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Topic Review
Nanofluids in Desalination
Desalination accounts for 1% of the total global water consumption and is an energy-intensive process, with the majority of operational expenses attributed to energy consumption. Moreover, at present, a significant portion of the power comes from traditional fossil-fuel-fired power plants and the greenhouse gas emissions associated with power production along with concentrated brine discharge from the process, pose a severe threat to the environment. Due to the dramatic impact of climate change, there is a major opportunity to develop sustainable desalination processes to combat the issues of brine discharge, greenhouse gas emissions along with a reduction in energy consumption per unit of freshwater produced. Nanotechnology can play a vital role to achieve specific energy consumption reduction as nanofluids application increases the overall heat transfer coefficient enabling the production of more water for the same size desalination plant. Furthermore, concentrated brine discharge harms the marine ecosystems, and hence, this problem must also be solved to support the objective of sustainable desalination. Several studies have been carried out in the past several years in the field of nanotechnology applications for desalination, brine treatment and the role of renewable energy in desalination. The content is focused on reviewing existing desalination practices, along with identifying the gaps in the development of sustainable desalination systems. Furthermore, the role of nanofluids is discussed as a potential tool to develop cost-competitive and energy-efficient standalone desalination system. Desalination is an energy-intensive process, and it's exceptionally crucial to power the process with a reliable independent source of energy along with coupling the desalination process with advanced systems to treat the brine and take benefit of economies of scale by producing more products from the same raw material (seawater). 
  • 797
  • 27 Oct 2020
Topic Review
Climatic Indices over Mediterranean Sea
The Mediterranean Sea, strategically situated across a dynamic frontier line that separates two regions with different climates (Europe and North Africa), has been the focus of attention of many studies dealing with its thermohaline circulation, deep water formation processes or heat and freshwater budgets. Large-scale atmospheric forcing has been found to play an important role in these topics and attention has been renewed in climatic indices that can be used as a proxy for atmospheric variability. This overview summarizes the recent advances that have been achieved in the understanding of the climatic indices and their influence on the functioning of the Mediterranean from a physical point of view
  • 681
  • 27 Oct 2020
Topic Review
Aquaponics
Aquaponics is an alternative method of food production that confers advantages of biological and economic resource preservations. Nonetheless, one of the main diculties related to aquaponics systems could be the outbreak and dissemination of pathogens. The present review summarized the principal plant pathogens, the conventional and alternative BCA treatments on aquaponics systems, while considering related research on aquaculture and soilless systems (i.e., hydroponic) for its applicability to aquaponics and future perspectives related to biological control.
  • 925
  • 27 Oct 2020
Topic Review
Groundwater Withdrawal-Induced Land Subsidence
Land subsidence is probably one of the most evident environmental effects of groundwater pumping. Globally, freshwater demand is the leading cause of this phenomenon. Land subsidence induced by aquifer system drainage can reach total values of up to 14.5 m. The spatial extension of this phenomenon is usually extensive and is often difficult to define clearly. Aquifer compaction contributes to many socio-economic effects and high infrastructure-related damage costs. Currently, many methods are used to analyze aquifer compaction. These include the fundamental relationship between groundwater head and groundwater flow direction, water pressure and aquifer matrix compressibility. Such solutions enable satisfactory modelling results. However, further research is needed to allow more efficient modelling of aquifer compaction. Recently, satellite radar interferometry (InSAR) has contributed to significant progress in monitoring and determining the spatio-temporal land subsidence distributions worldwide. Therefore, implementation of this approach can pave the way to the development of more efficient aquifer compaction models. This entry presents a comprehensive review of models used to predict land surface displacements caused by rock mass drainage, as well as (2) recent advances and (3) a summary of InSAR implementation over recent years to support the aquifer compaction modelling process. Therefore, the study presented would be of benefit to readers who are interested in the topic of interaction between the human population and the hydrogeological system in different regions. The research presented allows readers to better understand the factors, developments and effects of groundwater drainage and thus facilitate large - scale risk assessment and preventive planning.
  • 3.3K
  • 27 Oct 2020
Topic Review
Escherichia coli in Secondary Habitats
Escherichia (E.) coli are rod shaped, facultative anaerobic, gram-negative, coliform, fecal gammaproteobacteria that inhabit the intestines of endotherms (primary habitat) and the natural environment (secondary habitats). Due to historic thinking regarding the limited capacity of E. coli to survive in the environment, a great deal of research is needed to advance understanding of environmental factors influencing E. coli’s survival.
  • 1.1K
  • 27 Oct 2020
Topic Review
Biodiesel Production from Animal Fats
Animal fats, usually found as waste from slaughterhouses, meat processing industry, and cooking facilities, constitute some of the most relevant waste with costly treatment because environmental regulations are quite strict. Part of such costs may be reduced through the generation of biodiesel that constitutes a valid renewable source of energy because it is biodegradable, non-toxic and has a good combustion emission profile. Furthermore, biodiesel can be blended up to 20% with fossil diesel for its use in many countries. Up to 70% of the total cost of biodiesel majorly depends on the cost of the raw materials used, which can be reduced using animal fat waste because they are cheaper than vegetable oil waste. Transesterification with alkaline catalysis is still preferred at industrial plants producing biodiesel. However, recent developments in technologies for process intensification like ultrasound, microwave, and different types of reactors have been successfully applied in transesterification and improved biodiesel production. Better efficiency has been achieved with new heterogeneous catalysts and nanocatalysts that can be easily recovered, regenerated and reused, and immobilized lipases with increased stability and resistance to alcohol denaturation. Also new adsorbents for increased oxidation stability of biodiesel. All these developments are promising for industrial use in near future.
  • 2.3K
  • 27 Oct 2020
Topic Review
Metallic Iron for Environmental Remediation
Metallic iron (Fe0) used as a reactive material in subsurface permeable reactive barriers is comparable to iron pipes with three major differences: (i) corrosion is welcome because it is a rather useful process [7][8][9], (ii) a reactive wall is ideally permanently water saturated, and (iii) the length of used particles (< 5 cm) is tiny compared to pipes which are up to 12 m in length. On the one hand, Fe0 specimens used in water treatment comprise steel wool with thickness varying between 25 and 90 μm [10][11]. On the other hand, the length of these particles is comparable to the wall thickness of iron pipes (2–4 mm). There has been no real system analysis for remediation Fe0 materials with the aim to outline the differences making their peculiar characteristics. In addition, traceably deriving the longevity of remediation Fe0 specimens from Fe0 pipes is impossible because of the differences highlighted.
  • 646
  • 27 Oct 2020
Topic Review
Nanoparticle Number Concentration
The entry analyzes suspended particles number concentrations of 61 size fractions (184 nm to 17,165 nm) in the air at a traffic location. The average course of the individual fractions was analyzed at various intervals – daily, weekly, monthly and annually, in the period between 2017 and 2019. The data was then used to calculate the arithmetic mean for all the fractions (MS Excel, R) and then using a proprietary web application, heatmaps were constructed. The obtained results showed significant differences in both the annual and daily variation of number concentrations between the individual fractions differing in particle size. In the case of the annual variation, one can see a greater variability of smaller particles, which is most likely due to the source of the actual suspended particles. Meteorological and dispersion conditions are found as important factors for suspended particle concentrations. These can lead to significant differences from year to year. However, a comparison between 2018 and 2019 showed that even though the average absolute number concentrations can differ between years, the actual relative number concentrations, i.e. the ratios between the individual fractions remain very similar. In conclusion it can be said that the difference between the number concentration variation of the size fractions depends on both the actual pollution sources (especially in the long-term, i.e. the annual variation) and the actual size of the particles, which plays a role especially in the short-term (daily, weekly variation).
  • 678
  • 27 Oct 2020
Topic Review
Organic Fouling
Organic fouling in the forward osmosis process is complex and influenced by different parameters in the forward osmosis such as type of feed and draw solution, operating conditions and type of membrane. In this article, we reviewed organic fouling in the forward osmosis focussing on wastewater treatment applications. Model organic foulants used in the forward osmosis literature were highlighted, followed by the characteristics of organic foulants when real wastewater are used as feed solutions. The present study evaluated various physical and chemical cleaning protocols for organic fouled membrane and the efficiency of cleaning methods for the removal of organic fouling in the forward osmosis process. The study made recommendations on future cleaning technologies such as Ultraviolet and Ultrasound. Generally, a combination of physical and chemical cleaning is the best for restoring the water flux in the FO process.
  • 1.8K
  • 27 Oct 2020
Topic Review
Nitrogen Compounds Prediction
The prediction of nitrogen not only assists in monitoring the nitrogen concentration in streams but also helps in optimizing the usage of fertilizers in agricultural fields. A precise prediction model guarantees the delivering of better-quality water for human use, as the operations of various water treatment plants depend on the concentration of nitrogen in streams
  • 1.4K
  • 27 Oct 2020
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