High-salt Wastewater Research Articles

Uniformly porous PVDF-co-HFP membranes prepared by mixed solvent phase separation for direct contact membrane distillation

Membrane distillation has gained significant interest as a promising technology for treating high-salt wastewater. However, membranes with large and nonuniform pore structures are prone to wetting, which compromises their salt rejection efficiency. In this study, a highly uniform porous poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) membrane was designed and prepared through the mixed solvent phase separation (MSPS) method, which was utilized in direct contact membrane distillation to treat salt concentration solutions as high as 5.85 wt%. The results showed 13 % polymer concentration, 26 % octane concentration, and 90 s of cooling duration exhibited an optimal structure with an average pore size of 53 ± 3 nm, a surface porosity of 24.79 %, and a liquid entry pressure (LEP) value of 3.5 bar. The optimum MSPS PVDF-HFP membrane demonstrated a vapor flux of 27 kg m−2 h−1 and high salt rejection (more than 99.94 %), superior than that of the controlled NIPS membrane with nonuniform pore sizes and lower surface porosity. This desalination performance is comparable with the commercial PTFE membrane (99.68 %, 29 kg m−2 h−1) featuring an order of magnitude higher pore sizes and greater LEP. Importantly, the MSPS PVDF-HFP membrane maintained its high performance over the duration of a long-term experiment (>140 h).

Study on the effect of volatile organic compounds on the treatment of high-salt wastewater by low-temperature evaporation

ABSTRACT High-salinity wastewater, owing to its intricate composition and challenging treatment requirements, poses a significant hurdle in water environmental governance. In this study, low-temperature evaporation technology is used to tackle wastewater containing the volatile organic compound such as N,N-dimethylacetamide (DMAC). Utilisation of comprehensive approaches involving experimental testing, mathematical modelling, and Aspen Plus software simulations, The influence of DMAC on evaporation efficiency is researched through the following factors which encompassing its effects on boiling point elevation, partial molar activation energy, and the formation of by-products. Additionally, the comparation of the impact of temperature, ionic strength, intermolecular interactions on the evaporation rate and the concentration of the volatile component DMAC in the condensate is also conducted in this study. After conducting a multiple linear regression analysis of evaporation efficiency using the Statistical Product and Service Solutions (SPSS) tool, it was discovered that temperature serves as the primary determinant influencing the evaporation rate. Additionally, ionic strength impacts solution viscosity, intermolecular interactions, and saturated vapour pressure by altering the intermolecular forces, thereby indirectly influencing both the evaporation rate and the quality of condensate water. The comparative analysis of single-effect and double-effect evaporation indicates that the optimal operating condition for double-effect evaporation yields an evaporation rate of 70%, with a remarkable 88% reduction in steam consumption compared to single one. Based on heat and mass balance principles, the mathematical model for double-effect evaporation is established to offer crucial data support for practical industrial applications.

Research on a Metal–Organic Framework (MOF)-Derived Carbon-Coated Metal Cathode for Strengthening Bioelectrochemical Salt Resistance and Norfloxacin Degradation

Microbial fuel cells (MFCs) can realize the conversion of chemical energy to electrical energy in high-salt wastewater, but the easily deactivated cathode seriously affects the performance of MFCs. To enhance the stability and sustainability of MFC in such circumstances, a bimetallic organic framework ZIF-8/ZIF-67 was utilized for the synthesis of a carbon cage-encapsulated metal catalysts in this study. Catalysts with different Co and Ce ratio (Co@C (without the Ce element), CoCe0.25@C, CoCe0.5@C, and CoCe1@C) were employed to modify the activated carbon cathodes of MFCs. The tests demonstrated that the MFCs with the CoCe0.5@C cathode catalyst obtained the highest maximum power density (188.93 mW/m2) and the smaller polarization curve slope, which boosted the electrochemical activity of microorganisms attached to the anode. The appropriate addition of the Ce element was conductive to the stability of the catalyst’s active center, which is beneficial for the stability of catalytic performance. Under the function of the CoCe0.5@C catalyst, the MFCs exhibited superior and stable norfloxacin (NOR) degradation efficiency. Even after three cycles, the NOR degradation rate remained at 68%, a negligible 5.6% lower than the initial stage. Furthermore, based on the analysis of microbial diversity, the abundance of electrogenic microorganisms on a bioanode is relatively high with CoCe0.5@C as the cathode catalyst. This may be because the better cathode oxygen reduction reaction (ORR) performance can strengthen the metabolic activity of anode microorganisms. The electrochemical performance and NOR degradation ability of MFC were enhanced in a high-salt environment. This paper provides an approach to address the challenge of the poor salt tolerance of cathode catalysts in MFC treatment, and presents a new perspective on resource utilization, low carbon emissions, and the sustainable treatment of high-salt wastewater.

Environmentally friendly non-saponification solvent extraction and separation process for RE(III) (RE = Eu, Gd and Tb) in acetic acid solution using HEHEHP/n-heptane

The key to achieving sustainable metal extraction development is to avoid the generation of high-salt wastewater from the source. Here, a new system for the extraction and separation of lanthanide elements Eu(III), Gd(III) and Tb(III) from the acetic acid solution using HEHEHP (2-ethylhexyl hydrogen-2-ethylhexylphosphonate) was studied. The corresponding parameters including contact time, HEHEHP concentration, concentrations of rare earth metal ions and acetic acid in the initial solution, aqueous/organic phase volume ratio (R(A/O)), and temperature were considered to optimize the conditions for the separation of different rare earth elements. The results showed that the separation coefficients of Tb(III)/Gd(III) and Gd(III)/Eu(III) in the acetic acid system were approximately 6.2 and 1.7, with HEHEHP of 0.15 mol/L and R(A/O) of 2:1, and the extraction efficiency of RE(III) reached approximately 73.1%, which was higher than that in the hydrochloric acid and sulfuric acid systems. The mechanism associated with the extraction reaction was evaluated and discussed by the maximum loading capacity method, chromatographic analysis, and FT-IR spectrometric analysis. The mechanism followed a cation exchange reaction and acetic acid did not participate in the extraction process. The feasibility of the separation of Tb(III) from Eu(III) and Gd(III)was also given in terms of the separation coefficients between different elements at different extraction conditions. Since saponification is not necessary in the acetic acid extraction system, it can considerably reduce wastewater discharge to the ecological environment from the source.

Salinity responsive mechanisms of sulfur-based mixotrophic denitrification and ectoine induced tolerance enhancement

Increasing discharge of saline wastewater poses a challenge for heterotrophic and sulfur autotrophic denitrification (HSAD) in nitrogen removal. This study explored the response mechanism of mixotrophic denitrifying microorganisms to high-salt stress and feasible mitigation strategies. Results showed that denitrification efficiency was promoted at 2 % salinity but significantly decreased at 6 %, with NO3–-N removal rate decreased from 95.77 % to 38.01 %. The contribution of sulfur autotrophic denitrification (SAD) remained higher than heterotrophic denitrification (HD). High salinity stimulation led to an increase in reactive oxygen species (ROS) content, while the nicotinamide adenine dinucleotide (NADH) content, adenosine triphosphate (ATP) level, and electron transport system activity (ETSA) decreased by 10.74 %, 46.6 % and 56.28 % at 6 % salinity, respectively. Additionally, high salt inhibited the activity of nitrate reductase (NAR) and nitrite reductase (NIR), reducing the abundance of denitrifying bacteria. Notably, the addition of 250 mg/L of ectoine at 6 % salinity alleviated stress, promoted the secretion of extracellular polymeric substances (EPS) to protect the microorganisms, reduced microbial oxidative stress, and maintained metabolic and denitrification enzyme activities. Ectoine acted as an osmotic pressure regulator and protective agent, maintaining intracellular enzymes and macromolecular structure, thus enhancing denitrification efficiency. Microbial community analysis demonstrated a 3.99 % increase in HD functional bacteria abundance with ectoine addition, highlighting its crucial role in regulation community succession and stability. Structural equations modeling analysis identified the regulatory relationship paths involved in the response and mitigation of HSAD to high salinity stress. This study deepens understanding of the inhibition mechanism of HSAD caused by high-salt wastewater and provides a feasible technical solution for salt stress alleviation in sulfur-based mixotrophic denitrification.

Temperature swing solvent extraction for salt and glycerin separation from wastewater

A relatively novel temperature-swing solvent extraction (TSSE) technology was investigated for the separation of salt and glycerol from high-salt wastewater containing glycerol. Diisopropylamine (DIPA) was employed as the solvent for successfully treating ultrahigh-salinity wastewater. Experimental results indicated that the salt removal rate of TSSE technology reached up to 93.86% in saturated brine containing 10.00 wt% glycerol. After five cycles of solvent recovery, the salt removal rate remained at 84.55%. Additionally, when the glycerol mass fraction in saturated brine was 80.00 wt%, the water recovery rate of TSSE technology was 60.27%, with a salt removal rate of 92.88%. The study also analyzed the mechanism of TSSE, revealing that the difference in solubility between DIPA and NaCl in water is crucial for achieving TSSE. The unique capability of TSSE technology in treating high-salt wastewater containing organics was highlighted, achieving not only effective salt removal but also glycerol concentration. The findings of this research not only demonstrate the remarkable effectiveness of TSSE technology in addressing high-salt wastewater containing glycerol but also forecast its promising outlook and immense potential for widespread adoption in various industrial wastewater treatment sectors.

Salinity acclimation of nitrifying microorganisms: Nitrification performance, microbial community, osmotic adaptation strategies

Wastewater with high salinity (> 1%) presents a significant challenge to conventional wastewater treatment, particularly for the nitrification process. However, the osmotic adaptation strategies of nitrifying microorganisms remain poorly understood. In this study, we examined the impacts of salinity on the ammonia and nitrite oxidation processes in wastewater. The biofilm samples without salinity acclimation (0 g NaCl/L), after 1% salinity acclimation (10 g NaCl/L), and after 3% salinity acclimation (30 g NaCl/L) were inoculated to conical flasks containing synthetic high-salt wastewater (30 g NaCl/L), respectively. The research findings indicate that, following the salinity acclimation of biofilm, the activity of ammonia oxidation surpassed that of nitrite oxidation. 16S rRNA gene amplicon analysis revealed a noteworthy increase in the abundance of Nitrosomonas (ammonia-oxidizing bacteria) and an unclassified ammonia-oxidizing archaeon within the Nitrososphaeraceae family. In contrast, Nitrospira (nitrite-oxidizing bacteria) exhibited a significant decrease (p < 0.01). Metagenomic analysis indicates certain strains, such as Nitrosomonas sp. PL2, Nitrosomonas mobilis PL3, and Nitrososphaeraceae gen. sp. PL5, possessed various genes related to Na+ efflux, K+ uptake, glutamate synthesis or transport. However, Nitrospira sp. PL6 and Nitrospira sp. PL7 lacked K+ uptake genes. This study elucidates the microbial mechanisms underlying the variations in nitrification observed before and after salinity acclimation of biofilm, which helps to develop microbial evolution strategies to remove nitrogen pollutants under high salinity conditions.

Boric acid-modified activated carbon for glycerol removal from high-salt wastewater

Epoxy resin production wastewater contains glycerol and NaCl, which cause high energy consumption and environmental pollution during wastewater treatment. Therefore, the adsorption of glycerol on boric acid in low-temperature modified activated carbon was investigated for the first time. Under the optimum conditions of a modification temperature of 80℃, a mass ratio of boric acid to activated carbon of 1:1, and a modification time of 6 h, the modification of activated carbon was realized. It was found that the removal of glycerol by activated carbon before and after modification was found to be 0.10 % and 99.67 % (10 °C), indicating that boric acid endows activated carbon with a stronger ability to adsorb glycerol; The higher the pH of the wastewater, the higher the removal rate of glycerol, while the salt content of the wastewater has little effect. This study used batch adsorption to show that modified activated carbon could adsorb up to 1100 mg g−1 of glycerol, which was in line with the proposed pseudo-second-order kinetic model. After 8 cycles of adsorption and desorption, the modified activated carbon lost only 12.46 % of the adsorption capacity. Combined with the results, the existence of boron hydroxyl groups on activated carbon is the key to glycerol adsorption.

S-doped g-C3N4 on Co/Ni metal-organic framework as efficient bifunctional electrocatalyst for in-situ hydrogen production from high-salt wastewater

An efficient and stable catalyst is the key to electrocatalytic hydrogen production. Herein, a bifunctional electrocatalyst is developed for electrocatalytic hydrogen production by depositing S-doped g-C3N4 on Co/Ni metal-organic framework electrode (namely CoNi-MOFs/S-g-C3N4). Compared with the original Co/Ni metal-organic framework (CoNi-MOFs), the overpotential of hydrogen production on CoNi-MOFs/S-g-C3N4 is reduced by 49.5 %, the charge transfer resistance is reduced by 74.5 %, and the electrochemically active area is expanded by 60.1 times. Moreover, CoNi-MOFs/S-g-C3N4 can be used as an efficient bifunctional electrocatalyst for overall water splitting. Impressively, using CoNi-MOFs/S-g-C3N4 as the anode and cathode, the hydrogen yield can reach 5.513 mmol h−1 and the energy consumption is 5.822 kWh Nm−3 at a current density of 250 mA cm−2. In addition, an in-situ overall water splitting system was designed for hydrogen production using high-salt wastewater as water source without additional pre-desalination process, which realizes green hydrogen production and reduces the cost. The hydrogen yield was hold in the range of 5.2–5.3 mmol h−1 for a week, showing excellent performance of hydrogen production and strong stability. More importantly, the system can be applied to various high-salt wastewater with wider pH and salinity, and shows promising application potential for hydrogen production in actual wastewater.

Rational engineering of Halomonas salifodinae to enhance hydroxyectoine production under lower-salt conditions

Hydroxyectoine is an important compatible solute that holds potential for development into a high-value chemical with broad applications. However, the traditional high-salt fermentation for hydroxyectoine production presents challenges in treating the high-salt wastewater. Here, we report the rational engineering of Halomonas salifodinae to improve the bioproduction of hydroxyectoine under lower-salt conditions. The comparative transcriptomic analysis suggested that the increased expression of ectD gene encoding ectoine hydroxylase (EctD) and the decreased expressions of genes responsible for tricarboxylic acid (TCA) cycle contributed to the increased hydroxyectoine production in H. salifodinae IM328 grown under high-salt conditions. By blocking the degradation pathway of ectoine and hydroxyectoine, enhancing the expression of ectD, and increasing the supply of 2-oxoglutarate, the engineered H. salifodinae strain HS328-YNP15 (ΔdoeA::PUP119-ectD p-gdh) produced 8.3-fold higher hydroxyectoine production than the wild-type strain and finally achieved a hydroxyectoine titer of 4.9 g/L in fed-batch fermentation without any detailed process optimization. This study shows the potential to integrate hydroxyectoine production into open unsterile fermentation process that operates under low-salinity and high-alkalinity conditions, paving the way for next-generation industrial biotechnology.Key points• Hydroxyectoine production in H. salifodinae correlates with the salinity of medium• Transcriptomic analysis reveals the limiting factors for hydroxyectoine production• The engineered strain produced 8.3-fold more hydroxyectoine than the wild typeGraphical

Simulation and Experimental Study of Circulatory Flash Evaporation System for High-Salt Wastewater Treatment

Treatment methods for high-salt wastewater mainly consist of physical methods, chemical methods and biological methods. However, there are some problems, such as slow treatment speed, high investment costs and low treatment efficiency. To address NaCl solutions, in this study, a circulatory flash system was designed based on gas–liquid equilibrium, mass conservation equation and energy conservation equation. A circulatory flash evaporation simulation and a static flash evaporation experiment were conducted on NaCl solutions under various operating conditions to investigate the effects of heating temperature, flash pressure and initial NaCl concentration on the circulatory flash evaporation system. The significance of each factor’s influence on the evaporation fraction and energy consumption was examined through static flash experiments. The simulation results demonstrated that increasing the heating temperature, decreasing the flash pressure and having a higher initial NaCl concentration could enhance the treatment capacity of high-salt wastewater. The flow rate of vapor outlets increased with higher heating temperature but decreased as the flash pressure rose. The experimental results demonstrated that flash evaporation pressure was the primary factor influencing both the evaporation fraction and the energy consumption per unit mass of vapor produced. It was observed that with an increase in heating temperature, the flash pressure decreased and there was a corresponding decrease in energy consumption per unit mass of vapor produced. The optimal experimental conditions were achieved at a heating temperature of 99 °C, a flash pressure of 15 kPa, and an initial NaCl concentration of 20%.

Degradation of organic mercury in high salt environments by a marine aerobic bacterium Alteromonas macleodii KD01

Mercury (Hg), particularly organic mercury, poses a global concern due to its pronounced toxicity and bioaccumulation. Bioremediation of organic mercury in high-salt wastewater faces challenges due to the growth limitations imposed by elevated Cl− and Na+ concentrations on microorganisms. In this study, an isolated marine bacterium Alteromonas macleodii KD01 was demonstrated to degrade methylmercury (MeHg) efficiently in seawater and then was applied to degrade organic mercury (MeHg, ethylmercury, and thimerosal) in simulated high-salt wastewater. Results showed that A. macleodii KD01 can rapidly degrade organic mercury (within 20 min) even at high concentrations (>10 ng/mL), volatilizing a portion of Hg from the wastewater. Further analysis revealed an increased transcription of organomercury lyase (merB) with rising organic mercury concentrations during the exposure process, suggesting the involvement of mer operon (merA and merB). These findings highlight A. macleodii KD01 as a promising candidate for addressing organic mercury pollution in high-salt wastewater.

Pilot-scale poly(alkyl-biphenyl pyridine)-based monovalent anion perm-selective membranes with exceptional Cl−/SO42− selectivity in ion-distillation

Monovalent anion perm-selective membranes (MAPMs) were fabricated from poly (alkyl-biphenyl pyridine) backbone via Menshutkin reaction and in-situ thermal crosslinking. Compared to the commercial ACS membrane (Cl− flux of 2.44 mol m−2 h−1, selectivity of 5.55), the optimum MAPM exhibited superior Cl− ions flux of 2.78 mol m−2 h−1 and Cl−/SO42− selectivity of 10.5 at current density of 10 mA cm−2. Additionally, the optimum MAPM was successfully scaled up and comprehensively evaluated, demonstrating exceptional ion separation performance and operational stability. Notably, in the ion-distillation process, the scale-up membrane displayed an extremely high separation coefficient of Cl−/SO42− over 15,000. The membrane shows promise for practical applications in treating high salt wastewater and desalination processes requiring Cl−/SO42− separation.

Nitrilotriacetic acid/Fe0/H2O2 system enhanced by magnetic field and visible light promoted DMP degradation and high-salt wastewater treatment

Nitrilotriacetic acid/Fe0/H2O2 system enhanced by magnetic field and visible light promoted DMP degradation and high-salt wastewater treatment

Effect of salinity on biological nitrogen removal from wastewater and its mechanism.

The nitrogen discharge from saline wastewater will cause significant pollution to the environment. As a high-efficiency and low-cost treatment method, biological treatment has a promising application prospect in the removal of nitrogen from high-salt wastewater. However, the inhibitory effect of high salt on microorganisms increases the difficulty of its treatment. This review discusses the influence of salinity on the nitrogen removal process, considering both traditional and novel biological techniques. Common methods to enhance the effectiveness of biological nitrogen removal processes and their mechanisms of action in engineering practice and research, including sludge acclimation and inoculation of halophilic bacteria, are also introduced. An outlook on the future development of biological nitrogen removal processes for high-salt wastewater is provided to achieve environmentally friendly discharge of high-salt wastewater.

Highly salt-resistant 3D melamine sponge-polypyrrole composites for efficient solar interfacial evaporation

Solar desalination has received great attention as an environmentally friendly and cost-effective way to desalinate seawater. In this paper, a melamine sponge composite polypyrrole (MSPPy) evaporator was prepared by in-situ polymerization of Pyrrole (Py) on a melamine sponge (MS). PPy has an efficient light absorption ability. The large aperture network structure of MS can realize multiple reflections of light and greatly increase the absorption of light. Their synergistic effect makes the light absorption efficiency of the MSPPy evaporator reach 96.97%. Under one sun, the average evaporation rate of 1.886 kg⋅m−2⋅h−1 and energy conversion efficiency of 96.8% were achieved during 10 h. Moreover, the evaporator has an edge-priority crystallization function, which enables it to work for a long time in a high-salt environment. It works continuously for 12 h in simulated seawater with a salinity of 20% without further accumulation of salt crystals on its surface. More important, it can rapidly diffuse accumulated salt into the bulk water at night. This study provides a new idea for the application of solar steam generation technology in high-salt wastewater treatment.

Performance investigation on a self-powered microbial pollutant adsorption cell with N-LAC/PVDF cation exchange membrane

A high-efficiency, self-powered microbial pollutant adsorption cell with an N-LAC/PVDF cation exchange membrane was proposed to remove metal ions and organic dyes in high-salt wastewater. Nitrogen-doped alkali lignin (N-LAC) was synthesized using chitosan nanoparticles (CS) and alkali lignin (AL) using a blending method. The N-LAC/PVDF cation exchange membrane was prepared by chemically grafting polyvinylidene fluoride (PVDF). With modification, hydroxyl, carboxyl, carbonyl, and other hydrophilicity groups were introduced into the cation exchange membrane. The addition of N-LAC improved the membrane's hydrophilicity and adsorption capacity. FITR and SEM, respectively, characterized the surface morphology of the exchange membrane. The result showed that the contact angle reached 74.89° when the amount of N-LAC was 1 wt.%, and the desalination efficiency was 93.5 %, which increased by 70 %. The adsorption capacity of organic dye Pb and metal ion MB was 91 % and 94 %, respectively, showing an increase of 31.9 % and 43.5 %.

Degradation of phenol in high-salt wastewater by three-dimensional FeCu co-doped materials: Interaction of FeCu with g-C3N4–rGO and synergistic catalytic mechanism

In order to solve the problem of low activity of advanced oxidation processes (AOPs) in degrading high-salt organic wastewater. This study demonstrates a strategy to improve catalyst activity by co-doping with FeCu between the reduced graphene oxide (rGO) and graphitic carbon nitride (g-C3N4) layers. The g-C3N4-FeCu-rGO (GR-FeCu) reaction system achieved a phenol degradation rate of >96% in high-salinity wastewater, with a pH range of 2–8. After six cycles, the phenol degradation rate reached 100%. Electron spin resonance analysis identified·OH and·O2- as the primary active species in phenol degradation. The high activity of the catalyst in high-salt environments is attributed to the synergistic effect of FeCu and rGO-g-C3N4: The introduction of FeCu suppressed the formation of g-C3N4, leading to more defect structures and active groups (CO and C-N = C) in the catalyst. These structures provided active sites for H2O2 activation, enhanced H2O2 activation. The doping of Cu in the catalyst not only accelerates the accelerated Fe (III) reduction in the Fenton reaction, but also enhances the activity of N in g-C3N4. The three-dimensional interlayer structure with FeCu co-doping stabilized the metal ions and provided abundant active sites and metal anchoring structures, presenting a new approach to improve catalytic activity.

Electrochemical removal of nitrate in high-salt wastewater with low-cost iron electrode modified by phosphate

Nitrate (NO3–) is a widespread pollutant in high-salt wastewater and causes serious harm to human health. Although electrochemical removal of nitrate has been demonstrated to be a promising treatment method, the development of low-cost electro-catalysts is still challenging. In this work, a phosphate modified iron (P-Fe) cathode was prepared for electrochemical removal of nitrate in high-salt wastewater. The phosphate modification greatly improved the activity of iron, and the removal rate of nitrate on P-Fe was three times higher than that on Fe electrode. Further experiments and density functional theory (DFT) calculations demonstrated that the modification of phosphoric acid improved the stability and the activity of the zero-valent iron electrode effectively for NO3– removal. The nitrate was firstly electrochemically reduced to ammonium, and then reacted with the anodic generated hypochlorite to N2. In this study, a strategy was developed to improve the activity and stability of metal electrode for NO3– removal, which opened up a new field for the efficient reduction of NO3– removal by metal electrode materials.

Impact of salinity and time on structure and functional potential of wastewater treatment biofilms in intermittent sand bioreactors.

High salt wastewater is produced in industries, including seafood and pickling processing. The salinity in such wastewaters has been shown to negatively impact biological treatment efficacy. Little is known about the changes in the microbial community structure in the mature biological 2 treatment systems, the impacts of salinity on community composition, and the shifts over time during operation. This study aimed to identify the changes in the microbial community due to both salt and days of operation through 16s rRNA sequencing and KEGG functional predictions. Intermittent sand bioreactors (ISBs) with a focus on ammonia treatment were utilized. Results showed that the overall community structure and diversity were distinct as wastewater salinity varied from 0%-1.3%. At 1.3% salinity Zoogloea, a common genus in wastewater treatment plants, was not present and Aequorovita, Thauera and Dokdonella became the dominant genera. Nitrosomonas, an important ammonia oxidizing bacteria, increased in abundance with days of operation but was not significantly impacted by an increase in salinity. This finding was further supported by an increase in predicted nitrification potential with time of operation within all intermittent sand bioreactors tested. These results provide a deeper understanding of the impacts of salinity on microbial community development in biological treatment systems and elucidate the shifts in community structure occurring during early operations and into system maturity.