Rainfall and water is abundant in Vietnam and supplies are generally good quality, except in the downstream sections of major rivers which are affected by rapid urbanisation and industrialisation. Clean drinking water is available in most urban areas but there is scope to improve supplies in rural areas.
Potential projects include:
Purification, if the only water able to be accessed by people is turbid or contaminated with pollutants, bacteria and viruses. Small scale treatment systems can use disinfection, filtration or distillation technology depending on the type of contamination and the volume of water needed. Solar water treatment plants are an excellent way to treat relatively small volumes of water to make it safe for drinking. Low maintenance, solar powered filtration units can filter enough water for a small village and remove up to 99% of contaminants. Solar distillation plants are also available and are suitable for very remote areas. Although they are relatively low yielding, the clean water can be stored for later use.
Rainwater collection. Rain rarely falls when it is most needed. At several locations in Southeast Asia, UN Habitat and JICA have implemented underground rainwater harvesting utilising the Tametotto technology which is easily constructed and filters water using crushed stones and sand. If the area from which the rainwater is collected is kept free of contaminants, the water can be suitable for drinking or crop watering without further treatment.
(Vietnam.net; UN Habitat Knowledge Management Centre for Asia and the Pacific)
Source treatment, may be needed where water bodies receive runoff from urban or agricultural areas. Elevated levels of nutrients and contaminants in the water body can promote the growth of algae and cyanobacteria, making it unsuitable for use without treatment. Methods have been developed that are very effective at reducing the level of nutrients and contaminants in lakes and reservoirs. Water with excess phosphate can be treated to lock it up in sediment in a form that is not bio-available. UN Habitat supported a project in Mongolia using another method to remove nutrients that mimics natural processes by using aerobic bacteria and porous artificial stones. Floating reed beds in lagoons and lakes can also be used to extract pollutants from the water. A biofilm of algae and bacteria that forms on the reed roots transfers nutrients, metals and minerals from the water to the plants. Excessive plant growth can be directed to an anaerobic biodigester for energy generation.
(UN Habitat Knowledge Management Centre for Asia and the Pacific; CSIRO Managing Algal Blooms Case Study, 2017)
Desalination of brackish water or seawater. The most common and robust technologies are Multi-stage Flash distillation, Multi-Effect Distillation and Reverse Osmosis, which uses membranes rather than distillation. Multi-Effect distillation is particularly well-suited to being powered Concentrated Solar Power technology. Portable Reverse Osmosis desalination can also be used in disaster relief and recovery operations. Systems are available that are the size of a shipping container and can be transported by truck.
(Fichtner & Co., MENA Regional Water Outlook, 2011)
Possible sources of funding include:
- GEF Small Grants Programme
- Global Resilience Partnership Innovation Challenge
- Thanh Hoa Microfinance Institution
- Urban Climate Change Resilience Trust Fund