Determination of electro-dewatering performance of the yeast industry's sludges

To ultimately eliminate the sewage sludge, which is produced as a result of treatment processes of wastewater in great volumes, the water content of the sludge should be decreased significantly. In order to decrease the water content that is present inside the sludge in different forms (free water, interstitial water, capillary water, chemically bonded water), sludge dewatering techniques have been developed. Because, with the method known as mechanical dewatering, which involves pressing the sludge, only the free water is removed from the sludge. Studies on the methods that would lead to decreased water content in sludge with a lower cost have intensified. One of the methods developed in recent years is the electro-dewatering method. This method is based on the exposition of the sludge that is to be dewatered to an electric field. In this thesis, the availability of model reactor was evaluated to improve the dewatering capacity of the yeast industry's sludges. The dewatering capacity was determined with evaluation of capillary suction time (CST), viscosity, total solids (TS) and Exopolymeric substances (EPS) parameters. Also, soluble chemical oxygen demand (SCOD) was analyzed in effluent waters of the model reactor. Horizontal electric field system was used which is formed with vertical electrodes for to do electro-dewatering (EDW). The assessment of the experimental analysis results using Box-Behnken Design was carried out using MINITAB 17.1 computer program. The effects of tree independent variables (temperature, pH and process time) on dependent variables (CST, viscosity, TS and SCOD) were determined by making use of the statistical design analysis. Additionally, platinum electrode, copper electrode, stainless steel electrode and graphite electrodes were used to see the effect of different electrode types. As a result, graphite electrodes has been observed to be effective in all types of electrodes by considering the effect of dewatering of the electric field generated with model reactor. The proper distance between the electrodes was noted to 4.3 cm for the dewatering of sludge sample. Also the electricity field has affected the EPS and metal concentrations was detected. It was generally observed that keeping process time long and acidic pH had positive effect.