Mohamed Darwish

Reverse osmosis desalination system and algal blooms Part I: harmful algal blooms (HABs) species and toxicity

AbstractHarmful algal blooms (HABs) are a serious concern in the countries surrounding the Arabian Gulf (AG). A recent HAB event (2008–2009) forced partial (or full) shutdown of desalination plants, and reduced their productivity. Strong fouling in filter media occurred, and frequent backwash was not sufficient to maintain their removal. Some plants were shut down for as much as 32–55xa0d—in places where water storage may only be a few days—when pretreatment processes struggled to remove the increased biomass caused by the HAB species, and were shut down before more irreversible fouling of the reverse osmosis (RO) membranes could occur. HAB challenges are not limited to the algal biomass that may foul membranes, but extend to the toxins that can pass through the membranes and find their way into finished water. Within the AG region, great care is given to the engineering part (operation and maintenance) under normal conditions of the seawater; however, challenges in all levels and scales emerge due to HAB i...

What does Integrated Water Resources Management from Local to Global Perspective Mean? Qatar as a Case Study, the Very Rich Country with No Water

Management of water resources is a very challenging issue, particularly in regions of the world where water is almost absent. In the Gulf Region, this issue is especially complex due to harsh-arid environments and increasing anthropogenic input of pollutants from the energy industry. The emergence of nations rich in oil and gas, such as Qatar, but poor in water resources requires new and dynamic systems and plans for managing limited water resources in times of extreme growth, such plans are discussed in this paper. The State of Qatar’s average annual evaporation rate is 30 times more than precipitation and the country depends on desalinated water to meet 99xa0% of its municipal water needs. Additionally, increasing population growth coupled with tremendous urbanization and industrialization add more stress to the existing renewable water resources, and newly produced water, namely desalted seawater and treated wastewater. Absence of water tariff and a water pricing system along with a lack of conservation awareness places Qatar as one of the highest water consuming countries in the world. Municipal water consumption per capita per day reached 500xa0L/ca.d for the year 2013. Dumping of sea to build new cities and construct towers makes the area very susceptible to salt water instruction, a phenomenon that does not only affect the groundwater aquifer system but also the construction materials and building deformations. Currently, Qatar uses the most advanced technologies for treating wastewater; however, the pure treated wastewater is not considered a viable water resource and is not used in areas of critical water demand such as agriculture and landscaping. Social, religious, and local marketing views limit the current use of treated wastewater. Integrated water and wastewater management strategies are absent and the national players of the two sectors -water and wastewater-are different. Current plans for integrated water resources management (IWRM) cannot answer the basic questions, what to manage and in which scale; is it the brackish and unused groundwater or the desalinated water from the existing technologies, the supply or the demand or all? This paper tries to highlight some facts related to Qatar’s water situation as an arid Gulf State and introduces potential ideas for IWRM. The critical aspects of IWRM discussed herein are relevant to a number of nations in the global community dealing with issues of extreme water insecurity.

Qatar water challenges

Abstract Qatar has experienced rapid economic growth due to the discovery and production of fuel oil and natural gas (NG). The natural renewable water resources (rainfall and groundwater [GW]) are depleted; and are estimated as 71-m3/per year per capita in 2005. This is far below the water poverty line of 1,000-m3/yca. The GW withdrawal is excessive (compared to replenishment) and is used mainly for irrigation. A very small amount of GW is treated to become potable water and is distributed to consumers. The municipal potable water mainly contains (99%) desalted seawater (DW) and 1% GW. The consumption of DW and electric power (EP) is continuously rising due to the increase in both population and the standard of living. The population have been more than doubled from 2000 to 2010. The DW is produced in power plants generating both EP and DW, and is called Cogeneration Power Desalting Plants (CPDP). These CPDPs are using either: simple gas turbines (GT) cycle or GT combined with steam turbine (ST) to form a...

Thermal desalination in GCC and possible development

AbstractThe Water Desalination and Reuse Center in King Abdulla University of Science and Technology, in Saudi Arabia, held a workshop on thermal desalination on the 11th and 12th of March, 2013. This paper was presented as part of a lecture at the workshop. It presents the status and possible developments of the two main thermal desalination systems processing large quantities of seawater in the Gulf Cooperation Council, multi-stage flash, and thermal vapor compression systems. Developments of these systems were presented to show how these systems are competing with the more energy-efficient seawater reverse osmosis desalting.

Qatar and GCC water security

AbstractThe significant wealth in natural gas and oil makes Qatar the country of the highest income per capita in the world. Meanwhile, Qatar is among the world’s poorest countries in natural fresh water resources. The water scarcity severely limits agriculture food production. Agriculture in Qatar depends mainly on the over-exploited, depleted, and quality deteriorated ground water (GW). The use of GW for agriculture cannot be continued. Water scarcity is the main obstacle to achieve the food self-sufficiency. The possibility of using Qatar’s abundant energy to generate desalted seawater or wastewater treatment for agriculture purposes is thought by many. This possibility is studied in this paper, along with the interdependent relation between water, energy, and agriculture (and thus food).

Desalting seawater in Qatar by renewable energy: a feasibility study

Abstract Qatar is an arid country and suffers severe lack of natural water resources. Groundwater is overexploited and has become seriously depleted with deteriorating quality. Non-conventional alternative water resources, mainly desalted seawater (DW) and treated wastewater are used and are slowly being expanded to serve potable agricultural, and industrial needs. Qatar’s population growth, almost doubled in less than 10u2009years, has increased the demand for potable water and is exerting pressure on the government to build additional desalting plants. The multi-stage flash (MSF) desalting is the predominant method that is used in Qatar. Its energy consumption is high—an average 270u2009kJ/kg thermal energy and 14.4u2009kJ/kg pumping energy. In the present paper, several different types of desalting sweater methods of less consumed energy than the MSF are reviewed. Burning fossil fuel, mainly natural gas to supply the energy needed for DW units increases the emission of air polluting gases as well as greenhouse gas...

Thermal desalination and air conditioning using absorption cycle

AbstractWater shortage and hot climate are the most stressing problems in many places all over the world, especially in the Arabian Gulf region. Efficient and sustainable solutions for these problems are a real challenge facing the Gulf Co-operating Countries countries. Vapor absorption cycles have been used for refrigeration and air conditioning application many years ago. The absorption cycle systems are a heat-driven system that can be used as a refrigerator, a heat pump, or a heat transformer. In this work, a new configuration of an absorption cycle has been used to provide chilled water for air conditioning applications and to supply saturated steam to a thermal desalination unit using solar radiation as the driving energy for the cycle. Water–Lithium Bromide absorption cycle is adapted. A low temperature, multi-effect distillation system is combined with the absorption cycle. The combined absorption-desalination systems are modeled and simulated using IPSEpro software.

The forward osmosis and desalination

Forward osmosis (FO) has emerged as a method for desalting saline water and power production. It utilizes a chemical potential difference, or a salinity gradient to permeate fresh water through membranes. This paper investigates the feasibility of using the FO process for seawater (SW) desalination in terms of consumed energy, capital costs, water recovery, operation & maintenance, water quality, and the final product water cost. The study covers FO by itself, and when combines with other desalting systems such as reverse osmosis, multi stage flash (MSF), and multi effect distillation as pretreatment method. This paper reviews first the principles of fluid and solutes flow in the FO membranes, concentration polarization, the difference between the FO, pressure retarded osmosis processes, draw solutions, and the solutes involved in these draw solutions. Then, the main characteristics of the FO membranes and their commercial availability are presented. Previous experimental work and a commercial plant using FO for desalination are also given. The use of FO as pretreatment for other desalting methods is presented in light of two proposed research projects. The first research project proposes utilizing FO as pretreatment for processing treated wastewater and SW in one system. The second project utilizes FO as pretreatment for a once-through MSF desalting method. The analysis proved energy reduction in the energy consumption of both desalting systems by more than 50 and 18%, respectively.

Realistic power and desalted water production costs in Qatar

AbstractWater security in Qatar is of main concern. Low water pricing in Qatar does reflect the real value of water. The high cost of desalted seawater (DW) calculated in this paper calls for the use of more energy efficient desalting system such as the SWRO system in place of the multistage flash (MSF) and multieffect thermal vapor compression (METVC) methods presently used. Both MSF and METVC use thermal energy of about 270xa0kJ/m3 and pumping energy of 2–4u2009kWh/m3. In this paper, the mechanical energy equivalent to the thermal energy supplied to the MSF (or METVC) systems is calculated. When added to the pumping energy, it gives the specific consumed energy of more than 20u2009kWh/m3, compared to 4–5u2009kWh/m3 for SWRO system. Qatar’s ground water (GW) is overexploited, depleted, and quality deteriorated, and thus the demand for DW is on the rise, with the more financial burden. Moreover, DW productions mean more air and marine environment deterioration. The water subsidization by the government should be review...

PV and CSP solar technologies & desalination: economic analysis

AbstractThis paper presents an overview of using solar energy in running desalination systems, called solar desalination. Solar energy can be converted directly to electric energy, which can operate electrically driven desalting systems such as reverse osmosis (RO), electrodialysis (ED), and mechanical vapor compression systems. Solar energy can also be converted to the thermal energy that can operate the mainly used thermally operated desalination system such as multistage flash (MSF), conventional multieffect (ME), and multieffect thermal vapor compression (ME-TVC), and emerging membrane distillation and humidification–dehumidification desalination systems. The thermal energy converted from solar energy can also be used to produce high-pressure steam running power plant producing electric power to operate mechanically driven desalting systems, and/or extracted steam at relatively low pressure to operate thermally driven desalting system. The main obstacle that hinders the use of solar desalination is th...