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Title: Investigation into denitrification underground
Author: National Rivers Authority Anglian Region
Document Type: Monograph
This is the interim thirty three month report on a study conducted for Anglian Water into denitrification underground. Further experimentation with methanol has shown that denitrification can develop under both methanol limited and nitrate limited conditions. Denitrification was sustained even when an equivalent 24 hour dose of methanol was given over 4 hours per day. However, the process was not self sustaining once the supply of methanol was discontinued. The major disadvantage with the method is the development of biomass within the sand and gravel matrix which eventually blocked the upper section of the columns in both experiments. Furthermore, a distinct cloudiness and odour developed in the water leaving the nitrate limited experiment. After injection of methanol ceased, a 50 per cent decline in the heads measured along both columns was noticed. Continued experimentation with straw, aimed at optimising the denitrifying capacity of the bio reactor by increasing the amount of straw used, did not lead to a significant improvement in the technique. In the absence of an increased volume of sand and limestone support material, the result of this experiment was to strongly discolour the reactor effluent. An aeration stage between the straw reactor and filter column initially increased the oxygen content of the final water, but did not lead to an improvement in the overall colour of the water. A small scale experiment into blocking continues at present. A short column filled with a uniform grade sand has been subjected to denitrification and is now being prepared for microscopic inspection. The major difficulty with this work is the preparation of thin sections from saturated, unconsolidated material.
Publisher: National Rivers Authority
Publication Date: 1988
Publication Place: Peterborough
Subject Keywords: DenitrificationLaboratory experimentationChemicalsDataWater qualityNitrates
Extent: 20; + appendices
Total file downloads: 49

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