Desalination

An oxygen transport ceramic membrane was prepared with La0.6Sr0.4TixFe1−xO3−δ (x = 0.2 and 0.3) oxides which was synthesized by polymerized complex method. In order to investigate the effects of Ti substitutions into lanthanum–strontium ferrites, material property, thermal expansion coefficient, oxygen permeation, electrical conductivity and phase stability were examined according to Ti contents. The thermal expansion coefficients of LSTF6428 and LSTF6437 were 25.76 × 10−6 K−1 and 21.32 × 10−6 K−1 in the temperature range of 973−1273 K, respectively. The oxygen permeation fluxes through a disk type dense membrane of LSTF6428 and LSTF6437 with 1.6 mm thickness increased exponentially with increasing temperature and were 0.17 mL min−1cm–2 and 0.13 mL min−1cm−2 with Ph = 0.21 atm (O2 rich side) and Pl = 10−5 atm (lean side) at 1223 K, respectively. In the result of phase stability test with various conditions such as He, H2/N2 and CO2 atmosphere, La0.6Sr0.4TixFe1−xO3−δ was confirmed to be more stable than La0.6Sr0.4Ti0.2Fe0.8O3−δ through XRD and SEM analysis.

Special care must be taken when designing pre-treatment systems for iron-rich feed waters at high temperature. The essential need for a cooling tower introduces a potential source of algal, bacterial and suspended solids contamination not usually encountered in standard closed, low temperature systems.Membrane fouling with mineral salts is easily prevented, but the simplistic use of chlorine will generally still allow some degree of biological fouling.This paper looks at modifications made to the pre-treatment system as a result of practical experience and increased water demand.

Electrodialysis (ED) was employed to remove the organic and inorganic salts from actual 1,3-propanediol (PDO) fermentation broth. These salts cause many problems during the purification of PDO if not removed. Suitable operation parameters such as applied potential and the flow rate of streams were selected to ensure a stable and durative desalination process for PDO fermentation broth. Under these conditions, the membrane fouling can be alleviated effectively by changing pole and cleaning membranes so that further industrial production is possible. The experiment results show that about 90% of organic acid salts in PDO broth are removed by the ED process. In addition, a simulated diffusion PDO experiment proved that the diffusion of PDO results in its loss from fermentation broth and the loss ratio is less than 6% under the chosen operating conditions.

Poly(1,4-phenylene sulfide) was sulfonated with fuming sulfuric acid to different degrees. The products were ground and sieved (mesh size 50 μm) to obtain small particles. The particles and linear polyethylene were mixed in various ratios and the resulting blends were press-molded at 150°C to obtain the membranes. Membranes containing up to 66 wt.% of sulfonated particles could be prepared without any problem with the required mechanical strength. The membranes with high concentrations of highly sulfonated particles were as conductive as Nafion 117 membranes and had high values of permselectivity in HCl solutions.

The mechanical vapour compression process and its application to seawater desalination is presented. As an example the largest unit so far constructed by Sidem using this process is described: a 1,500 m3/d unit installed in the Nuclear Power Plant of Flamanville in France which supplies a high quality water to that plant.The advantages of this process are outlined, compared to other distillation processes: multiflash and ejectocompression, and the series of mechanical vapour compression units that Sidem has developed in a size range between 25 and 2,500 m3/d is also presented.

This compilation of test methods applies to both reverse osmosis and electrodialysis membranes currently available in the commercial market place. The techniques described can be used for quality control of manufactured products, newly purchased materials and those membrane products which have been in service. The procedures for the physical and chemical properties have been presented separately; however, in actual fact these properties are interrelated.The physical properties apply to equipment design and in addition they impact on the application to some extent. Some chemical methods have been included to provide an overall treatment.For those familiar with membrane technology, it will be apparent that many of the procedures described can be modified to reflect or nearly duplicate a particular application. In most cases this can be accomplished by the prudent choice of electrolyte, concentration, time or temperature used.These methods cannot be applied to those reverse osmosis devices supplied as hollow fiber modules. Operating characteristics of these devices have been addressed by ASTM. In general, however, this type of equipment must be tested as a complete installation by following the supplier's instructions. This type of detailed operation is outside the scope of this presentation.

This chapter discusses some of the fundamental characteristics of those flow phenomena that are encountered in multistage flash (MSF) and vertical-tube evaporator (VTE) desalination plants, and how they affect plant control and stability. Many of the factors affecting economic plant operation, such as stability, controllability, efficiency at reduced-load conditions, and nonequilibrium losses, are often not directly or easily observable, but should nonetheless be understood by the plant designer and operator.From both the modeling and the control standpoints, MSF processes are the more challenging. Descriptions of both single-phase and two-phase open-channel flow MSF models are presented, as are confirmatory data derived from a variety of experimental studies. Some of the problems to be encountered on the receiving end of the MSF process, i.e. in the control of condensation in horizontal tube bundles, especially during part-load and transient operation, are also noted briefly.VTE processes and their control characteristics and problems (or lack of problems) are outlined, along with results of some dynamics tests on VTE test beds.Finally, some research done on desalination plant process dynamics is described, including studies of various plants tied to different types of heat sources. Some control problems peculiar to MSF dual-purpose (electrical plus water) plants are also noted.

The quality of the drinking water supply has become more important with Hungary's entry into the European Community. In some regions of the country, similar to many parts of the world, arsenic removal from drinking water is an urgent task to supply water with an arsenic content under 10 μg/l. We have worked out a new technology for arsenic removal using a membrane technique. Measurements on site were performed in a pilot plant with equipped with a pre-treatment system and a ZW-1000 (Zenon) membrane module. Before expanding the technological process, experiments on laboratory scale were done to find out which kind of pre-treatment and membrane configuration are needed. These experiments were performed with water from deep wells, among them with a high arsenic concentration (200–300 μg/l). The steps of the pre-treatment process were: oxidation with potassium permanganate (KMnO4), coagulation with ferrous(III) sulphate (Fe2(SO4)3), fast mixing of chemicals with a mixer, coagulation with slow mixing and settlement. Following membrane separation, the arsenic concentration was under the permitted value (10 μg/l). Results of experiments on site proved that the new technology was successful and is suitable to produce drinking water at the required quality from raw water with a high arsenic content in a pilot plant.

The corrosion performance of 66-30-2-2 and 70/30 Cupro-nickels in sea water is influenced both by surface condiions and operating parameters. Corrosion tests performed in corrosion potentials of these alloys and their corrosion performance. The grwoth of cathodic oxide films is always a cause of intiation of localised corrosion. In this regard, the trend fo the corrosion potential during the first days of sea water exposure is of paramount importance.The effect of different pretreatments to keep corrosion potentials within the safe region and prevent the occurrence of pitting and under-deposit attack, was also studied.

This paper sets the foundation of the optimal design of most systems that use or produce heat and/or power including desalination. The separation process of the desalination technologies by membranes and by distillation is considered as an example for the purpose of clarity and for the special importance to desalination. Both the energetics and the economics of the separation process are based on a quantitative formulation of the second law of thermodynamics in terms of the concept of exergy and its destruction. The separation process is considered for five main desalination systems: reverse osmosis, electrodialysis, vapor compression, boiling evaporation and flash evaporation. The results of the energetic analysis show a close competition between reverse osmosis and distillation for seawater desalination. The electrodialysis process is justified for the treatment of more dilute brackish water. It is shown that the determination of the driving force associated with exergy destruction occupies a central position in this comparison. The optimal design of the separation surface for minimum cost of energy and surface requirements takes off smoothly from the energetic analysis and sets the basis of a general and powerful approach to optimal system design. A second paper [1] is devoted to the general approach and its extension to cover almost all kinds of industrial processes and their combinations to produce one or more products.

This paper outlines the operational experience with 2 × 11,500 m3 p.d. Multi Stage Flash desalination plants which were introduced to Bahrain in 1976. It attempts to place in perspective the problems which this technology presented, as it was new to Bahrain. The particular difficulties which resulted from use of bare carbon steel are identified. The corrective measures which were taken to minimise the rate of corrosion are stated. The paper concludes that careful specifications of materials for such plants is essential, and that the necessary expertise must be available at start up to achieve stable operation and to minimise down time.

A Pb2+-selective sensor was fabricated from polyvinyl chloride (PVC) matrix membranes containing the ionophore 3,7,11-tris (2-pyridylmethyl)-3,7,11,17-tetraazabicyclo [11.3.1] heptadeca-1(17),13,15-triene (I). The effects of anion excluders (KTpClPB, NaTPB) and plasticizers (o-NPOE, DBP, DOP) on the performance of the membrane sensor were studied. The membrane with the composition of I:PVC:o-NPOE:KTpClPB in the percentage ratio (wt.%) of 2:32:60:6 exhibited the best performance, having a slope of 28.5 ± 0.2 mV/decade in the concentration range 10− 6–10− 1 M, a response time of 20 s and a lifetime longer than four months. The sensor was selective for Pb2+ ions over other monovalent, divalent and trivalent interfering cations and could be used in the pH range of 5–8. The high selectivity in the presence of Cd2+ may be important for further studies. The efficiency of the proposed sensor was demonstrated by its application in Pb2+ ions determination in water samples.

The sorption kinetic and equilibrium data obtained at different water activities allowed us to determine the water sorption isotherms and mean diffusion coefficient in the Nafion® membrane. The water sorption isotherm is reminiscent of systems in which there is water clustering at high water activities, with a marked Langmuir sorption at low water activity for the acid form of the membrane. The variation of the diffusion coefficient with the water activity showed a maximum value whose coordinates depend on the counter-cation nature. The smaller the counter-cation, i.e. the larger the counter-cation hydration energy, the higher the diffusion coefficient and the lower the water activity at the maximum point.

The Saline Water Conversion Corporation, Research and Development Center (SWCC-RDC) carried out exploratory research study to evaluate the adaptability of the brackish water softening nanofiltration technique as a permeation pretreatment of feed to seawater reverse osmosis (SWRO) and as make-up to MSF. This exploratory work was designated as part I of an applied research project that was carried out from March 1997 to May 1998. Based on initial remarkable results, SWCC applied for a patent on the process during 1997. This paper reports on the pretreatment approach and its application to thermal desalination using MSF. The work carried out in part I of this project is reported where make-up to a 20 kiloliter/d MSF pilot plant distiller was either fresh nanofiltration permeate (NFP) or SWRO reject (while SWRO was fed with NFP). This paper also addresses the plan of elevating MSF top brine temperature (TBT) to as high as 160°C since operation at TBT of 120°C with very little or no scale control treatment gave excellent results.

Two case studies are described that explain the role, value, limitations and policy requirements for storing reclaimed water in aquifers for indirect reuse. The first case involves aquifer storage and recovery of water, the product of tertiary treated municipal sewage effluent, via a single injection and recovery well at Bolivar, South Australia. The recovered water, like the source water for injection, is used for unrestricted irrigation of horticulture. A limestone aquifer at a depth of 100 to 160 m confined by clay and containing brackish groundwater provides the storage zone. In the second case, located at Alice Springs, trials are proceeding to assist in the design and establishment of a soil–aquifer treatment system which will allow water derived from secondary treatment of municipal sewage effluent to be stored in an unconfined alluvial aquifer for irrigation of horticulture. Intermittent infiltration from basins provides supplementary water treatment. In each case, the motivations, choice of methods, required investigations, public consultation processes, and economics of subsurface storage are presented. The lessons learned that may assist with development of policies to facilitate environmentally sustainable subsurface storage of water in water reuse projects are discussed.

This study investigated the feasibility of applying ozone (O3) to reduce the color content of wastewater caused by two commercial reactive dyes (Blue-19 and Orange-13). In the bench-scale experiment, experimental parameters including pH, ozone dosage, and reaction time were evaluated in a 14-L reactor to obtain the optimal operating conditions. Results show that ozone dosage and pH dominated the effectiveness of the decolorization process. The color content could be reduced from 2000 to 200 ADMI (American Dye Manufacture Institute) values within a reaction time of 30 min with the ozone input rate of 2.66 g/h. The pH values of 3 and 10 favored decolorization of Blue-19 and Orange-13, respectively. This was due to the effects that reactive and oxidizing species of molecular ozone and hydroxyl radicals were predominant at low and high pH, respectively. Moreover, molecular ozone was more selective to certain dye structures during the oxidation process. Kinetic analyses show that decolorization of Orange-13 and Blue-19 followed first-order kinetics. The degree of decolorization was primarily proportional to the ozone dosage. Results from this study provide insights into the characteristics and mechanisms of decolorization by the O3 technique. Results will also aid in designing a system for practical application.

This paper presents the major design criteria and features for the 13.3 million gallons per day (MGD) seawater reverse osmosis (RO) desalination plant that is currently under construction in Madinat Yanbu Al-Sinaiyah, Yanbu Industrial City, in the Kingdom of Saudi Arabia. The seawater RO plant is made up of six trains of about 2.2 MGD capacity each. The plant consists of five major systems: seawater supply, seawater pretreatment, high pressure pumping, RO modules, and permeate posttreatment. The paper also discusses technical issues and parameters associated with the plant design, and advances made in the seawater reverse osmosis desalination technology.

The initial eighteen month period of operation of the 15,000 m3/day municipal plant on the Island of Corfu, Greece, is described.The 15,000 m3/day desalting plant employing the electrodialysis reversal process (EDR) produces potable water (500 ppm) from a blend of brackish sources with salinities up to 2000 ppm TDS. The paper describes the plant and integration of the plant into the municipal system. The unique system employed to segregate the treatment of the different brackish waters employing only the highest salinity water for blowdown water is also described.The plant was started up in the fall of 1977 and provided water to the municipal system during the 1978 season.The paper presents operating cost data for this period and compares these costs with projected costs which form part of the contractual agreement, with the Municipality.

The potential of industrial wastewater reuse in Jordan is discussed. Industrial water requirements, wastewater production, types of pollutants in industrial wastewater and the technologies for wastewater treatment have been evaluated. A total of thirty industries have been reviewed. The total effluent from the thirty industries reviewed estimated at approximately 10,200 m3/d. Of this amount, approximately 4,400 m3/d are discharged to public sewerage system, which is about 3% of the total flow. The amounts of metals to be controlled are: 6800 kg/y, 3000 kg/y, 45 kg/y, 65 kg/y, 20 kg/y, 2 kg/y, 25 kg/y, 60 t/y and 8 t/y of Cr, Zn, Cu, Pb, Ni, Cd, Sn, Fe and Al, respectively. Nineteen industries, which discharge mainly organic polluted process wastewater, are food industries. Approximately 5.3 t of BOD/d is discharged from these industries. Of these, approximately 2.2 t BOD/d are discharged to the public sewerage system and about 3.1 t BOD are used for irrigation. It has been shown that most of the selected industries require some treatment of their wastewater. It is recommended to carry out further studies to establish the type of wastewater pretreatment strategies and their estimated capital cost. There is a need for the introduction of a cleaner technology in the selected industries. This could include substitution of raw and auxiliary materials, water and energy saving, recirculation of water, recovery of chemicals, improved process control, waste minimization, and good housekeeping.

A powdered activated carbon/submerged microfiltration (PAC/SMF) system was investigated to examine the removal efficiency of 17β-estradiol (E2) as well as the membrane filterability in the presence of natural organic matter (NOM). The removal of E2 was approximately 92%, but the presence of NOM did not significantly affect the adsorption efficiency of E2 on PAC. When E2 was spiked in the raw water containing NOM, the coupling phenomena did not occur in the rejection of E2 and NOM, but took place in the membrane fouling. Although the reduction of filterability by E2 itself was not so significant, membrane fouling by the river water in the presence of E2 significantly deteriorated in comparison to that generated by filtrating only the river water without E2. This was because E2 induced the additional adsorption of weakly-adsorptive NOM. This coupling phenomenon was related to the initial contact concentration of E2 with the membrane surface. The higher the initial contact concentration, the worse the fouling by NOM.

In this biological nitrate removal study, the performance of the bacterial strain Acidovorax avenae subsp. avenae LMG 17238 using different carbon sources such as ethanol, methanol, sodium acetate, glucose and poly(ε-caprolactone) was investigated. Additionally the parameters such as an increase of nitrate concentration, carbon source amount (C/N) and dilution of a synthetic medium were studied. In laboratory conditions LMG 17238 and a mixed bacterial culture (soil suspension, wastewater treatment and macro algae Gracilaria verrucosa) have been immobilized as a comparative study to determine their efficiency in the biological denitrification of drinking water. For the continuous system as a carbon source, G. verrucosa was studied in fixed-bed columns. Various variables such as hydraulic retention time (HRT), mass amount of the substrate, and the initial nitrate concentration were investigated. A comparative study was achieved by using biodegradable poly(ε-caprolactone) as a carbon source using a mixed bacterial culture (LMG 17238 and G. verrucosa) in a fixed-bed column. Also Monod type equations were used to model the denitrification kinetics. The study proves that, LMG 17238 can be successfully used with different carbon sources. G. verrucosa can be considered as a promising alternative to poly(ε-caprolactone) with a maximum denitrification rate of 13.83 and 0.94 mg NO3−N/L d respectively.Research highlights► Investigating LMG 17238 using different carbon sources in a batch system. ► Promising results with carbon sources ethanol, methanol, sodium acetate and glucose. ► A comparative study for PCL in a fixed bed column with mixed culture. ► Monod type equations to model the denitrification kinetics.

Global concern about the persistence of endocrine disrupting chemicals (EDC) in the freshwater environment is more evident due to their possible disruptive effects. Even at nanogram levels these compounds increase the risk of cancer, decrease egg and sperm production, reduce gamete quality and tend complete feminization of the male fish. The present study demonstrated the potential of activated charcoal as adsorbent in removing synthetic estrogen 17α-ethynylestradiol (EE2) from aqueous phase by sorption process employing both agitated batch and column adsorption experiments. Batch sorption studies showed good removal of EE2 and dependent on the concentration loaded. Equilibrium data of EE2-charcoal sorption system showed a reasonably good fit with pseudo first-order kinetic plot. Intra-particle diffusion plot indicated the complex nature of EE2-charcoal sorption system involving both boundary layer and intra-particle diffusions. Experimental data confirmed to linear Langmuir's isotherm model. Highest EE2 sorption capacity of activated charcoal was observed at neutral conditions. Fixed bed column studies were performed with EE2 spiked untreated domestic sewage. Based on the data derived by fixed bed column studies, rapid small-scale column test (RSSCT) methodology was used to design full-scale GAC system. Total EE2 concentration was quantitatively estimated by direct competitive immuno-enzymatic colorimetric method.Research Highlights► Removal of synthetic estrogen (17-α ethynylestradiol (EE2)) was studied by adsorption. ► Batch sorption data showed good fit with linear Langmuir’s isotherm model. ► Fixed bed column studies for EE2 removal from domestic sewage was carried out. ► Rapid small-scale column test was employed for designing full scale GAC system.

The presented studies have focused on application of photocatalysis in degradation of azo-dye Acid Red 18 (C20 H11 N2 Na3 O10 S3) under UV irradiation. The effect of parameters such as initial dye concentration and catalyst dosage on the photocatalytic degradation of model dye was investigated. Another important factor affecting the photodegradation process performance was the temperature of the reaction mixture. The reaction temperatures were equal to 293, 323, 333 and 343 K. The initial dye concentrations amounted to 10 and 30 mg/dm3 and the photocatalyst (TiO2 Aeroxide® P25, Degussa, Germany) dosage was in the range of 0.1–0.5 g/dm3. The effectiveness of model dye photodecomposition was evaluated on the basis of changes of Acid Red 18 and total organic carbon (TOC) concentration and total dissolved substances (TDS) content. The effectiveness of photodecomposition of Acid Red 18 increased with increasing the catalyst concentration. However, an unfavourable effect of light scattering and reduction of light penetration through the solution in case of photocatalyst loading of 0.5 g/dm3 was observed. It was found that a linear correlation between the apparent rate constant and the reaction temperature exists in the range of 293–333 K. At the temperature of 343 K a decrease in the reaction rate was observed.

Whereas a very adequate inventory of desalting plants in operation around the world has been available for many years, there is no compilation of capital and operating costs for these plants. Yet for any agency or municipality considering desalination, such cost data is vital to making a decision on whether or not to build the plant, and if the decision is to build, what process to employ. The reasons for the unavailability of this information is due either to the reluctance of the owmers to release the information, or more likely, no standard format has been accepted by which costs can be compared.Accordingly the current needs must be met by periodic cost analyses, projections, and updates. It is with this objective this paper has been prepared. Available capital cost information on some past constructions is correlated. Current capital and operating costs are predicted for three commercially available processes, using a format similar to that used in the U.S. Office of Water Research and Technology Reports. (The most recent O.W.R.T. update was issued in 1981.)Looking beyond the present the author lists some factors which are likely to influence what type of plants will be built in the next ten years.

Photochemical degradation and relative toxicity reduction of agricultural wastewater contaminated with methyl 1-[(butylamino)carbonyl]-1H-benzimidazol-2-ylcarbamate (benomyl) by the sonophotocatalytic system was compared with that of the photocatalytic system. Under the optimal conditions, i.e., initial benomyl concentration was 3.2 mg/L, the concentration of TiO2 was 2 g/L and H2O2 concentration was 1.5 mM, the degradation rates with a sonication/UV/TiO2 system was about 1.5 times higher than with a UV/TiO2 system and sonication/UV/TiO2/H2O2 system was about 1.3 times higher than with a UV/TiO2/H2O2 system, respectively. Furthermore, the relative toxicity with a sonophotocatalysis was about 18% lower than with a photocatalysis within a reaction time of 120 min.