ANALYSIS OF FLOWRATE, SULFATE, AND TOTAL SULFUR PATTERN IN WASTEWATER INLET TANKS FOR HS MANAGEMENT

Abstract

Hydrogen sulfide (H2S) is a major source of concrete corrosion in a wastewater treatment plant (WWTP) that causes significant financial losses. Variations in the flow rate and composition of incoming wastewater has significant impact on H2S generation. During anaerobic conditions, sulfur present in excreta and sulfate from rainfall become the source of electron acceptors for the conversion of sulfate to sulfide in wastewater. Sulfide, in turn, is converted to H2S and later to sulfuric acid which leads to concrete corrosion. Flowrate directly relates to the amount of wastewater entering the plant. Hence understanding flow rate pattern will help to analyze H2S generation. Flow rate and H2S concentrations were recorded every two-hours for four days in a wastewater treatment plant. Wastewater samples of 50ml were collected at each sampling event coinciding the recording intervals. Samples were analyzed for sulphate and sulfide concentrations using HACH© kits. Total sulfur was calculated from the collected data. The correlations were analyzed using Minitab©. It was found out that average flow rate was negatively related to average H2S concentration. H2S concentration is higher during night when the flow rate is lower, which is a result of greater resident time. Flowrate changes in a cyclic manner throughout the day. During night, sulfate and total sulfur concentrations are higher, H2S concentration is maximum during this time. It is contrariwise during the day. Sulfate and total sulfide follow a pattern that is similar to that of flowrate. Analyzing these parameters is a critical step in successfully modelling H2S generation.