Please cite this article as: Al-Jassim, N., Ansari, M.I., Harb, M., Hong, P.-Y., Removal of bacterial contaminants and antibiotic resistance genes by conventional wastewater treatment processes in Saudi Arabia: Is the treated wastewater safe to reuse for agricultural irrigation?, Water Research (2015Research ( ), doi: 10.1016Research ( /j.watres.2015 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT Abstract 1This study aims to assess the removal efficiency of microbial contaminants in a local wastewater 2 treatment plant over the duration of one year, and to assess the microbial risk associated with 3 reusing treated wastewater in agricultural irrigation. The treatment process achieved 3.9 logs 4 removal of heterotrophic bacteria and up to 3.9 logs removal of fecal coliforms. The final 5 chlorinated effluent had 1.8 x 10 2 MPN/100 mL of fecal coliforms and fulfils the required quality 6 for restricted irrigation. 16S rRNA gene-based high-throughput sequencing showed that several 7 genera associated with opportunistic pathogens (e.g. Acinetobacter, Aeromonas, Arcobacter, 8 Legionella, Mycobacterium, Neisseria, Pseudomonas and Streptococcus) were detected at 9 relative abundance ranging from 0.010 to 21 % of the total microbial community in the influent. 10

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Anaerobic membrane bioreactors (AnMBRs) have recently gained consideration as an alternative technology for the treatment of municipal wastewater. Despite that, the effect of reactor configurations on their performance and sustainability remains understudied.This work aims to evaluate two different AnMBR types at low organic-loading conditions. Results show that the microbial consortium developed in each reactor can potentially have a significant impact on both biogas production and the microbial products that affect biofouling. Abstract 1Two lab-scale anaerobic membrane bioreactors (AnMBRs), one up-flow attached-growth 2 (UA) and another continuously stirred (CSTR), were operated under mesophilic 3 conditions (35 °C) while treating synthetic municipal wastewater (800 mg/L COD). Each 4 reactor was attached to both polyvinylidene fluoride (PVDF) and polyethersulfone (PES) 5 microfiltration (MF) membranes in an external cross-flow configuration. Both reactors 6were started-up and run under the same operating conditions for multiple steady-state 7 experiments. Chemical oxygen demand (COD) removal rates were similar for both 8 reactors (90-96%), but captured methane was found to be 11-18% higher for the CSTR 9 than the UA reactor. Ion Torrent sequencing targeting 16S rRNA genes showed that 10 several operational taxonomic units (OTUs) most closely related to fermentative bacteria 11 (e.g., Microbacter margulisiae) were dominant in the suspended biomass of the CSTR, 12 accounting for 30% of the microbial community. Conversely, methanogenic archaea 13 (e.g., Methanosaeta) and syntrophic bacteria (e.g., Smithella propionica) were found in 14 significantly higher relative abundances in the UA AnMBR as compared to the CSTR, 15 due to their affinity for surface attachment. Of the methanogens that were present in the 16 CSTR sludge, hydrogenotrophic methanogens dominated (e.g., Methanobacterium). 17 Measured EPS (both proteins and carbohydrates) -which has been broadly linked to 18fouling -was determined to be consistently lower in the UA AnMBR membrane samples 19 than in CSTR AnMBR membrane samples. Principal component analysis (PCA) based 20 on HPLC profiles of soluble microbial products (SMPs) further demonstrated these 21 differences between reactor types in replicate runs. The results of this study showed that 22 reactor configuration can significantly impact the development of the microbial 23

Although membrane bioreactor (MBR) systems provide better removal of pathogens compared to conventional activated sludge processes, they do not achieve total log removal. The present study examines two MBR systems treating municipal wastewater, one a full-scale MBR plant and the other a lab-scale anaerobic MBR. Both of these systems were operated using microfiltration (MF) polymeric membranes. High-throughput sequencing and digital PCR quantification were utilized to monitor the log removal values (LRVs) of associated pathogenic species and their abundance in the MBR effluents. Results showed that specific removal rates vary widely regardless of the system employed. Each of the two MBR effluents’ microbial communities contained genera associated with opportunistic pathogens (e.g., Pseudomonas, Acinetobacter) with a wide range of log reduction values (< 2 to >5.5). Digital PCR further confirmed that these bacterial groups included pathogenic species, in several instances at LRVs different than those for their respective genera. These results were used to evaluate the potential risks associated both with the reuse of the MBR effluents for irrigation purposes and with land application of the activated sludge from the full-scale MBR system.Electronic supplementary materialThe online version of this article (doi:10.1007/s11356-016-8211-y) contains supplementary material, which is available to authorized users.

Please cite this article as: Y. Xiong, M. Harb, P-Y. Hong, Characterization of biofoulants illustrates different membrane fouling mechanisms for aerobic and anaerobic membrane bioreactors, Separation and Purification Technology (2015), doi: http://dx.doi.org/10.1016/j.seppur. 2015.11.024 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. AbstractThis study compares the membrane fouling mechanisms of aerobic (AeMBR) and anaerobic membrane bioreactors (AnMBR) of the same reactor configuration at similar operating conditions. Although both the AeMBR and AnMBR achieved more than 90% COD removal efficiency, the fouling mechanisms were different. Molecular weight (MW) fingerprint profiles showed that a majority of fragments in anaerobic soluble microbial products (SMP) were retained by the membrane and some AnMBR systems and can be applied to facilitate the development of appropriate fouling control strategies.