Rainwater Collection and Solar Distillation

Since a substantial amount of groundwater is unsafe to drink, Bangladeshi people would benefit from supplementing their water needs with rainwater. Bangladesh receives a high amount of rainfall, around 2.0 meters annually[1]. Rainwater in some regions can provide water to a family for 185-240 days in a year.[2] Using cement ring tanks, which have the lowest cost per cubic meter ($24),[3]  Bangladeshi people in rural areas can feasibly reduce their exposure to salt and arsenic in the water for most of the year. Since these tanks are often set up on roofs or elevated platforms, there is little risk of floodwater contamination. However, rainwater collection can be unsafe if the rainwater collection systems are contaminated with animal wastes and sediment. This is one of the largest setbacks in increasing social acceptance of this system, as it requires constant monitoring and periodic bleaching.[4] Thus, it is up to individual families adopting this system to clean and maintain their rainwater systems. In order for Bangladeshi people to want to adopt this system, the risks of arsenic and salinity must be made clear to them through water safety campaigns. Additionally, water that is unsafe to drink can be easily distilled using solar power. By creating a box with a slanted glass top over a basin, filling it with questionable water, and setting it in the sun, one can end up with safe drinking water. The sun heats up the water and causes it to evaporate. Once the water evaporates, it condenses on the top of the box and slides down to a reservoir where the distilled water can be collected. The water produced can be increased by painting the box black, so as to increase heat and evaporation, or by adding mirrors to increase the amount of sun the box gets.

Several people have taken these processes for distillation and either modified them for more efficiency or applied them to actual communities. A great, easy to set-up solar distiller model is “eliodomestico” designed by Gabriele Damanti.[5] This design can generate about 5 liters a day, and the units are distributed at prices ranging from $20-$50, depending on the quantity ordered. This is an affordable option to provide safe water to impoverished communities.

One solution being applied to Bangladeshi communities consists of so-called “Water ATMs.” These ATMs are reverse osmosis distillation machines typically funded by local banks or NGOs. Residents can go up to these ATMs and buy 1 liter of perfectly clean water for 40 paisa (less than 1 cent USD). The money obtained from these machines is put into a fund for future maintenance.[6]

One relatively recent breakthrough in water treatment for Bangladesh was Dr. Abul Hussam’s arsenic water filter.[7] The Bangladeshi chemist developed a no electricity required, $35 gravity powered filter that removes arsenic from water and can produce 20 to 50 liters of purified water per hour. Additionally, these filters are guaranteed to have a 5 year life-span. As of now, they successfully provide clean water to over 1 million Bangladeshi people.

By Alejandro Miranda

 

References

  1. (1988) “The Climate of Bangladesh” The Geography Site. Retrieved from     http://www.geography-site.co.uk/pages/countries/climate/bangladesh_climate.html
  2. McBean, Edward. “Improved Sustainability of Water Supply Options in Areas with Arsenic-Impacted Groundwater.” Water 5, 1941-1951.
  3. Ferdausi, Shakil and Martin Bolkand. (2000). Rainwater Harvesting for Application in rural Bangladesh. 6th WEDC Conference. Retrieved from https://wedc-knowledge.lboro.ac.uk
  4. Khandaker, N., Chowdury, M., Bhattacharjee, S. (November 2015) “Social Acceptability of Rainwater Harvesting in Arsenic Affected Areas of Bangladesh: the Early Years” Research Gate.
  5. Damanti, G. (2012) “eliodomestico” Gabriele Damanti. Retrieved from http://www.gabrielediamanti.com/projects/eliodomestico—how-does-it-work/
  6. Alam, Tawhidul. (2017). Innovation to solve the water crisis among coastal communities in Bangladesh. Six Degrees News. Retrieved from http://www.sixdegreesnews.org
  7. An Invention with a Social Cause: Bangladeshi Scientist Develops Water Filter to Fight the Arsenic Menace. (n.d.). World Intellectual Property Organization. Retrieved from http://www.wipo.int