I remember the effort you put into your clever sand-filter water purification video. We're visiting Meaghan's Uncle who supports a lot of charity work in Guatamela, and getting good local leadership, reliable water, medical supplies, and micro-loans for business are his priorities.
Anyway, I immediately thought of you as I read this proposal for a solar-powered water purification system for remote, resource-poor communities.
Rainwater has a short shelf-life, unless it's filtered and treated, and recirculated to continuously keep it potable. In resource-poor locations, a solar-powered recirculation and filtration system for collected rainwater could provide water sustainably.
Before reading this, I did not realize the beneficial effect of debris in the holding tank, and organisms growing in the sand filter.
"Rainwater is regarded as a clean source of water due to its lack of contaminants and hard metals."
The rooves and surfaces that collect rainwater can't be guaranteed to be clean - "Pollutants on these catchments areas include leaves, dust particles and droppings of various animals. Due to these pollutants, it is necessary to filter and purify the water"
Holding tank: "Debris such as pollen and oil-based matter form a floating layer on the water surface. This builds up over time and eventually insulates the water from the air. This prevents the transfer of oxygen into the water, reducing the amount of aerobic microbial action that takes place."
"a slow sand filter in such a system design is a viable solution to provide potable water"
"After the rain is collected on the roof it flows through the following process steps: "Good primary rainwater filtration
Calming inlets
Floating suctions
Surface skimming overflows in the tanks
Post Filtration"
The WISY filter "filters away any particles larger than 28 microns"
"A slow sand filter was selected because it does not require a pump to force the water through the filter - it is run by gravitational force... Slow sand filtration has been an effective water treatment process for preventing the spread of gastrointestinal diseases for over 150 years...process is based on the ability of organisms to remove pathogens.
The top layers of the sand become biologically active by the establishment of a microbial community on the top layer of the sand...The majority of the community are predatory bacteria that feed on water-borne microbes passing through the filter..."
"After the fine filtration stage, the water will pass through an active carbon filter. From here the remaining bacteria in the water will be removed by passing the water over an ultra-violet filter."
Advantages:
"Very effective removal of bacteria, viruses, protozoa, turbidity and heavy metals in contaminated freshwater... simplicity of design... no (electrical) pumps required... Local materials can be used for construction... No necessity for the application of chemicals... Long lifespan (estimated >10 years)
Disadvantages:
"constant flow of low-turbidity fresh water required...Sandbed must be kept wet at all times... Cold temperatures lower the efficiency... regular maintenance essential... requirement of a large land area, large quantities of filter media and manual labour for cleaning..."
2.5 Solar Power "For the system to be fully automated and provide potable water for the household... an element of pumping will be required."
No comments:
Post a Comment