscopy technique. The results showed that the aerobic granular sludge had excellent denitrification ability; the removal efficiency of TN could reach 90%. The aerobic granular sludge could alleviate membrane fouling effectively. The steady membrane flux of aerobic granular sludge was twice as much as that of activated sludge system. In addition, it was found that the aerobic granular sludge could result in severe membrane pore-blocking, however, the activated sludge could cause severe cake fouling. The major components of the foulants were identified as comprising of proteins and polysaccharide materials.

Advances in Energy-Producing Anaerobic Biotechnologies for Municipal Wastewater Treatment

Municipal wastewater treatment has long been known as a high-cost and energy-intensive process that destroys most of the energy-containing molecules by spending energy and that leaves little energy and few nutrients available for reuse, Over the past few years, some wastewater treatment plants have tried to revamp themselves as ＂resource factories,＂ enabled by new technologies and the upgrading of old technologies. In particular, there is an renewed interest in anaerobic biotechnologies, which can convert organic matter into usable energy and preserve nutrients for potential reuse. However, considerable technological and economic limitations still exist. Here, we provide an overview of recent advances in several cutting-edge anaerobic biotechnologies for wastewater treatment, including enhanced side- stream anaerobic sludge digestion, anaerobic membrane bioreactors, and microbial electrochemical systems, and discuss future challenges and opportunities for their applications. This review is intended to provide useful information to guide the future design and optimization of municipal wastewater treatment processes.

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

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 HRTPN/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 NO_(2)^(−)-N/NH_(4)^(+)-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.

Comparative study of thermophilic and mesophilic anaerobic treatment of purified terephthalic acid (PTA) wastewater

The paper provides a critical comparison between mesophilic and thermophilic anaerobic treatment of PTA wastewater through diagnosis of a case study. Aspects covered are bioavailability, biodegradability, microbial population, thermodynamics, kinetics involved and bio-reactor design for PTA wastewater treatment. The results of the case study suggests that one- stage thermophilic anaerobic reactor coupled with coagulation-flocculation pre-treatment unit and an aerobic post treatment unit could be techno-economically viable for PTA wastewater treatment to ensure that the final effluent quality conforms to the international standard. The in-formation emanated from this study could be useful and thought provoking to the professionals and academia in the area of PTA wastewater treatment and can serve as impetus toward the development of research lines in similar problems like the treatment of other petrochemical wastewater such as phenol-con- taining wastewater, benzene/benzoic acid-con- taining wastewater or wastewater from other similar industrial settings.

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.

Microbial characteristics in anaerobic membrane bioreactor treating domestic sewage:Effects of HRT and process performance

Two anaerobic membrane bioreactors(AnMBRs)equipped with different membrane pore size(0.4 or 0.05μm)were operated at 25℃and fed with domestic wastewater.The hydraulic retention time(HRT)of the reactors was shortened.The microbial communities of the two AnMBRs were investigated by 16S rRNA gene amplicon sequencing to see the effects of HRT.The predominant Archaea was an aceticlastic methanogen Methanosaeta.The composition of hydrogenotrophic methanogens changed with the HRTs:the population of Methanobacterium was higher for longer HRTs,whereas the population of unclassified Methanoregulaceae was higher for shorter HRTs.The Anaerolineae,Bacteroidia and Clostridia bacteria were dominant in both of the reactors,with a combined relative abundance of over 55%.The relative abundance of Anaerolineae was proportional to the biogas production performance.The change in the population of hydrogenotrophic methanogens or Anaerolineae can be used as an indicator for process monitoring.The sum of the relative abundance of Anaerolineae and Clostridia fluctuated slightly with changes in the HRT in both AnMBRs when the reactor was stably operated.The co-occurrence analysis revealed the relative abundance of the operational taxonomic units belonging to Anaerolineae and Clostridia was functionally equivalent during the treatment of real domestic sewage.A principal coordination analysis revealed that the changes in the microbial community in each reactor were consistent with the change of HRT.In addition,both the HRT and the stability of the process are important factors for maintaining microbial community structures.

Membrane fouling control by ultrasound in an anaerobic membrane bioreactor

fouling online in an anaerobic membrane bioreac-tor(AMBR).Short-term running experiments were carried out under different operating conditions to explore feasible ultrasonic parameters.The experimental results indicated that when the crossflow velocity was more than 1.0 m/s,mem-brane fouling could be controlled effectively only by hydro-dynamic methods without ultrasound.When ultrasound was applied,an ultrasonic power range of 60-150 W was suitable for the membrane fouling control in the experimental system.The experimental results showed that the membrane fouling was controlled so well that membrane filtration resistance(ΣR)could stay at 5×10^(11)m^(−1) for more than a week with the crossflow velocity of 0.75 m/s,which equaled the effect of crossflow velocity of more than 1.0 m/s without ultrasound.

Aggravation of membrane fouling and methane leakage by a three-phase separator in an external anaerobic ceramic membrane bioreactor

The three-phase separator is a critical component of high-rate anaerobic bioreactors due to its significant contribution in separation of biomass, wastewater, and biogas. However, its role in an anaerobic membrane bioreactor is still not clear. In this study, the distinction between an external anaerobic ceramic membrane bioreactor (EAnCMBR) unequipped (R1) and equipped (R2) with a three-phase separator was investigated in terms of treatment performance, membrane fouling, extracellular polymers of sludge, and microbial community structure. The results indicate that the COD removal efficiencies of Rl and R2 were 98.2%±0.4% and 98.1%±0.4%, respectively, but the start-up period of R2 was slightly delayed. Moreover, the membrane fouling rate of R2 (0.4 kPa/d) was higher than that of Rl (0.2 kPa/d). Interestingly, the methane leakage from R2 (0.1 L/d) was 20 times higher than that from Rl (0.005 L/d). The results demonstrate that the three-phase separator aggravated the membrane fouling rate and methane leakage in the EAnCMBR. Therefore, this study provides a novel perspective on the effects of a three-phase separator in an EAnCMBR.

Impact of food to microorganism ratio and alcohol ethoxylate dosage on methane production in treatment of low-strength wastewater by a submerged anaerobic membrane bioreactor

The effects of food to microorganism （FIM） ratio and alcohol ethoxylate （AE） dosage on the methane production potential were investigated in treatment of low-strength wastewater by a submerged anaerobic membrane bioreactor （SAnMBR）. The fate of AE and its acute and/or chronic impact on the anaerobic microbes were also analyzed. The results indicated that AE had an inhibitory effect to methane production potential （lag-time depends on the AE dosage） and the negative effect attenuated subsequently and methane production could recover at FIM ratio of 0.088-0.357. VFA measurement proved that AE was degraded into small molecular organic acids and then converted into methane at lower FIM ratio （FIM 〈 0.158）. After long-term acclimation, anaerobic microbe could cope with the stress of AE by producing more EPS （extracellular polymeric substances） and SMP （soluble microbial products） due to its self-protection behavior and then enhance its tolerance ability. However, the methane production potential was considerably decreased when AE was present in wastewater at a higher FIM ratio of 1.054. Higher AE amount and FIM ratio may destroy the cell structure of microbe, which lead to the decrease of methane production activity of sludge and methane production potential.

生物炭强化厌氧膜生物反应器处理废水性能的研究进展

厌氧膜生物反应器(AnMBR)因其在各种废水处理中对有机物的高效降解和能量的回收能力而受到研究者的广泛关注。生物炭具有优异的吸附和导电能力,将其添加在AnMBR中用于厌氧消化处理污废水,可以提高反应器性能并促进能源回收。基于此,系统综述了生物炭的制备和改性方法对生物炭性能影响的研究,以及近年来利用生物炭强化AnMBR处理性能的研究进展,并主要讨论了生物炭在AnMBR中的作用及主要机制,指出了目前生物炭强化AnMBR研究存在的问题和未来的发展方向,为生物炭强化AnMBR处理废水提供理论依据与技术参考。

两级过滤AnMBR反应器的运行效能和污染特性

构建以高分子滤布及附着在其表面动态膜作为反应器的一级过滤系统及聚偏氟乙烯(PVDF)超滤膜的二级过滤系统组成的两级过滤式An MBR(F-An MBR),探究其在低浓度市政污水处理中的应用效果.结果表明,亲水性较好的聚酰胺滤布,80μm滤布在12LMH运行通量下有效拦截污泥,动态膜形成后TSS拦截率超过88%,适于F-An MBR.一级过滤显著提高了An MBR的抗污染性,PVDF超滤膜的临界通量从6LMH提升至12LMH,膜污染速率及跨膜压差的增长速率明显下降.分析显示,动态膜组件降低了膜池中50%以上的MLSS、MLVSS和EPS等膜污染物质,有效延缓超滤膜滤饼层污染的形成.然而,动态膜组件对SMP的拦截相对较弱,溶解性蛋白质含量仅减少19.34%,限制了对凝胶层污染的改善.

厌氧膜生物反应器出水溶解甲烷回收研究进展

厌氧膜生物反应器(AnMBR)是一种能耗低、处理效率高的污水处理技术.然而,受温度、污泥龄、水力停留时间等工艺参数的影响,生成的甲烷大量溶解在出水中形成过饱和溶液,并随出水排放至环境中,造成了能源物质损失和温室气体排放.若将溶解甲烷有效回收,其可作为补充能源或脱氮碳源原位利用,具有重要的应用价值.为了实现AnMBR出水溶解甲烷有效回收或再利用,本文阐述了目前3种主流回收溶解甲烷技术(膜回收技术、反硝化厌氧甲烷氧化技术、微生物燃料电池)的原理、回收效能和局限性.在此基础上,评估了AnMBR处理污水全过程的碳足迹,并针对AnMBR出水溶解甲烷回收的未来研究进行了展望.本研究可为双碳背景下AnMBR技术实现能量盈余和资源回收提供理论依据和技术参考.

DcMFC-AnMBR耦合系统处理含磺胺嘧啶养猪废水的性能研究

构建了双室微生物燃料电池-厌氧膜生物反应器(DcMFC-AnMBR)耦合工艺系统,探究了耦合系统处理含磺胺嘧啶(SDZ)养猪废水的产电、污染物去除及产气性能,同时分析了SDZ影响下膜污染特征变化。结果表明:1.0 mg/L SDZ存在下DcMFC-AnMBR耦合系统平均输出电压和库仑效率分别下降了6.11%和7%,耦合系统最大功率密度为35.34 mW/m^(2),COD去除率始终保持在98%,平均生物气产量为542.59 mL/d。同时,SDZ的存在使污泥混合液Zeta电位绝对值升高了25.83%,污泥平均粒径减小了14~16μm,可溶性微生物产物(SMP)和胞外聚合物(EPS)平均浓度分别上升了7.76%和35.43%。耦合工艺系统运行期间跨膜压差(TMP)始终在0附近,其污染缓解原因可能是电活性微生物对SMP和EPS进行了有效的氧化降解。

提标升级对乡镇污水处理厂碳排放特征的影响

在碳达峰、碳中和和流域水污染防治的背景下,乡镇污水处理厂减污降碳协同势在必行。基于成都市某乡镇市政污水处理厂2016—2022年水质水量数据,分析提标升级前后化学需氧量、氨氮、总磷、总氮的时间变异性,利用《IPCC 2006国家温室气体清单指南》(2019年修订版)、《城镇水务系统碳核算与减排路径技术指南》评估直接、间接碳排放强度特征,探究提标升级前后碳排放量对季节、水质及污染物削减量的响应。结果表明:1)污水处理厂主体工艺从周期循环活性污泥法(CASS)升级为厌氧-缺氧-好氧-膜生物反应器法(AAO-MBR)后,出水水质满足DB 51/2311—2016《四川省岷江、沱江流域水污染物排放标准》,升级后通过增加碳源、利用MBR膜截留污泥等措施,使出水水质指标更加稳定,对污染物的处理效率更高;2)提标升级后,直接、间接碳排放强度分别为0.296和1.082 kg/m^(3)(以CO_(2)当量计),分别增加41.59%和105.70%,且夏季碳排放强度显著低于其他季节(P<0.01),升级前后的间接碳排放强度均高于直接碳排放强度;3)提标升级后,总碳排放强度增加了0.643 kg/m^(3)(以CO_(2)当量计),工艺升级导致的电耗增加,使得间接碳排放强度变化更显著。乡镇污水处理厂提标升级在提高处理效能的同时也增加了碳排放量,建议在工艺改造中协同考虑污染物去除与能耗控制,以实现减污降碳协同增效。