A MODERN WATER PURIFICATION PLANT*

A MODERN WATER PURIFICATION PLANT*

The necessity of purifying public water supplies before delivery to consumers, when from sources subject to possible contamination, is now so well recognized as to need no advocacy or argument. The question is mainly the means to best and most economically accomplish the desired result. Of these there are several deserving of mention and some in use occasionally, to be mentioned only to warn against their adoption. The writer will take these up in the order of their efficiency as he sees them, by observation and study.

First, those that may be considered of doubtful value. These are confined to practically two principles, with variations, first the building in stream or lakebeds of gathering arteries below the beds, and a dependence on the percolation to the arteries for purification, a violation of every principle of both nature and science in water purification. One of the earliest ideas of this character was the construction of large open wells at or near the edge of the water, when the strata below the surface was composed of coarse sand or gravel, and depending on the water percolating through the bottom from the river or lake, or the construction below the bed of the river or lake of a perforated conduit or so-called gallery, consisting of either tile pipe with open joint or a wooden box three or four feet below the bed of the river or lake and covered with sand and gravel. The result is practically the same in either case. Percolation will take place to a certain extent, and ground water will be received in certain proportion. The ground supply will usually be pure from a sanitary standpoint though generally much harder than a river supply. The surface water finding its way into the conduits is strained, and more or less purified depending upon the thickness and character of the sand layer it must penetrate, and the velocity it must travel in its flow. The most that can be said in favor of this plant is that it is only a question of time when this cover layer becomes so clogged that further provision is necessary and consideration of proper means of purification often results from the first failure, although it sometimes happens that a continuation of such conduits a second and even a third time, with the wasted expense of so doing. is incurred before this happens.