ABSTRACT
Groundwater pollution by nitrate is a known problem which occurs worldwide. In its nitrate ( NO 3 − ) https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315886220/a6fe546a-ea89-429a-a914-e4cc365b5025/content/eq49.tif"/> form, nitrogen can infiltrate groundwater and also contributes to surface-water quality problems. Safe methods of treating nitrates with minimal costs are required technological endeavours in poor rural households in Africa. The basic principle for in situ denitrification is that a carbon source is placed perpendicular to the groundwater flow such that flow occurs through the carbon source layer. A chemical reaction mediated by naturally available bacteria then accelerates the natural process of denitrification. This paper discusses laboratory experiments and up-scaled field application of the method. A 2.15 m diameter × 1.37 m height tank filled with sawdust was buried to 3 m depth at a site with high industrial-level nitrate concentrations of above 1 000 mg/l as NO 3 − https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315886220/a6fe546a-ea89-429a-a914-e4cc365b5025/content/eq50.tif"/> . Boreholes in the vicinity of the carbon source were monitored for a number of parameters bi-weekly. Results showed that 100% of nitrate was removed from the treatment zone within 2 d. It was successfully demonstrated that in situ denitrification using sawdust as a cheaply available and slowly degradable carbon source can effect total removal of high industrial-level nitrate concentrations.
