[Report 1948] / Medical Officer of Health, Cheltenham Borough.

  • Cheltenham (England). Borough Council
Date:
1948
Catalogue details

Licence: Attribution 4.0 International (CC BY 4.0)

Credit: [Report 1948] / Medical Officer of Health, Cheltenham Borough. Source: Wellcome Collection.

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    1 he firm concerned, on notification of this unsatisfactory effluent, replied that they had no discharge of any description from any equipment connected to the surface water drains. The only explanation possible was that some unauthorised persons were tipping oil, suds, etc., down the surface water drains, and that notices had been posted throughout the works to the effect that anyone undertaking such a practice would be instantly dismissed. Wyman’s Brook A report was received of the death of a large quantity of fish in Pittville Lake. On examination of the water, arsenical compounds were found, and in the opinion of the Public Analyst, these arsenical com- pounds had been responsible for the death of the fish. This led to a thorough investigation of all possible sources of pollu- tion. Wyman’s Brook was surveyed from its source to its outlet in the lake, all factories bordering the brook being the subject of special atten- tion. As a result of this, 2 samples of effluent from a factory were taken, and one of stream water, with the following results :— (i) Sample of Effluent from Chrome Plant. Remarks. Total Chromium (as Cr) 13.1 parts per million Oxidised Chromium (as Cr) 8.9 parts per million Copper compounds (as Cu) 12.0 parts per million Other metals ... absent. In order to treat an effluent of this type satisfactorily, it would require the addition of Copperas (ferrous sulphate), and then a subsequent treatment with slaked lime (calcium hydroxide). The quantities required wrould depend on the amount of chromium present in the effluent, but a slight excess would not be injurious. Taking an effluent containing 20 parts per million of chromium, in order to reduce it to chromous compounds it would require 3.6 pounds of Copperas per 1,000 gallons of effluent. The liquid resulting from this treatment would then require to be treated with slaked lime in slight excess. The amount of lime required would depend on the character of the other ingredients in the water, but, normally speaking, one pound of slaked lime per 1,000 gallons would suffice. (ii) Sample of Effluent immediately prior to discharge into stream. Remarks. Chromium compounds Copper compounds Arsenical compounds Nickel Lead Zinc (as Cr) 4 parts per million (as Cu) 0.12 parts per million ... absent ... absent ... absent ... absent The analysis shows that this sample contains small quantities of copper and chromium compounds. In my opinion the quantity present is not sufficient to be injurious to fish, especially when there is dilution.
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