LESSENING OF TROUBLE.

Manawatu Standard, Volume LVIII, Issue 48, 25 January 1938, Page 8

LESSENING OF TROUBLE.

EFFECT OF COLDER WEATHER. “It is fully expected that with the cooler weather the trouble will soon be removed,” said the city engineer (Mr J. R. Hughes) to a “Standard” reporter, to-day, in commenting that there had been no complaints received latterly in regard to the city water supply, and that indications were that the taste and smell which had been noticeable in the past week or so had lessened appreciably. Concerning the samples of the water which had been forwarded to Wellington for analysis, a report from the Health Department was expected very shortly. Tho following statement wns culled by Mr Hughes from authoritative 'works on water supply and appears to touch on the trouble which has been experienced in the city“ There exists in many streams containing undecomposed organic matter, a continuous cycle of changes, resulting, ultimately in biological equilibrim, and, if no food material be forthcoming, in rapid decadence of organic life and mineralisation of the dead organic matter. In other words, growth of organisms, including bacteria, plays the most important role in self-puri-fication of streams. “In warm weather and during periods of low flow, putrefaction is likely to occur in river water, greatly changing its bacterial content. Although temperature itself has but slight influence upon the numbers of bacteria found, growths of antagonistic microscopic organisms (antagonistic to each other) are most frequent during the warmer months. With regard to odours in fiver waters, these are due to: (1) Organic matter other than living organisms; (2) decomposition of organic matter; (3) living organisms. “Under the third heading the natural odours caused by these organisms are produced by volatile oily compounds secreted by the organisms, the most notable ono being set free at the time the organism disintegrates. Microscopic organisms are believed to be harmless. Many, however, are objectionable from an aesthetic standpoint. Tho distinctive odours produced by certain organisms may he described by the three general terms, ‘aromatic,’ ‘grassy,’ and ‘fishy.’ “From th& particular smell and

taste in the city water during the past week the organism giving off a ‘fishy’ smell with a ‘cucumber taste’ is one of the protozoa called sjynura,’' said Mr Hughes. “This organism, together with at least 2.1 other varieties, is present more or less in all surface waters.” If the trouble did not right itself, continued Mr Hughes, he intended to ask the City Council to consider the question of either dosing the surface of the reservoir with a small quantity of copper sulphate, or, if further steps had to he taken, installing a chlorination plant.