Search

Saline wastewater is known to affect the performance of phosphate-accumulating organisms (PAOs) in enhanced biological phosphorus removal (EBPR) process. However, studies comparing the effect of salinity on different PAO clades are lacking. In this study, ‘Candidatus Accumulibacter phosphatis’ Clade I and II (hereafter referred to as PAOI and PAOII) were highly enriched (∼90% in relative abundance as determined by quantitative FISH) in the form of granules in two sequencing batch reactors. Anaerobic and aerobic batch experiments were conducted to evaluate the effect of salinity on the kinetics and stoichiometry of PAOI and PAOII. PAOI and PAOII communities showed different priority in using polyphosphate (poly-P) and glycogen to generate ATP in the anaerobic phase when exposed to salt, with PAOI depending more on intracellular poly-P degradation (e.g., the proportion of calculated ATP derived from poly-P increased by 5–6% at 0.256 mol/L NaCl or KCl) while PAOII on glycolysis of intracellularly stored glycogen (e.g., the proportion of calculated ATP derived from glycogen increased by 29–30% at 0.256 mol/L NaCl or KCl). In the aerobic phase, the loss of phosphate uptake capability was more pronounced in PAOII due to the higher energy cost to synthesize their larger glycogen pool compared to PAOI. For both PAOI and PAOII, aerobic conversion rates were more sensitive to salt than anaerobic conversion rates. Potassium (K+) and sodium (Na+) ions exhibited different effect regardless of the enriched PAO culture, suggesting that the composition of salt is an important factor to consider when studying the effect of salt on EBPR performance.

Background: High concentration of salt makes biological treatment impossible due to bacterial plasmolysis. The present research studies the process of electrochemical oxidation efficiency and optimal levels as important factors affecting pH, salt concentration, reaction time and applied voltage. Methods: The sample included graphite electrodes with specifications of 2.5 cm diameter and 15 cm height using a reactor with an optimum capacity of 1 L. Sixty samples were obtained with the aid of the experiments carried out in triplicates for each factor at 5 different levels. The entire experiments were performed based on standard methods for water and waste water treatments. Results: Analysis of variance carried out on effect of pH, salt concentration, reaction time and flow intensity in elimination of chemical oxygen demand (COD) showed that they are significant factors affecting this process and reduce COD with a coefficient interval of 95% and test power of 80%. Scheffe test showed that at optimal level, a reaction time of 1 hour, 10 g/L concentration, pH = 9 and 15 V electrical potential difference were obtained. Conclusion: Waste waters containing salt may contribute to the electro-oxidation process due to its cations and anions. Therefore, the process of electrochemical oxidation with graphite electrodes could be a proper strategy for the treatment of saline wastewater where biological treatment is not possible.

Peracetic acid (PAA) and performic acid (PFA) are two major peroxyacid (POA) oxidants of growing usage. This study reports the first systematic evaluation of PAA, PFA, and chlorine for their disinfection byproduct (DBP) formation potential in wastewater with or without high halide (i.e., bromide or iodide) concentrations. Compared with chlorine, DBP formation by PAA and PFA was minimal in regular wastewater. However, during 24 h disinfection of saline wastewater, PAA surprisingly produced more brominated and iodinated DBPs than chlorine, while PFA effectively kept all tested DBPs at bay. To understand these phenomena, a kinetic model was developed based on the literature and an additional kinetic investigation of POA decay and DBP (e.g., bromate, iodate, and iodophenol) generation in the POA/halide systems. The results show that PFA not only oxidizes halides 4-5 times faster than PAA to the corresponding HOBr or HOI but also efficiently oxidizes HOI/IO - to IO 3 - , thereby mitigating iodinated DBP formation. Additionally, PFA's rapid self-decay and slow release of H 2 O 2 limit the HOBr level over the long-term oxidation in bromide-containing water. For saline water, this paper reveals the DBP formation potential of PAA and identifies PFA as an alternative to minimize DBPs. The new kinetic model is useful to optimize oxidant selection and elucidate involved DBP chemistry.

Abstract Biological nutrient removal performances and kinetics of autochthonous marine biomass in forms of activated sludge and aerobic granular sludge were investigated under different salinity and sludge retention time (SRT). Both the biomasses, cultivated from a fish-canning wastewater, were subjected to stepwise increases in salinity (+2 gNaCl L−1), from 30 gNaCl L−1 up to 50 gNaCl L−1 with the aim to evaluate the maximum potential in withstanding salinity by the autochthonous marine biomass. Microbial marine species belonging to the genus of Cryomorphaceae and of Rhodobacteraceae were found dominant in both the systems at the maximum salinity tested (50 gNaCl L−1). The organic carbon was removed with a yield of approximately 98%, irrespective of the salinity. Similarly, nitrogen removal occurred via nitritation-denitritation and was not affected by salinity. The ammonium utilization rate and the nitrite utilization rate were approximately of 3.60 mgNH 4 -N gVSS−1h−1 and 10.0 mgNO 2 -N gVSS−1h−1, respectively, indicating a high activity of nitrifying and denitrifying bacteria. The granulation process did not provide significant improvements in the nutrients removal process likely due to the stepwise salinity increase strategy. Biomass activity and performances resulted affected by long SRT (27 days) due to salt accumulation within the activated sludge flocs and granules. In contrast, a lower SRT (14 days) favoured the discharge of the granules and flocs with higher inert content, thereby enhancing the biomass renewing. The obtained results demonstrated that the use of autochthonous-halophilic bacteria represents a valuable solution for the treatment of high-strength carbon and nitrogen saline wastewater in a wide range of salinity. Besides, the stepwise increase in salinity and the operation at low SRT enabled high metabolic activity and to avoid excessive accumulation of salt within the biomass aggregates, limiting their physical destructuration due to the increase in loosely-bound exopolymers. Graphical abstract Image 1 Highlights • Autochthonous marine bacteria were cultivated as granular and activated sludge. • Biomass metabolic kinetics were evaluated at different salinity and SRT. • Salinity did not affect the biomass kinetics within the range of 30–50 gNaCl L−1. • Biomass activity and performances decreased for both system because of a long SRT. • Destructuration of the microbial bioaggragates occurred due to salt accumulation. [ABSTRACT FROM AUTHOR]

Abstract Increasing amounts of saline (waste)water with high concentrations of organic pollutants are generated globally. In the anaerobic (waste)water treatment domain, high salt concentrations are repeatedly reported to inhibit methanogenic activity and strategies to overcome this toxicity are needed. Current research focuses on the use of potential osmolyte precursor compounds for osmotic stress alleviation in granular anaerobic sludges upon exposure to hypersalinity shocks. Glutamic acid, aspartic acid, lysine, potassium, gelatine, and tryptone were tested for their potential to alleviate osmotic stress in laboratory grown and full – scale granular sludge. The laboratory grown granular sludge was adapted to 5 (R5) and 20 (R20) g Na+/L. Full-scale granular sludge was obtained from internal circulation reactors treating tannery (waste)water with influent conductivity of 29.2 (Do) and 14.1 (Li) mS/cm. In batch experiments which focused on specific methanogenic activity (SMA), R5 granular sludge was exposed to a hypersalinity shock of 20 g Na+/L. The granular sludge of Do and Li was exposed to a hypersalinity shock of 10 g Na+/L with sodium acetate as the sole carbon source. The effects on R20 granular sludge were studied at the salinity level to which the sludge was already adapted, namely 20 g Na+/L. Dosing of glutamic acid, aspartic acid, gelatine, and tryptone resulted in increased SMA compared to only acetate fed batches. In batches with added glutamic acid, the SMA increased by 115% (Li), 35% (Do) and 9% (R20). With added aspartic acid, SMA increased by 72% (Li), 26% (Do), 12% (R5) and 7% (R20). The addition of tryptone resulted in SMA increases of 36% (R5), 17% (R20), 179% (Li), and 48% (Do), whereas added gelatine increased the SMA by 30% (R5), 14% (R20), 23% (Li), and 13% (Do). The addition of lysine, meanwhile, gave negative effects on SMA of all tested granular sludges. Potassium at sea water Na/K ratio (27.8 w/w) had a slight positive effect on SMA of Do (7.3%) and Li (10.1%), whereas at double the sea water ratio (13.9% w/w) had no pronounced positive effect. R20 granular sludge was also exposed to hyposalinity shock from 20 down to 5 g Na+/L. Glutamate and N-acetyl-β-lysine were excreted by microbial consortium in anaerobic granular sludge adapted to 20 g Na+/L upon this exposure to hyposalinity. A potential consequence when applying these results is that saline streams containing specific and hydrolysable proteins can be anaerobically treated without additional dosing of osmolytes. Graphical abstract Image 1 Highlights • Tryptone alleviates osmotic stress in anaerobic granular sludge. • Glutamic acid alleviates osmotic stress in anaerobic granular sludge. • Aspartic acid alleviates osmotic stress in anaerobic granular sludge. • Glutamate and N-acetyl-β-lysine are main osmoprotectants in 20 g Na+/L adapted granular sludge. [ABSTRACT FROM AUTHOR]

Abstract The aerobic granular sludge (AGS) dominated by halophilic microorganisms, was successfully cultivated in a lab-scale sequencing batch reactor (SBR) under varying salinity levels (from 0% to 6% (w/v)). Removal performance of AGS improved with the increase of salinity and increased up to 42.86 mg g−1 VSS h−1 at 6% salinity. Increased salinity resulted in better settling performance of AGS in terms of the sludge volume index (SVI), which was initially 148.80 mL/g at 0% salinity and gradually decreased to 59.1 mL/g at 6% salinity. The increase of salinity stimulated bacteria to secret excessive extracellular polymeric substances (EPS), with its highest production of 725.5 mg/(g·VSS) at 5% salinity. The total protein (PN) exhibited highly positive correlation with the total EPS (R = 0.951), indicating that selective secretion of some functional PN played a key constituent in resisting the external osmotic pressure and improving sludge performance. Salinicola, accounted for up to 91% relative abundance at 6% salinity, showed the high positive correlation (R = 0.953) with salinity. The enrichment of such halophilic or halotolerant microbial community assured both stable and improved removal performance in the AGS system. The enrichment of salt response pathways and altered metabolic processes for salt-tolerant bacteria indicated that the microbial community formed special metabolic pattern under long-term hypersaline stress to maintain favourable cellular activity and removal performance. Highlights • AGS dominated by halophilic microorganisms was successfully cultivated at 6% salinity. • Increased salinity resulted in enhancement of removal and settling performance of AGS. • The functional groups of PN contributed a lot to salt-tolerance ability of AGS. • Salinicola (91% at 6% salinity) showed the highly positive correlation with salinity. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The performance and microbial community of an anoxic-aerobic sequencing batch reactor (SBR) treating saline wastewater were investigated at different influent COD/N ratios. The average COD removal efficiencies at steady states were 87.46%, 73.75%, 64.87% and 88.34% at the COD/N ratios of 20, 10, 6 and 30, respectively. The average NH4+-N removal efficiencies were 79.74%, 74.34%, 64.55% and 89.29% at the COD/N ratios of 20, 10, 6 and 30, respectively. No obvious accumulation of NO2--N and NO3--N in the effluent was found during the whole operational period. The specific ammonium oxidation rate (SAOR), specific nitrite oxidation rate (SNOR) and specific oxygen uptake rate (SOUR) increased with the decrease of COD/N ratio from 20 to 6, whereas the specific nitrate reduction rate (SNRR) decreased. The diversity indices of microbial community in the SBR were 2.19, 2.10, 2.17 and 2.07 at the COD/N ratio of 20, 10, 6 and 30, respectively. Some bacteria were present at all the COD/N ratios, such as Nitrosomonas sp., Ohtaekwangia kribbensis and Propionicimonas paludicola, suggesting these bacteria could adapt to the shock of influent COD/N ratio. [ABSTRACT FROM AUTHOR]

The present study surveys halophilic bacteria that were isolated from various Tunisian biotopes such as saline, lagoon, fish farm, for their acclimation capacity in fish processing wastewater at 10% NaCl. Hydrolase activities such as protease and lipase were screened. Strains S6 and S10, isolated from fish farm in a lagoon area and showed a protease activity of 503 and 328 U/L in liquid media, were selected. These strains were identified as Salinivibrio genus and more precisely to the species Salinivibrio siamensis and Salinivibrio costicola subsp. alcaliphilus using 16S RNA gene sequencing analysis. Bioremediation of fish processing wastewater was investigated by the use of the selected strains, the species Salinivibrio siamensis and Salinivibrio costicola subsp. alcaliphilus in comparison with urban activated sludge. The experiments were performed at different salt concentrations (10–20%). As salinity increased, the TOC removal efficiency was decreasing, and then increasing progressively through time. The Total Organic carbon (TOC) removal decreased from 22% to 1% when the salinity increased from 100 g·L-1 to 200 g·L-1 NaCl after 24 h of incubation and reached 57% and 7%, respectively after 120 h of incubation. Meanwhile, no TOC removal was obtained with the use of urban activated sludge. [ABSTRACT FROM AUTHOR]

A granular sequencing batch reactor (GSBR) worked for 164 days to study the effect of salinity on aerobic granulation. The feeding had an organic loading rate (OLR) of 1.6 kg COD⋅m −3 ⋅d −1 and a gradual increase of salinity (from 0.30 to 38 g NaCl − ⋅L −1 ) to promote a biological salt-adaptation. First aggregates (average diameter ≈ 0.4 mm) appeared after 14 days. Extracellular polymeric substances (EPSs) analyses revealed that proteins were mainly higher than polysaccharides, and microorganisms metabolized EPSs as additional carbon source, mostly in feast phase, to face the energy demand for salinity adaptation. No significant worsening of organic matter removal was observed. The initial decrease of nitrification (from 58% to 15%) and the subsequent increase (up to 25%), confirmed the acclimation of AOBs to saline environment, while the accumulation of nitrites suggested NOBs inhibition. The nitrogen removal initially decreased from 58% to 15%, due to the inhibitory effect of salinity, and subsequently increased up to 29% denoting a simultaneous nitrification–denitrification. The dimensions of mature granules (higher than 1 mm) probably involved PAOs growth in the inner anaerobic layers. Nitrites caused a temporary deterioration of phosphorous removal (from 60% to almost zero), that increased up to 25% when nitrites were depleted. [ABSTRACT FROM AUTHOR]

The removal of Ca2+ and Mg2+ in saline wastewater is a significant environmental problem. In this paper, an innovative way to remove Ca2+ and Mg2+ ions by Mg–Al layered double oxides (LDOs) was studied. During the process, the adsorption of Ca2+ and Mg2+ was synchronous with the lattice reconstruction of Mg–Al layered double hydroxides (LDHs). The study found that adsorption isotherm at four experimental temperatures follows the Langmuir isotherm model. The maximum Ca2+ and Mg2+ adsorption capacities were 305.31 and 105.99 mg/g, respectively. The thermodynamic parameters calculated from the temperature-dependent isotherms indicated that the adsorption was a spontaneous and endothermic process, and the adsorption kinetics followed the pseudo-second-order model. Certain competitive and mutually promoted effects were observed during the Ca2+ and Mg2+ adsorption process in the binary ion system. Regeneration experiment showed that LDOs have excellent repeatability. The removal percentage of Ca2+ and Mg2+ in actual desulfurization wastewater can reach more than 70%. Further, the results of X-ray diffraction and scanning electron microscopy indicated that the structure of hydrotalcite lamellae collapsed after calcination, though the structure of hydrotalcite gradually recovered through a series of chemical reactions with the adsorption of Ca2+ or Mg2+ and the insertion of anion during the adsorption process. [ABSTRACT FROM AUTHOR]

Nanofiltration (NF) coupling processes have been applied to treat high salinity wastewater in many studies. The main reason that affects the industrialization of the wastewater treatment is the high cost, which is mainly caused by the energy consumption of the entire system. Therefore, how to evaluate the energy consumption of different process configurations is an important issue. In this work, a thermodynamical approach was explained in detail, which could be used for evaluating energy consumption for pressure-driven membrane processes (e.g., NF and reverse osmosis) and osmotically driven membrane processes (e.g., forward osmosis). The coupling process configurations of NF, reverse osmosis (RO) and crystallization (Cryst) were selected to evaluate the energy consumption for high NaCl and Na2SO4 concentration wastewater in this paper. Four different process configurations (NF-Cryst, RO-Cryst, RO-NF-Cryst, NF-RO-Cryst) were simulated using Aspen Plus. The processes were discussed using a thermodynamical approach with a customized NF model. The electrolyte Non-Random Two-Liquid (electrolyte-NRTL) model was employed to calculate the thermodynamic properties of the solutions. The simulation results showed that the energy consumption per cubic meter of treated water (Ewater) in NF-Cryst and NF-RO-Cryst processes were lower than that of RO-Cryst and RO-NF-Cryst. When ... was low (e.g., 15 g⋅L-1), there was not much difference in energy consumption between NF-Cryst and NF-RO-Cryst processes. Moreover, the high efficiency of NF was revealed in the separation of salt and decrease in the energy consumption of the whole process. [ABSTRACT FROM AUTHOR]

Autochthonous halophilic biomass was cultivated in a sequencing batch reactor (SBR) aimed at analyzing the potential use of autochthonous halophilic activated sludge in treating saline industrial wastewater. Despite the high salt concentration (30 g NaCl L −1 ), biological oxygen demand (BOD) and total suspended solids (TSS), removal efficiencies were higher than 90%. More than 95% of the nitrogen was removed via a shortcut nitrification-denitrification process. Both the autotrophic and heterotrophic biomass samples exhibited high biological activity. The use of autochthonous halophilic biomass led to high-quality effluent and helped to manage the issues related to nitrogen removal in saline wastewater treatment. [ABSTRACT FROM AUTHOR]

This study aimed to investigate factors that affect the conversion of sulphates and magnesium, and the recovery of gypsum and magnesium hydroxide in the neutralization of a sulphate rich stream using calcium hydroxide, in a laboratory scale seeded fluidised bed crystallizer. Particular focus was on reducing the precipitated fines that escaped with the treated water, through the use of seeds, while removing as much sulphate-compounds from the waste stream as possible. The composition of the total sulphate salts was as follows: 80% magnesium sulphate, calcium sulphate remaining at its saturation concentration (1.5 g/L), with the remainder being sodium sulphate based on typical reverse osmosis retentate concentrations ranging from 1.5 – 120 g/L of total sulphate salts. The fluidised bed crystallizer, using silica seeds, was found to be effective at reducing the formation of gypsum and magnesium hydroxide fines by almost half. Feed concentrations of 35 g/L of total salts yielded better sulphate conversions (±75%), compared to a feed concentration of 8 g/L (±30%). It was possible to remove 99% of the magnesium in the saline wastewater stream using a calcium to sulphate ratio of 1:1 for feed concentrations of 15 g/L and higher. Excess calcium hydroxide suspension improved sulphate conversions. [ABSTRACT FROM AUTHOR]

[Display omitted] • The resource conversion and recovery through EDM were systematically reviewed. • Various influencing factors were deeply discussed for EDM systems. • Limiting factors of EDM and possible solutions were detailly summarized. • The economic analysis of high-value products generated by EDM was outlined. • Future prospects of EDM in resource conversion and recovery were proposed. Over the past few decades, industrial society has undergone rapid development and produced a significant number of wastes, leading to an increased demand for sustainable resource conversion and recovery. Among the various techniques, electrodialysis metathesis (EDM) has exhibited excellent performance and emerged as a potential candidate. In this review, the applications of EDM were systematically summarized, including high-value conversion of salts, resource utilization of saline wastewater, recovery of ionic liquids and green synthesis of substances. Furthermore, the influencing factors including electric field intensity, initial solution concentration, feeding rate and coexisting ions on EDM performance were thoroughly reviewed. Specifically, the limiting factors of EDM and its mechanism were presented, and then the possible solutions were summarized. In addition, the economic analysis of the EDM process was outlined in detail. Finally, the future applications and prospects of EDM were presented. This work would provide guidance for electrodialysis metathesis in implement the resource recovery from the role of green chemistry and optimize process safety. [ABSTRACT FROM AUTHOR]

[Display omitted] • The aerobic total inorganic nitrogen removal efficiency reached 76.16% under 50 mT. • Nitrogen removal by fungal dissimilation was increased by 3.6 times. • The magnetic field shrinks the fungi and changes the community composition. • Bacteria Paracoccus and fungi Candida formed a synergistic interaction. 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. [ABSTRACT FROM AUTHOR]

Paper discuses changes in utilization rate of Low Molecular Weight polycyclic aromatic hydrocarbons PAHs in sequencing bath reactors (SBR) operating with flocked and aerobic granular activated sludge. Studies were carried out in laboratory scale SBR reactors filled with model wastewater characterized by salinity at level 4.00 g·dm−3. Wastewater inflowing to laboratory reactors was characterized by varying biological oxygen demand (BOD) load in the range of 0.05−1.60 kg BOD·kg−1·d−1.

A novel AF-MBMBR system (sponge moving bed membrane bioreactor coupled with a pre-positioned anoxic bio-filter) was proposed for treating saline wastewater from mariculture. Its development process was divided into 4 stages and the performance in each stage were evaluated in order to clarify the pollutants removal mechanism and the membrane filtration performance. The results showed that TOC removal efficiency was maintained at high level (92.8%–96.2%) throughout the development period due to the utilization of pre-acclimated biomass; Excellent TN (total nitrogen) removal efficiency (up to 93.2%) was progressively obtained which could be attributed to the combined effects of pre-positioned AF and sponge bio-carriers in MBMBR. Indeed, such an effective TN removal for the treatment of saline wastewater was rarely reported. Moreover, the short-cut nitrification-denitrification was observed to be the dominant nitrogen removal pathway in AF-MBMBR. Concerning membrane filtration performance, the filtration cycle was pronouncedly prolonged from 10 days to 44 days. Such an improvement was the result of mitigation on cake layer resistance, which could be attributed to the reduction of MLSS and organic load in MBR induced by pre-positioned AF, as well as the modification effect of sponge bio-carriers on mixed liquor in MBR. [ABSTRACT FROM AUTHOR]

High total dissolved solids (TDS) wastewater containing high amounts of organics with toxic and recalcitrant characteristics is a major concern in some petrochemical industries. This study was designed to evaluate a novel electrokinetic process for chemical oxygen demand (COD) removal. The removal of COD was carried out in some batch experiments in lab scale and effect of experimental factors such as the pH, current intensity, time, electrodes distances and TDS on the COD removal was evaluated. Also scale-up of the process was done in order to evaluate energy consumption. The obtained findings indicated that best conditions for COD removal were achieved in pH 5, current intensity of 0.5 A and electrodes distance of 2 cm. Pseudo-first-order kinetic model with rate constant of 0.0093 min −1 and significant coefficient of correlation (R 2 ) 0.948 was the best fitted with experimental results. Energy consumption was 32 KWh.m −3 while 80 fold scaling up the reactor resulted in lower energy consumption of 2.1 KWh.m −3 . Biodegradability improvement confirmed by BOD 5 /COD, average oxidation state (AOS) and carbon oxidation state (COS) indicators, Also GC chromatogram of the raw and treated wastewater showed removal and/or degradation of recalcitrant organics to more degradable and simpler compounds. [ABSTRACT FROM AUTHOR]

Effective biological treatment of high salt content wastewater requires consideration of both salt and organic toxicity. This study treated a synthetic saline wastewater containing NaCl (100 g L − 1 ) and 2,4-dimethylphenol (1.2 g L − 1 ) with a hybrid system consisting of a biological reactor containing spiral-coiled polymeric tubing through which the mixed feed was pumped. The tubing wall was permeable to the organic contaminant, but not to the salt, which allowed transfer of the organic into the cell-containing bioreactor contents for degradation, while not exposing the cells to high salt concentrations. Different grades of DuPont Hytrel polymer were examined on the basis of organic affinity predictions and experimental partition and mass transfer tests. Hytrel G3548 tubing showed the highest permeability for 2,4-dimethylphenol while exerting an effective salt barrier, and was used to verify the feasibility of the proposed system. Very high organic removal (99% after just 5 h of treatment) and effective biodegradation of the organic fraction of the wastewater (> 90% at the end of the test) were observed. Complete salt separation from the microbial culture was also achieved. [ABSTRACT FROM AUTHOR]

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 15.69 mg/L), 93.35% of TP (to 1.03 mg/L) and 90.02% of COD Cr (to 90.24 mg/L) were removed with 0.76 g/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. [ABSTRACT FROM AUTHOR]

Membrane fouling mitigation in a novel AF-MBMBR system (moving bed membrane bioreactor (10 L) coupled with anoxic biofilter (4 L)) 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 116.5 mg/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. [ABSTRACT FROM AUTHOR]

Background: Phenols are chemical compounds which are included in the high priority of pollutants by environmental protection agency (USEPA). The presence of high concentrations of phenols in wastewaters like oil refineries, petrochemical plants, olive oil, pesticide production and oil field operations contain high soluble solids (TDS) and in an olive oil plant, wastewater is acidic, high salty and phenol concentrations are in the range of 0.1-1%. Methods: Kinetic parameters were calculated according to Monod, Modified Stover- Kincannon, Hamoda and Haldane models. The influence of different initial phenol concentrations on the biodegradation rate was performed. The concentrations of phenol varied from 0 to 500 mg/l. Results: The value of Ki in saline phenolic wastewater in attached growth systems was higher than suspended growth systems that represented a higher phenol inhibition in suspended growth systems. It was obvious that the best model fitting the obtained data are Hamoda model and the Modified Stover-Kincannon model, having highest R² values of 0.991 and 1, respectively. The value of Ki in saline phenolic wastewater in attached growth system was higher than suspended growth systems which represented a higher phenol inhibition in suspended growth systems. Conclusions: Hamoda model and the Modified Stover-Kincannon model having highest R2 value of 0.991 and 1, respectively, and also predicting reasonable kinetic coefficient values. [ABSTRACT FROM AUTHOR]

In this study, the performance of 3,5-dimethyl-2,4-dichlorophenol (DCMX) degradation by a screened strain was investigated. 18S rDNA and the neighbor-joining method were used for identification of the isolated strain. The results of phylogenetic analysis and scanning electron micrographs showed that the most probable identity of the screened strain should be Penicillium sp. Growth characteristics of Penicillium sp. and degradation processes of DCMX were examined. Fourier transform infrared spectroscopy of the inoculated DCMX solution was recorded, which supported the capacity of DCMX degradation by the screened Penicillium sp. Under different salinity conditions, the highest growth rate and removal efficiency for DCMX were obtained at pH 6.0. The removal efficiency decreased from 100% to 66% when the DCMX concentration increased from 5 to 60 mg/L, respectively. Using a Box–Behnken design, the maximum DCMX removal efficiency was determined to be 98.4%. With acclimation to salinity, higher removal efficiency could be achieved. The results demonstrate that the screened Penicillium sp. has the capability for degradation of DCMX. [ABSTRACT FROM AUTHOR]

Levofloxacin (LEV), a fluoroquinolone antibiotic has been frequently observed in water resources imposing ecotoxicological effects on aquatic microbiota. The biodegradation and metabolic fate of LEV via a microalga, Scenedesmus obliquus in synthetic saline wastewater were investigated in this study. LEV removal (1 mg L − 1 ) by S. obliquus was relatively low in the synthetic wastewater without the addition of sodium chloride (NaCl); however, its removal increased significantly from 4.5 to 93.4% with increasing of its salinity from 0 to 171 mM NaCl. Kinetic studies showed that the removal rate constant (k) increased from 0.005 to 0.289 d − 1 and degradation half-life decreased from 272 to 5 d in the presence of NaCl (0–856 mM). The removal mechanism analysis showed that the major mechanism of NaCl mediated enhancement of LEV removal was the bioaccumulation and subsequent intracellular biodegradation of LEV in microalgal cells. Six metabolites were identified via gas chromatography–mass spectrometry analysis after biodegradation of LEV. A metabolic pathway was postulated with regard to various cellular biocatalytic reactions in S. obliquus , including decarboxylation, demethylation, dehydroxylation, side chain breakdown, and ring cleavage. [ABSTRACT FROM AUTHOR]

Anaerobic digestion was an important way to remove phenols from saline wastewater; however the anaerobic microorganisms were adversely affected by high concentration of salts. In order to clarify the performance robustness and microbial community structure for anaerobic digestion of saline phenolic wastewater, the UASB reactors were compared to treat phenolic wastewater under saline and non-saline conditions. The saline reactors were operated stably with phenols concentration increasing from 100 to 500 mg L −1 at 10 g Na + L −1 . The robustness of the saline reactors was weakened at 1000 mg phenols L −1 and 10 g Na + L −1 . However, the substrate utilization rates (SURs) for phenol, catechol, resorcinol, hydroquinone, and the specific methanogenic activity (SMA) of sludge were decreased by 95%, 85%, 97%, 78%, and 68%, respectively with phenols concentration enhancing from 1000 to 2000 mg L −1 . Moreover, the SURs for phenol, catechol, resorcinol, hydroquinone, and the SMA of sludge were reduced by 32%, 65%, 74%, 45%, and 59%, respectively with Na + concentration increasing from 10 to 20 g L −1 , in comparison with the values obtained at 10 g Na + L −1 and 1000 mg phenols L −1 . Finally, the analysis of microbial community structure demonstrated that phenols degraders were less tolerant to high concentrations of Na + and phenols than methanogens. [ABSTRACT FROM AUTHOR]

This study was aimed to investigate the effect of short-term salinity shock on unacclimated activated sludge with pressurized aeration. The activated sludge cultured with fresh wastewater under atmospheric pressure was transferred into a pressurized sequencing batch reactor (SBR) under 0.3 MPa gage pressure and exposed to saline wastewater with different salt concentrations. Another reactor was running in atmospheric environment as control reactor, with the same operation parameters except for the pressure. Substrate removal rate, specific oxygen uptake rate (SOUR) and soluble microbial products (SMP) were determined to reveal the influence rule at different salinities. The results indicated that for activated sludge without salt-resistant acclimation suffering a low strength salinity shock (below 2.0%), pressurized aeration could increase substrate removal rate and serve a positive function. SOUR of pressurized activated sludge was significantly higher than that of the control one ( p < 0.05). Concentrations of SMP in effluent from the pressurized reactor were also lower than that from the control reactor at 1.0% salinity. However, when activated sludge suffered high strength salinity impacts (2.5%, 3.0%), pressurized aeration would further deteriorate the treating effects, accompanied with lower SOUR and higher SMP concentrations compared to the conventional aeration method. [ABSTRACT FROM AUTHOR]

Treatment of a saline petrochemical wastewater with BOD 5 /COD ratio of less than 0.1 was investigated using a consortium consisted of three isolated salt-tolerant bacteria namely, Kocuria turfanesis , Halomonas alkaliphila and Pseudomonas balearica . Selected bacteria were isolated from petrochemical wastewater containing mineral salt mediums of 3% salinity. A lab-scale activated sludge bioreactor was used for startup in batch mode operation and after obtaining the MLSS concentration of about 3000 mg/L, the operation was changed to continuous flow mode to determine the biokinetic coefficients under different organic loading rates of 0.33–1.21 kg CODm −3 d −1 . The COD removal efficiency of 78.7%–61.5% was observed for treatment of real saline wastewater with a decreasing trend along with increasing the organic loading rate. In addition, results of kinetic investigation demonstrated that the yield(Y), endogenous decay coefficient (k d ), maximum reaction rate (K max ), maximum specific growth rate ( μ max ) and saturation constant ( K s ) were 0.54 mg VSS mg COD −1 , 0.014 day −1 , 1.23 day −1 , 0.66 day −1 , and 1315 mg L −1 , respectively. [ABSTRACT FROM AUTHOR]

The use of seawater and production of some chemicals produce a lot of saline wastewater. There are many treatment technologies for treating saline wastewater, such as physical, chemical and biological treatment. Biological treatment processes, especially the activated sludge processes, show advantages over other processes due to its cost-effectiveness and avoiding of secondary pollution, and many researches have been performed in this field. In this paper, the progresses of researches about the effect of salinity on activated sludge and its microorganisms were reviewed which included the effect of salinity on sludge structure and properties, microbial species and biomass, microbial physiological changes, and microbial molecules and cells. The mechanisms of the effect of salinity on sludge and the microbes were also summarized. Additionally, the feasibility of treatment of saline wastewater by using the acclimated salt tolerant activated sludge was evaluated. Future research needs were also proposed which include the study on the mechanisms of salt stress on activated sludge microorganisms at cellular and molecular levels and enzyme activity, screening and acclimation of salt-tolerant bacteria including halophiles, and optimizing of process parameters for saline wastewater treatment. [ABSTRACT FROM AUTHOR]

Membrane distillation (MD) has been identified as a promising technology to desalinate the hypersaline wastewaters from fracking and other industries. However, conventional hydrophobic MD membranes are highly susceptible to fouling and/or wetting by the hydrophobic and/or amphiphilic constituents in these wastewaters of complex compositions. This study systematically investigates the impact of the surface wetting properties on the membrane wetting and/or fouling behaviors in MD. Specifically, we compare the wetting and fouling resistance of three types of membranes of different wetting properties, including hydrophobic and omniphobic membranes as well as composite membranes with a hydrophobic substrate and a superhydrophilic top surface. We challenged the MD membranes with hypersaline feed solutions that contained a relatively high concentration of crude oil with and without added synthetic surfactants, Triton X-100. We found that the composite membranes with superhydrophilic top surface were robustly resistant to oil fouling in the absence of Triton X-100, but were subject to pore wetting in the presence of Triton X-100. On the other hand, the omniphobic membranes were easily fouled by oil-in-water emulsion without Triton X-100, but successfully sustained stable MD performance with Triton X-100 stabilized oil-in-water emulsion as the feed solution. In contrast, the conventional hydrophobic membranes failed readily regardless whether Triton X-100 was present, although via different mechanisms. These findings are corroborated by contact angle measures as well as oil-probe force spectroscopy. This study provides a holistic picture regarding how a hydrophobic membrane fails in MD and how we can leverage membranes with special wettability to prevent membrane failure in MD operations. [ABSTRACT FROM AUTHOR]

The impact of sea salt on the aeration coefficient kLa of fine-bubble aeration systems was investigated in clean water and in a model substance for simulating activated sludge. The investigations were carried out at laboratory and pilot scale. Sea salt was dosed in the form of artificial seawater, real seawater or simplified, by adding NaCl. The investigated media showed an increase of kLa with rising sea salt concentrations up to 10 g/L. The ratio between kLa and sea salt concentration is impaired by the air flow rate and the type of applied diffusers. Literature data show that the favourable effect of sea salt on kLa can also be found in the activated sludge of conventional municipal wastewater treatment plants. The results of this study allow the derivation of salt correction equations to be used in the design of fine-bubble aeration systems for taking into account the favourable impact of sea salt on kLa. By that means, a more precise design of respective systems will be enabled. [ABSTRACT FROM AUTHOR]

The complex non-linear behavior presented in the biological treatment of wastewater requires an accurate model to predict the system performance. This study evaluates the effectiveness of an artificial intelligence (AI) model, based on the combination of artificial neural networks (ANNs) and genetic algorithms (GAs), to find the optimum performance of an up-flow anaerobic sludge blanket reactor (UASB) for saline wastewater treatment. Chemical oxygen demand (COD) removal was predicted using conductivity, organic loading rate (OLR) and temperature as input variables. The ANN model was built from experimental data and performance was assessed through the maximum mean absolute percentage error (= 9.226%) computed from the measured and model predicted values of the COD. Accordingly, the ANN model was used as a fitness function in a GA to find the best operational condition. In the worst case scenario (low energy requirements, high OLR usage and high salinity) this model guaranteed COD removal efficiency values above 70%. This result is consistent and was validated experimentally, confirming that this ANN-GA model can be used as a tool to achieve the best performance of a UASB reactor with the minimum requirement of energy for saline wastewater treatment. [ABSTRACT FROM AUTHOR]

Constructed Wetlands (CWs) can be a valuable technology to treat high salinity wastewaters but it is not known their potential for removal of both nutrients and salt, and the type of plants to use. This study evaluated the effect of three plants on salt reduction and simultaneous nutrient removal in CWs microcosms with expanded clay and in hydroponic conditions. Initial values of the synthetic wastewater tested were EC = 15 dS m − 1 , SAR = 151; NH 4 + -N = 24 mg L − 1 ; PO 4 3 − -P = 30 mg L − 1 and NO 3 − -N = 34 mg L − 1 . With expanded clay CW removal efficiency for NH 4 + -N was 21, 88 and 85%, while for NO 3 – -N, it was 4, 56 and 68% for Spartina maritima , Juncus maritimus and Arundo donax , respectively. PO 4 3– -P was adsorbed completely in the expanded clay. However, in hydroponic system, removal efficiencies for NH 4 + -N were 53 and 50%, while PO 4 3– -P removal was 89 and − 14% for Spartina maritima and Juncus maritimus , respectively. Nutrient removal in planted microcosms was statistically higher than unplanted controls for NH 4 + -N and PO 4 3 − -P. However, salt removal was apparent in the hydroponic system only after 23 days of HRT, despite clear salt excretion visible in both Spartina maritima and Juncus maritimus . This study demonstrates the potential of two halophytic plants for saline wastewater treatment. However, salt removal in such a scenario could not be well documented and might prove to be impractical in future work. [ABSTRACT FROM AUTHOR]

In order to desalinate saline wastewater and achieve energy-efficient recovery of mixed salt (Na 2 SO 4 and NaCl), selectrodialysis (SED) stack with commercial monovalent selective anion exchange membranes (MVA) was utilized in this work. The experiments proved that the final concentration and purity of Na 2 SO 4 in Product could reach 0.84 mol·L−1 and 94.9%, respectively, under the optimal testing conditions (initial concentration of Product solution was 15 wt.% NaCl and the current density of 200 A·m−2). Simultaneously, the concentration and purity of NaCl in Brine achieved 1.90 mol·L−1 and 97.1%, respectively. In order to guide the engineering application, a formula was established to predict the termination time of SED process according to the applied current density. Furthermore, glycerol retention rate of the SED stack in Feed solution could reach more than 95%. And low energy consumption on Na 2 SO 4 and NaCl fractionation/concentration by 0.13–0.15 kWh·kg−1 at 200 A·m−2. Hence, this work illustrated the techno-economic feasibility of using SED for saline wastewater valorization. [Display omitted] • A single SED stack fractionated Cl−/SO 4 2− and simultaneously concentrated them more than 10 times with the purity over 95%. • A formula to predict the termination time of SED process was established. • High retention rate of glycerol and low energy consumption for salt concentration were obtained by SED process. [ABSTRACT FROM AUTHOR]

• The effect of Cl− on catalytic ozonation of organics was attributed to the transformation of ·OH to RCS. • The transformation of ·OH to RCS was affected by the type and concentration of organics. • Cl· does not contribute to organics degradation in the Co2+/O 3 process. • The electron-donating substituent weakened the inhibition of Cl− on benzoic acids degradation. Chloride ion (Cl−) is one of the most common anions in wastewater and saline wastewater, but its elusive effects on organics degradation are not clear yet in many cases. In this paper, the effect of Cl− on organic compounds degradation is intensively studied in catalytic ozonation of different water matrix. It was found that the effect of Cl− is almost completely reflected by transforming ·OH to reactive chlorine species (RCS), which is simultaneously competitive with organics degradation. The competition between organics and Cl− for ·OH directly determines the ratio of their consumption rate of ·OH, which depends on their concentration and reactivity with ·OH. Especially, the concentration of organics and solution pH may change greatly during organics degradation process, which will correspondingly influence the transformation rate of ·OH to RCS. Therefore, the effect of Cl− on organics degradation is not immutable, and may dynamically change. As the reaction product between Cl− and ·OH, RCS was also expected to affect the degradation of organics. But we found that Cl· had no significant contribution to the degradation of organics in catalytic ozonation, which may due to its reaction with ozone. Catalytic ozonation of a series of benzoic acid (BA) with different substituents in chloride contained wastewater was also investigated, and the results showed that the electron-donating substituents can weaken the inhibition of Cl− on BAs degradation, because they increase the reactivity of organics with ·OH, O 3 and RCS. [Display omitted] [ABSTRACT FROM AUTHOR]

Background and purpose:Moving Bed Biofilm Reactor is an aerobic attached growth with better biofilm thickness control, lack of plugging and lower head loss. Consequently, this system is greatly used by different wastewater treatment plants. High TDS wastewater produced petrochemical, leather tanning, sea food processing, cannery, pickling and dairy industries. The aim of this study was to evaluate the performance of MBBR in saline wastewater treatment. Materials and methods: In this study, 50 percent of a cylindrical reactor with 9.5 liter occupied media with 650 m2.m-3. In the first step, hydraulic regime was evaluated and startup reactor was done by sanitary sludge. Bio film was generated with glucose as the sole carbon source in synthetic wastewater. MBBR performance evaluation was performed in 6:30 and 8:45 with saline wastewater after bio film produced on media. Results: After 83 days of passing MBBR operation with saline wastewater containing 3000-12000 mg.L-1 TDS, organic loading rate of 2.2-3.5 kg/m3.d COD removal efficiency reached 80-92%. Conclusion: Moving bed biofilm reactor is effective in organic load elimination from saline wastewater.

Development of nitrification biomass that is growing attached on carried material was examined by measuring its ammonium or nitrit oxidation rates. Porous ceramic rings (36 pieces) were put into the fixed bed reactor (FBR ). The fixed bed reactor that was operated continuously for more than 500 day was continued to be operated at a HRT of 1 day, a DO of above 5 mg L-1 and pH of 8. Ammonia concentration in the feeding was 50 mg NH4+-N L-1. At days 1, 5, 12, 20, 33 and 50, six porous ceramic rings were taken out and then ammonia and nitrite removal rate by biofilm in the ceramic rings was separately measured. The measurement of rates was done in small cylindrical glass reactors with initial concentration of ammonia and nitrite was 10 mg N L-1. Until 50 days of incubation AORs were always higher than NORs. Additionally, ammonia oxidizers attach or grow faster in the porous ceramic material than nitrite oxidizers.

In order to find the optimal design characteristics of constructed wetlands for saline wastewater treatment, halotolerant microorganisms, isolated from the water of the Sečovlje salterns, were inoculated into the media of a pilot-scale constructed wetland (CW). The purpose of this study was to examine the influence of different salinities on the efficiency of halotolerant microorganisms for the removal of pollutants in order to evaluate the possibility of their employment for saline wastewater treatment. The efficiency of ammonium removal (34.1 %) was the highest with 0 % NaCl in wastewater and slightly lower (31.8) when 2 g/dm3 saccharose was added to aerated 1.5 % NaCl wastewater. The highest removal efficiency of chemical oxygen demand (COD) in the pilot-scale subsurface flow (SSF) CW was 83.6 % when saccharose (2 g/dm3) was added to aerated 1.5 % NaCl wastewater. It was found that removal efficiency of the pilot-scale constructed wetland with inoculated halo-tolerant microorganisms showed a higher sensitivity to aeration and the presence of saccharose than to variation of the salinity of the wastewater. It can be concluded that halotolerant microorganisms, isolated from the Sečovlje salterns, are not sensitive to the changes in salinity and are, therefore, an alternative in the treatment of saline wastewater with a constructed wetland. However, with aeration their efficiency could be further improved.

[Display omitted] • Permeate turbidity stayed at around 3–4 NTU when TMP was larger than −2.5 kPa. • The AnSFDMBR functioned continuously for 243 days with TMP-based backwashing. • EPSs did not accumulate in the dynamic layer during the fouling phase. • The impact of the total organic sulfur in EPSs on fouling was investigated. • Total organic sulfur and polysaccharides accumulated on mesh during fouling phase. A side-stream cross-flow anaerobic self-forming dynamic membrane bioreactor (AnSFDMBR) connected with an up-flow anaerobic sludge blanket (UASB) reactor was used to replace the UASB and middle settling tank in sulfate reduction, autotrophic denitrification, and nitrification integrated (SANI) process. To reduce the water and energy consumption for AnSFDMBR backwashing, the optimum condition of trans -membrane pressure (TMP)-based backwashing were investigated under sequential batch operations. Based on the optimum condition, a lab-scale AnSFDMBR was operated continuously for 243 days without a drop in flux, with good effluent quality. In the sequential batch operation study, AnSFDMBR showed no significant accumulation of total extracellular polymeric substances (EPSs) during 40 days of operation without backwashing. Polysaccharides slightly accumulated in the dynamic layer regardless of the final TMP and operation duration, indicating that TMP-based backwashing is suitable for the studied AnSFDMBR system. In long-term operation with TMP-based backwashing, total EPSs in dynamic layer to sludge ratio dramatically dropped during the fouling phase. According to the evaluation of total organic sulfur (TOS) in dynamic layer and mesh EPSs, it was found that TOS, mainly poly-sulfur generated in UASB reactor, played a critical role in fouling in saline wastewater treatment. TOS deposited on the mesh over 40% by weight of the total EPS in the fouling phase clearly led to system fouling. Additional sequential batch operations with different seawater percentages (%V/V) (control, 10%, 20%, 30% and 50%) demonstrated that the TOS accumulation on the mesh increased with time and salinity which also aligned with the long-term operation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Osmotic stress priming was elaborated the overpowering benefit on direct priming. • The salt environment mitigates the impact of organic loads. • Terephthalic acid is susceptible to salinity and organic loading. • Salinity causes degradation of toluate via terephthalate pathway. • Salt-tolerance genes differ in different salinity and organic load. 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 /m3. This study provided in-depth insight for microbial acclimation process of anaerobic priming of saline wastewater. [ABSTRACT FROM AUTHOR]

Selenium (Se) and tellurium (Te) wastewaters are typically characterized with higher salinities. Limited studies have determined microbial reduction of Se/Te oxyanions under saline conditions. This study reports bacterial reduction of Se(IV)/Te(IV) oxyanions at different salinities by a bacterial strain isolated from selenite-reducing halophilic aerobic granular sludge. Among several isolates, ORB-2 was consistent and efficient in reducing selenite and tellurite under saline conditions. This strain showed higher tolerance and grew rapidly in the presence of 10 mM selenite (790 mg L−1 Se(IV)) and 7.5 mM tellurite (957 mg L−1 Te(IV)). Growth was accompanied by Se(IV)/Te(IV) removal and conversion to cell-associated red/black elemental forms. Selenite (0.25–2 mM; 20–158 mg L−1 Se(IV)) removal efficiencies ranged between 82 and 96% with maximum removal by 48 h. For tellurite (0.25–2 mM; 32–254 mg L−1 Te(IV)), the removal efficiencies were 75–92% in 72 h. Growth of ORB-2 and concomitant removal of selenite or tellurite was observed in the presence of 2–8% NaCl. Biogenesis of Se(0) and Te(0) nanostructures was confirmed by micro-Raman spectroscopy. Extracted Se(0) and Te(0) nanostructures had a hydrodynamic diameter of 180 and 111 nm, respectively. Based on 16S rRNA gene sequencing, ORB-2 was identified as Alteromonas sp. Efficient conversion and association of biogenic Se(0)/Te(0) nanostructures with the cells under saline conditions shows promising use in bioremediation and scarce metal(loid) recovery. [Display omitted] • Isolated halophilic and selenite-reducing bacteria from aerobic granular sludge. • First report on bioreduction of Se(IV)/Te(IV) oxyanions by marine Alteromonas sp. • Efficient reduction of toxic selenite and tellurite under saline (2–8% NaCl) conditions. • Se(IV)/Te(IV) oxyanions were converted to microbe-associated Se(0)/Te(0) nanostructures. • Extracted biogenic Se(0)/Te(0) nanostructures formed stable colloidal suspension. [ABSTRACT FROM AUTHOR]

UV-E-chlorination/hematite nanoparticles (UV/E-Cl/HNs) as a heterogeneous photocatalytic activation of electrogenerated chlorine was assessed for the degradation of bisphenol A (BPA) as a new approach based on the generation of reactive chlorine and oxygen species. The prepared sample was characterized using multiple techniques, such as XRD, FTIR, FESEM, EDS, and BET-BJH. An excellent decontamination efficiency of 99.4% was achieved within 40 min of electrolysis under optimum conditions (pH of 5, HNs dosage 100 mg/L, current density of 20 mA/cm2, and NaCl concentration of 50 mM). The HOCl content was reduced more swiftly in the presence of ultraviolet (UV) irradiation and hematite, resulting in the production of oxidative radicals (i.e., •OH, Cl•, and Cl 2 • −). The scavenging experiments also verified the vital role of these radicals in oxidative treatment. The UV/E-Cl/HNs process is readily supplied with hydroxyl radicals through several mechanisms. Bicarbonate ions showed a noticeable inhibitory impact, whereas nitrate and sulfate anions only slightly affected BPA degradation. The HNs were a recoverable and stable catalyst for six cycles. Furthermore, the ECOSAR program predicted that the UV/E-Cl/HNs can be labeled as an environmental-friendly process. Eventually, reasonable degradation pathways were proposed based on the identified by-products through experimental and theoretical approaches. [Display omitted] • Electrogenerated chlorine was activated by UV and Fe 2 O 3 (HNs) simultaneously. • BPA was completed degraded by E-Cl/UV/HNs during 40 min electrolysis time. • Hydroxyl radicals (•OH) and dichlorine radical (Cl 2 •-) were the main responsible for BPA degradation. • The pathway of BPA degradation was evaluated and the toxicity of by-products was assessed. [ABSTRACT FROM AUTHOR]

A technique is proposed to treat saline hazardous wastewater by using marine activated sludge, cultivated with sea mud as seed. Since the developed marine activated sludge had phenol-tolerant microorganisms (MAS-1, MAS-2 and MAS-3) which originated from the ocean, it was envisaged that these bacteria could survive and breakdown phenol in saline environments. In this work, typical phenol-tolerant microorganisms were isolated from the marine activated sludge and identified. After a hierarchical acclimation process, the marine activated sludge was used to treat the industrial phenolic wastewater with high salinity. The marine activated sludge was able to break down phenol and other organic components effectively and efficiently in treating the wastewater with salinity of 5.7% w/v. The results showed a high removal of phenol (99%), COD (80%) and NH 3 -N (68%). [ABSTRACT FROM AUTHOR]

Saline wastewater originating from sources such as agriculture, aquaculture, and many industrial sectors usually contains high salts and other contaminants, which adversely affect both aquatic and terrestrial ecosystems. Therefore, the treatment of saline wastewater, for both salts and specific contaminant removal, has become a necessary task in many countries. Conventional methods (e.g., using physicochemical equipment, biological reactors, or a combination thereof) are feasible for treating most saline wastewaters (sometimes only for the removal of contaminants rather than the salts, e.g., biological reactors). However, the high cost of these techniques limits their application in many areas, especially in developing countries. For this reason, constructed wetlands (CWs) have been successfully used for treating a wide variety of wastewaters, and are eco-friendly and cost effective, and provide a potential alternative technology for saline wastewater treatment. The current review illustrates the latest knowledge on the use of CWs for treating saline wastewater. Though the function of plants and microorganisms in CWs is sometimes inhibited by salts, acceptable treatment effectiveness can still be achieved by screening halophyte, optimizing wetland structure and operation parameters, and by exploring the application of halophilic microorganisms. Factors influencing the effectiveness of CWs for saline wastewater treatment include; wetland structures, operation parameters, water pH, and temperature. Future studies are recommended on the removal of different types of target contaminants, strategies for strengthening the purification process, and on conducting large-scale field experiments under real-world conditions. [ABSTRACT FROM AUTHOR]

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 0.3 MPa for 71 days. 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, 50 g NaCl L −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. [ABSTRACT FROM AUTHOR]