Modern treatment technologies use new sources of water to expand water supplies
Many aquifers are facing depletion because of factors like over-extraction and drought. One study found that groundwater levels are declining in 36% of the world’s aquifers at a rate of more than 0.1 meters per year. Water tables are dropping by more than 3 feet per decade in these aquifers. As water levels drop in the U.S. and globally, both the quantity and the quality of the water diminish as concentrations of minerals and contaminants increase.
Water treatment facilities are under increasing pressure as populations grow and industrial and agricultural activities expand. In many regions, the days of relying solely on groundwater are numbered. To ensure that we have enough water and that the water we use remains safe, water treatment facilities must adapt.
The Growing Pressure on Water Treatment Facilities
Water treatment plants ensure that the water flowing into our homes and businesses is safe to use. However, rapid population growth, particularly in urban areas, is causing a surge in demand, and treatment plants are struggling to keep up.
Meanwhile, industries that rely heavily on water for their operations are expanding, further increasing the load on treatment facilities. More frequent and more severe droughts are reducing the amount of water available from traditional sources like rivers, lakes, and aquifers.
This has encouraged a growing reliance on nontraditional water sources. Communities and businesses need treatment processes that effectively and efficiently turn seawater, brackish water, and recycled wastewater into safe drinking water.
Effective Water Treatment
Traditional treatment methods are reliable, but they often fail to treat contaminants in nontraditional water sources.
Advanced technologies like membrane filtration and reverse osmosis (RO) can compensate. Ultrafiltration and reverse osmosis both rely on membranes to remove contaminants from water. The difference lies in the size of the pores in the membrane. RO membranes have finer pores that range from 0.0001 microns to 0.001 microns, small enough to remove molecules like salt ions that would pass through the larger pores—0.002 microns to 0.1 microns—of ultrafiltration membranes.
Ultrafiltration is very efficient at removing pathogenic microorganisms and suspended solids, including organic matter and silt, from the water. It is used in a wide range of water treatment applications, including as a pretreatment stage in reverse osmosis to prevent membrane fouling.
In reverse osmosis, water is forced through a semi-permeable membrane under pressure. The tiny pores in the membrane allow water to pass through while trapping salts, ions, and other contaminants.
The result: high-quality water.
These systems efficiently and effectively remove a wide range of contaminants, including pharmaceuticals, microplastics, and endocrine disruptors. Typically, they can be scaled up or down to meet varying demands and can provide safe and reliable drinking water for large urban centers and small communities.
Beyond Groundwater
According to the World Economic Forum, 25 countries, home to a quarter of the world’s population, regularly deplete their water supplies and face extreme water stress. At least half of the world’s population suffers high water stress for at least one month each year.
Water is critical for human survival. We need it to irrigate crops, water livestock, produce power, and provide clean water and sanitation.
Although freshwater supplies are declining, seawater, brackish water, and wastewater are abundant. To avoid extreme water stress, communities should diversify their water supplies to include these sources.
Doing so requires investing in alternative water treatment technologies, such as seawater reverse osmosis (SWRO) and brackish water reverse osmosis (BWRO), to desalinate and reuse wastewater and advanced digital systems to monitor and optimize treatment processes.
RO technology is widely used in desalination systems to remove salt and other impurities from seawater and brackish water and thus produce fresh, potable water. The key difference between brackish and saline water is the total dissolved solids (TDS) present in each. Brackish water contains lower TDS concentrations, typically between 1,000 to 10,000 parts per million (ppm). Concentrations of total dissolved solids in seawater are around 35,000 ppm, making seawater more expensive to process.
Since we generate wastewater whenever we use water, we have plenty of wastewater to use as an alternative source of clean water. With appropriate treatment, municipal and industrial wastewater can be used in non-potable applications like flushing toilets, irrigation, dust control, and cooling water. Wastewater treated for reuse produces high-quality effluent that is safe to discharge into the environment and can be used to recharge aquifers, replenishing the groundwater of depleted systems.
Although recycling wastewater reduces the aquatic pollution associated with effluent discharge and expands water supplies, socially, it’s not a slam dunk.
The Yuk Factor
One of the biggest hurdles to water reuse has been the yuk factor. Even the idea of reusing treated wastewater for non-potable purposes like irrigation has tended to put people off.
But this attitude isn’t impermeable. A recent survey of 2,500 participants in the United Kingdom, Spain, and the Netherlands showed that a surprisingly high percentage of respondents (65%, 73%, and 75%, respectively) support using recycled water for drinking water. The high rate of support is attributed to high trust in government agencies responsible for environmental control and water quality.
Achieving this level of trust elsewhere requires establishing appropriate environmental regulations and health standards for wastewater reuse that protect both the environment and public health.
Advanced water treatment technologies can be technically challenging and costly to implement. However, lease-plant programs and build-own-operate and build-own-operate-transfer agreements can help cash-strapped municipalities overcome these obstacles.
Other strategies that can help are rainwater harvesting and stormwater capture, with surplus water stored in rain barrels or retention dams. The harvested water can be used for non-potable applications. It can also be diverted to urban wetlands that serve as filtration beds, thereby reducing stormwater runoff and helping to recharge groundwater.
Public support is critical. To address widespread concerns, leaders must clearly explain alternative water sources’ safety, reliability, and benefits and build trust before supplementing traditional groundwater sources with recycling options.
