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[Display omitted] • C rosstalk between the secondary messenger and AHLs in granulation is studied. • c-di-GMP + AHLs accelerate the tricarboxylic acid (TCA) cycle for yielding excess proteins. • AI-2 + AHLs accelerate the glyoxylate (GCA) cycle for stimulating polysaccharides secretion. • c-di-GMP and AI-2 compete with the AHLs to decline the EPS secretion. • c-di-GMP + AHLs recovered PN-rich granules from refrigerated-stored and dried-stored AGS. Efficient quorum sensing (QS) response is the premise for recovering the activities of stored aerobic granular sludge (AGS). This study aims to explore the crosstalk between the secondary messenger and the N-acylated-homoserine lactones (AHLs) to yield protein-rich granules efficiently from stored AGS by enhancing its QS efficiency selectively. 80 nmol/L cyclic diguanylate (c-di-GMP) with 20 nmol/L AHLs could increase the activity of isocitrate lyase activity (ICD) by 89 % and isocitrate dehydrogenase activity (ICDHc) by 113.5 %, to accelerate the tricarboxylic acid (TCA) cycle for yielding excess proteins by 166.4 %. In contrast, 80 nmol/L autoinducer-2 (AI-2) with 20 nmol/L AHLs could increase the activities of ICD and ICDHc by 485 % and 54.5 %, respectively, accelerating the glyoxylate (GCA) cycle to activate fat acid synthesis for stimulating polysaccharides (PS) secretion by 137.9 %. The strategy with c-di-GMP successfully recovers the refrigerated-stored and dried-stored AGS into proteins-rich AGS, with enriched functional strains for the PN secretion. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Aerobic granules kept long-term stability treating low C/N (<4) wastewater. • Feasibility of granular SNDPR for simultaneous C, N, and P removal was verified. • EPS, especially fluorescence PN contributed to both stability and functionality. • Phylogenetic classification of key functional groups was explored by sequencing. Abstract The lab-scale aerobic granules process was applied for low carbon to nitrogen (C/N < 4) wastewater treatment under different hydrodynamic shear forces. Results revealed that aerobic granules exhibited strong adaptability and stability. The aerobic granules might adopt an extracellular polymeric substances (EPS) regulating mechanism to address the changes in operational conditions, especially through growing secretion of fluorescence protein. The hydrodynamic shear force determinedly shaped and regulated the diversity and structure of dominant microbial community, briefly, reduced aeration intensity with increased time led to higher microbial richness, lower diversity and evenness, and shifts of predominant microorganisms. Phylogenetic classification of the key functional groups including bacteria related to carbon and nutrients removal, EPS production and quorum sensing (QS) presented much more differences among the reactors subject to different conditions. Therefore, the present work adds insight into the comprehensive understanding of the effect of aeration induced hydrodynamic shear force on aerobic granules. [ABSTRACT FROM AUTHOR]

[Display omitted] • A flocculation method based on microalgal biomimetic silicification was proposed. • Harvesting efficiency of 93.49% was obtained using low-dose PDADMAC and nanosilica. • Enhanced secretion and changes in properties of LB-EPS contributed to flocculation. • The biomimetic silicification flocculation showed better microalgal biomass quality. This study posed a novel biomimetic flocculation approach, aiming to efficiently harvest high-quality biomass of Scenedesmus quadricauda cultured with anaerobic digestate. Here, that poly(diallyldimethylammonium chloride) (PDADMAC) could serve as mimetic silicified proteins to spontaneously incorporate nanosilica onto microalgal cells, imparting diatom-like characteristics to S. quadricauda. Compared to the exponential growth phase (day 3), the highest harvesting efficiency (93.49%) was obtained at a lower dosage of PDADMAC (5 mg/g) in the stationary phase (day 6), which was attributed to changes in properties and composition of microalgal LB-EPS. On day 6, the hydrophobic functional groups in LB-EPS provided more binding sites during the flocculation process and formed a network structure of microalgal cells-flocculants-nanosilica. The resulting larger and more stable biomimetic silica shell promoted microalgal flocculation and sedimentation. Compared to conventional harvesting methods (centrifugation, polyacrylamide, alkaline flocculation), this method had the minimal negative impact on harvested biomass, with 9.95% of cell membranes damaged. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pre-denitrification increased the mean nitrogen removal efficiency by 5% up to 96%. • Two stage process and nitrogen limited strategy alleviated inhibition of AnAOB by SMD. • AOB, AnAOB, DNB and OHOs achieved effective coexistence in SNAP reactor. • Ca. Kuenenia rapidly adapted to SMD and was enriched to 27–30% in SNAP reactor. This study evaluated the functional activity and microbial structure of a pre-denitrification and single-stage partial nitritation/anammox process (DB-SNAP) coupled system for effectively treating swine manure digestate (SMD). At influent ammonium concentrations of (1000 to 1500) mg/L, the pre-denitrification reactor increased the nitrogen removal efficiency (NRE) by 5%, resulting in an average NRE of 96%. The DB-SNAP and nitrogen-limited strategy facilitated the rapid adoption of anammox bacteria (AnAOB) in the SMD, maintaining a high specific rate of 0.3 gN/gVSS/d. A high secretion of tightly bound extracellular polymeric substances (76 mg/gVSS to 102 mg/gVSS) promoted micro-granule aggregation and stability. Moreover, Ca. Kuenenia, an AnAOB genus, was highly enriched from 21% to (27 to 30) %, whereas Nitrospira , a nitrite-oxidizing bacteria, was significantly suppressed to (0 to 0.05) %. These findings will provide valuable guidance in implementing the anammox process in swine wastewater treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • Protective effects of EPS on oxidative attack of CaO 2 revealed. • Genes exoP and SRP54 are crucial on regulating EPS secretion. • SOD, followed by CAT, plays a major role in alleviating oxidative stress. • CaO 2 greatly affects succession of bacterial community in anaerobic fermentation. • Acinetobacter and Alcaligenes related with hydrolysis and acidogenesis enriched. Although calcium peroxide (CaO 2) can enhance the short-chain fatty acids (SCFAs) production in sludge anaerobic fermentation, the microbiological mechanisms underlying this process remain unclear. In this study, it is aimed to elucidate the bacterial protective mechanisms in response to the oxidative stress induced by CaO 2. Results show that extracellular polymeric substance (EPS) and anti-oxidant enzymes play vital roles in protecting bacterial cells from CaO 2. The addition of CaO 2 resulted in increased relative abundances of genes exoP and SRP54, which are associated with EPS secretion and transportation. Superoxide dismutase (SOD) played a crucial in alleviating oxidative stress. The dosage of CaO 2 significantly influences the succession of the bacterial community in the anaerobic fermentation system. With 0.3 g CaO 2 /g VSS, the net income was approximately 4 USD/ton of sludge treated. The CaO 2 -assisted anaerobic fermentation process has the potential to recover more resources from sludge and thus, benefit the environment. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pollutant removal was slightly inhibited by NaCl (100 mg/L) and 4-CP (2.4–4.0 mg/L). • EPS secretion was significantly stimulated by combined NaCl and 4-CP than 4-CP. • The abundances of dominant microbes were affected by NaCl at the diverse levels. • Functional genes encoding proteins were stimulated to deal with NaCl and 4-CP stress. • Functional genes for N removal in denitrification were diverse under NaCl stress. Chlorophenols frequently occur alongside salinity in industrial wastewater; thus, the effects of low concentrations of salinity (NaCl, 100 mg/L) on sludge performance, microbial community, and functional genes were deeply analyzed among 4-chlorophenol (4-CP, 2.4–4.0 mg/L) wastewater treatment. The influent 4-CP was effectively degraded, but the efficiencies for PO 4 3−-P, NH 4 +-N, and organics reduction were slightly inhibited by NaCl stress. Long-term NaCl and 4-CP stress significantly stimulated the secretion of extracellular polymeric substances (EPS). The abundances of predominant microbes at different taxonomic levels were affected by NaCl, and the increased relative abundances of functional genes encoding proteins contributed to resist NaCl and 4-CP stress. The functional genes associated with phosphorus metabolism and nitrogen metabolism in nitrification were unaffected, but the functional genes in denitrification increased in diversity under NaCl stress in 4-CP wastewater treatment. This finding acquires useful insight into the wastewater treatment with low chlorophenols and low salinity. [ABSTRACT FROM AUTHOR]

A new operating approach by reducing the aeration time while keeping high intensity was evaluated for enhanced nutrients removal and maintenance of granular stability. Three aerobic granular sequencing batch reactors (SBR) performing simultaneous nitrification, denitrification and phosphorus removal (SNDPR) were run at different aeration time (120, 90, and 60 min). Aerobic granules could remain their integrity and stability over long-term operation under high aeration intensity and different time, and shorter aeration time favored the retention of biomass, better settleability, and more production of extracellular polymeric substances (EPS). Besides, efficient and stable reactor performance for carbon and phosphorus were achieved, especially, enhanced nitrogen removal was obtained due to reduction of aeration time. Further exploration revealed that the aeration time shaped the bacterial community in terms of diversity, composition, as well as the distribution of functional groups involving carbon, nitrogen and phosphorus removal. [ABSTRACT FROM AUTHOR]

The biofilm system is beneficial for Anammox process designed to treat landfill leachate. In this study, the composition of extracellular polymeric substances (EPS) and the microbial community in an Anammox biofilm system were analyzed to determine the functions driving the biofilm’s ability to treat landfill leachate. The results demonstrated that increasing influent carbon oxygen demand (COD) could stimulate EPS production. EPS helped enrich Anammox bacteria and supplied them with nutrients and enzymes, facilitating effective nitrogen removal (approximately 95%). The variation in Anammox bacteria was similar to the variation in EPS composition. In the tested Anammox Sequencing Biofilm Batch Reactor (SBBR) system, Candidatus Kuenenia was dominant among known Anammox genus, because of its high substrate affinity and because it adapts better to landfill leachate. The relative abundance of Candidatus Kuenenia in the biofilm rose from 3.26% to 12.38%, illustrating the protection and enrichment offered by the biofilm in carrying out Anammox. [ABSTRACT FROM AUTHOR]

Aerobic granular sludge (AGS) is a novel microbial community which allows simultaneous removal of carbon, nitrogen, phosphorus and other pollutants in a single sludge system. AGS is distinct from activated sludge in physical, chemical and microbiological properties and offers compact and cost-effective treatment for removing oxidized and reduced contaminants from wastewater. AGS sequencing batch reactors have shown their utility in the treatment of abattoir, live-stock, rubber, landfill leachate, dairy, brewery, textile and other effluents. AGS is extensively researched for wide-spread implementation in sewage treatment plants. However, formation of AGS takes relatively much longer time while treating low-strength wastewaters like sewage. Strategies like increased volumetric flow by means of short cycles and mixing of sewage with industrial wastewaters can promote AGS formation while treating low-strength sewage. This article reviewed the state of research on AGS formation mechanisms, bioremediation capabilities and biotechnological applications of AGS technology in domestic and industrial wastewater treatment. [ABSTRACT FROM AUTHOR]

This study was conducted to explore the mechanism of dewaterability improvement of waste activated sludge by the filamentous fungus Talaromyces flavus S1. When the fungal spores were inoculated to the sterilized sludge, the sludge dewaterability was significantly improved by 48.1% and the reasons can be attributed to sludge pellet formation and degradation of extracellular polymeric substances, in particular the slime-EPS and loosely-bound EPS (LB-EPS). With the addition of fungal mycelium into the either sterilized sludge or non-sterilized sludge, the values of CST decreased by 74.0% and 43.7%, respectively, suggesting the fungal mycelium can improve the sludge dewaterability. After conditioned by the mycelium, the sludge cake by the diaphragm filter press was thicker and showed less water content than the control sludge. The results in this study demonstrated that the Talaromyces flavus S1 can serve as an environmentally friendly biological dewatering agent and has a promising application potential in the future. [ABSTRACT FROM AUTHOR]

[Display omitted] • SDZ reduced the PN and PS contents of EPS by 28.7%-55.1% and 33.3%-61.4%. • Deterministic assembly process of biofilm transcriptome was evident in SDZ exposure. • SDZ stimulated the upregulation of FPKM levels of transporter protein genes. • The EPS, ARGs and transporter protein genes had direct effects on SDZ removal. The effects of sulfadiazine (SDZ) on responses of biofilm in a moving bed biofilm reactor were explored with emphasis on the changes in extracellular polymeric substances (EPS) and functional genes. It was found that 3 to 10 mg/L SDZ reduced the protein (PN) and polysaccharide (PS) contents of EPS by 28.7%-55.1% and 33.3%-61.4%, respectively. The EPS maintained high ratio of PN to PS (10.3–15.1), and the major functional groups within EPS remained unaffected to SDZ. Bioinformatics analysis showed that SDZ significantly altered the community activity such as increased expression of s_ Alcaligenes faecali. Totally, the biofilm held high SDZ removal rates, which were ascribed to the self-protection by secreted EPS, and genes levels upregulation of antibiotic resistance and transporter protein. Collectively, this study provides more details on the biofilm community exposure to an antibiotic and highlights the role of EPS and functional genes in antibiotic removal. [ABSTRACT FROM AUTHOR]

A new pretreatment method based on tetrakis hydroxymethyl phosphonium sulfate (THPS) biocide was tried to enhance sludge disintegration, and improved sludge biodegradability and subsequent volatile fatty acid (VFA) production. Sludge activity decreased to less than 10% after 2 days pretreatment using 20 mg/g-TSS THPS, which also obviously destroyed EPS and cell membrane, and dissolved more biodegradable substances (48.8%) than raw sludge (19.7%). Moreover, 20 mg/g-TSS THPS pretreatment shortened fermentation time to 4 days and improved VFA production to 2778 mg COD/L (4.35 times than that in control). Therein, the sum of n-butyric, n-valeric and iso-valeric acids unexpectedly accounted for 60.5% of total VFA (only 20.1% of that in control). The more high molecular weight VFAs (C4-C5) than low molecular VFAs (C2-C3) resulted from THPS pretreatment benefited to subsequent medium-chain volatile acids (C6-C12) generation to realize the separation and recovery of organic carbon more efficiently. [ABSTRACT FROM AUTHOR]

The evolution of removal performance and bacterial population dynamics of an aerobic granular sequencing batch reactor were investigated during stable operation and reactivation after prolonged storage. The system was run for a period of 130 days including the stable condition phase, storage period and the subsequent reactivation process. Excellent removal performance was obtained during the stable operation period, which was decayed by the extended idle conditions. The removal efficiencies for both carbon and nitrogen decayed while phosphorus removal remained unaffected. Both granules structure and physical properties could be fully restored. Microbial populations shifted sharply and the storage perturbations irreversibly altered the microbial communities at different levels. Extracellular polymeric substances (especially protein) and key groups were identified as contributors for storage and re-startup of the aerobic granular system. [ABSTRACT FROM AUTHOR]

The modification of the physical properties of aerobic granular sludge treating fish-canning wastewater is discussed in this paper. The structure and composition of the Extracellular Polymeric Substances (EPSs) were analyzed at different salinity levels and related to granules stability. Results outlined that the total EPSs content increased with salinity, despite the EPSs increment was not proportional to the salt concentration. Moreover, the EPSs structure was significantly modified by salinity, leading to a gradual increase of the not-bound EPSs fraction, which was close to the 50% of the total EPSs content at 75 g NaCl L −1 . The increasing salt concentration modified also the EPSs composition, causing the gradual reduction of protein content resulting in a decrease of granule hydrophobicity. The results pointed out that the granules stability significantly reduced above 50 g NaCl L −1 , suggesting the existence of a salinity threshold above which granules stability is compromised. [ABSTRACT FROM AUTHOR]

[Display omitted] • A positive correlation exists between granule size, specific activity and heme c content. • Anammox intuitively secretes EPS to favour microbial species and size dynamics. • Sinica and Sapporoensis dominate large granules while diversity upsurges in flocs. • Best performing anammox granules was identified to be LG size. Magnetite can be considered as an iron-rich carrier particles that can be ionized into Fe 2 + and Fe 3 + which improves the activity and aggregation of anammox bacteria. Three samples from this carrier assisted granulation reactor with size groups including Flocs, FL (0–300 µm), Small Granules, SG (300–500 µm) and Large Granules, LG (500–1000 µm) were used in this study. It was observed that as the granule size increased, the iron-rich carrier content increased, and their active crystals improved the microbial cell density. Specific anammox activity (SAA) was 34.63 ± 5.02, 55.29 ± 5.14, and 63.81 ± 7.50 mg-N/g-VSS/d for FL, SG and LG, respectively. In addition, in heme c content of LG was 31.5 % higher than SG and 62.9 % higher than FL. An in-depth study into the extracellular polymeric substances (EPS) showed that the secretion intensity of essential proteins followed the order of FL < SG < LG in loosely bound EPS and FL > SG > LG in tightly bound EPS. Functional group analysis confirmed that the hydrophobic C N and N H stretching vibration band had almost 3.5 times higher transmittance intensity in LG than the other sizes and the corresponding ratio of α-helix/(β sheet + random coil) in secondary derivative proteins analysis showed tightness in the protein structures of FL. The relative abundance of Brocadia Sinica increased from 0 % in FL to a high of 20.46 % in LG. This study aims to communicate the essence of in-depth EPS analysis beyond the usual EPS yield and major contents of proteins (PN) and polysaccharides (PS) analysis. [ABSTRACT FROM AUTHOR]

High levels of organics negatively affect Anammox for treating landfill leachate. To enhance the ability of Anammox to survive against adverse environments, a lab-scale two-stage Anammox system using a Sequencing Biofilm Batch Reactor was applied to treat mature landfill leachate under 35 °C. Over 107 days, with influent total nitrogen (TN) and chemical oxygen demand (COD) concentrations of 3000 ± 100 and 3000 ± 100 mg/L, effluent TN was below 20 mg/L. For extracellular polymeric substance (EPS) of Anammox, slime-EPS and loosely-bound-EPS of floccules were both higher than biofilm, while tight-bound-EPS of biofilm was significantly higher, contributing to biofilm formation. Quantitative microbial analysis showed that as influent COD increased, Anammox gene ratios of biofilm increased from 1.34% to 13.28%; the gene ratios of floccule first increased, then decreased to 3.88%. This indicated that Anammox and heterotrophic bacteria could coexist because of the biofilm, leading to stable nitrogen removal performance, even when organics were present. [ABSTRACT FROM AUTHOR]

With the demand of new sludge reduction processes, a vermifilter (VF) was studied based on a conventional biofilter (BF). The biofilm morphology was investigated using a new technique, the flow cytometer (FCM), to find a way to optimize VF structure. VF was inoculated with Eisenia fetida , packed with ceramsites, and operated stably at the organic load of 1.2 kg-VSS m −3 d −1 with BF as the control. Compared with BF, VF had about 13% more removal efficiency of excess sludge and 45% shorter biofilm update period. FCM profile showed the morphology of microbial cells in VF biofilms was significantly different from that in BF in upper layers, with decreases of average refractive index (about 72%) and size (about 22%), and suggested it was better to keep earthworms there to remove rod-shaped microorganisms with other filter media in lower layers to remove spherical ones combining the findings in SEM images and extracellular polymeric substances. [ABSTRACT FROM AUTHOR]

The sludge settleability is of prime importance for the activated sludge process. The effect of calcium ion on the biological performance of sludge was investigated in a lab-scale activated sludge system with varying Ca 2+ concentration. Results indicated that addition of 150 mg/L Ca 2+ to the influent significantly improved the settling characteristics and metabolic reactivity of activated sludge in the bioreactors. Analyses using denaturing gradient gel electrophoresis (DGGE) and 16S rRNA sequencing showed that a significant difference in the presence of certain bacterial groups between the sludge systems with 150 mg/L Ca 2+ and those with 0–100 mg/L Ca 2+ addition. Ca 2+ also increased the production of the extracellular polymeric substance (EPS) and facilitated the development of microbial cluster in the bioreactor. Study showed that an addition of 150 mg/L Ca 2+ to the influent provides a simple approach to improve the settling properties of activated sludge and maintain high pollutant removal efficiency. [ABSTRACT FROM AUTHOR]

[Display omitted] • Rapid start-up of A/O/A-SNDPR was achieved within 15 days. • With significant in situ sludge reduction, Y obs was as low as 0.017 g MLSS/g COD. • Under the condition of long SRT without sludge discharge, the removal rate of TP reached 96.37%. • Candidatus_Competibacter was enriched up to 29.06 % in the system. An anaerobic/aerobic/anoxic mode simultaneous nitrification, denitrification, and phosphorus removal system was visited for enhanced low-strength wastewater treatment and dramatic in situ sludge reduction. Results showed that rapid start-up was achieved with conventional activated sludge after 15 days, with effluent ammonia nitrogen, total nitrogen, total phosphorus, and chemical oxygen demand being 0.25, 7.89, 0.12, 24.37 mg/L, respectively. A two-stage biomass growth rate was observed with the sludge yield of 0.285 (day 1–50) and 0.017 g MLSS/g COD (day 51–110) without sludge discharge. Dynamics of bacterial community has been identified with outstanding accumulation of Candidatus_Competibacter up to 29.06 %, which contributed to both simultaneous nutrients removal and sludge reduction. Further analysis via PICRUSt2 revealed the main pathway of nitrogen metabolism, while proposed mechanism for phosphorus removal with no sludge discharge was analyzed from the intracellular and extracellular perspectives. Overall, this study provided guidance and reference for the development and application of A/O/A-SNDPR technology. [ABSTRACT FROM AUTHOR]

[Display omitted] • First report on exopolysaccharide production in marine Echinicola sediminis BBL-M-12. • 6.18 g L–1 of EPS was produced using lignocellulosic hydrolysate as a carbon source. • EPS was mainly composed of β-D-Glucopyranose, β-D-Galactopyranose & β-D-Xylopyranose. • EPS was able to remove textile dye, heavy metal, humic acid & suspended particles. The present study deals with the utilization of lignocellulosic hydrolysate-based carbon source for exopolysaccharide (EPS) production using newly reported marine Echinicola sediminis BBL-M-12. This bacterium produced 7.56 g L–1 and 5.32 g L–1 of EPS on supplementing 30 g L–1 glucose and 10 g L–1 xylose as the sole carbon source, respectively. Whereas on feeding Miscanthus hydrolysate (MCH) with glucose content adjusting to 20 g L–1, E. sediminis BBL-M-12 produced 6.18 g L–1 of EPS. The inhibitors study showed bacterium could tolerate higher concentrations of fermentation inhibitors include furfural (0.05%), 5-hydroxymethylfurfural (0.1%), vanillin (0.1%) and acetate (0.5%). Moreover, the EPS composition was greatly altered with the type and concentration of carbon source supplied, although β-D-Glucopyranose, β-D-Galactopyranose, and β-D-Xylopyranose were the dominant monomers detected. Interestingly, E. sediminis BBL-M-12 EPS revealed excellent environmental applications like clay flocculation, oil emulsification, and removal of humic acid, textile dye, and heavy metal from the aqueous phase. [ABSTRACT FROM AUTHOR]

Extracellular polymeric substances (EPS) play crucial roles in biofilm formation and biocorrosion resulting in heavy economic loss in an industrial setup. Hence, in an attempt to develop an agent to control the EPS across the hosts, the ability of 2,4-Di-tert-butylphenol (DTBP), a potent antioxidant, to modify the EPS of Serratia marcescens has been investigated in this study using biophysical methods. Protein, polysaccharides and eDNA components of EPS were inhibited significantly ( p < 0.05) upon exposure to DTBP. DTBP treatment reduced the crystallite size and crystallinity index of EPS and increased the dislocation density of crystallites without inducing stress, besides increasing the hydration of EPS which reduced its thermal stability. On the whole, this study highlights the efficacy of DTBP to modulate secreted EPS of S. marcescens which in turn could facilitate the disruption of biofilms besides favouring the diffusion of antimicrobials into the cell aggregates resulting eradication of persistent biofilms. [ABSTRACT FROM AUTHOR]

Two parallel sequence batch reactors (SBRs) were operated, with and without TCS addition, to research the causes of sludge reduction by uncouplers. Three possible mechanisms of sludge reduction by TCS were studied: (1) occurrence of metabolic uncoupling, (2) consumption of more energy to resist the infection of TCS, (3) promotion of lysis–cryptic growth by TCS addition. Results showed the remarkable reduction of electronic transport system (ETS) activity and specific cellular ATP (SATP) in TCS reactor, which proved the occurrence of metabolic uncoupling. The increasing amounts of extracellular polymeric substances (EPS), as measured by chemical methods and excitation–emission matrix (EEM) fluorescence spectra, implied microorganisms consumed more energy to resist TCS. The similar DNA concentrations of the effluents in two reactors indicated sludge lysis was not intensified by TCS. Therefore, uncoupler might not only cause metabolic uncoupling but also induce more energy consumption in the production of some substances to resist uncoupler. [ABSTRACT FROM AUTHOR]

The role of extracellular polymeric substances (EPS) in the enhanced biological phosphorus removal (EBPR) process was investigated in a P-accumulating granular sludge system by analyzing the distribution and transfer of P, K + , Mg 2+ and Ca 2+ in the sludge phase, EPS, and the bulk liquid. In the sludge phase, about 30% P, 44.7% K + , 27.7% Mg 2+ , 28% Ca 2+ accumulated in the EPS at the end of aeration. The rate of P, K + , Mg 2+ and Ca 2+ released from the EPS matrix into the bulk liquid in the anaerobic phase was faster than the rate they were adsorbed from the bulk liquid into the EPS in the aerobic phase. P, K + , Mg 2+ and Ca 2+ were retained in EPS before transferring into the phosphorus accumulating organisms (PAOs). These results suggest that EPS play a critical role in facilitating the accumulation and transfer of P, K + , Ca 2+ and Mg 2+ between PAO cells and bulk liquid. [ABSTRACT FROM AUTHOR]

Highlights: [•] Fouling and transmission studies of microalgae (Chlorella sp. suspension). [•] A quadratic model was developed to predict the permeate flux by RSM. [•] EPS transmission was studied in different TMPs, CFVs, and flow regimes. [•] Higher gas velocity resulted in higher shear stress and therefore more EPS release. [•] Slug flow resulted in higher flux enhancement in lower microalgae concentrations. [Copyright &y& Elsevier]

This study investigated the effects of chemical conditioning with three representative inorganic coagulants (FeCl 3 , polyaluminum chloride (PACl) and high performance PACl (HPAC) on sludge dewaterability. We monitored the particle size, kinetic viscosity (KV), fractal dimension ( D F ) and extracellular polymeric substances (EPS) located in different layers of sludge floc (soluble, loosely-bound (LB), tightly-bound (TB)) to understand the correlation of dewaterability and physicochemical properties of sludge under chemical conditioning. The conditioning process included the rapid aggregation of sludge particles induced by charge neutralization and bridging followed by floc densification caused by double electric layer compression. The floc size and D F were increased after chemical conditioning, indicating that larger and more compact floc formed. The floc conditioned with FeCl 3 was smaller but denser than that of PACl and HPAC. Furthermore, sludge dewaterability correlated well with the change in concentration of soluble EPS, LB-EPS and TB-EPS, but not with KV, D F , floc size. [ABSTRACT FROM AUTHOR]

Abstract: A microbial fuel cell (MFC) was successfully developed as a toxicity biomonitoring system, giving a quick response to Cu(II) toxic events. The objective was to increase MFC sensitivity to Cu(II) toxicity by evaluating the impact of shear rate caused by mixing and intermittent nitrogen sparging on the biofilm structure. Low shear rate – achieved by continuously feeding the wastewater into the MFC at a low flow rate of 1.3mLmin−1 during the enrichment period – resulted in low biomass density (124gVSSL−1 of biofilm), high porosity and reduced levels of extracellular polymeric substances (EPS). Consequently, the sensitivity was improved. Scattered nitrogen sparging also increased the sensitivity by reducing the EPS level. It suggested that MFC enriched under low flow rate with intermittent nitrogen sparging could produce an anodic biofilm that was less dense, more porous, contained less EPS and ultimately displayed higher sensitivity to Cu(II) toxicity. [Copyright &y& Elsevier]

Abstract: The biochemical characterization of 13 extracellular polymeric substances (EPS) producing bacterial strains were carried out by BIOLOG. The bacterial strains were cultured in sterilized sludge for EPS production. Flocculation and dewatering capabilities of produced EPS (broth, crude slime and capsular) were examined using kaolin suspension combined with calcium (150mg of Ca2+/L of kaolin suspension). BIOLOG revealed that there were 9 Bacillus, 2 Serratia and 2 Yersinia species. Most of these bacterial strains had the capability to utilize wide spectrum of carbon and nitrogen sources. EPS concentration of more than 1g/L was produced by most of the bacterial strains. Concentration of EPS produced by different Bacillus strains was higher than that of Serratia and Yersinia. Broth EPS revealed flocculation activity more than 75% for Bacillus sp.7, Bacillus sp.4 and Bacillus sp.6, respectively. Flocculation activity higher than 75% was attained using very low concentrations of broth EPS (1.12–2.70mg EPS/g SS). [Copyright &y& Elsevier]

Abstract: The enhancements of electrolysis-pretreated conditioning were investigated in this study. Normalized capillary suction time (CST) was used to evaluate sludge dewaterability. Extracellular polymeric substance (EPS) concentration, viscosity and scanning electron microscopy (SEM) were determined to explain the observed changes in conditioning process. It indicated that pretreatment at 50v and 5min with Ti/RuO2 anode was determined to be the optimal condition, which generated the lowest normalized CST and optimal soluble EPS concentration, leading to the decreasing of viscosity. EPS had positive correlation with the normalized CST. Subjecting to a combination of electrolysis pretreatment and flocculants conditioning, 50% dosage of cationic polyacrylamide (PAM) could be reduced. When co-conditioned with electrolysis and polymerization ferric sulfate (PFS), it did not present any clear advantages over PFS conditioning alone. Furthermore, SEM investigation indicated that electrolysis pretreatment could rupture sludge, release the interstitial water and extracellular substances, especially protein and polysaccharide, and consequently enhance its dewaterability. [Copyright &y& Elsevier]

Abstract: Foaming in Membrane BioReactor (MBR) is a frequently discussed topic. Some authors reported that the phenomenon is due to filamentous organisms, like at Conventional Activated Sludge (CAS) plants. However, in recent years, other authors reported that the Extra-cellular Polymer Substances (EPSs) concentration is an important factor for controlling foam as well. Nevertheless, even if a number of MBR plants are affected by foaming, presently there are no suitable methods to evaluate the phenomenon. To facilitate the study of this controversial phenomenon in an MBR system, certain foam tests proposed in the past for CASPs were investigated. The results of the tests were able to adequately measure quantity, stability and quality of the foam. In particular, the Scum Index increased proportionally with the EPS concentration and mixed liquor viscosity; Foam Power was mainly correlated with the protein concentration of in the EPS; Foam Rating was also correlated with the EPS concentration. [ABSTRACT FROM AUTHOR]

Abstract: The effect of extracellular polymeric substances (EPS) of Gram-positive Bacillus subtilis and Gram-negative Pseudomonas putida on Cu(II) adsorption was investigated using a combination of batch adsorption, potentiometric titrations, Fourier transform infrared spectroscopy. Both the potentiometric titrations and the Cu(II) adsorption experiments indicated that the presence of EPS in a biomass sample significantly enhance Cu(II) adsorption capacity. Surface complexation modeling showed that the pK a values for the three functional groups (carboxyl, phosphate and hydroxyl) were very similar for untreated and EPS-free cells, indicating no qualitative difference in composition. However, site concentrations on the untreated cell surface were found to be significantly higher than those on the EPS-free cell surface. Infrared analysis provided supporting evidence and demonstrated that carboxyl and phosphate groups are responsible for Cu(II) adsorption on the native and EPS-free cells. [ABSTRACT FROM AUTHOR]

Abstract: The relationship between extracellular polymerase substances (EPS) and sludge characteristic were investigated by extraction and analysis of EPS in different size biomass and membrane fouling in an aerobic granule membrane bioreactor (GMBR). The results indicated that the contents of EPS, polysaccharides and proteins in large granules (particle diameter, d >0.45mm) were significantly lower than that in small granules (d <0.45mm) and flocculent sludge. In addition, the content of EPS in membrane fouling was more than that in suspended biomass. For flocculent sludge, the sedimentation and filtering performance decreased markedly as increasing EPS content. However, for granular sludge, there was no significant correlation between EPS content and sludge characteristics. Furthermore, application of aerobic granule can improve sludge filtering properties and delay the process of membrane fouling, as a result of better morphological structure and lower EPS content. [Copyright &y& Elsevier]

Abstract: Equilibrium adsorption experiments, isothermal titration calorimetry and potentiometric titration techniques were employed to investigate the adsorption of Cu(II) by extracellular polymeric substances (EPS) extracted from Pseudomonas putida X4, minerals (montmorillonite and goethite) and their composites. Compared with predicted values of Cu(II) adsorption on composites, the measured values of Cu(II) on EPS-montmorillonite composite increased, however, those on EPS-goethite composite decreased. Potentiometric titration results also showed that more surface sites were observed on EPS-montmorillonite composite and less reactive sites were found on EPS-goethite composite. The adsorption of Cu(II) on EPS molecules and their composites with minerals was an endothermic reaction, while that on minerals was exothermic. The positive values of enthalpy change (ΔH) and entropy change (ΔS) for Cu(II) adsorption on EPS and mineral-EPS composites indicated that Cu(II) mainly interacts with carboxyl and phosphoryl groups as inner-sphere complexes on EPS molecules and their composites with minerals. [Copyright &y& Elsevier]

Extracellular polymeric substances (EPSs), produced by Dunaliella salina strain, increase concomitantly with salt concentration and maximum (944mg/l) were obtained at 5M NaCl, whereas minimum (56mg/l) at 0.5M salinity. Emulsifying activity was measured in terms of strength to retain the emulsion and comparatively 85.76% retention was observed at 0.5M salinity thereafter it intends to decline. The FT-IR-spectra reveal characteristic functional groups Ning, asymmetrical Cing vibration of aliphatic CH2-group, Cing of aromatic, C of aliphatic amine, Nprimary amine and C of alkyl-halides with a stretching of Ch name="sbnd" />C, Conding to the presence of carbohydrates. The FT-IR-spectra substantiated the presence of primary amine-group, aromatic-compound, halide-group, aliphatic alkyl-group and polysaccharides. Four monosaccharides (glucose, galactose, fructose and xylose) were also detected by HPLC analysis. Production of EPSs may allow further exploration of D. salina as potential EPSs producer and make it as a promising candidate for biotechnological and industrial exploitation. [Copyright &y& Elsevier]

The major operational problem associated with membrane bioreactors (MBR) is membrane fouling, for which extracellular polymeric substances (EPS) are primarily responsible. In this work both the soluble and bound EPS (i.e. SMP and EPS) produced in an MBR system operating under sludge retention times (SRT) of 10, 15, 20 and 33days were fractionized by means of membranes having variable molecular weight cutoffs (300kDa, 100kDa, 10kDa & 1kDa). The results show that increasing the SRT leads to a reduction of SMP and EPS and that these reductions are more pronounced for the SRTs in the range 10–20days. This reduction is more significant for carbohydrates than for proteins. The decrease of SMP and EPS with increasing SRT from 10 to 20days led to a significant decrease of the level of fouling. The further increase of SRT to 33days did not significantly impact on the level of fouling as the SMP and EPS concentrations did not change much. Under the examined operating conditions, EPS were found to be composed mainly of large macromolecules having a size of 0.45μm–300kDa and to a lower extent of very small molecules (<1kDa) that are not easily decomposed by the biomass activity. The majority of SMP is composed of very small molecules (<1kDa), while some macromolecules in the range of 0.45μm–300kDa are present. Consequently, both EPS and SMP were found to have a bimodal character. [Copyright &y& Elsevier]

Abstract: This study was conducted to investigate the chemical precipitation (CP) and membrane bioreactor (MBR) hybrid process for the treatment of piggery wastewater. Average removal efficiencies for BOD, COD and turbidity in CP process were 64.3%, 77.3% and 96.4%, respectively. CP process had a moderate effect on NH3–N removal (40.4%) which improved up to 98.2% mainly due to nitrification and filtration processes in MBR. The average removal efficiencies of BOD, COD and turbidity in MBR were 99.5%, 99.4% and 99.8%, respectively. Monod equation was used to explain the microbial activities in terms of specific growth rate. The specific growth rate of bacteria in aeration tank (N-batch) and anoxic tank (D-batch) were 0.013 and 0.005d−1 with a biomass yield of 0.78 and 0.43mg MLSS produced/mg COD utilized, respectively. Microorganisms from the N-batch and D-batch showed a low-level of nitrifying and moderate-level of denitrifying capabilities which were 1.08mg NH3–N/(g MLVSS.h) and 2.82mg NO3–N/(g MLVSS.h), respectively. Carbohydrates were the main component in extracellular polymeric substance (EPS) compounds that could be attached to the membrane surface easily and led to membrane biofouling. The increase of MLSS, EPS and sludge viscosity concentration, decrease of sludge floc size and incomplete chemical cleaning procedure resulted in the increase of membrane resistance. Total membrane resistance increased from 3.19×1012 m−1 to 5.43×1014 m−1. [Copyright &y& Elsevier]

[Display omitted] • Moving biofilm in MBBR is advantageous over fixed biofilm of other bioreactors. • Hydraulic shear force influences biofilm structure and stability. • Anammox-n-DAMO coupled processes can improve nitrogen removal efficiencies. • Nature of carrier surface affects biofilm growth in MBBR. • Hybrid MBBR systems can be beneficial for improved wastewater treatment. Among the several biofilm-based bioreactors, moving bed biofilm reactors (MBBR) have been extensively used for wastewater treatment due to low operational costs, technical feasibility, and stability. Biofilm forming strains, e.g., Stenotrophomonas maltophila DQ01, achieved 94.21% simultaneous nitrification and denitrification (SND) and 94.43% removal of total nitrogen (TN) at a cycle time of 7 h, and a biofilm consortium consisting of Chryseobacterium sp. and Rhodobacter sp. achieved 86.8% removal of total organic carbon (TOC) at hydraulic retention time (HRT) of 24 h using lab-scale MBBR. Modifications in the surface properties of the biocarrier materials achieved 99.5 ± 1.1% chemical oxygen demand (COD) and 93.6 ± 2.3% NH 4 +-N removal, significantly higher than the conventional commercial carrier. This review article summarizes the application of MBBR technology for wastewater treatment. The importance of bacterial biofilm and extracellular polymeric substances (EPS), anammox-n-DAMO coupled processes, and carrier surface modifications in MBBR technology have also been discussed. [ABSTRACT FROM AUTHOR]

Aerobic granules lose stability during storage. The goal of this work was to highlight the main cause of stability loss for stored granules as intracellular protein hydrolysis. The quantity of extracellular proteins was noted to be significantly lower during granule storage, and protease enzyme activities were correspondingly higher in the cores of stored granules. The proteolytic bacteria, which secrete highly active protease enzymes, were for the first time isolated and characterized by analyzing 16S rDNA sequences. The proteolytic bacteria belonged to the genera Pseudomonas, Raoultella, Acinetobacter, Pandoraea, Klebsiella, Bacillus and uncultured bacterium, and were grouped into Proteobacteria, Enterobacteria and Firmicutes. The PB1 (Pseudomonas aeruginosa) strain, which exhibited very high proteolytic activity during the skim milk agar test, was located at the core regime with active protease enzymes, and was close to the obligate anaerobic strain Bacteroides sp. Hence, the extracellular proteins in stored granules were proposed to be hydrolyzed by enzymes secreted by proteolytic bacteria with the hydrolyzed products ultimately being used by nearby anaerobic strains. This process gradually digests the protein core, and eventually consumes the entire granule. [Copyright &y& Elsevier]

[Display omitted] • R1 excelled at NH 4 +-N removal (95%, 60 ~ 70 mg/(L·d)) at 60 g/L salinity. • Excessive COD, not salinity, inhibited the nitrification capacity of biofilm. • The EPS content of biofilm depended on the capacity to remove organic matter. • SND Pseudomonas and Thauera were enriched in the three reactors. • The sulfur cycle in reactor might be prevent by controlling the organic load. The washing wastewater from the desulfuration and denitration of power plants has high salt (chloride and sulfate) and ammonia–nitrogen concentrations and is difficult to treat using microbiological methods. A novel anoxic/oxic biofilm process was developed to remove ammonia from wastewater. Three rapid strategies (sulfate concentration was increased from 0 to 60 g/L in 6, 13, and 22 days (R1, R2, and R3, respectively)) were applied and produced biofilm with the same nitrification capacity as slow strategies (100–203 days). Excessive organics inhibited the nitrification capacity of the biofilm. R1 excelled at ammonia removal (from 30% to 95%, 70 mg/(L·d), with an effluent ammonia concentration of 4 mg/L) at 60 g/L salinity after the organic load was reduced. The content of extracellular polymeric substances in biofilm depended on its capacity to remove organics. Pseudomonas and Thauera were enriched in the three reactors. Controlling the organic load might prevent the sulfur cycle. [ABSTRACT FROM AUTHOR]

• Pseudomonas sp. Y39-6 remove nitrate via denitrification and nitrate assimilation. • Pseudomonas sp. Y39-6 can remove nitrate at C/N < 1 and 4 °C. • Acetate active Pseudomonas sp. Y39-6 to form biofilm via oxidative phosphorylation. For solving the challenge in nitrate removal from low C/N wastewater at low temperature, Pseudomonas sp. Y39-6 was isolated and used in nitrate removal. It showed aerobic-heterotrophic denitrification with rate of 1.77 ± 0.31 mg/L·h and unusual aerobic-autotrophic nitrate removal (rate of 0.324 mg/L·h). The aerobic-autotrophic nitrate removal mechanisms were deep investigated by analyzing the nitrate removal process and genomic information. At aerobic-autotrophic condition, the strain Y39-6 could assimilate nitrate to amino acid (NO 3 − + PHA + CO 2 → C 5 H 7 O 2 N) with the carbon source from Polyhydroxyalkanoic acid (PHA) degradation and CO 2 fixation. Flagella motivation, swarming activity and extracellular polymeric substances (EPS) production regulated Pseudomonas sp. Y39-6 forming biofilm. Carriers immobilized with Pseudomonas sp. Y39-6 were used in moving bed biofilm reactor (MBBR) and achieved 24.83% nitrate removal at C/N < 1 and 4 °C. Results of this study provided a practical way for nitrogen removal from low C/N wastewater in cold region. [ABSTRACT FROM AUTHOR]

• EPS promoted COD and NH 4 +-N removal by 13.2%–33.8% and 27.8%–42.1% at 3.5% salinity. • EPS protected major carbon-related enzymatic reaction under salinity stress. • Tyrosine in EPS contributed most to mitigation of cytotoxicity from salinity. • Salt inhibited ATP decomposition by impeding Na+K+-ATPase activity by 44.3%–57.7%. • Models for calculation of COD and NH 4 +-N removal rate at 3.5% salinity were built. The role of EPS in removal of carbonaceous organic matters and NH 4 +-N in simulated mariculture wastewater was examined at salinity of 0–3.5% in a multi-soil-layering bioreactor. Results showed that at 3.5% of salinity, the total activity of dehydrogenases (which were used to decompose carbonaceous organic matters) could be promoted by 13.2%–33.8% by EPS, increasing the removal rates of COD and NH 4 +-N by 13.2%–33.8% and 27.8%–42.1%, respectively. Besides, the activity of amylase in EPS was enhanced by 79.8%. However, reactions of some key enzymes such as acetate kinase and Na+K+-ATPase would not be accelerated by EPS, resulting in an inhibition of 44.3%–57.7% on energy gaining from ATP, and further inducing cytotoxicity. It was found that the glycolysis efficiency was promoted by 4.12%–59.3% in the presence of EPS, and glycolysis could also occur in EPS. Additionally, tyrosine was the main component in EPS to balance osmotic pressure. [ABSTRACT FROM AUTHOR]

• Nitrate reduction of S.oneidensis.MR-1 was enhanced by CDs. • The mechanism of β-CD on nitrate reduction was studied. • More EPS of S.oneidensis.MR-1 was stimulated by β-CD. • The cell membrane permeability of S.oneidensis.MR-1 was increased by β-CD. • The β-CD enhanced ETSA and NAR activity. Cyclodextrins (CDs) have been widely used due to the excellent solubilization of hydrophobic organics. However, their effect on the biotransformation process of hydrophilic pollutants is unclear. This study first evaluated the effect and mechanism of CDs on nitrate reduction by S.oneidensis.MR-1. The three CDs (α-CD, β-CD and γ-CD) all accelerated nitrate reduction, among which β-CD had the best effect. The nitrate reduction rate was increased by 21.8% with 0.5 mM β-CD. As for the mechanism, β-CD increased the biomass, membrane permeability and EPS of S.oneidensis.MR-1. The nitrate reductase activity was also increased by 1.34-fold with 0.5 mM β-CD. The current exchange density and the electron transfer system activity were increased by 11.4% and 99.5% in the β-CD-supply system, respectively. It confirmed that β-CD enhanced the biological and electrochemical characteristics and then enhanced bio-activity. This study provides a new understanding of CDs in microbial remediation and broadens the practical application. [ABSTRACT FROM AUTHOR]

• Thermal-alkaline pretreatment synergistically release DOM from sludge EPS and cells. • The maximum attainable carbon removal efficiency achieved ~65% in sludge digestion. • Pretreatment-derived DOM as the key parameter in shaping sludge communities. • Digestion communities consists of both common and pretreatment-specific lineages. In this study, temporal impacts of thermal, alkaline/acid and thermal-alkaline sludge pre-treatments on digestion performance and microbiome were investigated and compared in methanogenic sludge digesters. Results showed that thermal and alkaline/acid pre-treatments were efficient in releasing intracellular and EPS organic matter, respectively. The thermal-alkaline pre-treatment showed synergistic impacts of both thermal and alkaline/acid pre-treatments by releasing the major portion of sludge organic matter from solid- to liquid-phase, which result in 60–65% organic carbon removal in subsequent sludge digestion and further optimizing digestion temperature had negligible improvement. The 16S rRNA gene-based analyses suggested that organic matter released from sludge pre-treatments is a major deterministic parameter in shaping sludge microbiome. Pre-treatment specific lineages were identified in different sludge digesters, whereas several taxa were identified as common functionally active populations in sludge digestion. This study provided mechanistic insights into impacts of pre-treatments on digestion performance and microbiome in methanogenic sludge digesters. [ABSTRACT FROM AUTHOR]

• Verified the ideal AnGS size in high load and low rising velocity sewage treatment. • TB-EPS replaced S-EPS as the main component of EPS in large granules. • When the gene copies decrease, the stable flora structure promotes increasing SAA. • PS is related to the formation of AnGS, while PN is the activity improvement. • Granule size >4.75 mm decreased the abundance of functional bacteria. An integrated investigation to structural, activity and microbial diversity of anammox granular sludge (AnGS) in a wastewater treatment system with high ammonia nitrogen load was performed and aimed to establish the relationship between granular size and performance. With the increase in granule size, the main component of extracellular polymeric substances (EPS) changed from slime EPS to tightly-bound EPS, while the organic component remained the same, and the specific anammox activity increased. However, the results of qPCR and high-throughput sequencing showed that for granules with sizes inferior than 4.75 mm, the abundance of ammonia-oxidizing bacteria (AnAOB) increased as the size increased, and the copies of AnAOB decreased when the granule size increased above 4.75 mm, and the community complexity increased. According to the correlation analysis results, AnAOB first accumulated and then optimized the flora structure to improve efficiency and 2.8 mm to 4.75 mm was the optimal size of AnGS. [ABSTRACT FROM AUTHOR]

• The N and P removal were achieved in P concentration high than 11.4 mg L−1. • The sludge bulking was an omen for floatation. • Increased EPS resulted in the deterioration of granules. • The main reason of floatation was unreleasable gas bubbles attached granules. • A sufficient supply of P was a controlling strategy for stable operation. The effect of phosphate concentration on the anammox-HAP process was investigated in this work. A high total nitrogen removal efficiency (>82.6%) and a stable total phosphate removal efficiency (>56.2%) was achieved in reactor with the phosphate concentration over 11.4 mg L−1. However, a phosphate concentration below to 5.7 mg L−1, a floatation of sludge occurred caused the deterioration of process. A new understanding for the floatation was divided into three stages: the stable stage, bulking stage and floating stage. First, anammox biofilm coupled with HAP for granulation in the stable stage. Second, the aggregation of bulking sludge resulted in changes in viscoelastic properties of the sludge. Third, the floatation resulted from unreleasable gas bubbles in the granules wrapped a high concentrations of slime layer proteins. Overall, this paper suggests that a control strategy was a sufficient supply of phosphate for the stable operation. [ABSTRACT FROM AUTHOR]

• Nitrite accumulation ratio achieved 96.36% and 77.30% in SBR and AeUSB respectively. • Secretion of EPS especially protein played an important role in granulation. • Protein secondary structure of α -helices and 3-turn helices promoted granulation. • Structure of micro-granules contributes to AOB-dominated nitrifying population. • Aggregation of sludge benefited start-up and stability of partial nitrification. In this study, sequencing batch reactor (SBR) and aerobic upflow sludge bed reactor (AeUSB) were used to investigate the effects of sludge granulation on establishing partial nitrification (PN) process and explore the potential mechanism. The particle size was positively related to the NO 2 −-N accumulating performance, satisfactory nitrite accumulation rate (NAR) of 96.4% and 77.3% were obtained with the appearance of micro-granules in SBR and AeUSB after day 105 and 83, respectively. To our knowledge, it is the first report describing the importance of extracellular polymeric substances (EPS) content and components, such as aromatic protein-like substances, by-product-like substances and special protein secondary structures (α -helices and 3-turn helices) for sludge granulation and even PN process. Quantitative microbial analysis suggested that ammonium oxidizing bacteria (AOB) predominated in nitrifying-bacterium in micro-granules system, guaranteeing a highly efficient PN process. [ABSTRACT FROM AUTHOR]

• Except for 4-CP, the pollutants removal was inhibited in alkaline conditions. • Alkaline conditions reduced TRGs production in saline 4-CP wastewater treatment. • The stimulated proteins in EPS and microbial diversity affected the contents of TRGs. • Selecting suitable carbon sources to achieve the removal of pollutants and ARGs. Considering the occurrence and spread of antibiotic resistance genes (ARGs) pose significant risks to public health, the effects of long-term exposure to alkaline conditions on the relative abundances of tetracycline resistance genes (TRGs) were studied in saline 4-chlorophenol (4-CP) wastewater treatment. Alkaline conditions were maintained by supplying the co-metabolic carbon source of sodium acetate. Results showed that except for the 4-CP, the removal of pollutants was significantly inhibited, and the relative abundances of the most TRGs were repressed. In addition, the removal of pollutants and the relative abundances of TRGs were moderately affected by the NaCl addition. The proteins in the extracellular polymeric substances (EPS) played key roles in reducing the relative abundances of TRGs, which were altered by the microbial diversity. In conclusion, for the pollutants removal and ARGs reduction in refractory industrial wastewater treatment, alkaline conditions should be maintained by selecting suitable co-metabolic carbon sources. [ABSTRACT FROM AUTHOR]

• COD removal rate could reach 92.1% with initial COD concentration of 960 mg/L. • Acclimation of the microorganism led to high removal efficiency of nitrogen. • AMS activity and protein content in EPS could be fit by quadratic function model. • A peak was identified as active substances in 3-D EEM diagram. • SDBS inhibited the transport and metabolisms of amino acids, carbohydrate and lipids. Sequential vertical flow trickling filter and horizontal flow multi-soil-layering bioreactor were investigated for the treatment of decentralized domestic wastewater at various concentrations of sodium dodecyl benzene sulfonate (SDBS). Results have shown that the removal rate of COD could reach 92.1% at initial COD concentration of 960 mg/L (800 mg/L was provided by SDBS). NH 4 +-N concentration could be reduced from 52.4 to 9.71 mg/L without aeration. Besides, a quadratic function model was fit to describe the relationship between the relative activity of amylase and the protein content in extracellular polymer substance. SDBS could inhibit the transport and metabolisms of amino acids, lipids and carbohydrates in biofilms. The analysis of three-dimensional fluorescence diagram indicated that the peak in excitation/emission wavelengths = 310–340/370–430 nm was the characteristic peaks of some active substances such as some enzymes in EPS. Only Microbacterium could totally offset the toxicity of SDBS degradation products. [ABSTRACT FROM AUTHOR]

• The ratios of ferrous and sulfur oxidizers on tailings biomining were studied. • EPS components were analyzed by 3DEEM- PARAFAC for the first time. • L. ferriphilum played a major role in the biomining by the mixed cultures. • The mineral surface was barely covered by secondary minerals during bioleaching. • A new strategy for biomining of low grade base-metal sulfide tailings is proposed. This study investigated the effect of designed microbial consortia on biomining of low grade base-metal sulfide tailings. The results show the amount of recycled metals were equal if the tailings were leached by mixed cultures of Leptospirillum ferriphilum and Acidithiobacillus thiooxidans at three different ratios or by pure culture of L. ferriphilum , which was better than the pure culture of Acidithiobacillus ferrooxidans. qPCR (quantitative polymerase chain reaction) demonstrated only L. ferriphilum functioned in the mixtures at initial stage. The results of extracellular polymeric substances (EPS) via three-dimensional excitation-emission matrix combined with parallel factor analysis (3DEEM-PARAFAC) collected from mixed or pure cultures indicated there were no interactions between two strains. Secondary minerals were formed, but did not influence the leaching process. A new strategy for tailings biomining was proposed: only ferrous oxidizers should be added during the initial and middle biomining stage, while sulfur oxidizers should be added at the end. [ABSTRACT FROM AUTHOR]

• Strain DC-1 was identified and removed 98.4% NO 3 –-N and 80.7% TOC under aerobic condition. • Strian DC-1 showed complete nitrogen removal pathway. • Strian DC-1 owed zero N 2 O-emitting and high auto-aggregation properties. A novel aerobic denitrifying strain Methylobacterium gregans DC-1 was isolated and identified. Strain DC-1 removed 98.4% of nitrate-nitrogen (NO 3 −-N) and 80.7% of total organic carbon with initial concentrations of 50 and 2400 mg/l, respectively. The N balance showed that most NO 3 −-N was converted to N 2 (62.18%) without nitrous oxide (N 2 O) emission. Response surface analysis showed that the optimal conditions for total N removal were carbon (C):N ratio of 18.7, temperature of 26.8 °C, pH of 6.5 and shaking speed of 180 rpm. In combination with the N balance and successful amplification of napA , nirK and nosZ genes, the metabolic pathway was as follows: NO 3 −NO 2 − → NO → N 2 O → N 2. Strain DC-1 had strong auto-aggregation rate (maximum 38.7%), produced large amounts of extracellular polymeric substances (EPS; maximum of 781.4 mg/g cell dry weight) and had corresponding strong hydrophobicity (maximum 83.2%). Pearson correlation analysis showed that EPS content and hydrophobicity were significantly positively correlated with auto-aggregation. [ABSTRACT FROM AUTHOR]

• A new method was proposed using Fe and Mn to enhance NH 4 +-N removal at 2 °C. • Fe and Mn could increase both growth and DHA of HITLi7T. • Fe and Mn could increase total EPS amount and PS ratio of HITLi7T. • Fe and Mn could change some functional groups of EPS secreted by HITLi7T. • More biomass, high DHA and changed EPS were 3 reasons for increased NH 4 +-N removal. In this study, trace metals (Fe & Mn) were applied to enhance NH 4 +-N removal in source water at 2 °C, and 22.7% of initial 2.20 mg/L NH 4 +-N was removed by pre-treating granular activated carbon (GAC) with Fe & Mn before immobilizing Acinetobacter harbinensis HITLi7T to form biological activated carbon (BAC). Biomass and dehydrogenase activity (DHA) on this modified BAC were 2.80 × 108 CFU/g-DW C and 0.50 mg/L/g-DW C, respectively, both the highest. Additionally, 4.76 times more biomass and 9.76 times higher DHA of HITLi7T were observed in the cultivation with Fe & Mn dosing. Extracellular polymeric substances (EPS) measurements found Fe & Mn dosing could increase total EPS amount (44.3% higher) and polysaccharide (PS) ratio (1.50% higher) secreted by HITLi7T. According to the results of 3D-excitation-emission matrix (3D-EEM) fluorescence spectra and infrared spectra (FTIR) analysis, Fe and Mn promoted the secretion of tryptophan-like substances and changed functional groups C OH, C O C, C O and COOH, which are associated with protein and PS. [ABSTRACT FROM AUTHOR]