Evaluation of enhanced nanofiltration membranes for improving magnesium recovery schemes from seawater/brine: Integrating experimental performing data with a techno-economic assessment.

The global demand for valuable metals and minerals necessitates the exploration of alternative, sustainable approaches to mineral recovery. Seawater mining has emerged as a promising option, offering a vast reserve of minerals and an environmentally friendly alternative to land-based mining. Among the various techniques, Nanofiltration (NF) has gained significant attention as a preliminary treatment step in Minimum Liquid Discharge (MLD) and Zero Liquid Discharge (ZLD) schemes. This study focused on the potential of two underexplored commercial polyamide based NF membranes, Synder NFX and Vontron VNF1, with enhanced divalent over monovalent separation factors, in optimizing the extraction of magnesium hydroxide (Mg(OH)2) from seawater and seawater reverse osmosis (SWRO) brines. The research encompassed a thorough characterization of the membranes utilizing advanced physic-chemical analytical techniques, followed by rigorous experimental assessments using synthetic seawater and SWRO brine in concentration configuration. The findings highlighted the superior selectivity of NFX for magnesium recovery from SWRO brine and the promising concentration factors of VNF1 for seawater treatment. Cross-validation of experimental data with a mathematical model demonstrated the model's reliability as a process design tool in predicting membrane performance. A comprehensive techno-economic evaluation demonstrates the potential of NFX, operating optimally at 23 bar pressure and 70% permeate recovery rate, to yield an estimated annual revenue of 5.683 M€/yr through Mg(OH)2 production from SWRO brine for a plant with a nominal capacity of 0.8 Mm3/y. This research shed light on the promising role of NF membranes in enhancing mineral recovery taking benefit of their separation factors and emphasizes the economic viability of leveraging NF technology for maximizing magnesium recovery from seawater and SWRO brines.

Remediation of oily-produced water from high-salinity oilfield using a low-cost, high-alumina calcium bentonite hollow fiber membrane.

Discharging improperly treated oily-produced water (OPW) into the environment can have significant negative impacts on environmental sustainability. It can lead to pollution of water sources, damage to aquatic ecosystems and potential health hazards for individuals living in the affected areas. Ceramic hollow fiber membrane (CHFM) technology is one of the most effective OPW treatment methods for achieving high oil removal efficiency while maintaining membrane water permeability. In this study, low-cost calcium bentonite hollow fiber membranes (CaB-HFMs) were prepared from high-alumina calcium bentonite clay with various preparation parameters, including calcium bentonite content, sintering temperature, air gap distance and bore fluid rate. The prepared CaB-HFMs were then subjected to characterization using scanning electron microscopy (SEM), a three-point bending test, porosity, average pore size, hydraulic resistance and flux recovery ratio (FRR) analysis. Statistical analysis employing central composite design (CCD) assessed the interaction between the parameters and their effect on CaB-HFM water permeability and oil removal efficiency. Higher ceramic content and sintering temperature led to reduced porosity, smaller pore size and higher mechanical strength. In contrast, increasing the air gap distance and bore fluid rate exhibit different trends, resulting in higher porosity and pore size, along with weaker mechanical strength. Other than that, all of the CaB-HFMs displayed low hydraulic resistance (<0.01 m2 h.bar/L) and high FRR value (up to 95.2%). Based on CCD, optimal conditions for CaB-HFM were determined as follows: a calcium bentonite content of 50 wt.%, a sintering temperature of 1096 °C, an air gap distance of 5 cm and a bore fluid rate of 10 mL/min, with the desirability value of 0.937. Notably, the optimized CaB-HFMs demonstrated high oil removal efficiency of up to 99.7% with exceptional water permeability up to 535.2 L/m2.h.bar. The long-term permeation study also revealed it was capable of achieving a high average water permeation and a stable oil rejection performance of 522.15 L/m2.h.bar and 99.8%, respectively, due to their inherent hydrophilic and antifouling characteristics, making it practical for OPW treatment application.

Assessment of the efficiency and stability of enzymatic membrane reaction utilizing lipase covalently immobilized on a functionalized hybrid membrane.

Enzyme immobilization in membrane bioreactors has been considered as a practical approach to enhance the stability, reusability, and efficiency of enzymes. In this particular study, a new type of hybrid membrane reactor was created through the phase inversion method, utilizing hybrid of graphene oxide nanosheets (GON) and polyether sulfone (PES) in order to covalently immobilize the Candida rugosa lipase (CRL). The surface of hybrid membrane was initially modified by (3-Aminopropyl) triethoxysilane (APTES), before the use of glutaraldehyde (GLU), as a linker, through the imine bonds. The resulted enzymatic hybrid membrane reactors (EHMRs) were then thoroughly analyzed by using field-emission scanning electron microscopy (FE-SEM), contact angle goniometry, surface free energy analysis, X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, attenuated total reflection (ATR), and energy-dispersive X-ray (EDX) spectroscopy. The study also looked into the impact of factors such as initial CRL concentration, storage conditions, and immobilization time on the EHMR's performance and activity, which were subsequently optimized. The results demonstrated that the CRLs covalently immobilized on the EHMRs displayed enhanced pH and thermal stability compared to those physically immobilized or free. These covalently immobilized CRLs could maintain over 60% of their activity even after 6 reaction cycles spanning 50 days. EHMRs are valuable biocatalysts in developing various industrial, environmental, and analytical processes.

Environmental impact assessment via life cycle analysis on ultrafiltration membrane fabricated from polyethylene terephthalate waste to treat microalgal cultivation wastewater for reusability.

The current study had conducted the life cycle analysis (LCA) to assess the environmental impact of microalgal wastewater treatment via an integrated membrane bioreactor. The functional unit selected for this analysis was 1 kg of treated microalgal wastewater with contaminants eliminated by ultrafiltration membrane fabricated from recycled polyethylene terephthalate waste. Meanwhile, the applied system boundary in this study was distinguished based on two scenarios, namely, cradle-to-gate encompassed wastewater treatment only and cradle-to-cradle which included the reutilization of treated wastewater to cultivate microalgae again. The environmental impacts and hotspots associated with the different stages of the wastewater treatment process had clearly elucidated that membrane treatment had ensued the highest impact, followed by microalgal harvesting, and finally cultivation. Among the environmental impact categories, water-related impact was found to be prominent in the following series: freshwater ecotoxicity, freshwater eutrophication and marine ecotoxicity. Notably, the key performance indicator of all environmental impact, i.e., the global warming potential was found to be very much lower at 2.94 × 10-4 kg CO2 eq as opposed to other literatures reported on the LCA of wastewater treatments using membranes. Overall, this study had proffered insights into the environmental impact of microalgal wastewater treatment and its stimulus for sustainable wastewater management. The findings of this study can be instrumental in making informed decision for optimizing microalgal wastewater treatment and reutilization assisted by membrane technology with an ultimate goal of enhancing sustainability.

On the evaluating membrane flux of forward osmosis systems: Data assessment and advanced intelligent modeling.

As an emerging desalination technology, forward osmosis (FO) can potentially become a reliable method to help remedy the current water crisis. Introducing uncomplicated and precise models could help FO systems' optimization. This paper presents the prediction and evaluation of FO systems' membrane flux using various artificial intelligence-based models. Detailed data gathering and cleaning were emphasized because appropriate modeling requires precise inputs. Accumulating data from the original sources, followed by duplicate removal, outlier detection, and feature selection, paved the way to begin modeling. Six models were executed for the prediction task, among which two are tree-based models, two are deep learning models, and two are miscellaneous models. The calculated coefficient of determination (R2 ) of our best model (XGBoost) was 0.992. In conclusion, tree-based models (XGBoost and CatBoost) show more accurate performance than neural networks. Furthermore, in the sensitivity analysis, feed solution (FS) and draw solution (DS) concentrations showed a strong correlation with membrane flux. PRACTITIONER POINTS: The FO membrane flux was predicted using a variety of machine-learning models. Thorough data preprocessing was executed. The XGBoost model showed the best performance, with an R2 of 0.992. Tree-based models outperformed neural networks and other models.

The potential of electrodialysis as a cost-effective alternative to reverse osmosis for brackish water desalination.

While electrodialysis (ED) demonstrates lower energy consumption than reverse osmosis (RO) in the desalination of low salinity waters, RO continues to be the predominant technology for brackish water desalination. In this study, we probe this skewed market share and project the potential for future disruption by ED through systematic assessment of the levelized cost of water (LCOW). Using rigorous process- and economic-models, we minimize the LCOW of RO and ED systems, highlighting important tradeoffs between capital and operating expenditure for each technology. With optimized current state-of-the-art systems, we find that ED is more economical than RO for feed salinities ≤ 3 g L-1, albeit to a minor extent. Considering that RO is a highly mature technology, we focus on predicting the future potential of ED by evaluating plausible avenues for capital and operating cost reduction. Specifically, we find that reduction in the price of ion-exchange membranes (i.e., < 60 USD m-2) can ensure competitiveness with RO for feed salinities up to 5 g L-1. For higher feed salinities (≥ 5 g L-1) we reveal that the LCOW of ED may effectively be reduced by decreasing ion-exchange membrane resistance, while preserving high current efficiency. Through extensive assessment of structure-property-performance relationships, we precisely identify target membrane charge densities and diffusion coefficients which optimize the LCOW of ED, thus providing novel guidance for future membrane material development. Overall, we emphasize that with a unified approach - whereby ion-exchange membrane price is reduced and performance is enhanced - ED can become the economically preferable technology compared to RO across the entire brackish water salinity range.

Microstructure-Driven Self-Transport and Convection of Water on Membrane Surface for Ultra-Fast, Highly Sensitive, Low-Cost Lateral-Flow Assays.

Lateral-flow assay (LFA) is one of the most commonly used detection technologies, in which the chromatographic membranes are currently used as the lateral-flow membrane (e.g., nitrocellulose membrane, NC Mem). However, several disadvantages of existing chromatographic membranes limit the performance of LFA, including relatively low flow velocity of sample solution and relatively more residuals of sample on membrane, which increase detection time and detection noise. Herein, a surface structure membrane (SS Mem) is proposed, which enables fast self-transport of water with a convection manner and realizes low residuals of sample on membrane surface after the flow. On SS Mem, the flow velocity of water is 7.1-fold higher, and the residuals of sample are decreased by 60-67%, comparing those in NC Mem. SS Mem is used as lateral-flow membrane to prepare lateral-flow strips of nanogold LFA and fluorescence LFA for rapid detection of SARS CoV-2 nucleocapsid protein. These LFAs require 210 s per detection, with limits of detection of 3.98 pg mL-1 and 53.3 fg mL-1, sensitivity of 96.5%, and specificity of 90%. The results suggest that SS Mem enables ultrafast, highly sensitive lateral-flow immunoassays and shows great potential as a new type of lateral-flow membrane to broaden the application of LFA.

Identification of performance and cost in a new backwash method to clean the UF membrane: backwashing with low dosage of NaClO.

Ultrafiltration (UF) is widely used in wastewater reclamation treatments. Conventional backwashing is usually performed at regular time intervals (10-120 min) with permeate and without the addition of chemicals. Chemical enhanced backwashing (CEB) is usually applied after 70-90 filtration cycles with added chemicals. These cleaning methods cause membrane fouling and require costly chemicals. Instead of conventional backwashing, we propose herein a new backwashing method involving backwashing the effluent with low doses of sodium hypochlorite (NaClO) named as BELN. The performance and cost of UF backwashing were investigated with Beijing wastewater reclamation treatment. The results showed that the transmembrane pressure (TMP) increased from 33.2 to 48.2 kPa during hydraulic backwashing after 80 filtration cycles but increased from 33.3 to 39.3 kPa during backwashing with a low NaClO content of 20 mg/L. It was also noticed that the hydraulic-irreversible fouling index decreased from 5.58 × 10-3 m2/L to 3.58 × 10-3 m2/L with the new method. According to the three-dimensional fluorescence excitation-emission (3D-EEM), the response increased from 11.9 to 15.2% with BELN. Protein-like material was identified as the main component causing membrane fouling by blocking the membrane pores. The results indicated that the low dosage of NaClO effectively stripped the fouling layer. Finally, based on an economic evaluation, the capacity of the UF process was increased from 76,959 to 109,133 m3/d with the new method. The amount of NaClO consumed for Beijing wastewater reclamation treatment was similarly compared with the conventional backwashing in per year under BELN. The new method has good potential for application.

Electrospun nanofibrous membranes for membrane distillation application-A dynamic life cycle assessment (dLCA) approach.

Membrane distillation (MD) for water desalination and purification has been gaining prominence to address the issues relating to water security and the destruction of aquatic ecosystems globally. Recent advances in electrospun membranes for MD application have improved antifouling and anti-wetting performance. However, the environmental impacts associated with producing novel electrospun membranes still need to be clarified. It is imperative to quantify and analyze the tradeoffs between membrane performance and impacts at the early stages of research on these novel membranes. Life Cycle Assessment (LCA) is an appropriate tool to systematically account for environmental performance, all the way from raw material extraction to the disposal of any product, process, or technology. The inherent lack of detailed datasets for emerging technologies contributes to significant uncertainties, making the adoption of traditional LCA challenging. A dynamic LCA (dLCA) is performed to guide the sustainable design and selection of emerging electrospun poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) electrospun membrane (E-PH) and hybridizing polydimethylsiloxane (PDMS) on E-PH membrane (E-PDMS) for dyeing wastewater treatment technologies. The associated environmental impacts are related to the high energy demands required for fabricating electrospun nanofibrous membranes. After LCA analysis, the E-PDMS membrane emerges as a promising membrane, due to the relatively low impact/benefit ratio and the high performance achieved in treating dyeing wastewater.

Energy behaviour and economic analysis of a photovoltaic-thermal (PV/T) collector coupled with a reverse osmosis (RO) desalination unit in Tunisian climatic conditions: a feasibility study.

Water scarcity affects about one billion people in the world. Around two billion people could be living in water-stressed areas by 2050. For this reason, the desalination is always evolving due to the importance of the water resources found in the seas and brackish water. As these systems are generally energy intensive, the use of a renewable energy source is among the most appropriate solution. In this paper, both experimental and numerical investigations have been conducted to evaluate the performances and the economic viability of a photovoltaic-thermal collector intended to supply a reverse osmosis (RO) unit. Experimental study is based on the input-output and dynamic system testing (DST) according to ISO 9459-5 standard method and computations use the energy and mass balances of the PV/T collector and the RO plant. Results of DST testing showed that the loss coefficient of the PV/T, the tank loss coefficient and the total tank heat capacity are 10.46 W.m-2.K-1, 1.596 W.K-1 and 388 MJ.K-1, respectively. The ability to couple the RO technology to PV/T systems has been demonstrated. The complete system has been simulated for a water salinity of 10,000 ppm and climatic data of Borj-Cedria (Tunisia) site (longitude 10° 25' 41″ E and latitude 36° 43' 04″ N). Numerical investigations showed that the electricity needs of a small off-grid desalination unit could be met by using a 6.48 m2 PV/T panel surface area. In this case, the purified water produced has a salinity of 1500 ppm and the flow rate is 24,000 l/day. For a grid connected site, the produced and auxiliary powers are found to be equal to 54% and 21%, respectively. Moreover, the economic cost of adding a PV/T system into an existing RO unit has been evaluated and the results showed that the payback period is 6 years.

Performance and economic evaluation of a pilot scale embedded ends-free membrane bioreactor (EEF-MBR).

In this work, an embedded ends-free membrane bioreactor (EEF-MBR) has been developed to overcome the fouling problem. The EEF-MBR unit has a novel configuration where a bed of granular activated carbon is placed in the bioreactor tank and fluidized by the aeration system. The performance of pilot-scale EEF-MBR was assessed based on flux and selectivity over 140 h. The permeate flux fluctuated between 2 and 10 L.m-2.h-1 under operating pressure of 0.07-0.2 bar when EEF-MBR was used to treat wastewater containing high organic matter. The COD removal efficiency was more than 99% after 1 h of operating time. Results from the pilot-scale performance were then used to design a large-scale EEF-MBR with 1200 m3.day-1 capacity. Economic analysis showed that this new MBR configuration was cost-effective when the permeate flux was set at 10 L.m-2.h-1. The estimated additional cost for the large-scale wastewater treatment was about 0.25 US$.m-3 with a payback period of 3 years. KEY POINTS: • Performance of new MBR configuration, EEF-MBR, was assessed in long term operation. • EEF-MBR shows high COD removal and relatively stable flux. • Cost estimation of large scale shows the cost effective EEF-MBR application.

Techno-economic assessment of a novel algal-membrane system versus conventional wastewater treatment and advanced potable reuse processes: Part II.

This study developed a comprehensive techno-economic assessment (TEA) framework to evaluate an innovative algae resource recovery and near zero-liquid discharge potable reuse system (i.e., the main system) in comparison with a conventional potable water reuse system (i.e., the benchmark system). The TEA study aims to estimate the levelized costs of water of individual units and integrated processes including secondary wastewater treatment, advanced water purification for potable reuse, and sludge treatment. This would provide decision-makers valuable information regarding the capital and operational costs of the innovative main system versus a typical potable water reuse treatment train, along with possible routes of cost optimization and improvements for the design of full-scale facilities. The main system consists of (i) a novel algal-based wastewater treatment coupled with a dual forward osmosis and seawater reverse osmosis (Algal FO-SWRO) membranes system for potable water reuse and hydrothermal liquefaction (HTL) to produce bioenergy and subsequent nutrients extraction from the harvested algal biomass. The benchmark system includes (ii) an advanced water purification facility (AWPF) that consists of a conventional activated sludge biological treatment (CAS), microfiltration (MF), brackish water reverse osmosis (BWRO), ultraviolet/advanced oxidation process (UV-AOP), and granular activated carbon (GAC), with anaerobic digestion for sludge treatment. Capital expenditures (CAPEX) and operational expenditures (OPEX) were calculated for each unit of both systems (i.e., sub-systems). Based on a 76% overall water recovery designed for the benchmark system, the water cost was estimated at $2.03/m3. The highest costs in the benchmark system were found on the CAS and the anaerobic digester, with the UV-AOP combined with GAC for hydrogen peroxide (H2O2) quenching as the driving factor in the increased costs of the system. The cost of the main system, based on an overall 88% water recovery, was estimated to be $1.97/m3, with costs mostly driven by the FO and SWRO membranes. With further cost reduction and optimization for FO membranes such as membrane cost, water recovery, and flux, the main system can provide a much more economically viable alternative in its application than a typical benchmark system.

A hybrid ultrafiltration membrane process using a low-cost laterite based adsorbent for efficient arsenic removal.

Adsorption has proven to be most effective for arsenic removal. But standalone adsorption cannot cater to the need for large-scale treatment in centralized water supply systems. Combining adsorption with other low-pressure membrane processes may aid in scaling up and intensifying the overall arsenic removal. In the present pilot study, a low-cost laterite-derived adsorbent (LDA) has been used in combination with cross-flow ultrafiltration (Ads-UF) to develop a strategy suitable for remediation of arsenic-contaminated water. Effect of adsorbent particles on permeate flux has been assessed at different transmembrane pressure (0.2-0.6 MPa). Two different hybrid configurations, with and without intermediate sand filtration (SF), i.e. Ads-SF-UF and Ads-UF, were considered. Resistance-in-series and combined complete pore block-cake layer models have been used to understand the flux profiles. In the case of arsenic-spiked groundwater, it was observed that flux decline, at 0.6 MPa, was 28% higher with Ads-UF during a 12 h run compared to Ads-SF-UF. Spent LDA retrieved from the sand column was found to retain the elemental composition as that of the unused LDA (as per FT-IR and EDX) and was considered safe for disposal based on Toxicity Characteristic Leaching Procedure (TCLP). Cost estimation for a facility with 200 m3/day treatment capacity has also been presented.

Experimental and economic evaluation of nitrate removal by a nanofiltration membrane.

Membrane nanofiltration (NF) process was employed to remove nitrate from synthetic and natural waters. The optimum technical and economic ranges of governing parameters for the water treatment process were determined using central composite design method and Verbernen's economic model. The results of nitrate removal from synthesized water showed the minimum and maximum rates of permeation were 16.5 and 84.3 L/m2h (LMH), respectively. The minimum and maximum nitrate rejection were 44.1% and 78.4%, respectively. Increasing pH had no significant effect on permeation flux but increased the nitrate removal rate. Additionally, as pressure was increased, the nitrate rejection and permeation flux both increased; but, as temperature was increased, the permeation flux increased while the nitrate removal decreased. In the case of natural water, the minimum and the maximum flow rate were 7.7 and 68.1 LMH. Furthermore, the minimum and maximum rejection rates of nitrate were 22.1% and 74.8%. The effects of variables on the permeation flux and nitrate removal for natural water were similar to those for synthetic water. However, by increasing pH, the amount of water passing through the membrane decreased. In all experiments, natural water had less permeation flux and less nitrate rejection than synthesized water. The presence of other anions and cations in the natural water decreases the amount of the nitrate removed. The total investment cost reduced as the pressure increased. The cost per m3 of treated water decreased from 3 to 7 bars, then increased as the pressure increased.

Lipophilicity profiling and cell viability assessment of a selected panel of endocrine disruptors.

Endocrine disruptors are chemicals widely used worldwide by industries in a variety of applications. Routinely exposure to these chemicals, even if at low doses, can cause damage effects on human health. In the present study, we evaluated toxic effects of nine chemicals, among which phthalates, using various cell lines to inspect their capability to interfere with cell proliferation and viability. Alongside, we investigated their affinity for phospholipids to assess the possible passage through biomembranes. Experimentally determined logkwIAM.MG values ranged from 1.37 to 3.49 whilst calculated log kwIAM.DD2 spanned from 1.80 to 5.21, supporting the target contaminants to exhibit lipophilicity moderate or very high. The achieved results were related to pharmacokinetic and toxicological properties by ADMET predictor™ and EPI Suite™ software. Triclosan and 4-Nonylphenol were found to be the most toxic against all cell lines screened, showing an IC50 of 30 µM for triclosan on human keratinocytes and of 50 µM for 4-Nonylphenol on human colorectal adenocarcinoma cells. Overall, even if the phthalates showed higher IC50 values (ranging from 170 µM to 280 µM), we can assert that all contaminants herein tested were able to interfere with cell growth and viability.

Economic feasibility of solar-powered reverse osmosis water desalination: a comparative systemic review.

Due to disparities in the allocation of rainwater and drought, extreme exploitation of groundwater reservoirs has depleted water supplies in many locations. In addition, improper disposal of domestic and industrial waste leads to poor drainage and deterioration of water quality. According to studies, desalination methods are an effective solution for treating unconventional water, i.e., sea and brackish water, and making it usable in daily life. Solar-powered desalination has recently received a great deal of attention around the world. Herein, we summarized challenges and future perspectives associated with solar-powered desalination units. Some hybrid technologies are also discussed like solar-wind desalination and RO-ED crystallizer technology in Morocco and the Middle East and North Africa (MENA) region. Previously, most experimental studies focused on the use of solar energy in traditional desalination methods such as multistage flash and multi-effect distillation. Desalination with reverse osmosis has become popular due to membrane technology improvement and benefits like high recovery ratios and low energy consumption. Furthermore, it has been seen that solar energy is less expensive than the energy obtained from traditional fuels in the MENA area. This article aims to comparatively and systematically review the economic feasibility of the use of solar photovoltaic reverse osmosis in desalination in the MENA region.

A membrane-based green and low-cost system for ensuring safe drinking water in a selenium-affected region.

Towards an efficient, low-cost solution to the problem of contamination of groundwater by selenium leached out from earth's mineral crust, a new system is developed using a novel graphene-based nanocomposite membrane. The system not only purified selenium-contaminated groundwater with high degree but also ensured safe disposal of the rejected selenium through algorithmic chemical stabilization in a mineral matrix. All experiments were conducted with live contaminated water from selenium affected area rather than using synthetic solution in a semi-pilot unit involving a largely fouling-free flat sheet cross-flow membrane module. Pure water flux of up to 190 Lm-2h-1(LMH) with 96-97% selenium rejection at an optimum operating pressure of only 14 bar could be achieved. Rejected selenium was stabilized in mineral matrix through chemical coagulation-precipitation using suitable coagulants following prior optimization of the critical operating parameters by Model-based calibration toolbox (MATLAB R2020a). A high degree of stabilization efficiency (99.8%) could be achieved as reflected in an error-index of only 1.13%. For selenium-affected region, the membrane-integrated hybrid treatment system proved to be a potential candidate technology offering safe drinking water at an approximate cost of only 1.77 $/m3 which was found to be affordable to the consumers in subsequent willingness to pay survey.

Biofouling of reverse osmosis membranes: assessment by surface-enhanced Raman spectroscopy and microscopic imaging.

The decline in the performance of spiral-wound reverse osmosis (SWRO) membranes is frequently due to biofouling. This study focus on qualitative and quantitative diagnosis of SWRO membrane biofouling. Bacterial counts on the different surfaces of the fouled membranes were carried out. Surface enhanced Raman spectroscopy (SERS) was performed to highlight clogging materials as well as their natures and identity. The topography of the fouled membranes and the structures of biofilms were visualized by fluorescence microscopy (FM) and scanning electron microscopy (SEM). The results indicated the presence of bacteria in the different SWRO membrane areas. Those strongly adhered were significantly higher than those weakly. It varied between 26 × 105 and 262 × 105 CFU m-2. However, SERS mapping showed different fouling levels and the thickness of the fouling layer was 5 µm. Microscopic imaging revealed biotic and abiotic deposits. These data can together allow better management of the seawater desalination process.

Nutrient recovery from wastewater treatment by ultrafiltration membrane for water reuse in view of a circular economy perspective.

The study aims to recover nitrogen from wastewater by employing ultrafiltration membrane in water reuse for agriculture purpose. To such aim, a new reclaimed water quality index (RWQI) is proposed and applied including an innovative protocol for its assessment. Specifically, the influence of filtration and backwashing times for an ultrafiltration system aimed to nutrient recovery has been analyzed. The final goal was to pin down the trade-off between operation costs and effluent quality. Results show that backwashing time play a crucial role in reducing the operation costs; indeed, low values (i.e., 0.5 min) lead to an increase in the number of required chemical cleanings and consequently operation costs (namely, up to 0.042 €/m3). The compromise among effluent quality and operation costs has been obtained for 7 min and 1 min, filtration and backwashing, respectively.