By Sonali Senaratna Sellamuttu
Senior Researcher and Head of Office, International Water Management Institute (IWMI) Southeast Asia, Vientiane, Laos
UN-Water has designated 2017 as the Year of Wastewater. On this World Water Day, it is important to consider the dangers of polluted waterways, and think about safe wastewater management for a healthy urban landscape as Vientiane develops quickly.
The canal system in Vientiane is an unexplored opportunity for making the city cleaner. Canals can provide natural filtration for street runoff, seepage from inundated septic tanks, and water from sinks, showers, and laundry machines. However, many canals have been cemented over. According to a study by the National University of Laos, this reduces bioactivity and natural filtration abilities, while also creating conditions for waterborne disease to gestate.
A study done by the International Water Management Institute (IWMI) identified floating wetlands as one possible solution to remediate urban channels, a method that has been successfully used in some countries. Planting or protecting existing wetlands on the banks of the canals in Vientiane could help to remove pollutants such as suspended solids, nitrogen, phosphorus, organic matter, and metals—pollutants that are dangerous to humans and deadly to fish.
Another great natural filtration system is offered by wetlands such as the That Luang marsh. Wetlands help clean water coming out of cities, and provide other benefits, like flood mitigation, climate regulation, and habitats for wildlife on which many livelihoods depend. In addition, there are other strategies for wastewater management that can be considered.
One is the improvement of smaller natural wetlands strategically located around the city to capture pollutants, a method that was studied by IWMI downstream of Hyderabad in India. IWMI also tested the use of nutrient-rich wastewater in India and Africa, especially for fodder production.
Another strategy is better fecal sludge management. Septic tanks require periodic emptying, at which point fecal sludge needs to be safely transferred to central disposal points. There is a tremendous opportunity to improve the management of fecal sludge and recover cost for sanitation by turning the waste into compost or nutrient-rich fertilizer that can then be sold to farmers. IWMI has analyzed this business option and has worked on developing fecal sludge fertilizer pellets in Ghana.
Ultimately, the key to safe wastewater treatment in Vientiane likely lies not in one solution, but instead in multiple forward-thinking and diversified solutions that take into consideration the local context and enable ecosystems to be resilient and livelihoods to be protected.