Due to increasing populations, the contamination of conventional surface water sources (such as rivers and lakes) and with the extraction of groundwater exceeding the recharge rate, water supplies are becoming increasingly insecure. As such, water treatment systems for both conventional and unconventional sources are becoming increasingly common. Solar powered water treatment including hybrid power systems are becoming increasingly common to offset the carbon cost of water treatment. In rural and remote areas, grid power is usually unavailable requiring the use of generators or off-grid renewable energy systems to power water treatment systems. Given supplying water treatment systems with consumables (including diesel) for remote areas can be difficult, renewable energy powered, chemical free treatment systems are preferred. Remote water treatment systems also need to be robust and easy to service and maintain locally.
Wind or solar powered water treatment systems are the most commonly used renewable energy systems. However the mix of energy for each site will be location specific. Solar powered water treatment systems have become increasingly prevalent at the smaller scale with wind powered/offset systems more common at larger scale. Renewable energy, when combined with chemical free water treatment, robust builds and local maintenance programs leads to reliable remote water treatment systems.
Given a combination of the hesitancy of consumers to consume treated wastewater and local regulations in most regions restricting the use of treated wastewater as a source of drinking water, the most used sources for drinking water treatment are surface water, groundwater and seawater. The type of treatment system selected will depend on the type of contaminants that need to be removed from each water source.
Solar powered surface water treatment
Surface water sources, when protected from run-off are predominantly contaminated with microbiological species and suspended solids. Surface water sources are usually too shallow to be highly saline, although storm surges can contaminate coastal surface water sources with salt. Sand filters are a cheap method to reduce suspended solid loads in water to allow for subsequent disinfection. Flocculant/coagulant dosing is used when there is a colloidal fraction in the suspended solids that would bypass sand filters. Sufficient suspended solids must be removed to allow for subsequent disinfection following filtration be it chlorine or UV based.
Chemicals such as disinfectants and coagulants can be difficult to source in rural and remote locations. Therefore Moerk Water have developed a solar power UV irradiation system. This system provides a chemical free method of filtration and disinfection. The unit is low maintenance, robust and locally maintained. Moerk Water also use solar powered ceramic ultrafiltration for remote surface water sources which are contaminated with colloidal particles.
Solar powered groundwater treatment
Groundwater sources can be contaminated with a wide range of materials including dissolved metals, microbial species, acidity, oils and agricultural run-off. Groundwater sources are also commonly contaminated with mineral species and can range in salinity from low brackish to hypersaline. For groundwater sources that are saline, particularly brackish levels of salinity, Reverse Osmosis is the treatment technology of choice due to its maturity and flexibility. The concentration of different contaminants will determine the pre-treatment system required for the treatment system. Moerk Water have developed a range of solar powered brackish water desalination systems to treat groundwater sources.
Solar power allows for remote installation. However groundwater systems will often require chemical dosing so this needs to be carefully considered during the design phase. Additionally, all Reverse Osmosis systems produce a waste stream that needs to be disposed of. For remote (inland) groundwater treatment systems, disposal options include injection, evaporation or the growth of halophytes.
Solar powered seawater desalination
For coastal locations, when there is not sufficient surface or groundwater sources available, seawater can be used as the feedwater for the drinking water treatment system. Seawater desalination is the most energy intensive water treatment method. It is generally used when there are no other options. Seawater desalination also requires chemical dosing if run at high recovery. Additionally it produces a reject stream that needs to be disposed of. Seawater desalination systems can be run chemical free by lowering the recovery. The chemical free recovery rate will be based on local water chemistry and temperature. By lowering the recovery rate, the waste from the system is easier to dispose of. Moerk Water have developed reliable low recovery rate solar powered seawater desalination systems.
Ensuring the smooth operation of a solar powered desalination system in a remote context is a difficult operation. Moerk Water have ~15 years of experience developing renewable energy powered seawater treatment systems. This experience allows Moerk Water to determine the best approach to ensure success for each location.
Contact Moerk Water today to find out more about sustainable water supplies for remote locations.
