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Topic Review
Water Scarcity
Water scarcity, defined as long-term water imbalances occurring when the level of water demand exceeds natural water availability and supply capacity, is expected to pose high risks to both societies and economies in the next decade.
  • 1.3K
  • 03 Feb 2022
Topic Review
Water Stress and Water Footprint
Physical water stress and scarcity are often used interchangeably, or the exact nature of the underlying data is not clearly defined or justified (e.g., water use versus consumption versus withdrawal). A number of authors have noted that there is no widely accepted definition for physical water stress and scarcity.   Comparing different definitions of water stress and scarcity, they seem to be converging on the definition given by the CEO Water Mandate (A NGO affiliated with the United Nations), who defines water scarcity as lack of physical abundance of freshwater resources without considering whether water is suitable for use, and water stress as lack of ability to meet human and ecological demand for freshwater, in terms of water quantity and quality and accessibility to water.
  • 927
  • 01 Feb 2022
Topic Review
Water Treatment Plant Sludge Dewatering
Using geotextile tubes as dewatering technology may significantly contribute to sustainable treatment of sludge generated in different industries, such as the water industry. This is an economical alternative for dewatering sludge from a Water Treatment Plant (WTP), which prevents sludge from being directly deposited in water bodies and makes it possible to then transfer the sludge to landfills. 
  • 1.2K
  • 27 Oct 2020
Topic Review
Water Treatment Residues and Methanogenic Activity in Wastewater-Sludge
The effect of adding alum water treatment residues (WTR) on the methanogenic activity in the digestion of primary domestic wastewater sludge was evaluated through laboratory experiments in sedimentation columns, using total suspended solids (TSS) concentrations from 0.37 to 1.23 g/L. The addition of WTR to primary clarifiers can benefit its effluent water quality in terms of colour, turbidity, chemical oxygen demand (COD), and TSS. However, the presence of WTR can negatively influence the production of methane gas during organic sludge digestion in primary clarifiers, for concentrations of TSS between 14.43 and 25.23 g/L and of VSS between 10.2 and 11.85 g/L. The activity of the Methanothrix sp., curved bacilli, methanococci, and Methanosarcina sp. decreases considerably after 16 days of anaerobic digestion, and methane production seems to only be associated with fluorescent methanogenic bacilli.
  • 849
  • 17 Mar 2022
Topic Review
Water Well
A water well is an excavation or structure created in the ground by digging, driving, boring, or drilling to access groundwater in underground aquifers. The well water is drawn by a pump, or using containers, such as buckets, that are raised mechanically or by hand. Wells were first constructed at least eight thousand years ago and historically vary in construction from a simple scoop in the sediment of a dry watercourse to the qanats of Iran, and the stepwells and sakiehs of India. Placing a lining in the well shaft helps create stability, and linings of wood or wickerwork date back at least as far as the Iron Age. Wells have traditionally been sunk by hand digging, as is the case in rural areas of the developing world. These wells are inexpensive and low-tech as they use mostly manual labour, and the structure can be lined with brick or stone as the excavation proceeds. A more modern method called caissoning uses pre-cast reinforced concrete well rings that are lowered into the hole. Driven wells can be created in unconsolidated material with a well hole structure, which consists of a hardened drive point and a screen of perforated pipe, after which a pump is installed to collect the water. Deeper wells can be excavated by hand drilling methods or machine drilling, using a bit in a borehole. Drilled wells are usually cased with a factory-made pipe composed of steel or plastic. Drilled wells can access water at much greater depths than dug wells. Two broad classes of well are shallow or unconfined wells completed within the uppermost saturated aquifer at that location, and deep or confined wells, sunk through an impermeable stratum into an aquifer beneath. A collector well can be constructed adjacent to a freshwater lake or stream with water percolating through the intervening material. The site of a well can be selected by a hydrogeologist, or groundwater surveyor. Water may be pumped or hand drawn. Impurities from the surface can easily reach shallow sources and contamination of the supply by pathogens or chemical contaminants needs to be avoided. Well water typically contains more minerals in solution than surface water and may require treatment before being potable. Soil salination can occur as the water table falls and the surrounding soil begins to dry out. Another environmental problem is the potential for methane to seep into the water.
  • 2.5K
  • 27 Oct 2022
Topic Review
Water-Energy Nexus in Africa
The operationalization of the Water-Energy Nexus in the water supply is gaining  a lot of attention among water utilities, water regulators and stakeholders in the water sector. This is due to the growing body of evidence on the potential benefits of exploration of potential energy savings in the supply of water services, as the largest controllable operational input with short payback periods on investment. As population grows, high urbanization and the demand for water services increases especially in Africa, water utilities are faced with the challenges of meeting the current demand and expansion of services. However, there is paucity in the assessment of energy input for water supply and energy use is not considered as a key performance indicator for water utilities. Yet, accrued benefits from scrutinizing energy input in the water sector provides potential benefits of savings, revenue recovery and expansion of water services.
  • 644
  • 20 Oct 2020
Topic Review
Water-Related Issues in Bhutan
Water for hydropower in Bhutan has been in focus as compared to that allocated for irrigation, industries, and environmental demand. The demand for water in Bhutan has also increased in the last decade due to population increase, changes in lifestyle, and economic advancements through tourism and hydropower projects.
  • 3.9K
  • 28 Apr 2021
Topic Review
Water-Saving Agricultural Technologies
Increasing food demand has exerted tremendous stress on agricultural water usages worldwide, often with a threat to sustainability in agricultural production and, hence, food security. Various resource-conservation technologies like conservation agriculture (CA) and water-saving measures are being increasingly adopted to overcome these problems. While these technologies provide some short- and long-term benefits of reduced labor costs, stabilized or increased crop yield, increased water productivity, and improved soil health at farm scale, their overall impacts on hydrology outcomes remain unclear at larger temporal and spatial scales. Although directly linked to the regional hydrological cycle, irrigation remains a less understood component. The ecological conditions arising from the hydrology outcomes of resource-conservation technologies are associated with sustainability in agricultural production.
  • 2.7K
  • 22 Mar 2021
Topic Review
Water-Soluble Organic Aerosols
Water-soluble organic aerosols (OA) are an important component of atmospheric particulate matter and one of the key drivers that impact both climate and human health. Understanding these processes involving water-soluble OA depends on how well the chemical composition of this aerosol component is decoded. Yet, obtaining such a detailed chemical information faces several challenges, of which the complexity of the sample matrix is one of the most demanding issues. A number of different advanced multidimensional analytical techniques are available today with the potential to tackel the complex chemical nature of water-soluble OA, allowing the untargeted profilling of new chemical structures without the need for use of databases or libraries. This critical review is aimed at nonspecialists who are interested in learning more about the potential and impact of such multidimensional non-targeted analytical strategies in water-soluble OA research.
  • 1.1K
  • 19 Mar 2021
Topic Review
Water-Soluble Organic Matter
Inspired by studies on outdoor organic aerosols (OA), recent studies discusses and prioritizes issues related to indoor water-soluble OA and their effects on human health, providing a basis for future research in the field. The following three main topics are addressed: (1) what is known about the origin, mass contribution, and health effects of water-soluble organic matter (WSOM) in outdoor air particles; (2) the current state-of-the-art on the WSOM in indoor air particles, the main challenges and opportunities for its chemical characterization and cytotoxicity evaluation; and (3) why the aerosol WSOM should be considered in future indoor air quality studies.
  • 1.1K
  • 08 Nov 2021
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