Desalination is a water (usually seawater) treatment process, which separates salts from the seawater to produce potable drinking water. There is a high consumption of energy during the production process. Salt water is channeled into the treatment plant that produces a stream of pure water and another stream of high concentrated brine.
The issue of water shortage is internationally recognized as a crisis due to the increased drought in different regions. While the concern is being addressed as a matter of importance, there are questions that require answers taking into consideration the negative impact of desalination methods. The most common desalination methods are reverse osmosis (RO) and thermal processes. Reverse osmosis is widely accepted in Europe due to its lower energy consumption compared to thermal alternatives.
Due to high population growth rate, industrialization, and urbanization, freshwater sources are being over-exploited. Therefore, the use of desalted water has been an alternative to address the issue of drinking water scarcity. However, the large-scale desalination is energy intensive. Additionally, the environmental impacts are critical given the huge amount of emissions released from fossil fuel combustion in the desalination plants. There is also the issue of brine discharge into the oceans, which is extremely concentrated with salts and chemicals derived from the treatment processes. The brine and those chemicals pose danger to marine animals.
Reverse Osmosis (RO) and its Impacts
Reverse osmosis is a desalination process that uses a fine membrane to filter out particles present in water. It not only removes the salt but also removes heavy metals and harmful microorganism in water. The traditional RO systems have been using fossil fuels to provide energy, which causes severe negative impacts on the environment. The release of greenhouse gases and the intensive energy consumption has been a threat to the environment. Even though it is an effective method to provide clean and pure drinking water, the use of fossil fuels remains a global concern.
The negative impacts can be minimized through the use of renewable sources of energy. Renewable energy provides a sustainable approach to increasing supply of clean water without degrading the environment. Places such as Asia and North Africa are the most hit by freshwater scarcity, but they have a high potential of the wind and solar energy to power desalination plants. If effectively utilized in desalination processes such as reverse osmosis, the freshwater shortage can be addressed in a more sustainable manner.
While RO technology has been in the market for quite some time, there are more innovations expected in order to meet the new demands for environmentally friendly productions. Globally, RO technology is now u. The technology is driven towards achieving energy efficiencies in reverse osmosis water production.
According to a research analysis in 2008, the major impacts of reverse osmosis were associated with the water intake, discharge of concentrated brine, and emission of greenhouse gas. Impingement and entrainment of marine animals such as fish were also a concern. Fish are trapped and transported to the RO plant, which are then killed during the filtration processes. However, a few practices and technologies have been identified to help in reducing such impacts. Some of the new changes include the water intake volume reduction, intake timing, intake placement, and intake location. Also, new screens are being designed.
Solar Powered RO Systems
Solar energy can be used either directly or indirectly in the reverse osmosis desalination process. The major disadvantage of using solar energy is the low production rate, especially where large scale RO water production is required. However, Concentrating Solar Power (CSP) can provide an effective option to power RO systems in large scale desalination plants. Areas such as Asia have a high potential of solar energy that can facilitate energy production needed to offset the startling drinking water deficit.
Health Impacts of Reverse Osmosis Water
Reverse osmosis uses a membrane to filter out molecules large than water. The particles of harmful contaminants are also removed, making the water safe for domestic and industrial use. For the patients who should not drink mineral water, RO water is their best alternative. It is free from microorganisms that cause diseases, and therefore suitable for cancer patients with low immune strength. More importantly, reverse osmosis water has no heavy metal traces. However, reverse osmosis has its own disadvantages too. During the filtering process, many of the essential minerals are removed from the water.