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To develop a reliable sulfide (S 2- ) autotrophic denitrification (SAD) process under S 2- and SO 4 2- salinity stresses, the biofilm performance and microbial mechanisms were comparatively studied using different inocula of activated sludge (AS) and intertidal sediment (IS). Biofilm IS enriched more denitrification genes (0.34 %) and S 2- oxidation genes (0.29 %) than those with AS. Higher denitrification performance was obtained under S 2- (100 mg/L) and SO 4 2- (5-15 g/L Na 2 SO 4 ) stresses, but no significantly differences were observed under levels of 0-200 mg/L S 2- and 30 g/L Na 2 SO 4 . Notably, biofilm samples in SAD systems with IS still had more S 2- oxidation genes at high S 2- levels of 100-200 mg/L and Na 2 SO 4 level of 30 g/L. The key functional genus Thiobacillus accumulated well at 30 g/L Na 2 SO 4 , but was strongly inhibited at 200 mg/L S 2- . The findings were advantage to SAD application under sulfide and salinity stresses., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The response of anammox bacteria to hydroxylamine has not been well explained. Herein, hydroxylamine was long-term added as the sole substrate to marine anammox bacteria (MAB) in saline wastewater treatment for the first time. MAB could tolerate 5 mg/L hydroxylamine. However, MAB activity was inhibited by the high dose of hydroxylamine (40 mg/L), and hydroxylamine removal efficiency was only 3 %. Remarkably, when hydroxylamine reached 20 mg/L, ammonium was produced the most at 2.88 mg/L, mainly by the hydroxylamine and hydrazine disproportionations. Besides, the relative abundance of Candidatus Scalindua decreased from 4.6 % to 0.6 % as the hydroxylamine increased from 0 to 40 mg/L. MAB secreted more extracellular polymeric substances to resist hydroxylamine stress. However, long-term hydroxylamine loading led to the disintegration of MAB granules. This work shed light on the response of MAB to hydroxylamine in saline wastewater treatment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Fungi have been found to exist in activated sludge treating saline wastewater, but their role in removing pollution has been neglected. This study explored the aerobic removal of total inorganic nitrogen (TIN) from saline wastewater under static magnetic fields (SMFs) with several strengths. Compared to the control, the aerobic removal of TIN was significantly increased by 1.47 times in 50 mT SMF, due to the increased dissimilation nitrogen removal by fungi and bacteria. Under SMF, fungal nitrogen dissimilation removal was significantly increased by 3.65 times. The fungal population size decreased, and its community composition changed significantly under SMF. In contrast, bacterial community composition and population remained relatively stable. Under SMFs, heterotrophic nitrification - aerobic denitrification bacteria Paracoccus and the fungi denitrifying Candida formed a synergistic interaction. This study elucidates the fungal role in aerobic TIN removal and provides an efficient solution to improve TIN removal from saline wastewater by SMF., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Osmotic stress priming (OSP) was an effective management strategy for improving microbial acclimation to salt stress. In this study, the interaction between pollutants and microbiota, and microbial osmoregulation were investigated triggered by OSP (alternately increasing salinity and organic loading). Results showed that OSP significantly improved COD removal from 31.53 % to 67.99 % and mitigated the terephthalate inhibition produced by toluate, decreasing from 1908.08 mg/L to 837.16 mg/L compared with direct priming. Due to an increase in salinity, Pelotomaculum and Mesotoga were enriched to facilitate terephthalate degradation and syntrophic acetate oxidation (SAO). And organic load promoted acetate formation through syntrophic metabolism of Syntrophorhabdus/Pelotomaculum and SAO-dependent hydrogenotrophic methanogenesis. K + absorbing, proline and trehalose synthesis participated in osmoregulation at 0.5 % salinity, while only ectoine alleviated intracellular osmolarity under 1.0 % salinity with OLR of 0.44 kg COD /m 3 . This study provided in-depth insight for microbial acclimation process of anaerobic priming of saline wastewater., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Ltd.)

In this study, a novel method of coupling phytohormones with saline wastewater was proposed to drive efficient microalgal lipid production. All the six phytohormones effectively promoted microalgae growth in saline wastewater, and further increased the microalgal lipid content based on salt stress, so as to achieve a large increase in microalgal lipid productivity. Among the phytohormones used, abscisic acid had the most significant promoting effect. Under the synergistic effect of 20 g/L salt and 20 mg/L abscisic acid, the microalgal lipid productivity reached 3.7 times that of the control. Transcriptome analysis showed that differentially expressed genes (DEGs) of microalgae in saline wastewater were mainly up-regulated under the effects of phytohormones except brassinolide. Common DEGs analysis showed that phytohormones all regulated the expression of genes related to DNA repair and substance synthesis. In conclusion, synergistic effect of salt stress and phytohormones can greatly improve the microalgal lipid production efficiency., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

The discharged saline wastewater has severely influenced the aquatic environment as the treatment performance of many wastewater treatment techniques is limited. In addition, the sources of saline wastewater are also plentiful from agricultural and various industrial fields such as food processing, tannery, pharmaceutical, etc. Although high salinity levels negatively impact the performance of both physicochemical and biological processes, membrane bioreactor (MBR) processes are considered as a potential technology to treat saline wastewater under different salinity levels depending on the adaption of the microbial community. Therefore, this study aims to systematically review the application of MBR widely used in the saline wastewater treatment from the perspectives of microbial structure and treatment efficiencies. At last, the concept of carbon dioxide capture and storage will be proposed for the MBR-treating saline wastewater technologies and considered toward the circular economy with the target of zero emission., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

A novel heterotrophic nitrification and aerobic denitrification (HN-AD) strain CY-10 was isolated and identified as Sphingopyxis sp. When ammonium, nitrate or nitrite was used as the sole nitrogen source (300 mg/L), the maximum nitrogen removal efficiency of strain CY-10 were 100%, 91.1% and 68.5%, respectively. The optimal salinity for ammonia nitrogen removal by strain CY-10 was in the range of 0-5%. At the salinity of 5%, a maximum nitrogen removal rate of 6.25 mg/(L·h) was realized. Metabonomics data showed that the metabolic levels of sucrose and D-tagatose increased significantly at 5% salinity condition, enabling the strain to regulate osmotic pressure and survive in high-salt environments. Functional genes were successfully amplified by quantitative PCR, and HN-AD pathway of strain CY-10 followed NH 4 + -N → NH 2 OH → NO 2 - . These findings show that strain CY-10 has great potential in nitrogen removal treatment of saline wastewater.2 O → N 2 . These findings show that strain CY-10 has great potential in nitrogen removal treatment of saline wastewater., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Although biological treatment of marine aquaculture wastewater is promising, the fundamental principles driving the adsorption of tetracycline to microbial cell membrane are not well understood. Using a combination of experiments and molecular dynamics (MD) simulations, the mechanism underlying the biological removal of tetracycline from seawater was investigated. More than 90% tetracycline removal was achieved in an aerobic granular sludge system, with degradation accounting for 30% of total removal. A model of the tetracycline-dipalmitoylphosphatidylcholine lipid bilayers was established to elucidate the transport mechanism of tetracycline from bulk solution to microorganisms' cell membrane. 62% of the driving force for tetracycline adsorption on the cell membrane originated from electrostatic attraction. The electrophilic groups on tetracycline (amino and aromatic groups) were attracted to the phosphate groups in the cell membrane. Sodium ions, which are abundant in seawater, decreased the interaction energy between tetracycline and the cell membrane., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

In this study modified microalgal-bacterial granular sludge (MBGS) was constructed and employed to compare the performance for treating 1%-5% saline wastewater with aerobic granular sludge (AGS). Filamentous algae were found to flourish at 1% salinity when nutrients were temporarily restricted to low level (COD 0, N 10 mg/L, P 0.5 mg/L). A significant improvement of granule stability was detected as the integrity coefficients of MBGS was only 0.12-0.24 rather than 0.19-0.48 of AGS under 1%-5% salinities, which reduced the risk of particle disintegration. Filamentous algae including Leptolyngbya and Geitlerinema occupied 91.2% of identified algae, and were beneficial for enhancing the biomass content and lipid production to about 1.27-1.37, 3.1-5.0 times than AGS. The MBGS had best nitrogen and phosphorus removal efficiencies of 93.4% and 64.6% at 1% salinity, and showed higher resistance to 3%-5% salinities. This study could provide meaningful information for using this modified MBGS technology in practice., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Saline wastewater was used in this study to culture freshwater microalgae Chlorella pyrenoidosa in sequencing batch photobioreactor to improve the sedimentation and lipid production of algal cells. Influent salinity of 0.5% or above effectively promoted the sedimentation of microalgae in the settling stage of photobioreactor, and greatly reduced the algal biomass in effluent. The mechanism of the saline wastewater in improving the sedimentation of microalgae included decreasing zeta potential, increasing cell particle size and promoting extracellular polymeric substances synthesis, which varied with influent salinity. Saline wastewater also promoted the lipid accumulation in microalgae. Lipid content of microalgae increased with increasing influent salinity. However, the growth of microalgae was greatly inhibited at the influent salinity of 2.0% and 3.0%. Therefore, the PBR with influent salinity of 1.0% achieved the highest productivity of microalgae lipid. The saturation of fatty acids of microalgae gradually increased with increasing influent salinity., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The utilization of halophilic bioresources is limited due to a lack of isolation and characterization work. A halophilic bacterium strain SND-01 of Exiguobacterium mexicanum was isolated in this study, which is the first report on its novel function in heterotrophic nitrification-aerobic denitrification (HN-AD). The strain SND-01 is slightly halophilic, surviving at 0 up to 9% (w/v) salinity. When utilizing ammonium, nitrate or nitrite as the sole nitrogen source in aerobic conditions, the isolated strain showed the maximum nitrogen removal rate of 2.24 ± 0.14 mg/(L·h), 3.63 ± 0.21 mg/(L·h) and 2.30 ± 0.23 mg/(L·h), respectively. Functional genes and key enzymes involved in heterotrophic-aerobic nitrogen transformations were characterized, establishing the pathway of HN-AD. The nitrogen removal via HN-AD is dependent on the C/N ratio, salinity and temperature. The halophilic Exiguobacterium mexicanum strain SND-01 shows a significant potential in biotreatment of saline wastewater in an easy and cost-effective way., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

This study investigated the influence of salinity on pollutant removal and bacterial community within a partially saturated vertical flow constructed wetland (PS-VFCW). High removal rates of NH 4 + -N (88.29 ± 4.97-100 ± 0%), total inorganic nitrogen (TIN) (50.00 ± 7.21-62.81 ± 7.21%) and COD (91.08 ± 2.66-100 ± 0%) were achieved at 0.4-2.4% salinity levels. The removal of ammonia, TIN and organic matter occurred mainly in unsaturated zone. Salt-adaptable microbes became the dominant bacteria with salinity elevated. The proportion of ammonia-oxidizing bacteria (AOB) in the 0-5 cm depth layer (unsaturated zone) decreased obviously as the salinity increased to 2.4%. Nitrite-oxidizing bacteria (NOB) in the 0-5 cm depth layer showed a decreasing trend with elevated salinity. Denitrifying bacteria (DNB) in the 0-5 cm depth layer maintained high abundance (27.70-53.60%) at 0.4-2.4% salinity levels. At 2.4% salinity, AOB, NOB and DNB were observed in the unsaturated zones and saturated zones, and showed higher abundance in the unsaturated zone., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

This study investigated the performance and microbiome of cyclic denitrification filters (CDFs) for wood and sulfur heterotrophic-autotrophic denitrification (WSHAD) of saline wastewater. Wood-sulfur CDFs integrated into two pilot-scale marine recirculating aquaculture systems achieved high denitrification rates (103 ± 8.5 g N/(m 3 ·d)). The combined use of pine wood and sulfur resulted in lower SO 4 accumulation compared with prior saline wastewater denitrification studies with sulfur alone. Although fish tank water quality parameters, including ammonia, nitrite, nitrate and sulfide, were below the inhibitory levels for marine fish production, lower survival rates of Poecilia sphenops were observed compared with prior studies. Heterotrophic denitrification was the dominant removal mechanism during the early operational stages, while sulfur autotrophic denitrification increased as readily biodegradable organic carbon released from wood chips decreased over time. 16S rRNA-based analysis of the CDF microbiome revealed that Sulfurimonas, Thioalbus, Defluviimonas, and Ornatilinea as notable genera that contributed to denitrification performance.2- accumulation compared with prior saline wastewater denitrification studies with sulfur alone. Although fish tank water quality parameters, including ammonia, nitrite, nitrate and sulfide, were below the inhibitory levels for marine fish production, lower survival rates of Poecilia sphenops were observed compared with prior studies. Heterotrophic denitrification was the dominant removal mechanism during the early operational stages, while sulfur autotrophic denitrification increased as readily biodegradable organic carbon released from wood chips decreased over time. 16S rRNA-based analysis of the CDF microbiome revealed that Sulfurimonas, Thioalbus, Defluviimonas, and Ornatilinea as notable genera that contributed to denitrification performance., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

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., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Biological nutrient removal and physical properties of halophilic aerobic granular sludge (hAGS) cultivated from autochthonous seawater-born microbes were investigated under hypersaline seawater conditions. hAGS achieved stable total nitrogen (TN) and total phosphorus (TP) removals of 96 ± 3% and 95 ± 4%, respectively, from seawater-based wastewater at 3.4% salt. At 4 to 12% salt concentrations, stable TN and TP removals of 82-99% and 95-96%, respectively, were maintained over 4 months under seawater conditions. Ammonium and phosphorus were mainly removed by nitritation-denitritation and enhanced biological phosphorus removal pathways, respectively. Stappiaceae (45%) and Rhodobacteraceae (21%) were the dominant genera in hAGS performing nutrient removal at 12% salt. hAGS contained acid-soluble extracellular polymeric substance as the major structural polymer which increased from 0.43 ± 0.02 g/gTS at 3.4% salt to 0.93 ± 0.03 g/gTS at 12% salt. Cultivation of hAGS from autochthonous wastewater-microbes can be a promising approach for achieving biological nitrogen and phosphorus removals from hypersaline seawater-based wastewaters., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Enhanced pollutants removal from saline wastewater was investigated in simultaneous anammox and denitrification (SAD) process with glycine betaine (GB) addition. Long-term operation indicated the optimal GB dose was around 0.4 mM, which enhanced both anammox and denitrifying activity by 30% and 45%, respectively. The total nitrogen and organic removal rates were 0.38 ± 0.2 kgN/m 3 /d and 0.34 ± 0.3 kgCOD/m 3 /d, respectively, which increased by 34.5% and 20.5%. Independent of GB dose, denitrifying activity was promoted, but anammox activity was drastically deteriorated after excessive GB addition. The optimal GB dose predicated by both Gaussian and Modified-Boltzmann models were 0.42-0.45 mM. Besides, the bacterial activity recovery after excessive GB addition could be analyzed by the Modified-Boltzmann model. With 1.5 mM GB, granular floatation occurred since numerous gas bubbles were inside the granules. In general, exogenous GB addition can mitigate salinity inhibition and promote pollutants removal from saline wastewater., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

This study proposed a novel approach of cultivating aerobic granular sludge (AGS) using intertidal wetland sediment (IWS) as inoculant in MBR for saline wastewater treatment. Granulation was observed in IWS-MBR during start-up, with increased sludge particle size (3.1-3.3 mm) and improved settling property (23.8 ml/g). The abundant inorganic particulates (acted as nuclei) and distinctive microbial community in IWS contributed to the granules formation. With the help of AGS, IWS-MBR system exhibited excellent TOC reduction of 90.3 ± 6.1% and significant TN reduction of 31.2 ± 5.0%, while the control MBR (Co-MBR) only showed 58.9 ± 7.2% and 10.4 ± 2.7%, respectively. Meanwhile, membrane fouling was mitigated in IWS-MBR, with a longer filtration cycle of 21.5 d, as compared with that of 8.9 d for Co-MBR. Microbial community analysis revealed that abundant functional bacteria associated with granulation and pollutants removal were enriched from IWS and set the basis for AGS formation and the superior treatment performance., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

To reveal nitrogen removal mechanisms under environmental stresses, biofilm reactors were operated at different temperatures (10 °C-35 °C) treating saline wastewater (salinity 3%). The results showed nitrogen removal efficiency was 98.46% at 30 °C and 60.85% at 10 °C, respectively. Both ammonia oxidizing archaea (AOA) and ammonia oxidizing bacteria (AOB) participated in nitrification. 94.9% of the overall ammonia oxidation was attributed to AOA at 10 °C, but only 48.2% of that was undertaken by AOA at 35 °C. AOA had a greater contribution at low temperature, which demonstrated that nitrogen removal pathway varied with temperature. Aerobic denitrification was more stable than anoxic denitrification. High-throughput sequencing showed Crenarchaeota was the dominant AOA (97.02-34.47%), cooperating with various heterotrophic AOB. Real-time PCR indicated that AOA was three orders of magnitude more abundant than AOB. AOA was more resistant to low temperature and high-saline stresses. Ammonia oxidizers had distinct responses to temperature change and showed diverse relationships at different temperatures., Competing Interests: Declaration of Competing Interest The authors declare that there are no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Nitrogen removal from saline wastewater is challenging due to adverse effects of salinity on biological processes. A novel sulfur-autotrophic cyclic denitrification filter (CDF) was tested for marine recirculating aquaculture systems (RAS) under varying conditions. Low ammonia, nitrite and sulfide concentrations were maintained at residence times between 4 and 12 h. After introduction of Poecilia sphenops, concentrations of NH 4 + -N, NO 2 -N were maintained below 1, 1, and 60 mg/L, respectively. Fish waste inputs to the CDF contributed to mixotrophic denitrification and low sulfate production. A mass balance showed that 7% of the feed nitrogen was assimilated by fish, 6% was removed by passive denitrification (e.g., in anoxic zones in filters), 60% in the CDF and 27% was discharged during sampling and solids removal. Daily fresh water addition was <2% of fish tank volumes. The results are promising as a low cost alternative for saline wastewater denitrification.- -N, NO 3 - -N were maintained below 1, 1, and 60 mg/L, respectively. Fish waste inputs to the CDF contributed to mixotrophic denitrification and low sulfate production. A mass balance showed that 7% of the feed nitrogen was assimilated by fish, 6% was removed by passive denitrification (e.g., in anoxic zones in filters), 60% in the CDF and 27% was discharged during sampling and solids removal. Daily fresh water addition was <2% of fish tank volumes. The results are promising as a low cost alternative for saline wastewater denitrification., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

In this study a continuous flow reactor (CFR) was employed to compare the feasibility of bacterial aerobic granular sludge (AGS-CFR) and algal-bacterial granular sludge (ABGS-CFR) for treating 1-4% saline wastewater. High salinity was found to enhance algae growth in ABGS-CFR, which exhibited slightly higher total nitrogen and phosphorus removal efficiencies at 1-3% salinity. ABGS-CFR maintained good granular stability at 1-4% salinity, while AGS-CFR gradually disintegrated at 4% salinity with 39.3% less accumulation of alginate-like exopolysaccharides in the extracellular polymeric substances. Indole-3-acetic acid (IAA) and superoxide dismutase (SOD) analysis suggested that bacteria and algae (Nitzschia) in ABGS-CFR formed a good symbiotic relationship under high salinity conditions, achieving rapid algae growth and 2 times lipid production. High salinity was conducive to enriching Halomonas and Nitzschia but unfavorable for Nitrosomonas and Flavobacterium. Results from this study could provide useful information on interactions between bacteria and algae in ABGS-CFR for its future practical application., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The performance of pollutant removals, activated sludge characteristics, and microbial communities of two biofilm membrane bioreactors coupled with pre-anoxic tanks (BF-AO-MBRs) (one using fiber bundle bio-carriers (FB-MBR) and the other using suspended bio-carriers (MB-MBR)) were compared at the salinity between zero and 60 g/L. At all salinities, three bioreactors showed good COD average removal efficiencies (>94.1%), and FB-MBR showed the best TN removal efficiency (90.4% at 30 g/L salinity). Moreover, FB-MBR had the faster process start-up time and better salt shock resistance. At high salinities (30-60 g/L), more extracellular polymeric substances were produced by the BF-AO-MBRs to avoid the penetration of salt and protect the bacterial community. Because of the different attachment patterns of biofilms, the microbial community structure in the FB-MBR exposed to 30 g/L salinity had higher nitrite-oxidizing/ammonia-oxidizing bacteria ratio (6.44) with more abundance of denitrifiers, which contribute to higher TN removal efficiency and lower nitrite accumulation., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The application of MBR in high saline wastewater treatment is mainly constrained by poor nitrogen removal and severe membrane fouling caused by high salinity stress. A novel carriers-enhanced MBR system was successfully developed for treating saline mariculture wastewater, which showed efficient TN removal (93.2%) and fouling control. High-throughput sequencing revealed the enhancement mechanism of bio-carriers under high saline condition. Bio-carriers substantially improved the community structure, representatively, nitrifiers abundance (Nitrosomonas, Nitrospira) increased from 2.18% to 9.57%, abundance of denitrifiers (Sulfurimonas, Thermogutta, etc.) also rose from 3.81% to 14.82%. Thereby, the nitrogen removal process was enhanced. Noteworthy, ammonia oxidizer (Nitrosomonas, 8.26%) was the absolute dominant nitrifiers compared with nitrite oxidizer (Nitrospira, 1.13%). This supported the finding of shortcut nitrification-denitrification process in hybrid system. Moreover, a series of biomacromolecule degraders (Lutibacterium, Cycloclasticus, etc.) were detected in bio-carriers, which could account for the mitigation of membrane fouling as result of EPS and SMP degradation., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

A salt-tolerant aerobic denitrifying bacterium, Zobellella denitrificans strain A63, was isolated, and its effects on the efficiency of denitrification of saline wastewater and the denitrifying microbial community structure in the matrix were studied in vertical-flow constructed wetlands (VFCWs). In a VFCW system with strain A63, the removal efficiencies of NH 4 + -N, and total nitrogen reached 79.2%, 95.7%, and 89.9%, respectively. Quantitative PCR analysis indicated that the amoA gene from ammonia-oxidizing archaea (AOA) was highly abundant, whereas amoA from ammonia-oxidizing bacteria and nxrA from nitrite-oxidizing bacteria were lowly abundant because of the influent salinity, irrespective of whether strain A63 was added. However, the addition of strain A63 significantly increased the abundance of nirK in the top layer of the VFCW. Therefore, AOA-driven partial nitrification and aerobic denitrification by strain A63 occurred in VFCWs. Our findings suggest that adding salt-tolerant denitrifying strains to constructed wetlands can enhance denitrification for saline wastewater treatment.3 - -N, and total nitrogen reached 79.2%, 95.7%, and 89.9%, respectively. Quantitative PCR analysis indicated that the amoA gene from ammonia-oxidizing archaea (AOA) was highly abundant, whereas amoA from ammonia-oxidizing bacteria and nxrA from nitrite-oxidizing bacteria were lowly abundant because of the influent salinity, irrespective of whether strain A63 was added. However, the addition of strain A63 significantly increased the abundance of nirK in the top layer of the VFCW. Therefore, AOA-driven partial nitrification and aerobic denitrification by strain A63 occurred in VFCWs. Our findings suggest that adding salt-tolerant denitrifying strains to constructed wetlands can enhance denitrification for saline wastewater treatment., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The use of constructed wetlands in combination with microbial fuel cells (CW-MFC) to treat saline wastewater may enhance electricity production by increasing the ionic strength, reducing internal resistance and stimulating microbes to accelerate electron transfer. In this study, salinity did not significantly inhibit the removal of TP and COD, but TN and NH 4 -N removal efficiencies during saline wastewater treatment (ST) were significantly lower than during non-saline wastewater treatment (NT). However, salinity significantly increased the power density (16.4 mW m + -N removal efficiencies during saline wastewater treatment (ST) were significantly lower than during non-saline wastewater treatment (NT). However, salinity significantly increased the power density (16.4 mW m -2 in ST and 3.9 mW m -2 in NT, a 4-fold enhancement) by increasing the electron transfer rate and reducing internal resistance (140.29 Ω in ST and 415.21 Ω in NT). The peptides in extracellular polymeric substances (EPS) acted as electron shuttles to promote the migration of electrons and protons in ST. From start-up to stable operation, though the microorganisms in ST were reduced in diversity relative to NT, the proportion of electrochemically active bacteria (EAB), such as Ochrobactrum, significantly increased (p < 0.05) and gradually predominated in the microbial community., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

This study investigated the growth dynamics of a freshwater and marine microalgae with supported biochemical performance in saline wastewater, the pollutants assimilation by a developed method, and the mechanism of salinity's effect to pollutants assimilation. Maximal biomass yield was 400-500 mg/L at 0.1-1% salinity while the TOC, NO 3 - -N, PO 4 3- -P were eliminated 39.5-92.1%, 23-97.4% and 7-30.6%, respectively. The biomass yield and pollutants removal efficiencies reduced significantly when salinity rose from 0.1 to 5%. The freshwater Chlorella vulgaris performed its best with a focus on TOC removal at 0.1% salinity. The marine Chlorella sp. was prominent for removing NO 3 - -N at 0.1-1% salinity. Through the developed method, the freshwater C. vulgaris competed to the marine microalgae referring to pollutants assimilation up to 5% salinity. This study unveiled the mechanism of salinity's effect with evidence of salt layer formation and salt accumulation in microalgae., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

There is a lack of information on denitrification of saline wastewaters, such as those from marine recirculating aquaculture systems (RAS), ion exchange brines and wastewater in areas where sea water is used for toilet flushing. In this study, side-by-side microcosms were used to compare methanol, fish waste (FW), wood chips, elemental sulfur (S 0 ) and a combination of wood chips and sulfur for saline wastewater denitrification. The highest denitrification rate was obtained with methanol (23.4 g N/(m 3 ·d)), followed by FW (4.5 g N/(m 3 ·d)), S 0 (3.5 g N/(m 3 ·d)), eucalyptus mulch (2.6 g N/(m 3 ·d)), and eucalyptus mulch with sulfur (2.2 g N/(m 3 ·d)). Significant differences were observed in denitrification rate for different wood species (pine > oak ≫ eucalyptus) due to differences in readily biodegradable organic carbon released. A pine wood-sulfur heterotrophic-autotrophic denitrification (P-WSHAD) process provided a high denitrification rate (7.2-11.9 g N/(m 3 ·d)), with lower alkalinity consumption and sulfate generation than sulfur alone., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Spectroscopic techniques were used to examine the subtle changes in soluble microbial products (SMP) of batch activated sludge bioreactors working at different salinities (i.e., 0%, 1%, 3%, and 5% NaCl). The changes in different fluorescent constituent were tracked by excitation-emission matrix combined with parallel factor analysis (EEM-PARAFAC), and the sequential production was further identified by two-dimensional correlation spectroscopy (2D-COS). Greater enrichment of tryptophan-like component and large-sized biopolymer were found in SMP for higher saline bioreactors, suggesting the SMP sources from bound extracellular polymeric substances and excreted intercellular constituents. 2D-COS revealed the opposite sequences of the fluorescence changes in SMP between the low and the high saline bioreactors, following the order of "tyrosine-like > tryptophan-like > humic-like fluorescence" for the latter. This study clarified the dominant mechanisms involved in SMP formation during elevating salinity, which were well supported by the changes in SMP spectroscopic features, microbial activity, and organic degradation rates., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

As an important alternative to alleviate the pressure of fresh water shortage, seawater application is facing a great challenge on the wastewater treatment due to the salinity brought from seawater. Spirulina platensis originated from salty lake was used to treat mixed synthetic toilet flushing wastewater of seawater with washing wastewater of freshwater. It was showed that 79.96% of TN (to 15.69mg/L), 93.35% of TP (to 1.03mg/L) and 90.02% of COD Cr (to 90.24mg/L) were removed with 0.76g/L of biomass production in the optimal ratio 7:3 of the above mixed synthetic wastewater. The performance was better than that of current strategy of seawater toilet flushing treatment. With the evaluation of nutrients uptake, biomass composition and microalgal aggregation, a model of nutrients recovery and metabolism of Spirulina platensis in saline wastewater treatment was proposed. It is provided a promising strategy for saline wastewater treatment with valuable biomass yield., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Membrane fouling mitigation in a novel AF-MBMBR system (moving bed membrane bioreactor (10L) coupled with anoxic biofilter (4L)) under high salinity condition (35‰) was systematically investigated. Pre-positioned AF served as a pretreatment induced significant decrease of suspended biomass by 85% and dissolved organic matters by 51.7% in subsequent MBR, which resulted in a reduction of cake layer formation. Based on this, sponge bio-carriers in MBMBR further alleviated the fouling propensity by modifying extracellular polymeric substances (EPS) properties. The protein component in EPS decreased from 181.4 to 116.5mg/g MLSS, with a decline of protein/carbohydrate ratio from 4.6 to 3.4. In particular, elimination of hydrophobic groups like aromatic protein-like substance in EPS was detected. These caused the less biomass deposition on membrane surface, thereby alleviating membrane fouling. In summary, mitigation of membrane fouling in AF-MBMBR should be attributed to contributions from both pre-positioned AF and sponge bio-carriers., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

This study was aimed to investigate the effect of moderate pressure on organic matter removal efficiency and microbial population of activated sludge treating saline wastewater. The activated sludge was cultivated with a gradual increase of salt concentrations under gage pressure of 0.3MPa for 71days. Microbial diversities of activated sludge sampled in different stages of domestication were investigated by Illumina sequencing technology. Results showed that pressurized aeration could improve the treatment efficiency and the dehydrogenase activity (DHA) of activated sludge, especially at high salinity (35, 50gNaClL -1 ). Bacterial richness and community diversity of activated sludge in the pressurized reactor were significantly higher than those in the control reactor. Microbial population structures were quite different between the two reactors. More species originating from fresh wastewater biological treatment process would survive and remain in pressurized activated sludge., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Chlorella vulgaris, a marine microalgae strain adaptable to 0-50 g L(-1) of salinity, was selected for studying the coupling system of saline wastewater treatment and lipid accumulation. The effect of total nitrogen (T N) concentration was investigated on algal growth, nutrients removal as well as lipid accumulation. The removal efficiencies of TN and total phosphorus (TP) were found to be 92.2-96.6% and over 99%, respectively, after a batch cultivation of 20 days. To illustrate the response of lipid accumulation to nutrients removal, C. vulgaris was further cultivated in the recycling experiment of tidal saline water within the photobioreactor. The lipid accumulation was triggered upon the almost depletion of nitrate (<5 mg L(-1)), till the final highest lipid content of 40%. The nitrogen conversion in the sequence of nitrate, nitrite, and then to ammonium in the effluents was finally integrated with previous discussions on metabolic pathways of algal cell under nitrogen deficiency., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Two pilot plant systems were investigated for the treatment of wastewater subject to a gradual increase of salinity. In particular, a membrane bioreactor (MBR) and a moving bed biofilm membrane bioreactor (MB-MBR) were analyzed. Carbon and ammonium removal, kinetic constants and membranes fouling rates have been assessed. Both plants showed very high efficiency in terms of carbon and ammonium removal and the gradual salinity increase led to a good acclimation of the biomass, as confirmed by the respirometric tests. Significant biofilm detachments from carriers were experienced, which contributed to increase the irreversible superficial cake deposition. However, this aspect prevented the pore fouling tendency in the membrane module of MB-MBR system. On the contrary, the MBR pilot, even showing a lower irreversible cake deposition, was characterized by a higher pore fouling tendency., (Copyright © 2014 Elsevier Ltd. All rights reserved.)