While it is internationally recognized that water shortages and drought have reached a crisis point and must be addressed as a matter of urgency, questions should still be answered as to the negative impact of traditional desalination methods. The most commonly used desalination technologies are reverse osmosis (RO) and thermal processes such as multi-stage flash (MSF) and multi-effect distillation (MED). In Europe, reverse osmosis, due to its lower energy consumption has gained much wider acceptance than its thermal alternatives. While reverse osmosis (RO) technology has been in the marketplace for decades, it’s expected that RO’s technical innovations, especially those that respond to consumers’ new demand for environmentally responsible “green” products, will continue apace. Worldwide, technology is being driven by the response to the fast-growing municipal seawater desalination market, where there is a push for increased RO water and energy efficiencies. Source: watertechonline.com The Negative Impact of Traditional Desalination Methods In Qatar, the multi stage flash (MSF) system which is predominantly used for desalting seawater has negative impacts on the environment due to burning fossil fuels that emit greenhouse gases. Impingement and entrainment of marine organisms at the intake, higher temperatures and salinity as well as chemical pollution at the outfall are the main footprints on the marine environment. This study showed that the seawater intake would be reduced about 3 times from 8.4 Mm3/d to 3.6 Mm3/d, which decreases the impingement and entrainment of marine organisms at the intake. Hence the corresponding discharge of brine and cooling water could be reduced from 7.2 Mm3/d to 2.4 Mm3/d for MSF and SWRO(seawater reverse osmosis), respectively. Moreover, the thermal pollution of the rejected effluents from MSF plants could be eliminated and the chlorine residual would be reduced dramatically when using SWRO. Finally, the use of SWRO saves up to 75% of energy use, and thus the CO2 emissions would be reduced from 3.564 to 0.891 million (M) tons per year. Source: cloudfront.net Until now the process of desalination is not per se environmentally friendly and seawater desalination plants also contribute to the wastewater discharges that affect coastal water quality.This is mostly due to the highly saline brine that is emitted back into the sea, which may be increased in temperature, contain residual chemicals from the pretreatment process, heavy metals from corrosion or intermittently used cleaning agents. The effluent from desalination plants is a multi-component waste, with multiple effects on water, sediment and marine organisms. It therefore affects the quality of the resource it depends on. Source: paua.de In 2008 the Committee on Advancing Desalination Technology, formed by the Water Science and Technology Board of the National Research Council published the results of their analysis of current desalination technologies and barriers to broader implementation. The study was motivated by the observation that while concerns are growing in the US about options for meeting future water needs, the US lags behind many other countries in the adoption of desalination technologies. The study produced a framework for a national research agenda, considering environmental an implementation issues as well as technology and costs. Read an excerpt from their conclusions. Environmental impacts of desalination plant operations From: superfund.ciesin.columbia.edu The National Research Council (NRC) 2008 analysis identified three major categories of environmental impacts associated with operation of a desalination plant that are relevant to the Haverstraw Bay, NY project proposed by United Water New York: (1) Impacts associated with the water intake; (2) Impacts associated with disposal of concentrate liquids; and (3) Greenhouse gas emissions associated with increased fossil fuel emissions derived from electricity generation. Impingement (fish being trapped and killed on the screens) and entrainment (fish eggs, larvae and fish being killed by being transported into a plant with the water) – have been extensively studied with respect to electricity generation plants. A number of technologies and practices have been identified that can reduce impingement and entrainment impacts. These practices and technologies include intake location and intake placement, screen design, intake volume reductions and intake timing. Health Impacts of Drinking Water Treated by RO According to Wikipedia, due to its fine membrane construction, reverse osmosis not only removes harmful contaminants present in the water, but it also may strip many of the good, healthy minerals from the water. A number of peer-reviewed studies have looked at the long-term health effects of drinking demineralized water. Further Reading The Key Issues for Seawater Desalination series is an update to the 2006 Pacific Institute report Desalination with a Grain of Salt, which has proven to be an important tool used by policy makers, regulatory agencies, local communities, and environmental groups to raise and address problems with specific proposals. Researchers conducted some 25 one-on-one interviews with industry experts, environmental and community groups, and staff of water agencies and regulatory agencies to identify key outstanding issues for seawater desalination projects in California. The resulting reports address proposed desalination plants in California, costs and financing, energy and greenhouse gas emissions, and marine impacts. Here a further article  “Spring Water vs. Purified Water (All You Need To Know)”.