Water. desalination + reuse

RESEARCH | 32 | Desalination & Water Reuse | February-March 2014 Completion of the second phase of the joint evaluation of membrane distillation technology by Qatar's ConocoPhillips Global Water Sustainability Center, Qatar Electricity & Water Co (QEWC) and Qatar University was celebrated on 27 November 2013. The research project (see D&WR feature August/September 2013) aims to prove that quality freshwater can be produced from brines discharged from thermal desalination plants using low-grade waste heat from industry and/or renewable sources. The Membrane Distillation Field Demonstration project started in October 2011 and was hosted in the Chemical Engineering Department. The technology uses less energy, has a lower environmental impact and is less costly than conventional methods for desalinating high salinity brines. In collaboration with QEWC, Phase 2 saw the units operating at the Ras Abu Fontas power and desalination plant to evaluate the process under industrial conditions. A waste-heat audit was conducted to identify opportunities whereby the energy needed by MD could be obtained from sources within two Qatari desalination facilities. Phase 2 of Qatar's MD research concluded About 15% of all domestic wells in Texas, USA, are at risk due to high salinity, according to a recent Texas A&M AgriLife Research study. The study Temporal Evolution of Depth-stratified Groundwater Salinity in Municipal Wells in the Major Aquifers in Texas was completed using the Texas Water Development Board's groundwater quality database for the period 1960-2010. Dr Srinivasulu Ale, AgriLife Research geospatial hydrology assistant professor, and Dr Sriroop Chaudhuri, his post- doctoral research associate, have had their study paper accepted for publication in Science of the Total Environment journal. Groundwater withdrawal accounts for about 36% of Texas' municipal water supplies, according to Ale. However, many water quality issues have been reported from around the state, raising serious concerns over groundwater use due to a rise in concentration of sulfates, chlorides, fl uorides, nitrates and total dissolved solids (TDS). TDS is a collective manifestation of all dissolved chemicals and is considered a measure of salinity and an overall indicator of water quality, relating to taste and palatability, he said. Previous hydrogeologic investigations of aquifers in Texas have also examined groundwater salinity, Ale said, but lacked depth-stratifi ed long-term evaluation of groundwater salinization with specifi c reference to potable use. The objective of this study was to offer a qualitative overview of the spatial, both horizontal and vertical, and temporal extent of groundwater salinization in light of regional differences in hydrochemical processes, or changes to the ambient water composition. "We identifi ed hot spots of groundwater salinization at shallow depths across vast regions of West Texas in the southern Ogallala, northwestern Edwards-Trinity and Pecos Valley aquifers; intermediate and deep depths in the southern Gulf Coast aquifer; and deep depths in North Central Texas in the Trinity region," Ale said. For both time periods, the highest average groundwater TDS concentrations in shallow wells were found in the Ogallala and Pecos Valley aquifers, and those in the deep wells were in the Trinity aquifer, he said. In the Ogallala, Pecos Valley, Seymour and Gulf Coast aquifers, about 60% of the observations from shallow wells exceeded the secondary maximum contaminant level for TDS in both time periods, which indicates persistent concern over potable water quality, Chaudhuri said. In the Trinity aquifer, 72% of deep water quality observations exceeded the secondary maximum contaminant level in the 1990s-2000s, compared to 64% observations in the 1960s-1970s, he said. Study fi nds salinity risk to Texas groundwater A study has just been published in Australia on development of a holistic framework for rigorous assessment of the economics of non-potable recycled water schemes, including residential, industrial, municipal and agricultural schemes. Supported by funding from the Australian Water Recycling Centre of Excellence, the study Economic viability of recycled water schemes was carried out by Marsden Jacob Associates. The report found that many water reuse schemes use a variety of limited assessment methods for their costing and planning decisions. Economic and commercial benefi ts are often inappropriately estimated and poorly delineated between parties, rendering the economic case for investment in recycled water projects diffi cult to establish in advance and to determine in hindsight. To remedy these defi ciencies, the report describes a general methodology for assessing both use and non-use values, and identifi es the most prominent costs and benefi ts that apply across all non-potable recycled water schemes. In addition to the general costs and benefi ts, the framework allows for the inclusion of other costs and benefi ts specifi c to each project. Looking at barriers to implementation of projects, the project says that the team's primary feedback was that the greatest impediments were cost-effectiveness and commercial risk. The report makes recommendations to smooth the process and to reduce the risk. Australian study looks at reuse scheme economics RESEARCH February-March 2014 | Desalination & Water Reuse | 33 | Biodiversity offset schemes often fail to meet aims NWRI seeking Clarke Prize nominations before April Pacific Institute reports on intakes and brine disposal Biodiversity offset schemes, similar to those implemented for desalination projects, do not always fully compensate for loss of habitat due to development, new research suggests. Writing in the journal Conservation Biology*, a team from Muséum National d'Histoire Naturelle in Paris, France, looked at 66 development projects in France with offset schemes. They found that numbers of species in offset sites was on average five times lower than in the land destined for development. Furthermore, even endangered species were not always protected by these offset sites. Under environmental legislation in Europe, as well as in the USA and other parts of the world, any development must maintain or restore a favourable conservation status for protected species. To do this, developers often use 'offset' land, restoring or creating habitats that can compensate for the development's effects by protecting the same species that have been lost in the development site. Few studies have assessed whether this is truly achieved. In this study, researchers reviewed the offset activities of 85 French development projects undertaken between 2009 and 2010, which affected 253 species in all. These included reversible developments, such as landfill sites, that can be restored in the future, and irreversible developments, such as roads. The results show that 19 of the 85 developments provided no offset measures at all and, out of the 66 that did, only 30 considered all affected species. A greater proportion of endangered species (82%) were protected than more common species (26%). However, the researchers stress that this result indicates that even endangered species were not always protected. On average, the offset sites had five times fewer species than the pre-development sites. In fact, when species richness was high (more than eight species per site) in pre- development sites, the numbers of species in offset sites were up to ten times lower. The area of the offset sites was smaller and all together only amounted to 37% of the area of development sites. *B Regnery, D Couvet, & C Kerbiriou (2013). Offsets and Conservation of the Species of the EU Habitats and Birds Directives. Conservation Biology. DOI: 10.1111/cobi.12123. The US National Water Research Institute (NWRI) is seeking nominations for 21st annual Clarke Prize for excellence in water research The prize, which includes a US$ 50,000 award and medallion, recognizes scholarly and practical achievements in water research. NWRI established the Clarke Prize in 1993 to recognize outstanding individuals who are significantly and actively contributing toward any of the following areas: the discovery, development, improvement, and/or understanding of the issues associated with water quality, quantity, technology, or public policy. Nominations are reviewed based on the following criteria: • Active engagement in current research endeavors • Professional career accomplishments • Demonstrated excellence through research contributions. Nominations are due by 1 April 2014. The award will be presented at the Clarke Prize Conference and Award Ceremony on 7 November 2014, in Orange County, California. More information about the nomination process may be found at www.nwri-usa.org/nominations.htm. A series of recommendations about the design of desalination intakes and outfalls has been published in a report by the Pacific Institute as part of its series on Key Issues For Seawater Desalination in California. The report, titled Marine Impacts, examines the affects of desalination intakes on marine life through entraining and impingement, and the introduction of highly concentrated reject brine into seawater. A review of current understanding the impacts of intakes is included in the report, with an overview of some of the technological, operational, and design measures developed to reduce them, including subsurface intakes. It also includes a review of brine studies that have been conducted at recently completed plants, with a description of observed impacts, and identifies research gaps. The regulatory system for seawater desalination in California is also examined. Principle recommendations of the report include: For intakes: • Intake pipes should be located outside of areas with high biological productivity and designed to minimize impingement and entrainment • Project proponents should thoroughly investigate the feasibility of subsurface intakes, including the evaluation of alternative siting and reduced design capacity of the project. For outfalls: • Water managers should avoid disposing of brine in close proximity to sensitive habitats, such as wetlands and some benthic areas • Water managers should carefully monitor, report, and minimize the impacts of brine disposal on the marine environment • More comprehensive studies are needed to determine the impacts of brine on the marine environment and to mitigate these impacts. The report also calls for more research about the impacts of intakes and brine disposal, and regulators are called on to insist on more monitoring of these impacts. It is available from: www.pacinst.org.

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