Transparent exopolymer particles (TEP) have been reported as one of the main factors of membrane fouling in seawater reverse osmosis (SWRO) process. Research has been focused on algal TEP so far, overlooking bacterial TEP. This thesis investigated the effects of coagulation on removal of bacterial TEP/TEP precursors in seawater and subsequent reduction on TEP fouling in ultrafiltration (UF), as a pretreatment of SWRO. Furthermore, the performance of pretreatment (coagulation + UF) has been investigated on a bench-scale SWRO system. TEP/TEP precursors were harvested from a strain of marine bacteria, Pseudoalteromonas atlantica, isolated from the Red Sea. Isolated bacterial organic matter (BOM), containing 1.5 mg xanthan gum eq./L TEP/TEP precursors, were dosed in Red Sea water to mimic a high TEP concentration event. Bacterial TEP/TEP precursors added to seawater were coagulated with ferric chloride and aluminum sulfate at different dosages and pH. Results showed that ferric chloride had a better removal efficiency on TEP/TEP precursors. Afterwards, the non-coagulated/coagulated seawater were tested on a UF system at a constant flux of 130 L/m2h, using two types of commercially available membranes, with pore sizes of 50 kDa and 100 kDa, respectively. The fouling potential of coagulated water was determined by the Modified Fouling Index (MFI-UF). Transmembrane pressure (TMP) was also continuously monitored to investigate the fouling development on UF membranes. TEP concentrations in samples were determined by the alcian blue staining assay. Liquid chromatography-organic carbon detection (LC-OCD) was used to determine the removal of TEP precursors with particular emphasis on biopolymers. Finally, SWRO tests showed that TEP/TEP precursors had a high fouling potential as indicated by MFI-UF, corresponding to the TMP measurements. Coagulation could substantially reduce TEP/TEP precursors fouling in UF when its dosage was equal or higher than 0.2 mg Fe/L. The flux decline experiments showed that coagulation + UF pretreated water had a smaller fouling potential than MF pretreated water. This thesis also provides useful and practical information on controlling bacterial TEP/TEP precursors fouling in UF and RO systems.

Abstract: The worldwide consumption of pharmaceuticals and personal care products for healthcare purposes has resulted in the occurrence of organic micropollutants (OMPs) in freshwater and wastewater resources. These pollutants are not entirely removed by conventional water and wastewater treatment plants, leading to potential human and animal health problems. Membranes are a promising technology capable of solving this problem. This study evaluated the ability of high-pressure driven membranes such as nanofiltration (NF) and reverse osmosis (RO) to remove OMPs. A total of 13 compounds were selected so that a broad range of molecular weights and octanol-water partition coefficients (log Kow) could be studied. Three commercial thin-film-composite polyamide membranes (NF1, NF6, and RO4) were tested. Filtration experiments were conducted using a cross-flow membrane system at pH 6 8 and 10. The membranes were characterized by atomic force microscopy and scanning electron microscopy that allowed a more profound understanding of the membrane surface structures. Experimental results showed that the permeate flux of NF6 is dependent on the pH of the feed solution. An increase in the feed pH from 6 to 10 resulted in an increase on the permeate flux from 14.5 to 24 L m-2 h-1 bar-1, which caused a drop in the rejection of some OMPs by NF6. Nevertheless, for most OMPs, as pH increased to 10, rejection increased for NF1 and RO4 due to electrostatic repulsion between the negatively charged membrane surface and the ionized OMPs. It was observed that ionic hydrophobic compounds could be highly rejected (> 95%) by NF1 and RO4. The study indicated that the rejection of non-ionic hydrophilic and hydrophobic OMPs were rejected effectively by RO4 (> 90%), and the rejection was mostly dominated by size exclusion and hydrophobic interactions between the membrane and the OMPs. Furthermore, the study revealed that the properties of the compounds, the intrinsic properties of the membrane, and the operating conditions have a significant influence on the rejection of OMPs.

No description available.

Detta arbete utreder möjligheten att säkra vattentillgången i Mönsterås kommun med hjälp av en avsaltningsanläggning för bräckvatten från östersjön. Det är högst troligt ett sådant vattenverk skulle kunna uppföras i kommunen och dessutom ge ett vatten med lägre halter av oönskade ämnen än vatten renat med konventionella metoder från yt- och grundvatten till en marginellt högre kostnad.I arbetet redovisas kortfattat principen för avsaltning med RO (Reverse osmosis). Uppbyggnaden av två vattenverk som använder den tekniken och likt Mönsterås ligger i Kalmarsund beskrivs. Med information från sjökort och kartor har troliga råvattentillgångar i kommunen identifierats och utifrån dessa grundar sig förslagen för placering.Med hjälp från ett flertal kontakter i branschen har en enklare projektering gjorts för ett vattenverk med kapacitet på 3000 kubikmeter dricksvatten per dygn.I resultatet redovisas några förslag på placering av ett vattenverk. / This work investigates the possibility of securing the water supply in Mönsterås municipality with the help of a desalination plant for brackish water from the Baltic Sea. It is highly likely that such a waterworks could be built in the municipality and also provide water with lower levels of unwanted substances than water purified by conventional methods from surface and groundwater at a marginally higher cost.In the work, the principle of desalination with RO (Reverse osmosis) is briefly presented. The construction of two waterworks that use this technology and, like Mönsterås, is located in Kalmarsund is described. With information from nautical charts and maps, probable raw water resources in the municipality have been identified and based on these, the proposals for placement are based.With the help of several contacts in the industry, a simpler design has been made for a water treatment plant with a capacity of 3000 cubic meters of drinking water per day.The result presents some suggestions for placement of a desalination plant.

Co-precipitation and absorption methods were investigated for removal of boron from produced water, which is groundwater brought to the surface during oil and natural gas extraction. Boron can be toxic to many crops and often needs to be controlled to low levels in irrigation water. The present research focused on synthetic reverse osmosis (RO) concentrate modeled on concentrate expected from a future treatment facility at the Arroyo Grande Oil Field on the central coast of California. The produced water at this site is brackish with a boron concentration of 8 mg/L and an expected temperature of 80°C. The future overall produced water treatment process will include lime softening, micro-filtration, cooling, ion exchange, and finally RO. Projected boron concentrations in the RO concentrate are 20 to 25 mg/L. Concentrate temperature will be near ambient. This RO concentrate will be injected back into the formation. To prevent an accumulation of boron in the formation, it is desired to reduce boron concentrations in this concentrate and partition the boron into a solid sludge that could be transported out of the area. The primary method explored for boron removal during this study was adsorption and co-precipitation by magnesium chloride. Some magnesium oxide tests were also conducted. Jar testing was used to determine the degree of boron removal as a function of initial concentration, pH, temperature, and reaction time. Synthetic RO concentrate was used to control background water quality factors that could potentially influence boron removal. The standard synthetic RO concentrate contained 8 g NaCl/L, 150 mg Si/L and 30 mg B/L. After synthetic RO concentrate was prepared, amendments (e.g. sulfate, sodium chloride) were added and the pH adjusted to the desired value. Each solution was then carried through a mixing and settling protocol (5 min at 200 RPM, 10 min at 20 RPM, followed by 30 min settling and filtration). Boron concentrations from the jar tests were determined using the Carmine colorimetric method. Boron removal with magnesium chloride was greatest at a pH of 11.0. At this pH 87% of boron was removed using 5.0 g/L MgCl2◦6H2O at 20°C. Mixing time did not greatly affect boron removal for mixing periods of 5 to 1321 minutes. This result indicates equilibrium was achieved during the 45-min experimental protocol. Maximum boron removal was observed in the temperature range of 29°C to 41°C. At 68°C boron removal decreased five-fold compared to the reduction observed at 29°C to 41°C. For treatment of the cool concentrate, this relatively low optimal temperature range gives magnesium chloride an advantage over magnesium oxide, which is effective only at high temperatures. Neither sodium chloride nor sodium sulfate affected boron removal by magnesium chloride for the chloride and sulfate concentrations expected in the produced water at this site. In contrast, silica did inhibit boron removal, with removal decreasing from 30% to 5% when silica concentration was increased from 0 to 100 mmols/L. This result was unexpected because other researchers have reported silica is necessary for effective removal of boron by magnesium chloride. To investigate the reasons for the differing boron removal results for magnesium chloride and magnesium oxide, solids produced by the two reagents were compared using X-ray diffraction spectroscopy (XRD). Solids from magnesium chloride contained 30% amorphous material versus 10% for magnesium oxide. The crystalline components from the magnesium oxide treatment were for the most part magnesium oxide, whereas magnesium chloride crystalline solids were a combination of brucite (Mg(OH)2) and magnesium chloride hydroxide. The greater boron adsorption observed with magnesium chloride could thus either be attributed to the greater surface area of the amorphous precipitate and/or the higher boron affinity of brucite and magnesium chloride hydroxide. Adsorption isotherms were plotted for boron removal by magnesium compounds formed during precipitation. Boron adsorption followed a linear isotherm (r2= 0.92) for boron concentrations up to 37.8 mg B/L. While the data also fit Langmuir and Freundlich models the data fell in the linear range of those models. The linearity of the adsorption curves indicates that adsorption sites for boron were not saturated at these concentrations. The linearity means that higher boron concentrations in the RO concentrate will lead to greater mass removal, up to concentrations of at least 37.8 mg/L boron. Using magnesium chloride, boron removal by co-precipitation was more effective than by adsorption to pre-formed precipitate. Removal approximately doubled for a given dose of magnesium chloride. The effectiveness of co-precipitation presumably occurs due to entrapment of boron as the precipitate forms. This study has shown the potential of magnesium chloride as an agent for boron removal by determining those conditions most effective for boron co-precipitation and adsorption. Magnesium chloride has been shown to be more effective than magnesium oxide. Magnesium chloride also out-performed treatment with slaked quicklime, which was tested previously by others. Two important limitations of boron removal with magnesium chloride are the high chemical requirements (5 g/L MgCl2) and sludge production (1 g/g MgCl2 used). These are greatly mitigated by treatment of RO concentrate rather than the full produced water flow. In addition, reagent use and sludge production might be decreased by recycling sludge from the up-front lime softening process. Compared to magnesium oxide, magnesium chloride removes greater quantities of boron per mole of magnesium added (20 mg B/g MgCl2). The magnesium chloride isotherm demonstrated that treatment of RO concentrate required less reagent and produced less sludge per mass of boron removed than treatment of the more dilute feed water.

Yes / The performance of a batch reverse osmosis (RO) desalination process in terms of permeate quantity and salinity as a function of feed pressure and feed salinity is evaluated by using laboratory experiments and process modelling. Special attention is paid to the water and salt permeability constants (Kw, Ks) which affect the permeate and salt flux across the membrane. Kw and Ks are found to be strongly pressure-dependent for the batch system which is in-line with earlier observations for continuous RO systems. However, the most important findings of this work are the dependence of Kw and Ks on feed salinity, something that have never been observed or reported in the literature. In order to better qualify these observations, further experiments with the batch system are conducted with a constant feed salinity so that the operating condition resembles that of a continuous RO process.

Yes / The reverse osmosis (RO) process is one of the most popular membrane technologies for the generation of freshwater from seawater and brackish water resources. An industrial scale RO desalination consumes a considerable amount of energy due to the exergy destruction in several units of the process. To mitigate these limitations, several colleagues focused on delivering feasible options to resolve these issues. Most importantly, the intention was to specify the most units responsible for dissipating energy. However, in the literature, no research has been done on the analysis of exergy losses and thermodynamic limitations of the RO system of the Arab Potash Company (APC). Specifically, the RO system of the APC is designed as a medium-sized, multistage, multi pass spiral wound brackish water RO desalination plant with a capacity of 1200 m3/day. Therefore, this paper intends to fill this gap and critically investigate the distribution of exergy destruction by incorporating both physical and chemical exergies of several units and compartments of the RO system. To carry out this study, a sub-model of exergy analysis was collected from the open literature and embedded into the original RO model developed by the authors of this study. The simulation results explored the most sections that cause the highest energy destruction. Specifically, it is confirmed that the major exergy destruction happens in the product stream with 95.8% of the total exergy input. However, the lowest exergy destruction happens in the mixing location of permeate of the first pass of RO desalination system with 62.28% of the total exergy input.

Yes / Clean water demand has significantly increased due to the rise in the global population. However, most water on the Earth has high saline content that cannot be consumed directly; only about one over forty of the total water source is freshwater. Desalinated water is one of the potential solutions to meet the growing demand for freshwater, which is highly energy intensive. This paper analyses the energy, economic and environmental performance of a 5 m3/day PV (photovoltaic) powered reverse osmosis (RO) desalination system. Three scenarios of PV-RO with and without battery storage and diesel generator hybrid systems have been analyzed and investigated for the annual estimate load, net present value, and payback period of the water and electricity production costs. Also, the CO2 avoidance over the lifetime operation of all scearios is evaluated. This study shows that the PV-RO system without battery with 6.3 kW PV panels installed and with a 2-days water storage tank system is the most profitable economically f. For this scenario, the Levelized Cost of Electricity (LCOE), Levelized Cost of Water (LCOW), and Payback Period (PBP) are found to be $0.154/kWh, $0.627/m3, and five years, respectively. In addition, for this scenario, the CO2 emissions avoidance was the maximum (111,690 kg.CO2eq per year) compared to other scenarios.

Yes / Phenol is one of the most toxic and harmful pollutants in industrial wastewater streams, the removal of which is therefore of critical importance. The use of reverse osmosis (RO) systems as a means of treating wastewater is continuously growing. This research investigates the effect of operating parameters on the performance of five different multistage RO configurations coupled with a trickle bed reactor (TBR) using model-based simulation. The results were compared, and an analysis was then performed to identify which hybrid TBR and multistage RO arrangement rejected the most phenol content. The basis for comparison was four performance metrics of permeate concentration, rejection, recovery, and specific energy. The study found that the flow rate and concentration have little effect on the operation unless there is a concurrent increase of both. It was also found that the four-performance metrics used were interlinked and affect the quality and quantity of the final freshwater product.

Water desalination has the potential to alleviate a significant part of the world’s thirst, with a majority of desalinated water capacity coming from seawater reverse osmosis (SWRO). However, SWRO membrane systems suffer from the loss of performance due to biofouling leading to economic costs. There is no control or preventive strategy for SWRO biofouling and current industry practices recommend chemical treatments to restore membrane performance. Chemical cleaning results in high economic costs due to chemical acquisition, storage, transportation, long plant downtimes and ultimately shorter membrane lifetime and early replacement; in addition to the environmental impact associated with disposing of chemicals. Therefore, there is a need for novel effective green cleaning strategies for SWRO to meet the increasing demand for desalinated water while taking care of the environment. Micronanobubbles (MNBs) consist of small gas cavities formed in aqueous solutions. This study evaluates the efficiency of both air-filled micronanobubbles (AMNBs) and CO2 nucleated MNBs as: i) curative cleaning-in-place (CIP) treatments and ii) preventive daily treatments for biofouling over long-term studies. Experiments were performed using the membrane fouling simulator (MFS) under conditions that are representative of SWRO membrane systems. Pressure drop was implemented as the main biofilm growth monitoring parameter as used by standard industry practices. Curative studies showed that both MNBs CIP treatments had high cleaning efficiencies of 49-56% pressure drop recovery. MNBs pressure drop recovery values were close to the conventional chemical cleaning (NaOH/HCl) at 51% and were significantly higher than the hydraulic flush (HF) physical cleaning control at 24%. The pressure drop recovery results were supported by the optical coherence tomography (OCT) images before and after CIP and biomass autopsy results. Similarly, preventive MNBs daily treatments showed a significant delay in the system’s performance decline. This delay was 5.1 days for the CO2 MNBs experiments, 4 days for the AMNBs, and only 0.6 days for the hydraulic flushing treatments compared to the control. Compared to the control the duration of the operation was doubled in time before the cleaning criteria was met. OCT images confirmed biofilm growth delay with lower biomass occurrence.