CO129-618-1 Institute of Medical Research- proposed construction 21-4-1947 - 5-12-1947 — Page 34

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Appendix B2

The

complete purification at the plant, would be freed from bacterial contamination by the time it arrived at the extraction wells. article states that this project is only one third as expensive as bringing water from the Colorado River, and that in spite of the natural prejudice against using sewage for domestio consump- tion, the project should be investigated at the policy rather than at the technical level. The geological conditions in Hong Kong do not lend themselves to any appreciable extent to the use of underground water storage, so that the use of the soil as a filter is unlikely to be found feasible. The alternative is to use overground filters, which can be made to serve the same purpose.

The daily per capita consumption of water is about 30 gallons, and all of this finds its way at present into the harbour. If it were found possible to reclaim even half of this, it would go a long way to solve the ever-increasing population. It is not stated in the article in question what is to be done with the solids from the plant, but I presume that they would be available for fertilizer as in other cases.

Power Gas from Sewage.

An artiole in "Civil Engineering" for October, 1946, describes the wartime German sewage plants, which were used largely for the value of their bye-products, rather than just to dispose of the sewage. Of particular interest is the development of the use of digester gas produced from the raw sludge. This can be used at the plant for sludge heating, or for power generation, but in Germany was compressed and used as a substitute for petrol for driving cars and trucks. The purified gas contains 90-94% methane, and about 135 cu. ft. of gas at atmospheric pressure is equivalent to one U. S. gallon of petrol. The cost is stated to have been the equivalent of about U.S. $0.30 per gallon.

(Signed) S.E. Faber.

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