High Salinity Wastewater Treatment Research Articles

Treatment of high salinity wastewater using CWPO process for reuse

AbstractA high salinity wastewater from epoxy resin was treated with the catalytic wet peroxide oxidation (CWPO) process, so that it can be reused as the chlor-alkali process feedstock. Both bench and pilot scale trials were conducted out in this research. The effect of oxidant (hydrogen peroxide) and catalyst (ferrous sulfate) dosages, and their dosing methods, pH value, temperature, and reaction time on TOC removal by the CWPO process were evaluated through bench experiment. The obtained optimal reaction conditions for the CWPO process were as following: H

Applicability of an integrated moving sponge biocarrier-osmotic membrane bioreactor MD system for saline wastewater treatment using highly salt-tolerant microorganisms

Abstract Osmotic membrane bioreactors (OsMBRs) are a recent breakthrough technology designed to treat wastewater. Nevertheless, their application in high-salinity wastewater treatment is not widespread because of the effects of saline conditions on microbial community activity. In response, this study developed an integrated sponge biocarrier-OsMBR system using highly salt-tolerant microorganisms for treating saline wastewater. Results showed that the sponge biocarrier-OsMBR obtained an average water flux of 2 L/m 2 h during a 92-day operation when 1 M MgCl 2 was used as the draw solution. The efficiency in removing dissolved organic compounds from the proposed system was more than 99%, and nutrient rejection was close to 100%, indicating excellent performance in simultaneous nitrification and denitrification processes in the biofilm layer on the carriers. Moreover, salt-tolerant microorganisms in the sponge biocarrier-OsMBR system worked efficiently in salt concentrations of 2.4%. A polytetrafluoroethylene MD membrane (pores = 0.45 μm) served to regenerate the diluted draw solution in the closed-loop system and produce high-quality water. The moving sponge biocarrier-OsMBR/MD hybrid system demonstrated its potential to treat salinity wastewater treatment, with 100% nutrient removal and 99.9% conductivity rejection.

Open porous hydrophilic supported thin-film composite forward osmosis membrane via co-casting for treatment of high-salinity wastewater

High-performance thin film composite (TFC) forward osmosis (FO) membranes with a low degree of internal concentration polarization (ICP) are critical for concentrating high-salinity wastewaters. This report focuses on the preparation of TFC FO membranes via a sacrificial approach. In order to improve the FO flux, hydrophilicity and morphology of the support membrane were mainly investigated. The hydrophilicity of the polysulfone (PSF) substrate was tuned by blending with sulfonated poly (ether ether ketone) (SPEEK), and the resulting SPEEK blended PSF membrane was denoted as SPSF substrate. The pore structure of the SPSF membrane was tailored by the application of a co-casting technique, which yielded a TFC membrane with a structure parameter (S) of 191μm. In contrast, the TFC membranes based on the PSF and SPSF substrates through single layer casting showed S values of 527μm and 361μm, respectively. These results indicate that the combined hydrophilicity and open pore structure are responsible for the lowered S value. Further application of the hydrophilic substrate based TFC membranes in the treatment of high salinity wastewaters (10wt%) demonstrated the higher initial water flux (28.3L/m2·h) with a water recovery rate of 53.2% in comparison to the TFC membrane based on the pristine PSF through the single layer casting. This new method paves a way to generate high-performing FO membranes.

Hybrid RED/ED system: Simultaneous osmotic energy recovery and desalination of high-salinity wastewater

Reverse electro-dialysis (RED) is a potentially available technology to harvest salinity gradient power, which can be extracted from high-salinity wastewater in industrial processes. This study proposes a hybrid RED/ED system to simultaneous osmotic energy recovery and complete desalination in the phenol-containing wastewater treatment process. Experimental investigation on standalone ED system reveals that the high stack resistance, resulting from the salinity difference between both feed streams, accounts for the inefficient desalination performance in early stages, which implies potential implication of RED as a pre-desalination process with natural driving force to reduce the salinity difference. Pre-desalination rate is related to power generation in RED stage and energy saving in ED stage under optimal operation conditions. Compared with artificial seawater, greater power generation is produced by using phenol-containing wastewater as the high-salinity stream. Economic analysis suggests that average power generation and limiting wastewater treatment capacity can provide insightful guidelines for the design and improvement of the hybrid system. Control conditions are listed as a fundamental criterion to search for potentially applicable wastewater systems in the hybrid system. Therefore, hybrid RED/ED system can realize triplex advantages of salinity energy usage, high-valued resource reclamation, and low-energy desalination in high-salinity wastewater treatment processes.

Anoxic oscillating MBR for photosynthetic bacteria harvesting and high salinity wastewater treatment

In this study, photosynthetic bacteria (PSB) were first harvested by MBR with pendulum type oscillation (PTO) hollow fiber module in succession and on a large scale. Based on unique properties of PSB, PSB/MBR was successfully applied for high-salinity wastewater treatment. Compared with control PSB-MBR (CMBR), PSB/PTO-MBR exhibited more excellent organics removal, which was mainly attributed to much higher biomass production for utilization. Meanwhile, the influence of light irradiation and aeration on activity of PSB was investigated in detail. Results showed that PTO-MBR with 12h light irradiation proved to be a promising and economical alternative. The cycle of dark/light and anoxic had a positive effect on PSB cultivating. Moreover, PTO-MBR exhibited much higher flux than CMBR even if large amounts of biomass existed, which demonstrated that the strong shear stress on interface of liquid-membrane played important roles on membrane fouling reduction.

Effect of high salinity on yeast activated sludge reactor operation.

Yeast activated sludge was developed and operated at salinities of 0, 15, 30, 45, and 60 g/l NaCl. The kinetics of the various sludges degrading a wastewater with glycerol as the carbon source were determined. Inhibition due to salinity was analyzed and it was found that the limiting concentration of NaCl is 120 g/l. Salinity affects the maximum growth rate of the sludge. Reactors were exposed to shock salinity changes. Salt shocks affected maximum growth rate of the reactors but treatment was still effective. The effect of pH adjustment was investigated and it was determined that hourly adjustments of pH led to the most effective treatment outcomes. Finally, DNA of the reactors was investigated. Although Scheffersomyces spartinae (Debaryomycetaceae family) was clearly more suited to the high salinity environment than other yeast species, even at high salinity the number of species was diverse. This suggests the potential to use a number of yeast species for high salinity wastewater treatment.

Use of horizontal subsurface flow constructed wetlands to treat reverse osmosis concentrate of rolling wastewater

ABSTRACTAccording to the characteristics of the reverse osmosis concentrate (ROC) generated from iron and steel company, we used three sets of parallel horizontal subsurface flow (HSF) constructed wetlands (CWs) with different plants and substrate layouts to treat the high-salinity wastewater. The plant growth and removal efficiencies under saline condition were evaluated. The evaluation was based entirely on routinely collected water quality data and the physical and chemical characteristics of the plants (Phragmites australis, Typha latifolia, Iris wilsonii, and Scirpus planiculmis). The principal parameters of concern in the effluent were chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP). The results showed that the CWs were able to remove COD, TN, and TP from ROC. S. planiculmis was not suitable for the treatment of high-saline wastewater. The sequence of metals accumulated in CW plants was K>Ca>Na>Mg>Zn>Cu. More than 70% of metals were accumulated in the aboveground of P. australis. The CW filled with gravel and manganese ore and planted with P. australis and T. latifolia had the best performance of pollutant removal, with average removal of 49.96%, 39.45%, and 72.01% for COD, TN, and TP, respectively. The effluent water quality met the regulation in China. These results suggested that HSF CW planted with P. australis and T. latifolia can be applied for ROC pollutants removal.

Membrane distillation of high salinity wastewater from shale gas extraction: effect of antiscalants

AbstractAlthough shale gas has become an important source of natural gas, it has problems associated with water pollution by producing high salinity wastewater (i.e. TDS > 100,000 mg/L). Membrane distillation (MD) can be applied to treat such wastewater but may suffer from fouling due to scale formation. Accordingly, this study focused on the use of antiscalants to retard scale formation in MD process for the treatment of high salinity wastewater. Experiments were performed using a laboratory-scale direct contact MD (DCMD) system. Seven different antiscalants were applied to the simplified synthetic wastewater. The results were analyzed using a simple theoretical model. It was found that the abilities to retard scale formation were different for different antiscalants. The difference in chemical structures of the antiscalants was attributed to the changes in their effect on scale prevention. Moreover, the mechanisms of flux decline seem to be different in the presence of antiscalants. Not only surface blo...

Graphene-based Recyclable Photo-Absorbers for High-Efficiency Seawater Desalination.

Today's scientific advances in water desalination dramatically increase our ability to transform seawater into fresh water. As an important source of renewable energy, solar power holds great potential to drive the desalination of seawater. Previously, solar assisted evaporation systems usually relied on highly concentrated sunlight or were not suitable to treat seawater or wastewater, severely limiting the large scale application of solar evaporation technology. Thus, a new strategy is urgently required in order to overcome these problems. In this study, we developed a solar thermal evaporation system based on reduced graphene oxide (rGO) decorated with magnetic nanoparticles (MNPs). Because this material can absorb over 95% of sunlight, we achieved high evaporation efficiency up to 70% under only 1 kW m(-2) irradiation. Moreover, it could be separated from seawater under the action of magnetic force by decorated with MNPs. Thus, this system provides an advantage of recyclability, which can significantly reduce the material consumptions. Additionally, by using photoabsorbing bulk or layer materials, the deposition of solutes offen occurs in pores of materials during seawater desalination, leading to the decrease of efficiency. However, this problem can be easily solved by using MNPs, which suggests this system can be used in not only pure water system but also high-salinity wastewater system. This study shows good prospects of graphene-based materials for seawater desalination and high-salinity wastewater treatment.

Exploration and optimization of two-stage vacuum membrane distillation process for the treatment of saline wastewater produced by natural gas exploitation

Membrane distillation has recently been recognized as the emerging foremost membrane separation technology for applications in industrial wastewater treatment and desalination. By employing polypropylene hollow fiber membrane, this study firstly performed the optimization of the vacuum membrane distillation (VMD) process. Subsequently, the feasibility of the VMD for the treatment of real saline wastewater produced by natural gas exploitation was investigated under optimized operation conditions. An ultrahigh water flux of 30.4kg/(m2·h) with a salt rejection rate of 99.8% was achieved. Membrane fouling was observed during experiment, which induced a sharp decrease in permeate flux and salt rejection. Thus, membrane was cleaned and the VMD performance was recovered. The membrane cleaning intervals were shortened when wastewater became concentrated. After being treated for 110h, the wastewater was filtered and then further concentrated for another 20h through the second-stage VMD. The final conductivity of wastewater feed reached 230,000μS/cm, indicating a total water recovery rate of 88.6%. This study successfully treated wastewater produced by natural gas exploitation via a newly developed two-stage VMD process, which would provide an insightful guideline for its further industrial applications and may open up alternative options of effective technologies for the treatment of high-saline wastewater.

Entrapped Biomass in Membrane Bioreactor for the Treatment of High-Saline Pharmaceutical Wastewater

Entrapped Biomass in Membrane Bioreactor for the Treatment of High-Saline Pharmaceutical Wastewater

Salt inhibition on anaerobic treatment of high salinity wastewater by upflow anaerobic sludge blanket (UASB) reactor

The adverse effects of salt concentration on anaerobic treatment of synthetic high salinity wastewater were investigated using four lab-scale upflow anaerobic sludge blanket reactors at different salt (NaCl) concentrations. The reactors were inoculated with granular sludge previously not adapted to salinity, and they were fed with synthetic wastewater containing the salt concentrations of 0, 10, 25, and 50 g L−1 NaCl. Hydraulic retention time and organic loading rate were kept constant at 1 d and 2 kg chemical oxygen demand (COD) m−3 d−1, respectively. Salt inhibition on the COD removal rate and efficiency, methane production were determined. COD removal rate and efficiency significantly decreased when the salt concentration in the feed increased to 50 g L−1 from 0. The maximum COD removal was obtained at salt concentration of 10 g L−1.

Treatment of High Salinity Wastewater Using an Intermittently Aerated Membrane Bioreactor

In this study, high salinity wastewater was treated by an intermittently aerated membrane bioreactor (IAMBR) and the salinity loadings were set at 35g/L. The activated sludge was inoculated from the municipal wastewater treatment plant. The influent salinity level gradually increased from 0 to 35 g/L with every 5 g/L. With the salt concentration increased to 35 g/L, the performance of IAMBR was significantly affected by higher salinity. The removal efficiencies of the total organic carbon (TOC), ammonia nitrogen (NH4+-N) and total nitrogen (TN) were about 83%, 70% and 51%, respectively. It is indicated that the domestication of activated sludge from municipal wastewater treatment cannot obtain a better performance at high salinity.

Energy consumption in desalinating produced water from shale oil and gas extraction

On-site treatment and reuse is an increasingly preferred option for produced water management in unconventional oil and gas extraction. This paper analyzes and compares the energetics of several desalination technologies at the high salinities and diverse compositions commonly encountered in produced water from shale formations to guide technology selection and to inform further system development. Produced water properties are modeled using Pitzer's equations, and emphasis is placed on how these properties drive differences in system thermodynamics at salinities significantly above the oceanic range. Models of mechanical vapor compression, multi-effect distillation, forward osmosis, humidification–dehumidification, membrane distillation, and a hypothetical high pressure reverse osmosis system show that for a fixed brine salinity, evaporative system energetics tend to be less sensitive to changes in feed salinity. Consequently, second law efficiencies of evaporative systems tend to be higher when treating typical produced waters to near-saturation than when treating seawater. In addition, if realized for high-salinity produced waters, reverse osmosis has the potential to achieve very high efficiencies. The results suggest a different energetic paradigm in comparing membrane and evaporative systems for high salinity wastewater treatment than has been commonly accepted for lower salinity water.

Screening of the Salt Tolerant Plants for High Salinity Wastewater Treatment by the Artificial Wetland

Tanggu, as the core area in Binhai New Area, is currently one of the fastest developing areas in Tianjin City. Because of the saline alkali soil and other natural conditions, wastewater reuse is restricted by high salinity. The removal of high concentration chloride by Phragmites australis, Suaeda salsa, Artemisia anethifolia Weber, Iris wilsonii, Salicornia europaea, and Spartina anglica in light polluted water was compared by the simulation experiment of artificial wetland. The plants with stronger removal ability were selected and the ecosystem condition with maximum removal rate was determined. The results showed that the removal effect of chloride by salt-tolerant plants in artificial wetland was: Phragmites australis Suaeda salsa Artemisia anethifolia Iris wilsonii Salicornia europaea Spartina anglica. The removal efficiency reached balance after four days. This study provided a scientific basis for the high salinity wastewater treatment by artificial wetland.

Schwertmannite as a new Fenton-like catalyst in the oxidation of phenol by H2O2

In this study, schwertmannite was prepared through a hydrothermal method and used as a new Fenton-like catalyst in the oxidation of phenol by H2O2. The synthesized iron oxide had a formula of Fe8O8(OH)4.5(SO4)1.75 with a weak crystalline structure as well as a high specific surface area of 325.52m2g−1. However, schwertmannite has not been used as a Fenton-like catalyst so far, and its catalytic mechanism in the oxidation of phenol is still unknown. This study confirmed that schwertmannite had a good catalytic activity in the oxidation of phenol via a OH radical mechanism. The free radicals could be generated on the schwertmannite surface by Fe(III) species and in bulk solution by dissolved Fe(III) over a wide pH range. The synthesized schwertmannite also showed a high catalytic ability in the oxidation of phenol in the presence of 0.5M nitrate, chloride or sulfate anions at initial pH 5.0, indicating its potential application in the treatment of high salinity wastewater. In addition, phenol removal percentage could still reach 98% after schwertmannite was successively used for 12 cycles, indicating the good reusability of this catalyst, although a phase transformation of schwertmannite to goethite was observed.

High salinity wastewater treatment

The shock effect, survival and ability of activated sludge to acclimatize to wastewater containing different concentrations of NaCl and Na2SO4 were investigated under laboratory conditions. To accomplish this, the potential penetration of a sewage system by seawater as a consequence of storm surge flooding was simulated. The experiments were conducted using activated sludge taken from the aeration tank of a communal wastewater treatment plant and adding different concentrations up to 40 g/L of NaCl and 4.33 g/L of Na2SO4. The effects of salinity on the activated sludge were monitored for 5 weeks based on the values of pH, dissolved oxygen, total suspended solids, volatile suspended solids, sludge volume, sludge volume index, electrokinetic potential, respirometric measurements and enzymatic activity. The addition of salt sharply reduced or completely inhibited the microbial activity in activated sludge. When salt concentrations were below 10 g/L NaCl, microorganisms were able to acclimatize in several weeks and achieve the same initial activity as in raw sludge samples. When the salt concentration was above 30 g/L NaCl, the acclimatization process was very slow or impossible.

Ternary cycle treatment of high saline wastewater from pesticide production using a salt-tolerant microorganism

The material of this study is provided by biological aerobic treatment of high saline wastewater from pesticide production. The microorganism used for biodegradation has been identified by gene-sequencing as a strain of Bacillus sp. SCUN. The best growth condition for the salt-tolerant microorganism has been studied by varying the pH, immobilized microorganism dosage and temperature conditions. The feasibility of pretreating wastewater in ethyl chloride production containing 4% NaCl has been discussed. It was found that under the pH range of 6.0-8.0, immobilized microorganism dosage of 1.5 g/L, temperature of 30 °C, and NaCl concentration of 0-3%, the microorganism achieves the best growth for biodegradation. After domestication, the strain can grow under 4% NaCl. This salt-tolerant microorganism is effective in the pretreated high saline wastewater. With a newly developed ternary cycle treatment, the chemical oxygen demand removal approaches 58.3%. The theoretical basis and a new method for biological treatments in biodegradation of high saline wastewater in ethyl chloride production are discussed.

Comparison between MBR and A/O processes treating saline wastewater

Membrane bioreactor MBR and A/O processes are employed to treat saline wastewater. The mixed liquid suspended solids in the MBR and A/O were 7,000 and 3,500 mg/L, respectively. With the same influents, MBR process was more suitable for the treatment of high-salinity wastewater. The chemical oxygen demand and ammonia removal efficiencies were 75 and 82%, respectively, with the salinity of 24.5 g/L. Both were higher than that through the A/O process. Autotrophic nitrifying bacteria could be enriched and had sufficient time to accommodate to the saline environment. Both sludge volume index (SVI) decreased with salinity increment. However, the SVI of MBR dropped more than that of A/O, which indicated a better sludge-settling property in the MBR process. Filamentous bacteria existed in the A/O reactor and made the sludge-settling property worse than that in the MBR process. Membrane fouling occurred inevitably during the MBR process. Microbes and organics could be removed by combined physical and chemical cleaning.

The Effect of Feed Steam on MED Dealing with High-Salinity Wastewater

The treatment of high salinity wastewater treatment in refinery has been widely noticed due to more and more stringent laws and regulations. In the paper, in order to deal with the high salinity wastewater efficiently, a MED process was performed, and mathematical modeling was established to discuss the effect of feed steam on MED dealing with high-salinity wastewater. The results indicated that the temperature of steam produced by different low-temperature heat and pressures of the steam could all affect the MED system obviously. For example, the mass of pure water increased slightly with the increase of feed steam temperature in 3 effects system. With the same pressure feed steam, more mass of pure water was produced by fewer effects system, etc. This paper would provide a very useful reference for the high-salinity wastewater reduction via MED process in petroleum refinery.