Suchergebnisse

Water Security was a central theme of WANA Forum 2010, where regional experts warned that the wars of the 21st century will be fought over water. Climate change will only exacerbate problems in a region already stressed by lack of water, food and political and social unrest. Across the Arc of Crisis, from Somalia, Sudan and Egypt in Africa to Yemen, Iraq, Pakistan, and Afghanistan in West Asia, water scarcity in the region has already lead to drought and famine, loss of livelihood, the spread of water-borne diseases, forced migrations and open conflict. Water scarcity is closely linked to food and health security, making better water management a key stepping stone for poverty reduction and economic growth. If nothing changes, most of the WANA countries will encounter, in less than a generation, serious problems in managing inland freshwater, the availability of which, in sufficient quantity and quality, may become, as it is already the case in several of these countries, a main challenge for economic and social development. Wastage and pollution will then be such that « water stress » will affect, in a way or another, most of the populations of WANA countries and the poorest first of all. The effects of global warming will increase current trends. On the other hand, water scarcity in the WANA region is an issue of growing concern. With heavy demand from agriculture, growing populations and virtually no remaining untapped water sources, the need to establish water-management strategies in the region is of vital importance. WANA countries can be divided into three major agro-ecologies, each facing slightly different challenges. Rain-fed areas are dependent on a low and extremely variable rainfall, resulting in minimal yields, a problem exacerbated by frequent drought. Rainfall occurs in the form of intense and unpredictable storms, and as a result, the crusting soils are unable to absorb the moisture, which rapidly becomes lost through evaporation or runoff. Irrigated areas utilize rivers and groundwater sources, which are becoming depleted from over-use. Water scarcity is a manmade phenomenon brought about by the increasing demands of the population for water. The imbalance in the population-water resources equation strains society and has an adverse impact on domestic hygiene, public health, and cost of domestic water, and could impart political problems as serious as bringing down governments. On the social side, water scarcity adversely impacts job opportunities, farm incomes, credibility and reliability of agricultural exports, and the ability of the vulnerable to meet the cost of domestic water. Economically, the adverse impact is displayed in the loss of production of goods, especially agricultural goods, the loss of working hours because of the hardships society faces as a result of water scarcity. Thus, there is a need for preventive policy in the context of water security, and a process of networking to exchange the views of experts and specialists in this area, because, there is considerable knowledge of water scarcity in the WANA region, but what is needed is to consider ways that contribute to addressing this scarcity.

Human urine is a unique solution that has the right composition to constitute both a severe environmental threat and a rich source of nitrogen and phosphorous. In fact, between 4-9% of urine mass consists of ions, such as K+, Cl-, Na+ or NH4+. Because of its high ionic strength, urine osmotic pressure can reach values of up to 2000 kPa. With this in mind, this work aimed to study the effectiveness of real urine as a novel draw solution for forward osmosis. Water flux, reverse nitrogen flux and membrane fouling were investigated using fresh or hydrolysed urine. Water flux as high as 16.7 ± 1.1 L.m-2. h-1 was recorded using real hydrolysed urine. Additionally, no support layer membrane fouling was noticed in over 20 hours of experimentation. Urine was also employed to dewater a Chlorella vulgaris culture. A fourfold increase in algal concentration was achieved while having an average flux of 14.1 L.m-2. h-1. During the algae dewatering, a flux decrease of about 19% was noticed; this was mainly due to a thin layer of algal deposition on the active side of the membrane. Overall, human urine was found to be an effective draw solution for forward osmosis. ; This research was supported by the National Research Foundation of Korean Grant funded by the Korean Government (MSIP) (No. NRF-2015R1A5A7037825) and by the Australian Research Council through Future Fellowship (FT140101208). HY and CL are grateful for the support of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) through the "Human Resources Program in Energy Technology" project (No. 20164030201010) funded by the Ministry of Trade, Industry and Energy, Republic of Korea.

Membrane fouling limits the performance of membrane distillation (MD) and its application to seawater brine treatment. Silica fouling is considered one of the most complex type of fouling. In this study, we evaluated the flux decline and fouling ratio due to colloidal silica fouling in direct-contact MD and characterized the fouled membranes. We also tested the efficacy of high flow-rate water flushing for the restoration of flux after fouling. The formation and removal of silica scaling were monitored in real-time with optical coherence tomography (OCT). Our work demonstrated that fouling formation is influenced by silica particle size, feed temperature, salinity, and flow rate. Notably, silica formed cake-layer fouling on the MD membranes. Smaller silica particle size resulted in a higher flux decline and a denser cake layer. A higher feed temperature resulted in a higher flux, but more severe fouling. We also found that fouling was minimized at an optimal flow rate and salinity did not significantly affect fouling formation. OCT monitoring showed that silica fouling deposited on the membrane surface and evaluated the effect of each cleaning strategies on the cake layer. This comprehensive investigation provides valuable insights for the development of silica fouling control strategies in MD. ; The research reported in this paper was supported by King Abdullah University of Science and Technology (KAUST), Saudi Arabia. This research was also supported by a grant (code 21CTAP-C157250-02) from the Technology Advancement Research Program of the Ministry of Land, Infrastructure and Transport of the Korean Government.