Qatar Foundation Annual Research Conference Proceedings Volume 2016 Issue 1

Qatar is a country with huge potential for solar energy applications due to its reasonably high global horizontal radiation value. Further, solar energy can be used to reduce the demand on fossil-fuel generated electricity hence creating more revenues for Qatar from its natural gas resources. Currently, the residential sector consumes 57% of the total electricity consumption in Qatar. Moreover, Qatar has one of the highest electricity consumption per capita rates in the world; >15,000 kWh/year. Subsequently, at an individual level, the carbon footprint is high. It is important that we find cost effective ways to reduce dependence on fossil-fuel generated electricity as a step towards sustainable energy generation and use. Rooftop solar in the residential sector is identified a promising solution for Qatar to be sustainable in terms of energy use. The concept of using solar PV systems in homes is not a new one and has been applied in many countries. The private sector, in particular, has done a very good job in increasing the deployment of rooftop solar. However, at a corporate level, solar PV companies have to deal with a lot of economic and legal challenges. The main challenges are affordable financing and a resilient business model. One company that has managed to overcome these two challenges and become a pioneer at installing rooftop solar systems at a nationwide scale is SolarCity in the U.S. SolarCity was set up in 2006 and by 2014 it became the largest supplier and installer of rooftop solar systems in the U.S., accounted alone for one third of the residential solar market in the U.S. and had a cumulative installed capacity of 650 MW. A lot of lessons and strategies can be learnt from SolarCity's successful experience which can be used in Qatar. This research, hence, highlights the major factors behind SolarCity success and how Qatar can benefit from it in implementing rooftop solar at a large scale.

The United States is one of the biggest markets and innovations pools for the global solar industry. In fact, by the end of 2014, the U.S had the third largest installed capacity of PV (photovoltaics) globally; 6.2 GW (Brunisholz 2014). In 2014, the U.S. solar industry grew by 34% over the 2013 growth rate (SEIA 2014). This growth was mainly driven by the PV residential and utility sectors which both grew by 51% and 38% respectively in 2014 (SEIA 2014).

The growth and development of the U.S solar PV industry has been led by many private and public firms, the most famous among which is SolarCity. SolarCity was founded in 2006 by Elon Musk (chairman), Lyndon Rive (CEO) and Peter Rive (CTO). It is a private enterprise that sells and leases solar PV systems for homes, government agencies, universities and many other types of customers. SolarCity is now America's largest solar power provider employing more than 10,000 employees and serving nearly 217,000 customers in 18 states in the U.S. By the end of the first quarter of 2014, SolarCity has installed 26% of all PV installations in the U.S.

SolarCity's operation strategy is very simple and yet innovative. The company is based in San Mateo, California but its operations are carried by local centers in different states in the U.S. Membership in SolarCity's program starts with the customer checking through SolarCity's website whether their house is eligible for a solar installation; by considering the state which they live in and the average electricity bill. The customer contacts SolarCity's representatives in their area and schedules and site visit. During the site visit, SolarCity's engineers will assess the suitability of the house for a solar installation, the electricity consumption of the house, the average savings expected from the solar system and the financing plan. The customer, once satisfied, signs the contract with SolarCity. Usually, the whole process takes around 2 months from the first call to the time the solar system is installed on the house.

SolarCity provides three payments options for its customers; PPA (power purchase agreement), lease and My power. PPA and lease plans allow the customer to rent (or lease) the solar PV system from SolarCity for a given period (usually 20 years) and make monthly payments. However, there is a small difference between both plans in terms of how payments are made. My power scheme is an ownership program that allows the customer to purchase the solar PV system by making annual payments over a given period, at the end of which they own the solar system and its subsequent benefits (like state rebates and tax incentives). The solar lease plan is the most popular and has been chosen by over 50,000 customers (SolarCity 2015).

Financing of rooftop solar is the most difficult part in the process of solar energy deployment, especially in the residential sector. Currently, the U.S. solar industry operates on a third-party-ownership (TPO) model. In this business model, large financial institutions like banks provide the major funding for solar projects. The TPO model has been working well so far because it gives customers the opportunity to use solar electricity without baring the heavy capital costs.

In the broad sense, solar electricity providers use one of two methods to finance their projects: Bonding: Bonding refers to the process of taking loans from large finance institutions which have the necessary liquidity to fund solar electricity projects. In finance terms; it is “the process of securitizing debt and then issuing it into the capital markets via bonds” (Travis Lowder and Michael Mendelsohn 2013). The debt provider (also known as a tax-equity holder because that provider acquires all the tax incentives from the project they are funding) also receives an interest rate from their contribution to the project; usually 5–7% in solar projects. This form of financing is the most commonly used in the solar industry. However, the major drawback of this scheme is that it largely reduces the profit margin of solar companies by taking all of their tax credits. In addition this scheme is a highly complex and illiquid one and many experts believe that it can not meet the escalating demand of the solar energy market in the U.S (Travis Lowder and Michael Mendelsohn 2013). Securitization: This is a relatively new term in the U.S solar industry and has only recently been used. Securitization is defined as “the process of transforming illiquid assesst (such as cash flows from a solar lease) into tradeable instruments” (Travis Lowder and Michael Mendelsohn 2013). Securitization is a financial mechanism that allows solar companies (whether they are suppliers or installers) to have more control over the funding of their projects. Essentially, solar companies will issue asset backed notes (or securities) in the marketplace for investors to buy. An investor who purchases such an asset will be entitled to a portion of the profits generated from that asset (e.g cash flows from solar leases). This proves to have two main advantages; provide a source of low-cost financing and raise significant capital for solar companies (Travis Lowder and Michael Mendelsohn 2013, T. Alafita and J.M. Pearce 2014).

Being sustainable (in finance terms) is of high importance to U.S. solar companies especially because the ITC, which was the main driver for the growth of the solar industry, is expected to reduce from 30% to 10% by 2017 (Travis Lowder and Michael Mendelsohn 2013). This leads us to the first success factor of SolarCity which was completing the first ever securitization of rooftop solar asset in the U.S solar market in November 2013 (Ucilia Wang 2013). This marked a huge transition in the solar PV financing market. SolarCity, at that time, sold $54.23 million worth of notes with a 4.8% interest rates. In October 2014, SolarCity further developed their securitization model and implemented the first ever direct public offering (DPO) of solar bonds (shares in SolarCity's funding) allowing normal individuals and businesses to get attractive returns on their investments in solar energy (Canales 2014). The value of the solar bonds (or shares) for 2014 was $200 million and could be purchased for a little as $1000 per bond with an interest rate of up to 4%. The cash flow to pay for SolarCity's bonds comes from customers' payments in their solar leases or PPA's 20-year contracts. The second success factor in SolarCity's business model is also related to financing but concerns the other competitors in the solar market. The U.S. solar market has over 5000 companies but most of them will go out of business as Lyndon Rive, SolarCity's CEO, said (Margaret Rhodes 2012). This is because the majority of these competitors, due to limited funding options, only focus one part of the solar industry chain (such as only supplying equipment or only installation). Few companies actually provide the full service of providing the equipment, installing and maintenance. Among these are SolarCity and Vivnet Solar. Both of these companies follow the TPO model and have been doing very well indeed; they are the only two national completely vertically integrated residential solar companies (Green Tech Media 2014). Being vertically integrated means working in the whole solar PV supply and operations chain.

Vertical integration benefits solar companies in two ways; it increases the profit margin and gives them “visibility into the strategies of their competitors” (Green Tech Media 2014). In 2013, SolarCity acquired Zep Solar, a solar mounting startup which was for years a major supplier of equipment for SolarCity (Eric Wesoff 2014). Zep Solar was known for its innovative grooved frame that makes mounting of solar panels much faster. Through the use of Zep Solar's technology, SolarCity was able to reduce the installation time from 2–3 days to less than one day. In addition, in 2014, SolarCity acquired Silevo, a solar technology and manufacturing company whose solar panels had a good combination of energy output and low cost. In fact, SolarCity is planning to take vertical integration in the solar industry to next levels when it announced in 2014 plans to build the U.S largest solar cells manufacturing facility in the state of New York with a capacity of more than 1 GW. SolarCity views vertical integration as the best way to cut down operation cost and reduce dependence on government subsidies. This explains why in the “sunny” states like California, SolarCity is able to sell electricity at a price less than the utility but at the same time maintain profits.

A SolarCity-inspired model that can help Qatar make a transition towards mass adoption of residential rooftop solar must have five components: Government policies and agencies that encourage (through incentives) citizens to invest in solar electricity. Improve the public awareness about the benefits and technology of solar electricity. Significant investment in R&D to build local knowledge, capacity and products within the solar PV supply and operations chain. An advanced smart grid that improves solar electricity integration. Customized and innovative financial instruments and models (such as Islamic finance) which benefit from global efforts but at the same time address local challenges.

Further research in this topic requires formulating innovative business and finance models that provide an affordable and reliable source of liquidity for solar firms in order to drive the rooftop solar industry in Qatar forwards. Particularly, we need to focus on how Islamic banks and Islamic finance can support the solar industry in Qatar. We need to ensure such measures reduce the risk from the lender and borrower's perspectives and that there is a high level of confidence on solar energy technologies as a worthy investment sector.

1. Background

Depleted uranium (DU) has been used extensively during weapons testing and recent military conflicts. All three main isotopes of U (235U, 236U, 238U) are radioactive. The firing of depleted uranium (DU) weapons during conflicts and military testing has resulted in the deposition of DU in a variety of sand-rich environments. Iraq, a near neighbor to Qatar, has received extensive (400 tons) DU contamination from the two wars in 1991 and 2003 (Shomar et al., 2013). Radioactive fallout from past accidental releases of radioisotopes during ground nuclear tests has contaminated the globe with radioactive materials. Most of these radio-contaminants are fission products of uranium and plutonium. Among these, 90Sr, 137Cs, 235U, 238U, 238Pu, 239Pu, and 240Pu have been identified in some soils around the world. Therefore, radioisotopes represent long-term health and environmental problems. Knowledge of the concentrations of these radioisotopes and their isotopic compositions in soil provide valuable information concerning nuclear activities in the affected regions.

2. Objectives

The objectives of this work are to (1) determine the occurrence and distribution of the anthropogenic radioisotopes 90Sr, 137Cs, 235U, 236U, 238U, 238Pu, 239Pu, and 240Pu in the topsoil of Qatar; (2) establish a baseline in the soil in Qatar before commissioning the installation of various nuclear machinery in the area; (3) map and assess the fallout radioisotopes of concern in Qatar; and (4) trace the origin of these contaminants.

3. Methodology

3.1. Instrumentation

The measurements were performed using triple quadrupole collision/reaction cell inductively coupled plasma mass spectrometry (CRC-ICP-MS/MS, Agilent 8800), which has been developed recently by Agilent Technologies (Fernandez et al., 2015). The CRC-ICP-MS/MS combines two quadrupole mass filters, Q1 and Q2, before and after the Octopole Reaction System (ORS3) cell, respectively, in a tandem mass spectrometer (MS-MS) configuration. The normal mode of operation of the 8800 is MS-MS mode, where the first quadrupole works as a unit mass filter, restricting the ions entering the reaction cell to a single mass to charge ratio (m/z) at any given time. In this way, ions entering the collision reaction cell are precisely controlled, resulting in the ability to exactly control the reaction chemistry occurring in the cell, even if the sample composition changes. A high performance sample introduction system (AridusTM-II, CETAC) that incorporates a low-flow fluoropolymer nebulizer was coupled to the CRC-ICP-MS/MS instrument. The spectrometer was optimized to provide the highest ion counts of 88Sr, 133Cs, or 238U ions. Argon and reactive gases used in the experiments were grade five (99.999%). The measurements of pure Sr, Cs, and Pu fractions extracted from soil samples were performed using CRC-ICP-MS/MS in single MS mode. Direct measurements of 90Sr, 137Cs, 238Pu, 239Pu, and 240Pu in leached solutions were conducted on the CRC-ICP-MS/MS in MS-MS mode using reactive gases for isobaric separation.

3.2. Quality control/quality assurance (QC/QA)

In order to check the feasibility of the proposed analytical techniques, a set of standard reference materials and proficiency test samples were measured with CRC-ICP-MS/MS as validation experiments.

3.3. Collection of soil and sediment samples and sampling strategy

A systematic sampling plan was followed in the collection of the soil samples in Qatar. Sampling points are located at regular intervals on a 1:10000 square grid. The regular spacing on this grid is 10 km, resulting in approximately 132 soil samples and coastal sediment samples from locations distributed across the country. Sampling locations were demarcated using a Global Positioning System (GPS) and were then positioned in the maps using a Geographic Information System (GIS). The Geostatistics tool in ArcGIS was used to interpolate the concentration and distribution of the radioisotopes in the top soil of Qatar.

3.4. Leaching of Sr, Cs, or Pu from large soil samples

Because of the extremely low levels of 90Sr, 137Cs, 238Pu, 239Pu, and 240Pu in the environmental soil samples, it was necessary to bulk sample extracts to ensure that sufficient analyte is present for an accurate and precise analysis. For this purpose, we applied the procedure developed by Maxwell et al. (2013) with slight modification. The radioisotopes were extracted from1000 g of the Qatari soil samples by concentrated nitric and hydrochloric acids.

4. Results and Discussion

The developed methods were applied to measure the 90Sr, 137Cs, 235U, 236U, 238U, 238Pu, 239Pu, and 240Pu concentrations in the topsoil samples collected from the 132 sites in Qatar. The concentrations of 90Sr in the collected Qatari soil samples vary from 0.18–0.99 fg/g (1.00–5.49 Bq/kg) with a mean value of 0.606 fg/g (3.364 Bq/kg) and a median value of 0.610 fg/g (3.390 Bq/kg). The average atomic concentrations and equivalent activities of 90Sr in the Qatari topsoil samples are presented in Table 1. A comparison with 90Sr activities in other countries are presented in Table 1. The concentrations of 137Cs vary from 0.030–1.210 fg/g (0.098–3.993 Bq/kg) with a mean value of 0.619 fg/g (2.038 Bq/kg) and a median value of 0.620 fg/g (2.051 Bq/kg) (Table 2). The corresponding distribution map for the 137Cs activities is given in Fig. 1. The U concentrations range from 0.05 to 4.7 mg/kg and the 235U/238U isotopic signatures are in the range 0.007–0.008, i.e. comparable to the isotopic ratio in natural uranium (NU). The concentrations of 238Pu vary from < 0.026–0.058 fg/g ( < 0.016–0.027 Bq/kg) with a mean value of 0.034 fg/g (0.0195 Bq/kg) and a median value of 0.032 fg/g (0.0195 Bq/kg). The concentrations of 239Pu fall in the range 18.31–113.85 fg/g (0.042–0.261 Bq/kg) with a mean value of 65.59 fg/g (0.150 Bq/kg) and a median value of 66.16 fg/g (0.152 Bq/kg). The concentrations of 240Pu fall in the range 3.12–30.35 fg/g (0.027–0.258 Bq/kg) with a mean value of 12.06 fg/g (0.103 Bq/kg) and a median value of 10.78 fg/g (0.092 Bq/kg). The combined concentrations of 239+240Pu in environmental soil samples from Qatar and other countries are presented in in Table 3. A thematic maps were built using the Geographic Information System (GIS) software. The concentration and distribution trends of 90Sr are 137Cs, were found to be similar. On the other hand, The concentration and distribution trends of U are Pu were found to be similar. The results showed that residential areas, including the capital Doha, had the lowest concentrations of the radioisotopes in the country, while the western part of Qatar exhibited the highest values. More importantly, due to the low concentration of organic matter (OM) in Qatari soil, the very limited P-fertilization, the alkaline nature of the soil (pH 8), and the low Fe/Mn content, the U and Pu concentrations in the soil are slightly low compared to those of 90Sr and 137Cs. The isotopic and activity concentration ratios of 238Pu/239Pu, 240Pu/239Pu, and 238Pu/239+240Pu can be used to identify the source of these materials. The mean238Pu/239Pu isotope ratio in Qatari soils is (3.674 ± 1.053) ×  10^− 4 (Table 4). The 238Pu/239Pu isotope ratio from the reported global fallout and Chernobyl fallout are 1.77 ×  10^− 4 and 4.3 ×  10^− 3, respectively. The mean isotope ratio of 240Pu/239Pu in Qatari soils is 0.179 ±  0.035. The mean 240Pu/239Pu isotope ratios from the reported global and Chernobyl fallouts are 0.18–0.19 and 0.34–0.57, respectively. The average isotopic and activity ratios of 238Pu/239,240Pu in Qatari soils are (3.061 ±  0.879) ×  10^− 4 and 0.052 ±  0.004, respectively. The activity ratio 238Pu/239+240Pu in releases from nuclear fuel reprocessing plants, nuclear tests, nuclear weapons, and the Chernobyl fallout are approximately 0.25, 0.026, 0.014, and 0.47, respectively, (Bu, et al., 2015). Therefore, it is difficult to identify the source of the Pu, but it may be due to the contribution of more than one source. The most probable sources are both the Chernobyl fallout of Pu isotopes and several decades of fallout plutonium accumulation due to nuclear weapons testing.

5. Conclusions

In general, no anomalous results were recorded. The concentrations of U observed in soils collected throughout the State of Qatar were well within the normal background levels. 235U/238U activity ratios do not indicate DU contamination, within statistical detectability, anywhere in the country. The data confirm that the source of the 90Sr, 137Cs, 238Pu, 239Pu, and 240Pu is the global fallout. The concentrations of these anthropogenic radioisotopes are extremely low and do not pose threats to the environment or to human health.

6. Novelty

New data bank was established for (1) the concentrations of the radioisotopes 90Sr, 137Cs, 235U, 238U, 238Pu, 239Pu, and 240Pu in topsoil of Qatar, and (2) the isotopes ratios of U (235U/238U) and Pu (240Pu/239Pu, 238Pu/239Pu, and 238Pu/239, 240Pu).

7. Recommendations

This work provides a basis for monitoring the concentration of anthropogenic radioisotopes, which may be affected by events connected with any nuclear activity and/or accidents occurring in the future. It is recommended to establish a monitoring program to provide a rapid warning system in the event of excessive radioisotopes production and fallout in the region. In particular, it would be especially advisable to continue isotopic monitoring of the most sensitive regions of Qatar on an approximately yearly basis.

Acknowledgment

This article was made possible by NPRP award [NPRP4-1105-1-173 and NPRP08-187-1-034] from the Qatar National Research Fund (a member of The Qatar Foundation). The statements made herein are solely the responsibility of the author.

Cyanide is one of anions of concern due to its high toxicity. It causes death at a low dosage (2.6 mM) and the allowable level should be lower than 1.9 mmolar according to World health Organization (WHO). Cyanide contamination in the environment comes from many sources as metallurgy, gold mining, cyanide fishing, manufacturing acrylonitriles and related polymers, and natural sources. Cyanide also is present in some foods and food products such as cassava, bitter almonds, apple seeds, and some beans. The wide spread of cyanide in these food is of concern and the levels should be monitored and evaluated. In addition cyanide, may leak and get into water bodies or soil accidentally or intentionally, therefore, developing an easy, simple method for its detection is a priority. Many methods have been developed for detection of cyanide and anions such as titrations, distillations, GC-ECD, and spectrophotometrically. Colorimetric methods have been developed which are easy and simple that can give qualitative results visually and quantitatively using absorption or fluorescence spectroscopy. We have tuned into using dyes and natural dyes that are none toxic and available to use as visual (colorimetric) using both absorption and fluorescence techniques. Curcumin [1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione] is obtained from dry rhizomes of Curcuma longa, as the main yellow pigment used as spices, cosmetic and traditional medicine. It has been reported that curcumin also has many pharmacological functions like antioxygenation, antibiosis and antitumor. Despite the fact that extensive colorimetric and related photophysical studies of curcumin has been extensively studied, less study has done on its potentiality in application as a colorimetric and naked eye sensor of biologically and environmentally important anions like fluoride, acetate and phosphate. Some studies reported interaction of curcumin with cyclodextrin based on changes in basicity in acetonitrile which showed its importance in supramolecular chemistry. We herein describe a simple and efficient visible colorimeric cyanide and fluoride ions detection using commercially available curcumin as a receptor. The method could allow application in detection of curcumin, fluoride and cyanide, important chemical and biological species The choice of curcumin as a sensor for anion was mainly based on the fact that curcumin is a phenol and therefore exist in a equilibrium between its protonated and deprotonated forms in relatively basic media. It also contains a carbonyl group succeptable to nucleophilic addition, this will make it have two anion receptors., hydroxyl for hydrogen bonding to associate with basic anions. The carbonyl is areceptor for nucleophilc anions such as cyanide. Due to this reason curcumin can interact differently with different anions and enhance its selectivity based on the sovent choice. It will behave as a chemodosimeter. Acetonitrile, a polar aprotic solvent is is a good media for the analysis, it does not compete with anion in the recognition sites of curcumin. Variation in color changes of curcumin in acetonitrile was done by addition of aliquots of various anions as tetrabutylammonium salts. Addition of fluoride and cyanide ions induced color change from yellow, purple, blue to deep blue with intensity at every level dependent on the fluoride ion concentration. Acetate ion changed the color of solution to light purple, while dihydrogen phosphate induced only a tinge of color enhancement. Chloride, bromide and perchlorate were found to show no effect on the solution of curcumin. In an aquaeous acetonitrile solution the effect was observed only for cyanide only with a clear color change from yellow to red. While other anions had no significant effect. This indicates that the mechanism of interaction is based on nucleophilic addition in the case of cyanide in aqueous media and hydrogen bonding in nonpeotoc solvents. The stoichiometry was determinned to be 1:1 for cyanide and 1:2 for fluoride. The binding constants and detection limits were calculated form the UV-vis absorption titrations. In this presentation the method, structures of dye and complexes, the titration curves, color changes, binding constants and aplication will be discussed.

This work was supported by NPRP grant # NPRP-7 – 495-1-094 from the Qatar National Research Fund (a member of Qatar Foundation).

The main objective is to contribute via this study, in solving an environmental issue and helping Qatar in finding suitable water resources; useful in agriculture. Qatar faces diverse water challenges; the number one that threats here is scarcity as water is not renewable. Due to scarcity of good quality water, reusing of low quality and contaminated water is highly increasing in Qatar. The main source of water in Qatar is desalination stations. Most of the desalinated water is for human usage. Agriculture in Qatar depends mainly on underground water; it is available but always saline and found in insufficient quantities. Due to the increasing demand for water among industries and irrigation, using other alternative water resources such as produced water during oil and gas extraction would be of importance. Generally, produced water is the water that exists in subsurface and is moved to the surface through oil and gas processes. The volume of produced water and pollutants concentration vary depending on the nature and location of the oil products. It represents the major waste stream related to oil and gas processes. Large volume of produced water generated in Qatar has the potential to enhance the water resources. The crucial goal of produced water management is to eliminate dissolved harmful components and use it for beneficial uses that can efficiently improve environmental impact and water shortage. An exclusive characteristic of produced water comparing to other wastewater resources is the large variation and complexity in water chemistry. This would play a vital role in the remediation processes.

Remediating produced water for irrigating use has been explored as a substitute to conventional disposal and discharge processes. Produced water is described by high concentrations of heavy metals, salts, toxic organic components, and total dissolved solids (TDS). Consequently, the produced water need to be remediated to meet the Qatari and international standards appropriate for the anticipated end use and to have a valuable resource rather than a waste.

However, the objective of this study was mainly dealing with using the adsorption technique in remediating benzene, toluene, ethyl-benzene, and xylenes (BTEX) and heavy metals from the produced water, After a fully determination of the quality of the produced water, the first part of the project was emphasized on remediation of BTEX and heavy metals to facilitate it to use for beneficial areas such as irrigation. In this study, activated carbon (AC) was used to remediated the soluble organics from the produced water and heavy metals. In addition, microemulsions was also used to modify the AC to selectivity remediate different types of pollutants. AC and microemulsions modified AC was used for effectively remediate BTEX and heavy metals from the produced water under specific conditions.

A representative sample of the produced water was collected from different sources at different times; the samples were collected in 20 liters container where two samples was collected per day,6 days ×  20 litters × 2 = approximately 240 litters were mixed together and stored in a big storage container. A local sand sample (10 Kg) mixed with raw clay (2%) was used for the preparation of the sand filtration column (length 120 cm and 10 inches diameter), which was needed for the pretreatment step of the produced water. The produced water sample was then filtered and collected from the column with rate 12 ml/min. Different experiment parameters such as the effect of activated carbon mass (50, 35 and 20 g), particle size, pH (4, 6 and 8) and the temperature on metal and BTEX remediation were investigated. Glass columns with length 15 cm and 3 cm diameter were used for the experiments. One liter of the filtered produced water samples were filtered from each column with a rate of 2 ml/min. Microemulsion modified AC was prepared by mixing AC with surfactant Triton 100, then the mixture was shaked and dried at 80°C for 48 h.

A comprehensive chemical and physical characterizations of the produced water was conducted; namely pH (4.78), COD (6760 ppm), TOC (1550 ppm), TN (45.45 ppm), TDS (4490 ppm), conductivity (6800 μs/m), alkalinity (124 ppm, Hardness (1060 ppm). Several metals concentration was determined such as Ag, Al, As, B, Cd, Cr, Li, Mn, Sb, and Sr and the result were 0.31, 28.54, 0.00, 4363.76, 0.29, 16.97, 2231.59, 263.87, and 134.87 ppb; respectively.

The Fourier transform infrared (FTIR) spectra of sand filter, AC, and microemulsion modified AC were recorded using the FTIR Perkin Elmer. The FTIR analysis was carried out to interpret the functional groups which occurred in the AC and the modified form. The FTIR measurements was performed over 4000–400 cm^− 1. Scanning electron microscope (SEM) was also used to evaluate the surface morphology of the adsorbents using the JEOL model JSM-6390LV.

The overall of the results were extremely excellent in which the metals concentration and BTEX was dramatically reduced when activated carbon was used as an adsorbent. According to the results, the activated carbon with of the different ranges and concentrations had been extremely efficient in removing benzene and toluene from the produced water. It can also be noted that with the increase of AC concentration, contaminants removal efficiency becomes higher up to a level were no BTEX compounds can be detected anymore.

The future work of the study will be designed to adopt environment-friendly method, such as phytoremediation to remove contaminants from water and soil to reuse that water in landscape and biofuel plantation. Three crop plant species Helianthus annuus (sunflower), Zea mays (maize) and Medicago sativa (alfalfa) in addition to Qatari endemic desert plants that are known to be salt tolerant and survive under contaminated soils such as Atri[lex leucoclda Bioss (Raghl)], Cyperus jeminicus Rottab (Rukbah), Tamarix aucherana (Decne) Baum (Tarfa), Phragmites australis (cav.) ex Steud (Ghab) will be used in this study and their associated microbes will be utilized to develop an effective cost method to remove contaminants from such polluted water and reuse it.

Acknowledgement

This paper was made possible by UREP grant # (UREP17-076-1-008) from the Qatar national research fund (a member of Qatar foundation). The statements made herein are solely the responsibility of the author(s).

The state of Qatar has a strategic location within the heart of the Arabian Gulf, the richest oil area in the world. Its extensive coastline (700 km) is experiencing some of the most radical environmental conditions in the world's oceans including extreme temperature, high UV irradiance as well as high evaporations. These extreme conditions are pushing many marine biota to function close to their physiological limits. On the top of the extreme natural hydrographic conditions, there are tremendous stress exerted by oil exploration, production and transportation and probably any remnants from the largest oil spills in history, during the Gulf war in 1991. The present study is the first comprehensive study in the Gulf that is designed to assess the spatial and temporal variability of levels of Poly Aromatic Hydrocarbons (PAHs) in sediments of the Qatari coastal water and their bioaccumulation by dominant benthic invertebrates. Sediments and dominants benthic organisms samples were collected seasonally from thirteen locations in the coastal water of Qatar starting in the winter of 2014 and for four consequent seasons. Ten abundant benthic invertebrate species representing different trophic levels were selected to assess the spatial and temporal variability of PAHs in the Qatar costal water. These species have limited or no mobility, a major criteria for selecting benthic organisms in bio-monitoring programs. These species included gastropods, bivalves, and crustaceans with different trophic positions including carnivores, omnivores, herbivores and detritivores. Samples were analyzed for 16 parent PAHs including low molecular weight parent PAHs (LPAHS) and high molecular weight parent PAHs (HPAHs), 18 alkyl homologs and dibenzothiophenes. The results of the present study will be used for ecological risks assessment.

Levels of PAHs in sediments and tissue residues are found to be significantly variable with species, locations, seasons and also with distance from shore (P < 0.05). PAHs concentrations in sediments is negatively correlated with the water temperature (r = − 0.65) indicating the impact of temperature and probably levels of UV radiations on the fate of PAHs. Levels of PAHs in sediments indicated the presence of few moderately contaminated sites near point sources. Concentrations of PAHs in sediments showed wide spatial and temporal range (5 8.5%) presenting a range of trophic levels including carnivores and filter feeders. Significant correlations (P < 0.05) were found between PAHs tissue residues concentrations and signatures of carbon and nitrogen stable isotopes emphasizing the roles of trophic pathways on the uptake and bioaccumulation levels of individual PAHs in marine invertebrates. The present results are to be supported by more samples from two more seasons. The knowledge from this study intended to assist PAHs monitoring and identification of potential sources to guide management decisions. The outcome of the study is expected to help the regulatory agency (Qatar Ministry of Environment) as well as Gulf organizations such as ROPME to improve environmental laws and set standards based on these studies. Acknowledgements: This Research was supported by a grant (NPRP-6-442-1-087) from the Qatar National Research Fund (a member of Qatar Foundation) to Yousria Soliman, Ebrahima Al Ansari, Terry Wade, and Jose Sericano.

Lack of sufficient oxygen within sewer networks leads to anaerobic bioprocesses occurring, including hydrolysed organic degradation by methanogensis and sulfate reduction. These anaerobic processes produce methane, a greenhouse gas twenty-one times more potent than carbon dioxide; and hydrogen sulfide, a toxic and corrosive gas responsible for severe sewer corrosion and public odour nuisance. These gases are typically controlled by chemically dosing oxygen or nitrate into the sewers. Urine contains roughly 80% of the nitrogen in wastewater and can be easily separated at the household using specialized toilets. If nitrified decentrally it could be discharged to sewer as nitrate to control sewer gas while achieving simultaneous nitrogen removal in the underground sewer network.

In this study a 13.8 L lab-scale urine nitrification sequencing batch reactor was operated for 335 days to assess its performance treating real urine diluted to 30%, a concentration that could be expected from urine-source separating toilets. The reactor had a daily 1 hr anoxic fill and was aerated at 5 L/min for the remainder of the day by coarse bubble diffuser. The influent volume was increased from 1 to 2.65 L/d over the first 170 days of operation. The reactor was settled for 10 mins and decanted once the exchange volume capacity was exceeded, which occurred every 2–5 days depending on influent volume. Alkalinity as NaHCO3 was added stoichiometrically in the influent at a ratio of 1.05 mol:mol-N to allow complete nitrification. Seeding sludge was taken from a municipal wastewater treatment plant.

Between days 227–335 twelve batch tests were done to understand the activity of the various microbial groups including ammonia oxidizing bacteria (AOB), nitrite oxidizing bacteria (NOB) and heterotrophic bacteria (HB) under varying pH (7–9), free ammonia (42–194 mg-N/L) and free nitrous acid concentration (0–0.205 mg-N/L). In these tests a 5 L reactor was operated for 6 hours with approximately 700 mg-VSS/L of biomass measuring changes in ammonia, nitrite, nitrate and chemical oxygen demand (COD) which were used to calculate biomass specific removal/production rates.

The diluted urine in this study had an average total nitrogen concentration of 1790 mg-N/L, a COD of 1460 mg/L and a pH of 9.3. Nitrification was stable throughout the study with a maximum volumetric rate of 450 mg-N/L.d achieved and nitrate as the final nitrification product.

In the batch inhibition testing it was found the optimal pH of the system for ammonia oxidation was at 8.5 with only an 11% reduction in oxidation rate at the highest pH tested of 9. This reflected operational conditions of the reactor where the pH exceeds 9 at the start of a reactor cycle when nitrification begins. Conversely, nitrite oxidation rates were greatest at the lowest tested pH of 7. In a normal reactor cycle ammonia oxidation reduces the pH by consuming alkalinity. Due to the faster growth of AOB and high demand for oxygen the NOB were generally suppressed in a typical cycle until ammonia oxidation was complete, at which time the pH was near 7. This indicated a niche group of organisms adapted to the operational conditions and surrounding microbial community within the reactor.

Under varying free ammonia concentrations it was shown that inhibition for ammonia oxidation and organic oxidation began somewhere near 100 mg-N/L which corresponded roughly with the maximum levels encountered in the reactor. On the other hand free nitrous acid caused a 24% reduction in nitrite oxidation at a concentration of 0.1 mg-N/L.

This was not significant as free nitrous acid in a typical reactor cycle did not exceed 0.04 mg-N/L but could prevent NOB growing if nitrite build-up occurred, in which case concentrations could exceed 0.4 mg-N/L. Organic oxidation was inhibited by free nitrous acid somewhere above 0.1 mg-N/L, but during the initial two hours of a cycle when organics are predominantly degraded free ammonia concentrations are typically less than 0.001 mg-N/L. This study demonstrates the feasibility of decentralized urine nitrification to produce nitrate under stable conditions. The features and ability of the microbial community in such a reactor is strongly associated with the operational conditions imposed.

In the past decades, microbial fuel cells (MFCs) have been intensively studied in order to provide sustainable and environmentally friendly wastewater treatment concurrent with energy harvesting. A highly porous, highly efficient, light-weight, and inexpensive 3D sponges consisting of interconnected carbon nanotubes (CNTs) were developed as anodes of MFCs in order to allow more efficient microbe-to-anode electron transfer that are key to the operation of MFCs. The MFCs equipped with the 3D CNT sponge anode generates high power densities of 2150 Wm^–3 (per anode volume) or 170 Wm^–3 (per anode chamber volume), comparable to those of commercial 3D carbon felt electrodes under the same conditions (1). The high performances are due to excellent charge transfer between CNTs and microbes, which is evident by the 13 times lower charge transfer resistance compared to that of carbon felt. The 3D CNT sponges produced here has low cost (∼$0.1/gCNT) and high production rate (3.6 g/hr) compared to typical production rate of 0.02 g/hr of other CNT-based materials (1). The high production rate and low cost of this highly efficient electrode material can make MFCs more feasible to be scaled up for various applications such as desalination of seawater or saline water. Also, other electrode materials were compared to the 3D CNT sponge in evaluating the efficiency of the MFC and extending the use of these electrode materials to a field of microbial desalination cell (MDC).

Once MDCs are applied to the desalination process, there are several challenges that need to be addressed. First, a pH gradient forms between anode and cathode chambers (due to proton accumulation in the anode chamber and hydroxyl ion accumulation in the cathode chamber). In addition, chloride ion accumulation inhibits the activities of electrochemically active microbes. Together these activities degrade the overall performance of the system. Recirculation of the anolyte and catholyte provides one solution to addressing this challenge. However, this approach results in lower Coulombic efficiency. Here, we studied to develop a modified three-chamber configuration where part of the anode chamber and part of the cathode chamber are directly connected through a cation exchange membrane, thus partially allowing transport of protons between the chambers, and thereby limiting the drop in pH, while still maintaining charge differences that drive Cl^– and Na⁺ ions to move from seawater to the anode and cathode chambers. Practical MDCs require continuous or batch-mode feeding of wastewater into the anode chambers of the system, thus accumulated chloride ions will be simply flushed out or diluted due to the influx of new wastewater or catholyte. This aspect will mitigate the impacts of the chlorine ion accumulation problem. Also, a pivotal performance limitation centers on the cathode catalyst layer owing to sluggish kinetics of the oxygen reduction reaction and several transport losses. On the cathode side, expensive precious metal catalysts have been used in conventional systems to overcome the slow reactions on the electrode. Platinum and Pt-based electrocatalysts, commonly used in the electrodes, not only contribute to high fuel cell cost but also lead to durability concerns in terms of Pt cathode oxidation, catalyst migration, loss of electrode active surface area, and corrosion of the carbon support. So, this study used Pt-free 3D carbon-based cathode for MDC system.

Reference

[1] Celal Erbay, Gang Yang, Paul de Figueiredo, Reza Dadr, Choongho Yu, Arum Han, “Three-dimensional porous carbon nanotube sponges for high-performance anodes of microbial fuel cells”, Journal of Power Sources, (2015), 177–183.

Microalgae biomass is considered as one of the promising alternative feedstock for biofuel production. The biomass productivity of some of the microalgae can exceed an order of magnitude compared to any other terrestrial plant. Apart from nitrogen and phosphorus, iron is one of the major elements that must be provided to microalgae culture for high density biomass production. The amount of iron that is required per cell or per unit of microalgae biomass will vary among microalgae strains. Depending on the concentration of iron in the cultivation media, the microalgae will accumulate different amount of iron and this process may alter the compositions of other major metabolites. In order to be competitive the cost of microalgae biomass production should be lower and the desired metabolites should be present in higher percentages; therefore, the appropriate concentration of iron should be determined. On the contrary, there are very limited study on the microalgal iron requirement. The first objective of this study is to determine the minimum concentration of iron requirement by some of the locally isolated potential microalgae. The second objective of this study is to characterize the lipid accumulation under different iron concentrations. Gillard f/2 and BG-11 are the two common nutrients composition used to culture marine and freshwater microalgae respectively. In these two nutrients media, the concentrations of iron are 0.65 mg/l and 1.24 mg/l for Guillard F/2 and BG-11 media respectively. Due to some limitations, in most of the cases the concentrations of phototrophic microalgae in large scale biomass production doesn't exceed 0.5 g/L. If these two media are to be used in large scale, iron requirement can be calculated as 1.3 kg (6.3 kg as FeCl3.6H2O) and 2.4 kg (12 kg as FeCl3.6H2O) respectively for each ton of biomass production. Therefore, the cost of the iron fertilizer can be significant for low cost feedstock; furthermore, if there is residual iron in the discharge water it will require additional treatment steps. Three local marine microalgae (Nannochloris sp., Tetraselmis sp., Chlorocystis sp.) and three local freshwater microalgae (Scenedesmous sp., Chlorella sp., Neochloris sp.) were selected to study their iron requirement. Apart from iron, all the nutrients were added as per f/2 or BG-11 media concentrations. However, for the marine microalgae, the range of iron concentration was 0 to 1 mg/L while for the freshwater microalgae it was 0 to 3 mg/L. All the experiments were conducted in triplicates. 10 ml of culture was inoculated in 90 ml containing any culture media in a 250 ml flask; the flasks were kept in an orbital shaker which was maintained at 120 rpm speed, 25°C, 12 hours photoperiod. The growth period for any strain was kept fixed at 7 days. It was found that marine Naanochloris sp. didn't require the addition of iron; the available iron in the seawater is sufficient to produce 0.5 g/L biomass density. The other two strains had also smaller iron requirement compared to f/2 media. For the three freshwater microalgae, there was also minor requirement for iron (1 mg/L) which was much lesser than iron concentration in BG-11 media. Iron deficiency, during the cultivation process, resulted in bleaching and changes in metabolites (especially in pigments). Nannochloris sp. and Scenedesmous sp. will be later grown in outdoor small raceway tanks (1000 liter) to verify the indoor small scale results.

Nowadays, global fresh water shortage is becoming the most serious problem affecting the economic and social development. Water treatment including seawater desalination and wastewater treatment is the main technology for producing fresh water. Membrane technology is favored over other approaches for water treatment due to its promising high efficiency, ease of operation, chemicals free, energy and space saving. Membrane filtration for water treatment has increased significantly in the past few decades with the enhanced membrane quality and decreased membrane costs. In addition to high permeate flux and high contaminant rejection, membranes for water treatment require good mechanical durability and good chemical and fouling resistances. Thus, investigation of the mechanical behavior of water treatment membranes with underlying deformation mechanisms is critical not only for membrane structure design but also for their reliability and lifetime prediction.

Compared to ceramic and metallic membranes, polymer membranes with smaller pore size and higher efficiency for particle removal are widely used in seawater desalination with a high applied pressure. However, polymer membranes are mechanically weaker and have lower thermal and chemical stability compared to inorganic membranes. Blending of polymers with inorganic fillers is an effective method to introduce advanced properties to polymer based membranes to meet the requirements of many practical applications. The reinforced polymeric membranes with inorganic fillers can provide desirable mechanical strength as well as mechanical stability. Carbon nanotubes (CNTs) have received considerable attention from academic and industries over the last twenty years. In addition to their excellent electrical and thermal properties, CNTs exhibit outstanding mechanical characteristics due to its instinct mechanical strength and high aspect ratio. For the application of water treatment membranes, CNTs could be the excellent channels for water to go through and therefore, CNTs have proven to be excellent fillers in polymer membranes improving the permeability and rejection properties. In literature, it is reported that the mechanical strength of the polymer membranes was improved with the embedding of CNTs due to reinforcement effect of the more rigid CNTs. The mechanical responses of polymer_CNTs composites depended on the interfacial adhesion between the CNTs and the membrane-based polymer as well as the dispersion and distribution of the CNTs within the polymer matrix.

In this study, a vertical chemical vapor deposition reactor was designed in order to synthesize CNTs of high aspect ratio using continues injection atomization. Bundles of high purity (99%) and high quality CNTs were produced by this system. The produced CNTs had diameters ranging from 20 to 50 nm and lengths ranging from 300 to 500 micron (corresponded aspect ratios ranging from 6000 to 25000). A novel polysulphone (PSF) based nanocomposite membrane incorporated with the produced high aspect ratio CNTs was then casted via phase inversion method, at a wide range of CNTs loading (0–5 wt. %), in polysulphone-dimethylformamide solutions using the Philos casting system. The poly(vinylpyrrolidone) was used as pore-forming additive. To demonstrate the effect of nanocomposite morphology on the mechanical behavior of the prepared membranes, a set of control samples consisted of PSF membranes embedded with commercial CNTs at the same CNTs loading, were casted at the same conditions. The commercial CNTs had a lengths of 1 μm to 10 μm and outer diameters of 10 nm to 20 nm (corresponded aspect ratios ranging from 50 to 1000), with purity >95% and BET surface area of 156 m²/g.

The effects of CNTs content and aspect ratio on morphological, water transport and mechanical properties of the prepared PSF-based porous membranes were investigated. The surface and cross-section morphologies of PSF/CNTs porous membranes were examined using scanning electron microscopy (SEM). The orientation, dispersion and distribution of CNTs within polymer membranes were evaluated for the membrane samples with different CNTs content and CNTs aspect ratio. The average membrane pore size was evaluated by using SEM image analysis software.

Uniaxial tensile behavior of the membranes was characterized by means of a universal material testing machine under different testing conditions. Wet specimens were carefully cut from the casted membranes by using a razor blade. Elastic, plastic and failure behaviors of the membranes are analyzed with the impacts of CNTs content and aspect ratio. The macroscopic mechanical behaviors of the membranes are correlated with their strain induced microstructure evolution by using SEM. In this, pore shape evolution, pore and CNTs orientations, neighboring pore interaction, interface between the CNTs and PSF matrix and the failure behavior of the deformed porous membranes were analyzed. The macroscopic stress-strain responses of the membranes were correlated with the microstructure of the studied nanocomposites membranes to provide a better understanding of materials' processing-microstructure-properties relationship.

Liquid wastewater streams that contain nitrogen must be treated before being discharged into the environment to prevent eutrophication. Already there are several existing conventional treatment technologies that can remove the nitrogen from the wastewater in combination of multiple processes. Depending on the processes involved, a fraction of nitrogen will be released to the atmosphere. On the contrary, there are several types of microalgae have the voracious demand of nitrogen and can assimilate waste bound nitrogen in a single step mostly as intrinsic proteins. Once the microalgae are separated from the water the minerals inside the microalgae cells remain available for plants and it can be used as fertilizer for the plants. Furthermore, removal of microalgal biomass from the wastewater at the end of the process may completely, or at least partially, treat the waste water minimizing the processes and cost of conventional treatment processes. Qatar's climate and non-arable land are ideal combinations for cultivating microalgae. The harvested microalgae can be dried and stored for future growth of fodder plants. On theory, every kg of microalgae biomass will require 1.73 kg of CO2. Some of the microalgae can also utilize specific organic carbon sources that are available in wastewater. However, the concentration of available organic carbon in the wastewater is not sufficient to support complete removal of nitrogen by microalgae. Hence, carbon dioxide must be supplied for complete and faster treatment. As the minerals will be utilized by the fodder plants, a fraction of the organic carbon associated with the microalgae biomass will be locked in the soil and thus increasing the soil's organic content. Therefore, successful application of wastewater grown microalgae biomass as biofertilizer can provide (1) a cost and energy effective wastewater treatment process, (2) nutrients (N, P and other minerals) recycling, (3) sustainable and environmental friendly agricultural application, and (4) carbon sequestration. Algal technology group of Qatar University is growing microalgae biomass in large scale open ponds. Mineral composition of a marine microalgae, Chlorocystis sp., biomass was characterized as 3.45? N, 0.22? P, 2.78? Ca, 0.39? Fe, 0.01? Cu and 0.02? Zn. Currently, this biomass is used to study its application as biofertilizer for the growth of sorghum plants. Soil was mixed with microalgae biomass and 5 kg of the soil mix was added in each pot. Three different microalgal biomass concentrations were applied in peat soil: 1.5 g/l, 3 g/l and 4.5 g/l. In another pot 3 g/kg NPK fertilizer was added while in another pot there was no inclusion of any fertilizer. Currently, each pot is irrigated with freshwater twice a week and the experiment will continue for two months. In parallel, Scenedesmous sp., a local fast growing freshwater microalgae, is currently being grown in wastewater collected from a small wastewater treatment plant, with an aim to be used as biofertilizer. The mineral composition of wastewater-grown Scenedesmous sp. will be determined and used as appropriate ratio for growing sorghum plants. Results obtained for different fertilizers (i.e., 1. NPK, 2. marine microalgae biomass, and 3. Wastewater grown microalgae biomass) will be compared in terms of plant growth, residual minerals in the soil.