IT is no secret that our attitude towards water has changed drastically in the last few years. What used to be seen as an inexhaustible natural resource is now a scarce commodity.
“By 2025, most countries in Africa will face severe water scarcity, due to increasing population and demands on water,” the United Nations Environment Programme predicts.
There has never been a greater need for alternative water supplies. Water Purification Solutions (WPS) believe that water reuse is paramount in combatting water scarcity in Africa.
Water reuse (also commonly known as water recycling or water reclamation) reclaims water from a variety of sources, treats it, and reuses it for beneficial purposes. Water reuse can provide alternatives to existing water supplies and can be used to enhance water security, sustainability, and resilience.
Sources of reusable water
Sources of water for potential reuse can include municipal sewage water, industrial effluent, stormwater, and agriculture runoff.
These sources of water can all be treated to meet fit-for-purpose specifications for a particular beneficial use such as irrigation, potable water supplies, and industrial processes.
Municipal sewage
Treating sewage for reuse is a complex process. The sewage must undergo chemical, physical and biological procedures to ensure the removal of all contaminants. This requires specialty water treatment that includes advanced technologies such as flocculation, disc filtration, ultrafiltration and reverse osmosis.
Industrial effluent
Effluent can be treated for reuse across almost all industries, including, for example, agriculture, food and beverage, metal finishing, plastic manufacturing, and textile.
With any effluent treatment, one of the main challenges is that there is a multitude of influents, resulting in the effluent that requires treatment being of a significantly complex nature.
Influents in a metal finishing factory, for instance, can stem from acid wash, alkaline wash and zinc bath processes. These result in fluctuating levels of pH and metal concentrations.
Stormwater
Stormwater is rainwater that runs off land and moves away from the area where it originally falls. It can soak into the soil, be stored on land in ponds and puddles, evaporate, or contribute to surface runoff.
The treatment of stormwater for reuse enables this water to be reused for a variety of applications including irrigation, water features, toilet water flushing, process water, and cooling tower feedwater.
Technologies for water reuse:
- Disc Filtration
Disc filtration offers depth filtration where the particles to be filtered are trapped between discs and filtered water continues through to the next stage of treatment.
A differentiating factor between various disc filter manufacturers is not only the type of disc assisting with improved filtration but also the cleaning mechanism employed to offer superior backwashing in terms of water and power efficiency.
AZUD is a Spanish water treatment company that develops innovative technologies for water management and its Helix Automatic FT200 AA DLP disc filter performs in-depth 3D filtration, followed by automatic, air assisted (AA) backwashing. Data Loss Prevention (DLP) technology enables the sequential low-pressure backwashing of each filter using a mix of filtered water and compressed air stored in an auxiliary tank, while the filtered water continues to be supplied.
- Membrane technology
Ultrafiltration is a membrane filtration method that is intended for the removal of microbiological particles. An ultrafiltration filter has a pore size around 0.01 micron. The process of ultrafiltration removes bacteria, microorganisms, larger particles, and some viruses from water.
Moreover, when employing ultrafiltration secondary (coagulation, flocculation, sedimentation) and tertiary filtration (sand filtration and chlorination) often aren’t necessary. This is because ultrafiltration, as a type of primary filtration, can stand alone.
Reverse osmosis is a water purification process that uses a partially permeable membrane to separate ions and unwanted molecules from water. After the water passes through a reverse osmosis filter, it is essentially pure water.
Reverse osmosis removes most minerals in the water as well as organic molecules and viruses.
- For more information Email: info@wps.co.za or Tel: 021 851 2451.
