chlorine. Some are thermal, such as boiling and solar heating. Others are mechanical, such as ceramic filtration. And some utilize radiation, such as ultraviolet (UV) treatment. Criteria for selection of the technology for the hypothetical case study included low cost, ease of assembly or manufacture, safety and simplicity in home operation, maintainability and sustainability, and worldwide experience with successful commercial exploitation. Some of the thermal methods are nearly free (the SODIS system requires only a blackened soft drink bottle and four hours on a sunny roof), although they may require extensive training so that users acquire the discipline necessary for health protection. Because there is no clearly preferred technology for efficiency and commercial opportunity, two distinct business models were studied. It is hoped, however, that a potential investor or entrepreneur will realize that the business models can be applied to a variety of technologies.

The two technological models described here are ultraviolet disinfection, as utilized in the business model of WaterHealth International (WHI) of California for sales in developing countries, and ceramic filtration, as promoted by Potters for Peace of Managua, Nicaragua. The business models are quite different.

The patented UV Waterworks (UVW) ultraviolet disinfection unit is at the core of the large systems sold by WaterHealth International to franchisees who use them to produce and sell potable water in containers to consumers at prices below those of bottled spring water. Other WHI products, such as community-scale water systems, are sold to governments or communities directly, and provide enough safe water to meet nearly all daily domestic needs, including hand and food washing and bathing. The operating costs for a system that can serve at least 3,000 people are less than $4 per person per year. Treated water is sold to recover the investment and maintenance costs of these systems at prices that are within the reach of the populations being served.

The Filtron ceramic filter technology is promoted by Potters for Peace and marketed by individual filter producers directly to households for operation by the end user. It provides safe drinking water for a family of six at a cost of about $7 for two years.

Ultraviolet Filtration

Figure B-1 is a schematic diagram of the UVW unit, which was invented by Ashok Gadgil of Lawrence Berkeley National Laboratory in California and licensed to WHI.

In the UVW system, the UV source is suspended above the water being treated rather than submerged in the water. Water passing through the system is irradiated at high intensity amplified by reflection. This

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