What was the ingenious technical refinement Gadgil used in the UV Waterworks design?

Answer

Suspending the UV lamp *above* the water surface using an aluminum reflector.

Gadgil solved the problem of lamp fouling by designing the system so the UV lamp was situated above the flowing water, utilizing an aluminum reflector to direct the light back down onto the stream.

What was the ingenious technical refinement Gadgil used in the UV Waterworks design?
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