Evolution of Macronutrients Content during Thermal Drying of Faecal Sludge

Abstract

Research has shown that an increase in urbanization is an increase in urban population, which relate to increase in waste production. Sub Saharan African countries are experiencing a lot of urbanization and most of the population is not connected to waste water treatment systems but instead using onsite sanitation systems. Statistics shows that 80% of the faecal sludge produced as waste is left untreated and not converted into any productive use. This study focused on the evolution of faecal sludge macronutrients due to thermal drying. Faecal sludge was thermally dried using an oven at drying temperatures of 200°C, 100°C and 50°C to obtain moisture content of 50%, 25% and 0% for each drying temperature. Faecal sludge was tested for nutrients contents of nitrogen, ammonium, nitrite, nitrate, phosphate, orthophosphate and potassium at each condition. Thermal drying and loss of moisture content proved to have an effect on nutrient content of faecal sludge. It shows that with varying of drying temperature and loss of moisture content nitrogen mineralises, and changes form. Nitrogen fractions ammonium, nitrite and nitrate proved to be more volatile to change in drying temperatures and loss of moisture content. Phosphate and orthophosphate were also affected by varying of drying temperatures and loss of moisture as concentration kept changing at different conditions due speciation of phosphorus. Potassium was not significantly affected by change in drying temperatures and loss of moisture content because it is strongly bond to the dry matter.