Qatar Foundation Annual Research Conference Proceedings Volume 2016 Issue 1

The current study is a laboratory investigation to estimate the levels of activity concentrations of Naturally Occurring Radioactive Materials (NORM) in groundwater in the Dukhan area in the State of Qatar. The primary radionuclide associated with clear gamma-ray decay signatures of concern in NORM wastes is 226Ra (from the 238U decay series) and its decay progenies 214Pb and 214Bi. Previous studies which were conducted on radioactivity concentration in soil in the State of Qatar have shown elevated levels of enhanced radioactivity in the area, North-West Dukhan, known for its oil fields. With the original aim of investigating the correlation between the underlying geological background and any measured elevation in the activity concentration of 226Ra, an anomalously high value of 226Ra activity had been observed for a number of measured samples in our earlier work, in this particular area and in particular. The weighted mean value of the activity concentrations of 226Ra in one of the samples was found to be around approximately a factor of 10 higher than the accepted worldwide average value of 35 Bq/kg. Our first study reported a value of about 201.9 ± 1.5Stat. ± 13Syst. Bq/kg for 226Ra in one sample,¹ while our further and focused (smaller grids) investigation in the latest work determined a measured value for 226Ra of about 342.00 ±  1.9Stat. ± 25Syst. Bq/kg in a sample taken from the same locality.² This is significantly higher than all the other investigated soil samples in the current and previous work and was likely to be in a heterogeneous distribution. This was found to be attributed to the weak correlation between the levels of activity concentration of 226Ra and the type of soil in this area implying that the increased 226Ra concentration arises from discharging co-produced water directly to land surface in this area. A preliminary study on the level of natural radionuclides in eight groundwater samples for this specific area using five cutting edge techniques in the national and collaborating laboratories will be presented. About half of those samples were collected from Dukhan farms where the groundwater was used for irrigation. Measurements for 222Rn concentrations in groundwater will be conducted using Rad-7 and a Liquid Scintillator Counter (LSC) at the Physics Department, Faculty of Sciences, Princess Nora Bint Abdul Rahman University, KSA. The activity concentration of 210Po and 210Pb will also be analyzed using alpha spectrometry and LSC at the National Physical Laboratory, UK. Gamma measurements using Low-level HPGe Detector will focus on activity concentration levels of 228, 226Ra and their decay progenies 214Bi, 214Pb, 228Ac, 212Pb and 208Tl and they will be conducted at the Radiation Measurements Laboratory, Ministry of Environment, Qatar. A general chemical analysis using ICP-MS will be conducted at the laboratory of Qatar Environment and Energy Research Institute (QEERI) in order to support the radiological analysis in the project. The results of this study will be essential to further clarify the reasons behind this elevation in this area. In addition, it will help in characterizing the areas of concern and explore the beneficial use and the suitable and feasible treatment options of the co-produced water and positively contributing to the water security target.

References

1. Al-Sulaiti, H., Regan P. H., Bradley D. A., Malain D., et al., A preliminary report on the determination of natural radioactivity levels of the State of Qatar using high-resolution gamma-ray spectrometry. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment (NIM-A), 2010. 619(1–3): p. 427–431.

2. Huda Al-Sulaiti, Tabassum Nasir, K.S. AlMugren, et al., Determination of the Natural Radioactivity Levels in North West of Dukhan, Qatar Using High-Resolution Gamma-ray Spectrometry, Proceedings of the 8th International Topical Meeting on Industrial Radiation and Radioisotope Measurement Applications (IRRMA-8) Applied Radiation and Isotopes, July 2012, Volume 70, Issue 7, p. 1344–1350.

Abstract Background: The plant growth and production rely on the supporting favorable environmental conditions throughout its growing stages. In harsh environmental conditions such as in Qatar, agricultural growth is limited by water availability, salinity and drought, leading to low yield. In soil, there are different kinds of microbiota including fungi, bacteria, actinomycetes, algae as well as various types of plant species. Fungi are important components of the soil microbiota. For example, soil-borne fungi cause a significant yield loss for many vegetable and fruit crops in Qatar including tomatoes, cucumbers, legumes, limes, strawberries and others. Several recent studies have demonstrated that the adaptation of plants to severe environmental conditions is attributed to genetic abilities of their associated microbes. For example, all plants in natural ecosystems are thought to be symbiotic with mycorrhizal and/or endophytic fungi reflecting fitness benefits conferred by fungi that contribute to or are responsible for plant adaptation to stress. In Qatar, there are many plant species that can survive under adverse abiotic conditions of salinity and drought rendering them as rich resources for structuring their associated microbes. Objectives: The aims of this study were to: (i) investigate the effect of different ecosystems on the structure and distribution of soil-borne fungi; (ii) inspect the ability of plant-associated microbes to tolerate harsh environmental conditions; and (iii) examine the effectiveness of isolated fungi as potential biological control agents. The ultimate goal of this study is to improve the sustainable agriculture in Qatar through the implementation of plant-associated microbes for biological control of important diseases and enhance plant tolerance to abiotic stress. Materials and Methods-Isolation of plant associated microbes: Samples from plant rhizosphere and soil were collected from four different plant species grown under different ecosystems in Qatar. Qatar University Farm (Al-Zubara Area, Qatar) exemplifies the agricultural ecosystem; in addition to six private farms represent different ecosystems. Four plant species were considered in this study namely Launae capitata, Lycium shawii, Ziziphus lotus and Zygophyllum qatarense (Tetraena qatarense). Samples from plant rhizosphere and soil were collected in January. Soil-borne fungi were isolated from the rhizosphere and soil using direct plate method. About 0.5 g of homogenized soil sample was plated on melted potato dextrose agar supplemented with Rose Bengal. Plates were incubated at 25°C for 3–7 days and colonies with different morphological characters were isolated and purified. Fungal isolates were identified morphologically using light microscopy. DNA was extracted using QIAGEN kit for molecular analysis. Effect of abiotic stress on the growth of Trichoderma spp.: different concentrations of sodium chloride (NaCl) were used to induce salinity stress. NaCl concentrations include 0 (control), 10 mM, 50 mM, 100 mM, 250 mM, 500 mM, 1 M, 1.25 M, 1.5 M, 1.75 M, 2 M, 2.25 M, 2.5 M, 2.75 M and 3 M. Fifty ml of potato dextrose broth medium, with different salt level, was inoculated with five mm disc of Trichoderma spp. Poly Ethylene Glycol (PEG) was used to induce drought effect on Trichoderma spp. Different percentages of PEG were performed including 0% (control), 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% and 100%. In 100 ml conical flask; 50 ml of PDB medium with different percentages of PEG was inoculated with five mm disc of Trichoderma spp. The antagonistic effect of the fungal isolates was tested using the direct opposition method. Antagonistic test was performed between Trichoderma spp. which has an effective biocontrol activity towards many soil-borne pathogenic fungi and Ceratocystis radicicola (Thielaviopsis paradoxa), which causes many diseases in date palm trees. The test was performed in dual culture on PDA medium. Five mm disc of each fungus was placed at peripheral end (five cm between each other) of Petri plate. The plates were incubated at 25°C for 7 days. Three replicates were considered. Results: Tthirty-nine of fungal genera were isolated from the plant rhizosphere and soil. Results showed that the most dominant genus was Aspergillus niger (48.5%) followed by Rhizopus spp. (26.8%). Other fungal communities were also detected such as Aspergillus vesicolory, Aspergillus sydowii, Aspergillus wentii, Fusarium oxysporum, Penicillia oxalicum, and Rhizoctonia solani. Results also showed that Aspergillus terreus is associated with rhizosphere of plant species growing in harsh conditions. However, plants grown under agricultural conditions showed a biodiversity in their associated-fungal species, the most common fungi are Fusarium sp. and Trichoderma sp., which were isolated from rhizosphere of Launaea capitata and Ziziphus lotus grown in harsh conditions. In vitro, Trichoderma spp. was able to grow in high concentrations of salt (2 M) and PEG (80%) reflecting a high adaptation of plant associated microbes to both salinity and drought stresses. Results from the antagonistic test showed that Trichoderma spp. caused a remarkable growth inhibition of C. radicicola the causal agent of many diseases in date palm trees. Conclusion: Data obtained from the current study will lead to the initiation of a Qatari fungal culture collection, which will help conserve the biodiversity and could be essential for future studies. Additionally, plant-associated microbes isolated from different ecosystems can further be used for biological control of important plant diseases and enhancing plant tolerance to abiotic stress. Altogether, results from the current study suggest a prospective implementation of plant-associated microbes for a sustainable agriculture in Qatar.

Municipal solid waste management is one of the major challenges facing Qatar with more than 2.5 million tons of municipal solid waste each year, a very high waste generation rate in a country with small land mass. Solid waste in Qatar consists mostly of organic materials (60%) with the remaining made up of recyclables, such as glass, metals and plastics. Qatar's ambitious development strategy targets environmental sustainability and invests in research on key grand challenges including water/food security. Fortunately both can be addressed through value-added conversion of solid organic waste into biochars. Solid municipal wastes such as newspaper, cardboard, woodchips and plant residues from landscaping can be converted to biochar for mitigation of their environmental impact and value-addition. On the other hand, agricultural soils have significant deficiencies in a range of essential trace elements and macronutrients and often exhibit low water holding capacity. These deficiencies impact both the yield and the nutritional quality of edible crops with direct consequences cost-effectiveness and human health. Fortunately, these challenges can be advantageously addressed by production of biochars from organic sources such as mixed organic solid waste from municipalities as well as agricultural and landscaping operations. The landfill and composting of these solid municipal wastes generate greenhouse gases that contribute to climate changes. Biochars prepared from solid municipal wastes can greatly benefit the carbon content of soil. Additionally, biochar may interact with fertilizers to deliver indirect improvements in plant growth and reduce the emission of greenhouse gases from native organic matter. Biochars can also be custom-designed to increase/decrease native soil pH to bring it closer to the optimum range for microbial and plant growth. These applications give solid organic municipal wastes promising potential as precursors for value-added biochars with varied physicochemical characteristics allowing them to be used not only as an alternative to bio-waste management and greenhouse gas mitigation but also as means to improve depleted soil. We hypothesize that soil deficiencies in soil can be remedied by the application of biochars that are custom-designed to possess the right physicochemical characteristics suitable to improve soil fertility. The aim of this study was to: (1) produce biochars from mixed solid organic waste for use in soil quality enhancement, (2) investigate the effect of biochar addition to soil on plant germination and growth and (3) evaluate the potential of biochars in mitigating green house gas (GHGs) emissions. Select solid organic municipal wastes (newspaper, cardboard, woodchips and landscaping residues) were used as a precursor for biochar preparation. A blend of 25% of each precursor was used and pyrolyzed at 700°C for 2 hrs under N2 gas at a flow rate of 0.1 mL min^− 1 using a Lindberg box programmable furnace equipped with an air-tight retort. Soil fertility parameters such as pH, water retention and macro and micronutrients were analyzed. Fine sandy clay loam soil from the Ap horizon (0-15 cm deep) was amended with biochar at the rate of 2% (w/w). To test the germination rate in soils, with and without biochars (produced from municipal solid waste precursors of 25% blend of four types of waste materials), hybrid savoyed spinach seeds were sown in germination trays (3 seeds/well) for two weeks in climate controlled greenhouse settings. Trays were watered twice daily to maintain moisture level between 10 and 12 percent. The percentage of seed germination was calculated and the plant growth measured as dry biomass. Incubation experiments were conducted to measure GHGs production in sealed glass vials containing soil with and without biochar or raw materials from which this biochar was produced. Greenhouse gases emission differential between the biochars and their corresponding raw feedstocks in treated soil was used as indicator of GHGs emission by biochars during the incubation period Biochars prepared from blends produced at 700°C pyrolysis temperatures and used at 2% application rate to soil showed higher pH (6.8), increased water retention, and high K and NO3-N content. The net effect of these changes in soil properties positively impacted both seed germination and biomass yield of the plants (up to two folds in soil amended with biochars). At the same time, conversion of solid organic wastes into biochar enabled 14% reduction in GHGs emission compared to the solid waste precursors, as indicated by lower CO2 emission. Biochar amendment in soil significantly reduced the CO2 emission (14%), which would otherwise have increased greenhouse gas due to solid waste decomposition in soil. This differential is mainly due to respiration controlled by microbes. Soil amended with biochar closely followed the trend of soil treatment signifying no additional contribution to CO2 efflux. The increase in CO2 efflux seen in feedstock-amended soil can be attributed to the decomposition of feedstock during the time incubation period. In summary, biochars from mixed solid organic wastes at 2% carbon to soil ratio improved seed germination, increased plant biomass yield, and reduced GHGs emission compared to precursors. To reach the maximum benefits, pyrolysis conditions and feedstock selection are critical steps to produce biochars with desirable properties for specific soil amendment. From the present study, it is clear that constituents of municipal solid organic wastes hold promising potential as inexpensive precursor for value-added biochar manufacturing with varied and customizable physicochemical characteristics that would be beneficial in soil amendments while alleviating the problem of solid waste disposal and contributing to mitigation of GHGs. Further studies are need needed to confirm the reported advantages in natural field settings.

The Northeastern Qatari coast is comprised of diverse and sensitive flora and fauna such as seagrass meadows, turtles, algae, and coral reefs/patches that tolerate harsh environmental conditions. In the near future, this area may see a rise in anthropogenic activity in the form of coastal development projects, which will add to the existing natural stresses, such as high temperature, high salinity and low rates of precipitation. Therefore, there is a need to characterize the area and assess the potential impacts that these anthropogenic activities may have on the region. Eco-hydrological models are theoretical, mathematical representations of natural systems, made to help understand their functionalities under physical forcing. Site-specific data, hydrodynamic models, and ecological and physical phenomena are combined to build a functional ecosystem model that mimics real environments. These models can then be used to predict the impacts of anthropogenic and natural stressors on real systems. There are two main types of Eco-hydrological models: analytic and computational. Analytic models are usually less complex since they have an analytical solutions, and are used to represent simple or abstract systems with well-known behaviors. Alternatively, computational models are considered to be more ecologically sensible, as they can be used to solve complex systems that require the use of numerical techniques. The results of the computational model can vary between different numerical techniques or modeling software, resulting in uncertainty and variability that should be estimated. Given the complex nature of the environmental system in the Northeastern Qatari coast, numerical solutions using modeling software are developed to establish an adequate representation. There are three main modeling programs that have been used for the development of Ecological Response Models in Qatar (SWAN, GEMSS, and TELEMAC-2D). GEMSS provides a set of hydrodynamic, transportation and water quality modules allowing for the development of an integrated Eco-hydrological model according to the needs of each modeling application, which makes it the most appropriate software to use in this study. The aim of this study is to develop hydrodynamic and sediment transport models for a stretch of the Jabal Fuwairat Coastline in Qatar, using GEMSS and bathymetric LIDAR data processed with ArcGIS. The hydrodynamic model (HDM), which will be calibrated and tested using field data, simulates the spatial and temporal dynamics of the water, while the sediment transport model (STM) identifies, under present or simulated scenarios, the fate of the suspended sediments in the studied coastal zone. The STM provides data about sediment typologies, suspended particulate matter and currents that are near the seafloor (shear stress). The developed models will be tested using potential scenarios of future anthropogenic activities forecasted to take place in the area. The results will show the effects on water and sediment behavior, and provide a scientific basis for key stakeholders to make decisions with respect to the management of the considered coastal zone. It also provides a tool/framework that can be utilized in future hydrodynamic studies along other areas of the Qatari coastal zone. Furthermore, the outcomes are fundamental to developing a complete and accurate Eco-hydrological model. Keywords: Hydrodynamic Model, Sediment Transport Model, Anthropogenic stressors, coastal dynamics, GEMSS, ArcMap, LIDAR.

Organic electronic devices based on polymers received significant attention in the last decade, especially for organic photovoltaics (OPVs) and field-effect transistors (OFETs) despite their performances and stability clearly falling short of today's state-of-the-art crystalline silicon or copper indium germanium selenide (CIGS)-based devices. Flexibility in the manufacturing, light weight, lower fabrication cost, ease of integration into various devices, and large area coating are some of the major potential advantages of polymers over inorganic devices.

1 Among organic polymers, conjugated polymers attracted widespread attention for a wide range of applications. Thiophene-containing conjugated polymers, especially, poly(3-alkylthiophne) (P3AT) has been subjected to intensive research over last decade due to their excellent optical and electronic properties.

2 Moreover, poly(thienylenevinylene) (PTV) class of polymers displays high charge carrier mobilities in OFETs and promising performances in OPVs.

3 When a single solubilizing alkyl chain is included onto the PTV backbone, the resulting copolymer can be solution processed for optical devices. One simple strategy to manipulate the copolymer property is by changing the heteroatom of the thiophene from sulfur to other chalcogens, selenium or tellurium.

4 Theoretical calculations indicated that substitution with selenium or tellurium may reduce the optical band gap of the resulting polymer in comparison to their sulfur-containing analogues. Inclusion of larger and more polarizable selenium or tellurium also expected to have a strong influence on the charge transport properties. Notably, Heeney and co-workers showed that the band gap of P3AT can be reduced by as much as 0.3 eV by only substituting sulfur with selenium in the polymer backbone.

5 The reduction of band gap resulted from larger and more polarizable selenium facilitate better π orbital overlap with the polymer backbone and thus stabilize the polymer LUMO (lowest unoccupied molecular orbital). Low-lying LUMO levels are believe to facilitate both electron injection and transport. Recently, PBDTT-SeDPP polymer showed a high Jsc of 16.8 mA/cm², a Voc of 0.69 V, and a FF of 62%, enabling the best PCE of 7.2%.

6 However, despite fascinating properties of selenium substituted polymers, tellurium containing polymers are less explored, may be due to challenging tellurium chemistry. Jahnke and co-workers recently reported first soluble tellurophene polymer, poly(3-alkyltellurophene) (P3ATe), prepared by both electrochemical and Kumuda coupling polymerization method.

7 Even though, preliminary PCE (1.1%) was modest, tellurium substitution resulted in red-shifted film absorption. In this contribution, we report the synthesis and characterization of vinylene copolymers containing 3-alkylthiophene, selenophene or tellurophene. This allows us systematically investigate the role of selenium or tellurium on the polymer properties. Here, we report the first synthesis of novel 2,5-dibrominated 3-alkyltellurophene monomer and its Pd[0]-catalyzed copolymerization with (E)1,2-bis(tributylstannyl)ethylene to afford poly(3-alkyltellurophenylenevinylene) (P3ATeV).

8 We compare the optoelectronic properties of P3ATeV with analogous sulfur (P3ATV) and selenium (P3ASV) containing polymers. Preliminary OFET data will also be incorporated. Scheme 1. Structures of P3AX, P3AXV copolymers.

References

1. Gang Li, Rui Zhu and Y. Yang, Nature Photonics 2012, 6, 153–161.

2. M. T. Dang, L. Hirsch and G. Wantz, Adv. Mater. 2011, 23, 3597–3602.

3. D. Astruc, E. Boisselier and C. Ornelas, Chem. Rev. 2010, 110, 1857–1959.

4. M. Jeffries-EL, B. M. Kobilka and B. J. Hale, Macromolecules 2014, 47, 7253–7678.

5. M. Heeney, W. Zhang, D. J. Crouch, M. L. Chabinyc, S. Gordeyev, R. Hamilton, S. J. Higgins, I. McCulloch, P. J. Skabara, D. Sparrowe and S. Tierney, Chem. Commun. 2007, 5061–5063.

6. L. Dou, W.-H. Chang, J. Gao, C.-C. Chen, J. You and Y. Yang, Adv. Mater. 2013, 25, 825–831.

7. A. A. Jahnke, B. Djukic, T. M. McCormick, E. B. Domingo, C. Hellmann, Y. Lee and D. S. Seferos, J. Am. Chem. Soc. 2013, 135, 951–954.

8. M. Al-Hashimi, Y. Han, J. Smith, H. S. Bazzi, S. Y. A. Alqaradawi, S. Watkins, T. D. Anthopoulos, M. Heeney, Chem. Sci. 2015, DOI: 10.1039/C5SC03501E.

In order to ensure long-term sustainability of the reservoir, the gas industry in Qatar is faced with the challenge of reducing the volume of produced and process water (PPW) sent to disposal wells by 50% [1-3]. Recently, Qatargas initiated a project to recycle process water and thus, reduce disposal volumes using commercial advanced water treatment technologies [4]. One emerging technology, “osmotic concentration” (OC) has been identified that offers a low-energy alternative to conventional thermal or membrane volume reduction methods. Osmotic concentration is a membrane filtration process that mimics first step in a forward osmosis (FO) system. It requires a high salinity draw solution (DS) which passes on one side of a semi-permeable FO membrane while the feed passes on the other side. Water from the feed is drawn through the membrane, via natural osmosis, reducing the feed volume and increasing the volume of the draw solution. This paper summarizes the results of bench-scale volume reduction tests with PPW collected from Qatar's North Field operations as the feed and either seawater or the concentrated brine from thermal desalination plants as the draw solution. While in conventional forward osmosis, the draw solution is regenerated, in OC, there is no regeneration of the draw solution. The diluted seawater or brine would be simply discharged to the Arabian Gulf. For future projects/developments, the authors have proposed OC for PPW volume reduction, which can be a cost-efficient alternative to achieve 50% reduction in disposal volumes (Fig. 1). This approach is particularly applicable in Qatar due to close proximity of desalination plants and gas processing facilities. In all membrane processes, the driving force for permeation is pressure. The mechanism by which the pressure is created differentiates various membrane processes: Reverse osmosis: static pressure generated by a pump Membrane distillation: vapor pressure differential due to a difference in temperature Osmotic concentration: osmotic pressure differential due to a difference in salinity. In these examples, the driving force or transmembrane pressure (TMP) can be measured in units of kPa or bar. In reverse osmosis, the TMP ranges from 15 to 60 bar depending on the salinity of the feed. In osmotic concentration, a comparable TMP of 15 to 60 bar is generated simply by high salinity the draw solution, i.e. without any static pressure being required and hence the low energy requirements for OC processes. In addition to significantly lower operating energy requirements [5], an OC process offers the following advantages over reverse osmosis (RO): Lower capital cost because pressure-rated vessels and high pressure pumps are not required [6]; There is strong evidence that FO membranes are less prone to irreversible fouling than RO membranes and foulants can be removed by simple flushing with clean water with no addition of chemicals [7,8]; The water discharged to the Arabian Gulf is of lower salinity and that provides an environmental benefit. The primary disadvantages of OC are that there is no water recovery after the separation process and there is limited experience from full-scale water treatment installations. The main objective of this study was to investigate the feasibility of OC to concentrate PPW from gas operations by 50% using brine from thermal desalination plants as draw solution. The PPW was a combination of gas field produced water extracted from an offshore reservoir and process water from onshore operations. The blending ratio between produced and process water was approximately 1:5. The PPW underwent deoiling, H2S removal and cartridge filtration (2 mm). The detailed composition of PPW and brine from thermal desalination plant are shown in Table 1. During this study, experiments were conducted to evaluate OC performance in treating PPW in the following areas: membrane configuration membrane fouling effect of pretreatment process optimization long-term stability/performance. In all tests, the active layer faced the feed solution (AL-FS mode) since this configuration provides better control of feed-side fouling. Membrane configuration During this project, two membrane configurations were evaluated: Flat sheet (FS) membranes, commercially available [9]Hollow fiber (HF) membranes, Singapore Membrane Technology Centre [10, 11]. The membrane surface areas were 0.014 and 0.0106 m² for the FS and HF modules, respectively. Experiments were conducted using two feed solutions: DI water and PPW. Results showed that the HF membranes had improved performance from both the water flux and reverse solute flux (RSF) perspectives. The HF membrane flux was ≈ 35 to 45% higher for both DI water and PPW (Fig. 2). With PPW as feed at 25?°C, the RSF was measured for both membranes and the results showed that HF membranes exhibited ≤ 3 mmol/m² h RSF for Na⁺ and Cl⁻  while FS membranes showed a RSF of ≈ 20 mmol/m²h for both ions. RSF is highly sensitive to operating temperature. Because HF membranes showed superior performance and there are also commercial advantages (higher packing density, lower fabrication cost), experiments focused on evaluating HF performance in treating PPW. Membrane fouling: To assess if membrane fouling occurred, a benchmark test with DI water as feed solution and 1M NaCl as draw solution at 25?°C was conducted before and after each fouling test. A decline in the benchmark flux after treating PPW would indicate that membrane fouling had occurred. The fouling tests were conducted on two feed streams: synthetic PPW (mimicking only the inorganic content of PPW) and real PPW. During the experiments, the initial volume of PPW was reduced by 50% and the draw solution (DS) was 1M NaCl. The DS concentration, for both benchmark and fouling tests, was maintained constant throughout the experiments by adding concentrated NaCl solution based on conductivity measurements. While the results for synthetic PPW showed that no fouling had occurred, the results showed that PPW could cause fouling on the membrane surface since the benchmark flux decreased from 17.5 to 15 L/m^2?h (Fig. 3). The fouling was attributed to the organics present in the PPW since no flux decline was observed on the when synthetic PPW was used as feed. These results highlighted the need for effective pretreatment to remove organics. Effect of pretreatment: To determine if pretreatment could remove the organics responsible for fouling, a number of methods were screened and ultimately powdered activated carbon (PAC) was selected for pretreatment of the PPW. PAC is widely used for organics removal and previously evaluated for similar applications [12]. Lab results showed that at a dosage of 500 mg/L PAC, the TOC from the PPW was reduced from 132 to 45 mg/L. The PAC dosage was considered very high for a full-scale application and further pretreatment optimization is needed before field implementation. OC performance experiments showed no decline in benchmark flux when the volume of pretreated PPW was reduced by 50% indicating that pretreatment is essential for the successful implementation OC to reduce PPW disposal volumes. Results also showed that the HF membranes have good rejection for organics. For both the treated and untreated PPW, the TOC in the draw solution after OC treatment was below the 1 mg/L detection limit indicating that the membrane rejection of the organics was >99%. Process optimization: Box-Behnken design: The main operating parameters for this application were optimized using a Box-Behnken design (BBD) [13, 14]. BBD is a response surface methodology that explores the effect of different input variables (temperature, draw solution concentration and feed crossflow velocity) on the output response (flux). This statistical tool takes into consideration the combined effects and interdependence of the input variables and significantly reduces the number of tests required as compared to the conventional factorial experimental design. The following parameters and test values were used during the BBD experiments: Temperature: 25, 35 and 45?°C Draw solution concentrations: 40, 55 and 70 g/L NaCl Feed crossflow velocity: 40, 60, 80 cm/s. Results showed that the temperature has the greatest impact on the flux, since it influences the water viscosity. DS concentration directly affects the osmotic pressure, influencing the flux. The feed crossflow velocity did not affect the process performance over the range tested. These results are consistent with authors’ expectations and general published results. Based on the BBD analysis, the optimized process conditions were: 45°C temperature, 70 g/L draw solution concentration and 80 cm/s feed crossflow velocity. Figure 4 shows the comparison of the OC performance, to achieve 50% feed volume reduction, at benchmark (25?°C, 70 cm/s, 58.5 g/L NaCl) and optimized (45?°C, 80 cm/s, 70 g/L NaCl) conditions. Long-term performance and water quality: The elimination of the water recovery step in osmotic concentration makes it an energy efficient process [5]. To confirm if the brine from thermal desalination plants is a suitable DS for the treatment of PPW, a long-term experiment was performed simulating full-scale operation. In earlier experiments, the concentration of the DS was maintained constant, by adding concentrated DS. Since this is not feasible in full-scale applications, a process stability experiment was carried out without controlling the DS's concentration, allowing it to dilute with time as water permeates through the FO membrane. The experiment was conducted using pretreated PPW as feed and brine from thermal desalination plant as DS. The solution temperature was 45?°C since this is the expected temperature of the brine discharged from the desalination plant. The feed and draw solutions crossflow velocities were 80 and 40 cm/s respectively. The test was conducted for 80 hours. The PPW initial volume was 42 L and it was reduced in volume by 50% while the volume of the draw solution, initially 21 L, was increased to 42 L, reducing its salinity by 50%. A relatively stable performance was observed throughout the experiment with a 30% decrease in flux (from 28 to 20 L/m²?h) due to the decrease of the effective osmotic pressure and to the influence of the internal concentration polarization (ICP). After a sharp initial decline in osmotic pressure differential, the decline in flux almost tracked the decline in the osmotic pressure differential (Fig. 5). DI water fluxes during benchmark tests conducted before and after the experiment remained constant at 19.4 L/m²?h indicating that negligible fouling occurred. To evaluate the ability of HF membranes to reject specific contaminants, various water quality analyses were performed. Results showed that HF membranes have high rejection capabilities. The ions with the highest solute fluxes values were sodium and chloride with a RSF of 120 and 91 mmol/(m²?h) respectively at 45?°C (Table 2). Although a small amount of nitrogen passed through the membrane from the PPW to the draw solution, at the levels found (5.8 mg/L), it was below the discharge limits set by the State of Qatar and the European commission (10 mg/L) [15]. The results also showed that the organic carbon present in the PPW was rejected by the membrane and retained in the PPW. A slightly increase in the TOC concentration in the DS was observed and it could be attributed to uncertainties in the analysis since the results were at the low end of the measurement accuracy. Finally, preliminary cost estimates and energy calculations showed that OC is economically feasible to reduce PPW injection volumes from gas fields in an environmentally sustainable manner. The research team is currently evaluating different pilot testing opportunities to further demonstrate the cost-effectiveness of this technology under relevant field conditions.

The Khor Al-Adaid “Inland sea” in Qatar is a unique desert lagoon, located in the South east of Qatar and is characterized by a distinct salinity gradient (ca. 4% halite salt to saturated conditions). In the framework of the QNRF funded NPRP project, researchers from Qatar, Germany and Austria have succeeded to isolate and cultivate a new unicellular eukaryote (protist) from Qatar's unique Inland Sea (Khor Al-Adaid). Initial genetic marker analyses pointed to the novelty of this organisms and morphological characterization confirmed that this isolated organism is not yet known and described from any other place in the world. Even though only 1/50th of a mm in length, this organism may hold secrets worth unlocking: the Qatar's Inland Sea is characterized by extremely high salt concentrations. With the discovery of this new organism from the Inland Sea the team of researchers hold in their hands a valuable unique treasure from Qatar's natural heritage. Future efforts will be to exploit this treasure for its genomic and biotechnological potential. The new species belongs to the genus Euplotes, and is coined the name Euplotes qatarensis nov. spec.

GCC's climate has a high ambient temperatures throughout most of the year, therefore, the air conditioning is not optional or luxury, it is a necessity. Residential sector in those countries represents the largest portion of electricity consumption. According to Qatar National Development Strategy (QNDS) 2011-2016, two-thirds (67 percent) of total residential power consumption in Qatar is due to air conditioning units (AC), Such heavy cooling demand is expected to approximately triple by 2030. Thereby, the fuel needed to power air-conditioning units in the GCC will is expected to 1.5 million barrels of oil per day. Energy efficient system is basically depending on two different categories; technological modification program and behavioral modification program. Both programs are required for energy efficient air conditioner systems. Existing air conditioner systems are based on conventional technological modification systems without considering the behavioral modification program which are impacted by the cost of implementation, impact on running systems as well as providing a fixed step algorithm of closed loop control between utility and residential customer. Therefore, we present a novel embedded real-time, smart, active energy and efficient air conditioning system for minimizing energy consumption, and minimizing energy cost per day while considering residential customer preferences, comfort level in behavioral modification program and health aspect, which provides opportunity for residential customer to reduce energy consumption improve energy efficiency with cost effective manners and healthcare concept. The proposed algorithm automatic adjustment air conditioning temperature below the outdoor temperature as recommended from physiologists. In addition the proposed energy efficient Air-conditioning system equipped with embedded tools to collects and monitor energy information for each air conditioning through measurements of current, voltages, frequency, active power (kW), reactive power (kVAR), apparent power (kVA), power factor (PF), total harmonic distortion (THD) to increased awareness of the importance of energy efficiency and energy saving benefits. The system has three modes of operation; automatic, semi-automatic and manual. The automatic status i.e. the system smartly and completely controls airflow/energy consumption of air conditioner at all times based on Psychrometric Chart; semi-automatic status is designed to quickly and efficiently controlled energy usage with fixed selected temperature value. The manual status is considered as a conventional, delivery and use of energy without any control. The Smart energy efficiency algorithm is set based on psychrometric chart, load importance, comfort level, room temperature, and internet weather service. The proposed novel system leads to achieve comfortable temperature with less energy consumption over many hours during the day. The proposed energy management strategy aims to save around 15-26% of daily energy consumption. Index Terms -Energy-efficient, air conditioning, Energy saving.

The coalescence of a water drop in a dieletric oil phase at a water layer interface in the presence of an electric field is simulated by solving the Navier-Stokes and charge conservation equations with the finite element method. The proprietary software Comsol Multiphysics is used for this purpose. The interface between the oil and water phases is tracked by implementing a level-set approach. Preliminary simulations to assess the sensitivity of the model with respect to some input parameters are reported. In particular, the calculations are very sensitive to the size of the computational grid elements and the interface thickness parameter. Nevertheless, the model is able to reproduce the occurrence of partial coalescence for the experimental case examined. Good quantitative agreement can be obtained if the parameters are suitably tuned.

Introduction

The application of an external electric field is a technique currently used in the oil industry to promote migration and enhance coalescence of droplets in the water-in-oil emulsions formed during the oil extraction process [1, 2]. It is generally acknowledged that the effect of the electric field is to increase film drainage and hence the thinning rate between two coalescing droplets [1]. However, an excessive value of the field strength can reduce the quality of coalescence, as secondary droplets form [3-6] as a result of an incomplete coalescence process. The efficiency of the process would be significantly improved if the operating conditions to prevent partial coalescence from occurring were known. In this regard, it has been shown [5] that the ratio between the volume of the secondary droplet formed and the initial drop volume can be described as a function of a dimensionless number which is the product of the Weber and Onhesorge numbers. The same authors have recently addressed the effect of the electric field type on the coalescence quality. Their experimental results have revealed that the volume of the secondary droplet decreases if pulse-DC fields are applied, leading to the transition from partial to complete coalescence under certain conditions [6]. These findings can have an important impact on the development of compact electrocoalescer designs. The aim of this work is to provide a mathematical description of the phenomenon. For this purpose, a finite element approach combined with the level-set method [7] is adopted in this work to analyse the process of partial coalescence. To the authors' knowledge, there are no attempts at predicting numerically the occurrence of incomplete coalescence in the presence of an electric field. The proprietary software Comsol Multiphysics (Comsol, Sweden) software has been used for this purpose, in an attempt to assess the capability of the proposed approach to reproduce and analyses the phenomenon.

Model Equations

A level-set approach is employed to track the boundaries between different phases. The evolution of the boundary is described by the equation: where is a smooth step function which varies from 0 to 1 across different phase domains, is a reinitialization parameter which gives stability to the solution and is related to the thickness of the interface. The fluid velocity is denoted by u (bold letters denote vectors). It should be noted that Eq. (1) is the non-conservative formulation of the level-set equation, which attains convergence more easily but introduces some errors in the calculations. However, the non-conservative formulation is more suitable for a rapid test of the model capabilities. Navier-Stokes and continuity equations are solved using average physical properties for the two phases: where and are the volume fraction weighted density and viscosity, which differ from the pure liquids properties only at the interface. In eq. (2), forces due to surface tension and induced by the electric field are included. The force due to surface tension is calculated as: where is the surface tension coefficient, the local surface curvature, n the outward pointing interface normal vector and d is a smooth approximation of the Dirac function which is non-zero only at the interface. The electric force is calculated from the divergence of the Maxwell tensor: where is the average permittivity. The electric field E is computed by satisfying the charge conservation equation: where is the average conductivity. With reference to the computational domain depicted in Fig. 1, the following boundary conditions have been applied in order to solve this set of equations: the upper boundary is kept at a fixed electric potential while the opposite one is earthed and no-slip conditions are prescribed for both boundaries; the domain is axisymmetric; slip conditions are considered on the right boundary, as this allows significant reduction of the simulation domain. The properties of the two liquids correspond to the sunflower oil/water system investigated experimentally by Mousavichoubeh et al. [5] and are reported in Table 1. The interfacial tension is equal to 25 mN mm^–1, as measure experimentally. In order to assess the effect of and the mesh element size, the following case is analysed. The initial drop size is 1.196 mm and the electric field strength is 373 V mm^–1. Under these conditions, partial coalescence occurs and the ratio between the volume of the secondary droplets formed and the initial drop volume is equal to about 0.088, as measured by Mousavichoubeh et al. [3].

Results

The calculated values of this ratio are reported in Table 2. For all cases, the reinitialization parameter is set equal to 1 m/s, which is comparable to the maximum fluid velocity in the system. The results shown in Table 2 reveal that the tuning of the interface thickness, is strictly connected to the level of mesh refinement (hmax/D is the maximum element size in the computational grid). With, the calculated volume of secondary droplets becomes invariant with the grid element size when this is sufficiently small. In this case the volume ratio of the secondary droplet to that of the initial drop is very close to the experimental value. However, the phenomenology described in the two simulations is different, and the results are compared in Figs. 2 and 3. The value of does not produce realistic results and convergence fails in a number of cases of the behaviour observed experimentally is also reported in Fig. 4. The numerical results obtained with reproduce the experimental observations exactly, whereas with a jet-like behavior is reproduced. This may be due to the larger interface thickness, which makes the droplet more deformable and the break-up process more difficult, although the predicted volume ratio is very close to the experimental value. problems, and a solution is obtained only for, which, however, provides a higher value of the secondary droplet volume formed as compared to the experiments. Decreasing further the grid element size to 0.02 causes non-convergence again, as should usually be smaller than the maximum grid size. This requirement becomes more critical when is small.

Conclusions

A model to describe partial coalescence in the presence of an electric field has been proposed. It has proved to be capable of reproducing the phenomenon observed in experimental work previously reported in the literature. A satisfactory quantitative agreement can be achieved by the right selection of the interface thickness parameter and computational grid size. This study constitutes the basis for the development of a reliable mathematical description which can be used for the design of a compact and efficient electrocoalescer.

Acknowledgement

This work was made possible by NPRP grant #5-366-2-1435-366-2-143 from the Qatar National Research Fund (A Member of The Qatar Foundation). The statements made herein are solely the responsibility of the authors.

References

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