Waste water can be a valuable resource at times of drought, and provides a suitable water source for uses that do not require drinking quality water. As rainfall in Vietnam becomes more variable due to climate change, it makes sense to use it only for households and business and, where possible, use recycled water for industrial use and gardens. Preserving high quality water supplies for drinking, cooking and manufacturing processes improves the resilience of a community to drought and climate variability.
Potential projects include:
Stormwater treatment, to prevent contaminated runoff from roads and pavements affecting local wildlife and aquatic environments when carried to creeks, rivers and lakes. Water can be treated to a high quality and then discharged to the environment, or used for cleaning or irrigation where potable water is not required. An effective processes to treat storm water is to simply slow the rate of flow, which allows suspended solids and heavy metals to settle to the bottom. This can be done through the use of an artificial swale, retention basin or constructed wetland depending on the volume of storm water to be treated. These are low cost options to construct and maintain that rely only on gravity and need no energy to operate. When combined with a simple grate at the point of inflow to sieve litter, retention basins and wetlands are very effective at cleaning storm water while also providing wildlife habitat. The addition of wetland plants, particularly Phragmites karka and/or Typha latifolia, can increase the removal of suspended solids, nitrate, phosphate and potassium.
(Sustainable Treatment and Reuse of Municipal Wastewater by M. Libhaber and A.O. Jaramillo, 2012)
Industrial waste water treatment, to remove or reduce levels of heavy metals, chemicals, oil and grease, and various forms of nitrogen or phosphorus. If treated properly, much industrial wastewater can be suitable for reuse or can be released to water bodies without negatively affecting them. Treatment with non-oxidised iron powder is effective in removing substances such as trichloroethane and arsenic from groundwater or industrial wastewater. When industrial wastewater is passed through iron filings, non-biodegradable industrial chemicals react on the surface of the iron and become degraded. The iron filings are oxidised during the process and need to be replenished regularly. The remaining wastewater, with biodegradable contaminants, can then be treated as municipal wastewater.
This system was developed in China and tested at the Taopu Industrial Area in Shanghai, which is now the site of the Shanghai Taopu Smart City Project.
Possible sources of funding include:
- GEF Small Grants Programme
- Thanh Hoa Microfinance Institution
- Urban Climate Change Resilience Trust Fund