The effect of air supply on nitrogen removal using a biological filter proposed for ventilated pit latrines

Abstract

About 18.4 million people in South Africa do not have access to proper sanitation systems, of which 6.7 million do not have any sanitation service at all (DWAF, 2009). The system recom mended by government (DWAF, 1996) as a basic level of service for a household is the ventilated improved pit latrine (VIP). Ventilated improved pit systems which are poorly designed and operated, or where the soil characteristics are not favourable, can create a real danger of groundwater pollution. Most of the pollutants are normally bound in the soil matrix by a variety of chemical, physical and biological processes, preventing these from reaching the groundwater. Nitrate, however, is not bound and moves freely through the soil matrix to the groundwater (Fourie and Van Ryneveld, 1995). Various researchers have confirmed that elevated nitrate concentrations occur in ground water in the vicinity of pit latrines (Lewis et al., 1980). Nitrate is a health risk, especially for babies younger than 6 months, as it causes methaemoglobinaemia (also known as ‘blue babies’).

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