Membrane Technology For Treatment Research Articles

Brackish water treatment for reuse using vacuum membrane distillation process

The availability of fresh water is vital for all human activities and in particular for improving living conditions, health and overall well-being. Pressure on scarce fresh water resources can be reduced by treating and reusing brackish water by advanced membrane treatment technologies. In this study, brackish water originating from effluent discharge of a local coal mine, seawater, groundwater and salt water swimming pool is treated by a laboratory-scale vacuum membrane distillation (VMD) system. VMD is an emerging technology that has the potential to become as important as conventional distillation system and aims to remove particles and dissolved impurities by evaporation and condensation techniques that mimic what occurs in nature. This study validates the mathematical modeling of the transport mechanisms used in the VMD process using data collected for different experimental situations. The response of flux rate to various process operating parameters, including pressure, temperature, flow rate and salinity concentration, is also demonstrated. This thermally driven separation process enables to remove 99.9% of total dissolved solids (TDS) from brackish water. The quality of the permeate water from all four water sources studied is of acceptable standards for potable use; however, it requires mineralization efforts before direct consumption.

Membrane-based treatment for tanning wastewaters

Tanning wastewater was subjected to different unit operations to select the best treatment sequences. Textile membrane filtration (TMF), microfiltration (MF), and ultrafiltration (UF) were complemented by screening, flocculation or flotation operations. The general chemical characterization determined that the wastewater had a high organic load. The ecotoxicological study classified the wastewater as highly ecotoxic. The sequence of screening – TMF – UF was found to be the optimal treatment for wastewaters of the first and second soaking stages, while the sequence of screening – TMF – flotation – UF proved to be adequate for the liming wastewater concerning productivity and water quality. Larger pore sizes MF membrane or higher molecular weight cut off (MWCO) UF membranes with higher permeability to pure water showed lower permeation fluxes for tanning wastewater. After membrane treatments, a decrease in the ecotoxicity was measured. The use of membrane treatment technology showed to be promising in removing organic pollutants and allowing the reuse of water and chemicals in the process.

The role of membrane technologies in water reuse applications

The world is not running out of water; the relatively fixed quantity is becoming too contaminated for many applications. In many cases, it is possible to collect and treat this contaminated water and reuse it. The crossflow, pressure-driven membrane technologies of microfiltration, ultrafiltration, nanofiltration, and reverse osmosis play an important role in water reuse activities. This study identifies the sources of “used” water (residential, commercial, industrial, and municipal), defines the contaminant parameters, addresses the appropriate membrane treatment technologies, and details system designs necessary to produce water for specific applications, such as potable.

Effect of wastewater colloids on membrane removal of antibiotic resistance genes

Recent studies have demonstrated that wastewater treatment plants (WWTPs) significantly alter the magnitude and distribution of antibiotic resistance genes (ARGs) in receiving environments, indicating that wastewater treatment represents an important node for limiting ARG dissemination. This study examined the potential for membrane treatment of microconstituent ARGs and the effect of native wastewater colloids on the extent of their removal. Plasmids containing vanA (vancomycin) and blaTEM (β-lactam) ARGs were spiked into three representative WWTP effluents versus a control buffer and tracked by quantitative polymerase chain reaction through a cascade of microfiltration and ultrafiltration steps ranging from 0.45 μm to 1 kDa. Significant removal of ARGs was achieved by membranes of 100 kDa and smaller, and presence of wastewater colloids resulted in enhanced removal by 10 kDa and 1 kDa membranes. ARG removal was observed to correlate significantly with the corresponding protein, polysaccharide, and total organic carbon colloidal fractions. Alumina membranes removed ARGs to a greater extent than polyvinylidene fluoride membranes of the same pore size (0.1 μm), but only in the presence of wastewater material. Control studies confirmed that membrane treatment was the primary mechanism of ARG removal, versus other potential sources of loss. This study suggests that advanced membrane treatment technology is promising for managing public health risks of ARGs in wastewater effluents and that removal may even be enhanced by colloids in real-world wastewaters.

Operational experience of the brackish water reverse osmosis of the water treatment plant in Sant Joan Despí

To ensure correct operation of any facility that uses membrane treatment technology (ultrafiltration, reverse osmosis, etc.) requires a set of maintenance and cleaning operations, which allow correct operation and optimum duration of membranes, and also ensure the quality of water produced. In 2009, the existing drinking water treatment plant in Sant Joan Despí started operating a treatment combining ultrafiltration and reverse osmosis technologies to ensure compliance with the health limits set by the Spanish Royal Decree RD140/2003. Specific antiscalant was developed especially for controlling calcium carbonate, calcium phosphate, and barium sulfate scales, which are the most problematic insoluble species in the brine of the reverse osmosis at the water treatment plant in Sant Joan Despí. Specific software was developed to calculate the optimum dose of antiscalant based on the feedwater chemistry, the temperature, and the RO plant’s conversion, thus minimizing operating costs. Furthermore, Adiconline RO was installed to measure online and in real time the concentration of antiscalant in the feed. This system analyzes the active ingredients of the antiscalant and allows controlling the dosage level of antiscalant at the required level. The operational data of the RO and the results of autopsy of different elements confirmed that actions taken had been appropriate to provide efficient operation.

Analysis of energy usage at membrane water treatment plants

The production and supply of potable water using seawater and brackish water desalination, and reclamation of wastewater for reuse by membrane processes has seen a rapid growth in the last decade to meet the growing demands of water in many regions of the world. Energy consumption plays a critical role in the selection of appropriate membrane treatment technologies for potable water production. For example, wastewater reclamation for reuse by membrane filtration is more attractive than reverse osmosis (RO) desalination due to much lower specific energy consumption and materials costs. Specific energy consumption reflects the energy efficiency of a membrane process but is not a realistic indictor for comparing the power requirements of different membrane processes. A parameter called, comparative-kW, is proposed for comparing the power requirements of various membrane based plants operating under a wide range of product water recoveries. Several cases are analysed to illustrate the usefulness of comparativ...

Application of indigenous inorganic sorbents in combination with membrane technology for treatment of radioactive liquid waste from decontamination processes

Abstract The purpose of the work was to improve the process for treatment of liquid radioactive waste containing complexing agents, which are generated during the decontamination operations. We performed some experiments using simulated waste solutions like secondary waste from the modified CANDEREM process (Canadian Decontamination and Remediation Process) and secondary waste from the modified CANDECON process (Canadian Decontamination Process). To improve efficiency and economics of the process it was proposed to treat the waste by combining the sorption of radionuclides on natural inorganic sorbents (zeolites) with membrane filtration. Standard procedures are applied to compare the sorption of radionuclides on different sorbent forms-determination of the ion exchange capacity, construction of sorption isotherms, determination of the distribution coefficients, and kinetics experiments. To check the influence of converting the sorbents to various cationic forms on their sorption properties, distribution coefficients of 137Cs and 57Co on natural zeolites from local deposits converted to NH4 +, Na+ or H+ forms were determined. The results obtained show that the distribution coefficients of 137Cs on the materials converted to Na+ form are higher than for the remaining forms studied [1]. The parameters of Langmuir, Freundlich and Dubinin–Radushkevich adsorption isotherms have been determined using sorption data. The Dubinin–Radushkevich model shows better correlation between the theoretical and experimental data for 137Cs sorption on natural zeolites from local deposits converted to NH4 + and H+ forms than Langmuir and Freundlich equations. Kinetic studies were carried out with various zeolite forms. The sorbents studied are natural zeolites from local deposits (Marsid-Romania). The batch sorption kinetics has been tested for pseudo-second order reaction. The pseudo-second order model fits the experimental data well for all of the systems studied.

Membrane-based treatment for tanning wastewatersA paper submitted to the Journal of Environmental Engineering and Science.

Tanning wastewater was subjected to different unit operations to select the best treatment sequences. Textile membrane filtration (TMF), microfiltration (MF), and ultrafiltration (UF) were complemented by screening, flocculation or flotation operations. The general chemical characterization determined that the wastewater had a high organic load. The ecotoxicological study classified the wastewater as highly ecotoxic. The sequence of screening–TMF–UF was found to be the optimal treatment for wastewaters of the first and second soaking stages, while the sequence of screening–TMF–flotation–UF proved to be adequate for the liming wastewater concerning productivity and water quality. Larger pore sizes MF membrane or higher molecular weight cut off (MWCO) UF membranes with higher permeability to pure water showed lower permeation fluxes for tanning wastewater. After membrane treatments, a decrease in the ecotoxicity was measured. The use of membrane treatment technology showed to be promising in removing organic pollutants and allowing the reuse of water and chemicals in the process.

Long Term Application of Bioreactor and Membrane Technologies for Treatment of Metalworking Fluid Wastewaters

Long Term Application of Bioreactor and Membrane Technologies for Treatment of Metalworking Fluid Wastewaters

Comparison of surface water pre-treatments for ultrafiltration

The River Trent runs through both Severn Trent and Anglian Water regions, and has been identified as a potential new water resource for both companies. It contains treated effluent from 4 million people and industry in the Midlands. As part of an ongoing project, comparing conventional water treatment processes with membrane technologies for treatment of the River Trent to potable standards, pre-treatment processes for ultrafiltration are being compared. Depth filtration gave the best particulate removal, whereas the package filters performed as per the manufacturers' specifications. Package filters tended to increase the small particulate fraction between 2-5 μm, so although these may remove problems caused by large particles they could aggravate pore blocking and membrane penetration related fouling. There is a direct trade off between the capital cost of pre-treatments vs. increased running costs (higher TMPs, more frequent cleaning, extensive cleaning requirements).

Pilot Scale UF and RO Studies on Water Reuse in Corrugated Board Industry

The coloured effluents from pulp and paper mill industry are treated anaerobically and/or aerobically by a two stage membrane system with high efficiency. Three different types of membranes (UF and RO (BW and SW)) were used in the experiments. Surface area of each membrane was 2 m2. The combination of ultrafiltration (UF) and reverse osmosis (RO) treatment achieve a very high removals of COD (98-99%), colour and conductivity. At the end of a single pass with RO using seawater (SW) membrane, the initial COD, colour and conductivity values were reduced to 10–20 mg/l, 0–100 Pt-Co units and 200–300 μs/cm, respectively. The influent, UF permeate, RO permeates for brackish water (BW) and seawater (SW) membranes were 6000–6700 μs/cm, 5500–5900 μs/cm and 200–300 μs/cm, respectively. Excellent conductivity rejections were obtained in the UF and RO membrane systems. Almost complete colour removals were achieved in the RO experiments with SW membranes. RO studies with BW membranes were also performed with the same permeate from the first stage UF study. The observed flux has declined with time and membranes were cleaned periodically to maintain a constant flux. Applying this advanced membrane treatment technology, it is clear that about 60 percent of the process water can be recycled in the investigated industry.

Pilot scale UF and RO studies on water reuse in corrugated board industry

The coloured effluents from pulp and paper mill industry are treated anaerobically and/or aerobically by a two stage membrane system with high efficiency. Three different types of membranes (UF and RO (BW and SW)) were used in the experiments. Surface area of each membrane was 2 m2. The combination of ultrafiltration (UF) and reverse osmosis (RO) treatment achieve a very high removals of COD (98–99%), colour and conductivity. At the end of a single pass with RO using seawater (SW) membrane, the initial COD, colour and conductivity values were reduced to 10–20 mg/1, 0–100 Pt-Co units and 200–300 μs/cm, respectively. The influent, UF permeate, RO permeates for brackish water (BW) and seawater (SW) membranes were 6000–6700 μs/cm, 5500–5900 μs/cm, 1000–1500 μs/cm and 200–300 μs/cm, respectively. Excellent conductivity rejections were obtained in the UF and RO membrane systems. Almost complete colour removals were achieved in the RO experiments with SW membranes. RO studies with BW membranes were also performed with the same permeate from the first stage UF study. The observed flux has declined with time and membranes were cleaned periodically to maintain a constant flux. Applying this advanced membrane treatment technology, it is clear that about 60 percent of the process water can be recycled in the investigated industry.

Use of Membrane Technology in Florida

Florida water suppliers have been using membrane treatment technology for decades. The first membrane systems were used in isolated instances for desalinating limited amounts of seawater; costs were high and the technology was relatively unperfected. Rapid development of coastal areas, with their abundant supplies of brackish water, has led many larger water suppliers to turn to membrane systems to meet increasing demand. Advances in membrane technology, its ability to produce high‐quality water, and the flexibility offered by modular expandability have enhanced the cost‐effectiveness of reverse osmosis and electrodialysis as treatment options. Almost 100 Florida water systems are now using membrane processes to produce a total of nearly 50 mgd, and existing plans call for total production capacity to more than triple.