The use of relatively complex conventional drinking water treatment processes used in the developed world (for example clarification and rapid filtration) is impractical in remoter parts of the developing world due to a lack of skilled operatives, lack of maintenance parts for electro-mechanical & control systems, unreliable power supply and poor access to treatment chemicals.
Development strategies in these areas have aimed to provide improved water supplies from “safe” water sources such as groundwater accessed via. boreholes and hand pumps, capped springs, infiltration and impounded waters mainly without treatment. Whilst many gains have been made; aquifers can become polluted and shallow wells easily contaminated. In other cases, a population may continue to rely on an untreated contaminated surface water source, rather than a new borehole, simply because it tastes better, without understanding the hidden dangers. An iron laden source which is acceptable in other respects may be neglected because the water appears dirty - a treatment capability could make this acceptable. There may be merit in assessing where the existing water supplies come from before making changes.
I have attempted to address some of these issues by developing an appropriate type of water treatment for use in areas with little or no technical support and for use in disaster response. The treatment comprises a low maintenance self-washing clarifier/filtration arrangement which incorporates upstream spray aeration (when required) and downstream disinfection using a chlorine (soluble tablet feeder) together contact time. The process targets removal of micro-biological pathogens, turbidity, suspended solids, particulate iron etc. Other processes may be required to remove chemicals such as nitrates. A degree of arsenic removal may be possible using an advanced filter media together with vigorous upstream aeration.
The target aims of the system are as follows:
- Community water treatment for development & disaster response
- Self-backwashing system - wash cycle cleans both clarifier and filter without intervention
- No moving parts, actuated valves, power supply or control system
- Low capital cost and low maintenance
- No chemicals other than chlorine tablets
- Assembled from locally available parts - plastic pipes, tanks, plumbing.
- Workshop assembly without a manufacturing process.
- Rapidly deployable and to remote areas with no road access- Replicable and scalable.
|New Implemented Countries||India, Uganda|
|Recruit||Local technical volunteers required - preferably water/mechanical engineers/plumbers but if not good practical skills. Other developed country volunteers who wish to help take this forward.|
|New Feature||Addition of tube clarifier upstream of filter to improve performance with turbid water.|