Drying dairy manure using a passive solar still: A case study

Abstract

The pyrolysis of wet biomass such as faecal sludge and cow manure requires an extra drying step to reduce the moisture content before pyrolysis can occur. Open-air solar drying is a technique routinely used to dry faecal sludge and dairy manure. In this method water held within the biomass is lost to the atmosphere. A simple solar still was constructed in order to both dry cow manure and to capture water as part of the drying process. Measurements included solar radiation, cover temperature and internal solar still temperature and chemical analysis of the distillate. The maximum internal temperature of the solar still was recorded at 52.9 °C and the minimum recorded at 10.1 °C. The key objectives were to investigate the use of solar still technology in drying cow manure and determine the chemical properties of the distillate with a view to its re-use as irrigation water. The moisture content of the cow manure was reduced by 13%, however, the pathogen content of the resultant distillate contained 8,010 Escherichia Coli per 100 ml.