Employing Fered-Fenton advanced oxidation process for waste-activated sludge stabilization and reuse

Abstract

a b s t r a c tIn this study, the Fered-Fenton advanced oxidation process is utilized for sludge stabilization and reuse. According to US EPA, reductions in volatile solids (VS) and fecal coliforms are considered as the criterion of sludge stabilization. VS removal efficiency of 78±5%, 60±5% and 55±5% can be achieved at different pH levels of 3.0, 5.0, and 7.0, under operational conditions as follows:, retention time = 240 (min), and current density = 600-800 (mA). Moreover, Fecal coliforms decrease significantly (more than 99.9%) and according to pathogen reduction requirements (US EPA), the stabilized sludge samples are classified as class A. This sludge can be used for agricultural and forestall areas, lawns and home gardens. The effect of the Fered-Fenton process on nutrients in sludge was investigated. The average values of carbon/nitrogen (C/N) ratio, nitrogen, phosphorus, ammonium, nitrate, potassium, calcium and sodium reductions are 21.1%, 55%, 41.7%, 61.4%, 66.4%, 7.3%, 30.6% and 3.8%, respectively. It is assessed that the stabilized sludge at pH 7.0 has higher fertilizing quality than the same at pH 3.0 and pH 5.0. The results of the Fered-Fenton process indicate that this system, not only has a good ability to stabilize the sludge but also the output sludge could be used as a fertilizer in agriculture.