Water Pollution

Abstract

THE forty-sixth Bedson Lecture was delivered by Sir Robert Robertson on May 8 in King's College, Newcastle-upon-Tyne. Sir Robert confined himself to two recent investigations connected with the subject of water pollution. The first of these concerns the pollution problems of the River Tees. A thorough biological and chemical survey of this river has been carried out. This has shown that, whilst the river is unpolluted until its union with the Skerne, the entry of sewage from Darlington in this tributary causes appreciable pollution of the lower reaches. In the estuary, the condition of the river is rendered much worse by industrial refuse containing cyanide. As a result of the investigation, the sewage disposal system of Darlington has been improved, and several undertakings upon Teeside have modified their plants, so that cyanide does not enter the river. With regard to the second topic-the disposal of milk factory waste—Sir Robert said that diluted milk, on account of its easily oxidizable nature, is a potent fish poison. As a result of its consistency, the refuse is difficult to treat by ordinary filtration methods, and success was first obtained by a modified activated sludge process. However, better results have been obtained by use of two filters in series. The refuse is passed first to one filter, A, and thence to the second, B. When A shows signs of clogging, usually in about three weeks, the direction of flow is reversed, that is, the liquid passes first to B and then to A. Filter A then recovers, and in due course the direction of flow is again reversed, and so on.