Feasibility study for the production of multi-oxidants from the desalination of seawater brine

Impact of seawater intrusion and disposal of desalinization brines on groundwater quality in El Gouna, Egypt, Red Sea Area. Process analyses by means of chemical and isotopic signatures

A novel hybrid process of reverse electrodialysis and reverse osmosis for low energy seawater desalination and brine management

Chlorite, chlorate, bromate and trihalomethane's (THMs) are included in WHO guidelines for drinking water quality. This study examined dosing different chlorine concentrations as calcium hypochlorite (Ca(ClO)2) to water containing chlorine dioxide to evaluate the control of water quality in storage and the distribution system in Qatar with emphasis on chlorite, chlorate, bromate, pH and other parameters. Seven water samples were collected from the Ras Laffan-Q Power desalination plant outlet in amber bottles having a chlorine dioxide concentration of 0.3 mg/l in 1 liter. The bottles were spiked with Ca(ClO)2 in sequence to give concentration of 0.2, 0.4, 0.6, 0.8, 1.0, and 1.2 mg/l as free chlorine. The mixtures were stored for 7 days at 25°C in the dark then heated to 45°C for two days more, and analyzed daily for physical and chemical parameters. A total of 312 sub-samples were analyzed for chlorite, chlorate, bromate, bromide, chloride, nitrate, nitrite, sulfate, THMs, temperature, pH, electrical conductivity, and chlorine and chlorine dioxide residuals. Chlorite concentration reductions were observed from the first day forward as 59, 65, 68, 94, 100, and 100%, and 17.4, 22.1, 39.2, 63.9, 66.0, 68.9% (from 0.157 to 0.049 mg/l) respectively based on observed means for seven days the commensurate respective chlorate concentrations increases were 196, 344, 516, 602, 703, 787% (from 0.035 to 0.313 mg/l) based on observed mean values for seven days. These data were statistically analyzed by multivariate regression. There were no significant changes in THMs concentrations and the reductions in chlorite and increases in chlorate concentration are chlorine dosage dependent. No bromate formation was observed. Chlorine dioxide levels decrease as the free chlorine residual levels increased. This study demonstrates that hypochlorite/chlorine can be used as an operational tool to control the chlorite levels, and slow the disappearance of the chlorine dioxide over time during distribution, that is usually faster than chlorine disappearance. The original chlorine dioxide dosage will determine the ultimate chlorate concentration, which must also be managed.ReferencesEPA guidance manual Alternative Disinfectants and Oxidants EPA 815-R-99-014, April 1999. 9-1 and 9-25.WHO, Guidelines for drinking-water quality, fourth edition. 2011(1)179,180, 325 and 326.E. Marco. Aieta, Paul V. Roberts; Kinetics of the reaction between molecular chlorine and chlorite in aqueous solution Environ. Sci. Technol., 1986.Daniel P. Hautman and David J. Munch. EPA - Method 300.1. Determination of inorganic anions in drinking water by ion chromatography Revision (1.0) 1997.J.W. Eichelberger, J.W. Munch, and T.A.Bellar EPA Method-524.2. Measurement of Purgeable Organic Compounds In water by capillary column gas chromatography/mass spectrometry, (Revision 4) 1992.Charles Z. Steinbergs, Removal of By-products of Chlorine and Chlorine Dioxide at a Hemodialysis Center 1986. Katherine Alfredo, The Potential Regulatory implications of Chlorate (AWWA), March 2014.C.J. Volk, R. Hofmann, C. Chauret, G.A. Gagnon, G. Ranger, and R.C. Andrews, Implementation of chlorine dioxide disinfection: Effects of the treatment change on drinking water quality in a full-scale distribution system 2002.Mary Ann H. Franson, Standard methods for the examination of water and waste water 2005 (21st, Edition) 4-67 and 4-79.Ron Hofmann, Robert C. Andrews, and Georges Ranger, Water Quality and Disinfection Impact of ClO2 Contamination by free Chlorine: A Case Study (NRC Canada) 2004.Mj Bekink and DJ Nozaic, Assessment of Chlorine Dioxide Proprietary Product for Water and Wastewater Disinfection May 2012.

The desalination process of highly mineralized waters is a rather multifactorial process that depends on a number of technical, economic and environmental aspects. This is an important stage for obtaining fresh water for its further use in various areas: from drinking water supply to industry. Processing of reverse osmosis water desalination concentrates is a relevant area of research not only in terms of waste disposal, but also in the development of low-waste resource-efficient production, which requires the implementation of innovative solutions and obtaining secondary useful products. One of the promising approaches to the implementation of processes for processing sodium chloride solutions is the use of electrochemical methods of chloride oxidation to obtain sodium hypochlorite and other products of oxidized chlorine - effective reagents for water disinfection, bleaching of fibrous materials, disinfection of various environments. The aim of the article is to study the processes of electrochemical processing of sodium chloride solutions - waste from the processes of desalination of water containing chlorides in three-chamber electrolyzers with the production of oxidized chlorine compounds and alkali solutions, determining the efficiency of capturing active chlorine in the anode chamber using a highly basic anion exchanger. To achieve the set goal, the following tasks were solved: - The parameters of the process of effective purification of solutions from sodium chloride in the working chamber of a three-chamber electrolyzer were determined depending on the concentration of sodium chloride and the anode density of the steam. - The efficiency of capturing active chlorine in the anode region by a highly basic anion exchanger was studied depending on the parameters of the electrolysis process. The processes of processing sodium chloride solutions, close in composition to the concentrates of reverse osmosis water desalination by electrodialysis in a three-chamber electrolyzer using a cationic membrane MA-40 and anionic membrane MA-41, were studied. The cathode chamber is filled with an alkali solution with a concentration of 50 mg-eq/dm3, the anode chamber is filled with a sodium chloride solution and highly basic anion exchanger AB-17-8, the working chamber is filled with a sodium chloride solution. During electrolysis, alkalinity was determined at equal intervals in the cathode region; in the working chamber, the concentration of chlorides and alkalinity or acidity; in the anode chamber, the concentration of chlorides, active chlorine, and acidity were determined. Also, during the electrolysis process, the exchange capacity of the anion exchanger for active chlorine was determined. For this, a certain volume of the anion exchanger was placed in a flask and filled with a sodium sulfite solution of a certain concentration. The flask was hermetically sealed and left for a day. The next day, the residual amount of active in the solution was determined by the iodometric method. It has been shown that the efficiency of chloride oxidation increases with increasing their concentration and increasing the electrolysis time. The electrolysis process proceeds with the formation of active chlorine and hypochlorite. In addition to these substances, the formation of chlorite, chlorate and chlorine dioxide is possible. Degassing of active chlorine and chlorine dioxide leads to significant losses of oxidized chlorine compounds and to a decrease in the current yield of these products. The process is accompanied by significant acidification of the anolyte, which contributes to the acceleration of degassing of active chlorine, a decrease in its current yield, and a decrease in the intensity of chloride diffusion from the working chamber to the anode zone. The use of a highly basic anion exchanger that adsorbs hypochlorite anions, as well as, in the case of formation, chlorite and chlorate anions, contributes to the reduction of losses of oxidized chlorine compounds.

A previous study by the authors evaluated the efficiency of producing multi-oxidants using anodes coated in precious metal. This study showed that a titanium anode coated in ruthenium generates the largest amount of active chlorine (chlorine dioxide). The results from the efficiency evaluation also show that DuPont Nafion N-2030 ion film is the most efficient of the diaphragms that were tested. To increase the recovery rate for ClO2, this study optimizes the composition of the anode electrolyte. Sodium chlorite is added into the brine and an electrolysis reaction is performed at 40 °C and 12 V for batch operation. The principal product is ClO2 with a maximum concentration of 1,074 mg L−1. During continuous electrolysis, when the inflow rate for the anode electrolyte is increased to 120 mL min−1, ClO2 is produced at a constant concentration of 60 mg L−1 after 30 minutes. An analysis of the multi-oxidants generated from brine to detect disinfection byproducts shows very little trichloromethane is formed, much less than the standard for total trihalomethanes in drinking water in Taiwan (0.1 mg L−1). The disinfection efficiency of the multi-oxidant produced in this study is about three times greater than that of commercial hypochlorous acid. These results show that multi-oxidant products retrieved by recycling brine from desalination plants are commercially applicable and have economic value.

BackgroundAs an appropriate tool, membrane process is used for desalination of brackish water, in the production of drinking water. The present study aims to investigate desalination processes of brackish water of Qom Province in Iran.MethodsThis study was carried out at the central laboratory of Water and Wastewater Company of the studied area. To this aim, membrane processes, including nanofiltration (NF) and reverse osmosis (RO), separately and also their hybrid process were applied. Moreover, water physical and chemical parameters, including salinity, total dissolved solids (TDS), electric conductivity (EC), Na+1 and Cl−1 were also measured. Afterward, the rejection percent of each parameter was investigated and compared using nanofiltration and reverse osmosis separately and also by their hybrid process. The treatment process was performed by Luna domestic desalination device, which its membrane was replaced by two NF90 and TW30 membranes for nanofiltration and reverse osmosis processes, respectively. All collected brackish water samples were fed through membranes NF90-2540, TW30-1821-100(RO) and Hybrid (NF/RO) which were installed on desalination household scale pilot (Luna water 100GPD). Then, to study the effects of pressure on permeable quality of membranes, the simulation software model ROSA was applied.ResultsResults showed that percent of the salinity rejection was recorded as 50.21%; 72.82 and 78.56% in NF, RO and hybrid processes, respectively. During the study, in order to simulate the performance of nanofiltartion, reverse osmosis and hybrid by pressure drive, reverse osmosis system analysis (ROSA) model was applied. The experiments were conducted at performance three methods of desalination to remove physic-chemical parameters as percentage of rejections in the pilot plant are: in the NF system the salinity 50.21, TDS 43.41, EC 43.62, Cl 21.1, Na 36.15, and in the RO membrane the salinity 72.02, TDS 60.26, EC 60.33, Cl 43.08, Na 54.41. Also in case of the rejection in hybrid system of those parameters and ions included salinity 78.65, TDS 76.52, EC 76.42, Cl 63.95, and Na 70.91.ConclusionsComparing rejection percent in three above-mentioned methods, it could be concluded that, in reverse osmosis process, ions and non-ion parameters rejection ability were rather better than nanofiltration process, and also better in hybrid compared to reverse osmosis process.The results reported in this paper indicate that the integration of membrane nanofiltration with reverse osmosis (hybrid NF/RO) can be completed by each other probably to remove salinity, TDS, EC, Cl, and Na.

The kinetics and mechanisms of chlorine dioxide and chlorine in water distribution network is described, and a multi-species network water quality model is built in this paper. Experiment was composed of two parts, static test and dynamic test. The cast iron pipe, steel pipe, and PVC pipe were selected to carry out static experiments. In order to study the kinetic and mechanism of the combination disinfection of chlorine dioxide and chlorine, the reaction was under the condition of different chlorine dioxide and chlorine dosing ratio and different chlorination method. Dynamic experiments carried out in the cast iron pipe in different chlorine dioxide and chlorine dosing ratio and different flow conditions to study the kinetic and mechanism of the combination disinfection of chlorine dioxide and chlorine .A multi-species network water quality model using EPANET-MSX toolkit is built based on kinetic and mechanism of the combination disinfection of chlorine dioxide and chlorine. The concentration of residual chlorine (Cl2), chlorine dioxide (ClO2), chlorite in the bulk water and biofilm was taken as the main parameters. And the model was calibrated by the experiment data. The water quality model application in a large water distribution network, of which the total demand is 800,000 m 3 /d in China. The results show that the combination of chlorine dioxide and chlorine disinfection can reduce the chlorine and chlorine dioxide disinfection by-product and residual chlorine concentration distribution was more reasonable.

Disinfection by-product formation during seawater desalination: A review

Changes in characteristics of polyamide reverse osmosis membrane due to chlorine attack

Chapter 2 - Water Desalination by (Nonsolar) Renewable Energy-Powered RO Systems

Trichloromethane Formation Potential in Killing Algae with Chlorine Dioxide

Desalination technology provides one promising solution to the global water shortage problem yet brings about a new challenge of managing massive waste brines. Recently, interfacial solar steam generation technology has gained increasing attention for brine treatment due to its high energy‐conversion efficiency and applicability to hypersaline brines. However, it is challenging to maintain high performance because of salt fouling problem. Herein, this study presents a novel salt excretion approach to maintaining the evaporation efficiency of interfacial solar steam systems for improved long‐term stability in brine desalination. By creating a directional flow, accumulated salts are excreted via discharging the concentrated brine. This approach is effective and applicable for brines with a broad range of concentration owing to its tuneable concentrating performance. With the capability of continuously producing clean water and near‐saturation brine, this work advances solar steam technologies toward practical applications, such as brine concentration and resource recovery.image

Feasibility assessment of alternative environmentally friendly disinfection technique for reverse osmosis-based desalination process

The basis of a novel method for seawater desalination is outlined. In this work, pressure-retarded osmosis (PRO) energy is obtained and used posteriorly for the reverse osmosis (RO) process for seawater desalination. Although PRO process coupled with an RO process has been studied in the past, however, in this work, there is a fundamental difference. Instead of bringing river or wastewaters with low salinity to the coast to be mixed with the seawater to run the PRO process, here is the seawater which is deliberately salinized. This technique has one important consequence, namely, that it is no longer required to be in places where rivers or wastewaters flow into the sea. This important difference eliminates this until now somehow paradoxical requirement if one considers that regions needing desalination are generally poor of water resources. On the other hand, it is not a coincidence that regions needing desalination plants are also regions with rich open salt deposits in the neighborhood; high evaporation, high concentration of salt deposits, and the need for freshwater are all of them directly correlated. Therefore, the idea proposed in the paper is consistent with the problem. The high evaporation in the region which is causing the need for desalination also is creating the solution to do this by using the salt deposits created. The economic feasibility of this method is preliminarily assessed in terms of the thermodynamic limits of extractable energy and then with the cost of the salt required to obtain this energy which is compared with the price from electrical grid. It was found that in order to reduce the amount of salt required for the process, and to make the cost of energy competitive, it is necessary to direct the hypersaline draw solution (draw solution) in a cyclic loop and to have the highest possible volume fraction for the nonsalinized solution (feed solution). Additional R&D is required to explore the possibilities of this concept.

Chemical demand, yield, water consumption, effluent load and treatability, pulp organic chlorine compounds (OX), brightness stability, refinability, and strength are drivers for choosing bleaching technology. This work critically reviews the state-of-the-art processes for oxygen delignification, first stage, second stage, and final bleaching of eucalyptus kraft pulp in light of those drivers. Emerging technologies, such as the PMo stage and formaldehyde assisted bleaching, are discussed. Implementation of single- or double-stage oxygen delignification is determined by the pulp “true” lignin content. High pulp HexAs content and poor selectivity limits dropping kappa number under 9-10 in single or double O-stage. Mo-catalyzed acid peroxide delignification after O-stage allows further reduction of kappa number to 3-4. Efficient post-oxygen washing is the key for low cost bleaching, with a kilogram of COD/o.d. ton consuming the equivalent to 0.085% active chlorine. A/D-(EP)-D type three-stage sequence suffices for bleaching eucalyptus kraft pulps. The inclusion of a fourth stage is desirable for high brightness/low reversion pulps. Chemical consumption is strongly influenced by brown pulp origin, with variations of 3.2% to 7.7% active Cl2 demand, depending upon the pulp type. The type of elemental chlorine free (ECF) bleaching technology, based on chlorine dioxide, affects chemical consumption only slightly. Hot acid/hot chlorine dioxide bleaching technology saves small amounts of active chlorine for high bleachability pulps, but none for low bleachability ones. Atmospheric extraction (EP) suffices for eucalyptus kraft pulp bleaching. Formaldehyde saves more chlorine dioxide when used in D1 than in D0/DHT stages. A final peroxide stage improves pulp brightness stability. The production of organically bound chlorine decreases by 30% with hot chlorine dioxide bleaching, but this gain disappears after effluent biological treatment.