Access to safe and clean drinking water is a basic human necessity. In a densely populated and flood-prone country like Bangladesh, ensuring a consistent supply of potable water has long been a public health priority. With challenges ranging from groundwater arsenic contamination to pollution in surface water bodies, the treatment process to make water fit for human consumption is both complex and vital.
But first, what is potable water? Potable water refers to water that is safe to drink or to use for food preparation. It is free from harmful levels of contaminants, bacteria, and viruses. In Bangladesh, where natural water sources are vulnerable to contamination, significant efforts are made to treat water to meet potable standards.
Understanding the Context in Bangladesh
Bangladesh primarily relies on surface water (from rivers and lakes) and groundwater (from wells and aquifers) for its water supply. While groundwater is less exposed to immediate pollution, in many parts of Bangladesh, it is contaminated with naturally occurring arsenic and iron. On the other hand, surface water, though easier to access, is more likely to be polluted by industrial discharge, agricultural runoff, and domestic waste.
Given this situation, a well-defined potable water system becomes crucial. A potable water system involves the infrastructure and processes designed to treat and distribute safe drinking water to consumers. In Bangladesh, these systems vary depending on the region, urban versus rural settings, and the available water sources.
Steps in Potable Water Treatment in Bangladesh
- Collection of Raw Water: Water is first collected from surface sources like rivers or groundwater sources through tube wells. This raw water contains various physical, chemical, and biological contaminants and is not safe for immediate consumption.
- Coagulation and Flocculation: In water treatment plants, coagulants like alum are added to the raw water to bind small particles into larger clumps, or flocs. These particles may include dirt, bacteria, and organic matter. The process helps in making these contaminants easier to remove.
- Sedimentation: Once flocculation is complete, the water is allowed to sit in sedimentation tanks. The flocs settle at the bottom due to gravity, and the clearer water remains at the top.
- Filtration: The next step is filtration, where the water passes through layers of sand, gravel, and sometimes activated carbon to remove remaining particles, bacteria, and impurities. This is a critical step in transforming raw water into potable water.
- Disinfection: Disinfection is perhaps the most vital step in ensuring that the water is safe to drink. Chlorine or other disinfectants are added to kill any remaining harmful microorganisms. In some areas, UV treatment or ozonation is also used as an additional safety measure.
- pH Adjustment and Mineral Addition: Treated water may be slightly acidic or lack essential minerals. Adjusting the pH level and reintroducing minerals like calcium or magnesium not only improves the taste but also ensures the water is suitable for long-term consumption.
- Storage and Distribution: After treatment, potable water is stored in clean, covered reservoirs or tanks and distributed to households through a network of pipes. Maintaining hygiene in storage and distribution is just as important as the treatment itself.
What is Potable and Non Potable Water?
It’s important to distinguish between potable and non-potable water. Potable water is treated and safe for consumption, cooking, and personal hygiene. Non-potable water, on the other hand, is untreated or partially treated and should not be used for drinking. In Bangladesh, many rural households rely on non-potable water for irrigation and livestock, but they mustn’t use it for drinking without adequate treatment.
Decentralized Potable Water Solutions
In remote or rural areas of Bangladesh where large treatment plants are not viable, decentralized systems like community-based filtration units, arsenic removal filters, and solar-powered purification systems have gained popularity. These systems are cost-effective and sustainable, often run by local community groups, and tailored to the specific contamination challenges of the region.
How Ion Exchange Contributes to Sustainable Water Treatment Solutions?
Ion Exchange, a leading company in water treatment solutions, has been instrumental in Oman’s quest for water sustainability. The company provides advanced technologies and systems to address the country’s unique water challenges.
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Reverse Osmosis (RO)
It is a cutting-edge technology used to remove the majority of contaminants from water by applying pressure to force water through a semi-permeable membrane. This membrane allows the passage of water molecules while blocking dissolved salts, organics, bacteria, and pyrogens. The high-pressure pump increases pressure on the salt side, pushing water across the RO membrane and leaving most dissolved salts behind in the reject stream. The treated water typically has 95% to 99% of dissolved salts removed.
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Ultraviolet (UV) Technology
It offers an effective method for eliminating biological contaminants. These purifiers guard against waterborne viruses, bacteria, and microorganisms such as Giardia and Cryptosporidium. Exposure to UV radiation within the flow chamber purifies harmful microbiological impurities.
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High Recovery RO (HRR) Technology
The innovative High Recovery RO (HRR) process, featuring the Water Saver Cartridge (WSC), continuously sweeps away salts and kills microbes, allowing operation at high recovery levels. This process achieves up to 70% recovery from a single RO membrane, three times higher than conventional systems, and saves over 80% of water, making it eco-friendly with a high shelf life for treated water.
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Electrolytic Sanitizing System (ESS) Technology
Conventional UV systems can suffer from slime buildup, bacterial growth, voltage fluctuation, and quartz scaling, leading to poor disinfection. The patented ESS technology by ZeroB ensures complete microbial kill, overcoming these drawbacks and preventing water recontamination.
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Resin Technology
Ion exchange resins play a crucial role in various separation, purification, and decontamination processes. Ion Exchange manufactures a range of resins, including poly-iodinated and iron-specific resins, which eliminate microbial contaminants and reduce iron levels to safe drinking standards (less than 0.3 ppm).
Conclusion
The journey of water from a natural source to your glass involves multiple treatment stages, advanced technology, and consistent monitoring. In a country like Bangladesh, where water sources are under constant pressure from population growth and climate change, ensuring a safe and reliable potable water system is both a challenge and a necessity. Understanding what is potable and non-potable water, and how treatment transforms one into the other, empowers communities to make better choices and demand safer infrastructure.