Wykorzystanie reakcji Fentona do ograniczania procesu zagniwania i powstawania siarkowodoru w ściekach komunalnych

Hydrogen sulphide (H2S) gas is typically formed in sewage collection systems that are conducive to creation of septic conditions. Collection systems in warm climates that have a flat grade or do not have the flow-through velocities (minimum two feet per second) to prevent the stagnation of fluid, allow the septic conditions to occur. In general, septic conditions occur when bacteria use all of the available oxygen while decomposing organic matter in wastewater for energy. Sewers with low velocities encourage the growth of anaerobic bacteria in a slime layer coating the sewer. These bacteria reduce sulphur compounds such as sulphate (SO4), thereby producing sulphites (SO2). These compounds occur naturally in domestic sewage but also can be concentrated in industrial waste streams. One of the more frustrating problems of H2S development from domestic and industrial wastewaters in collection systems is odours. Odour problems often are resolved by chemical addition. Chlorine compounds such as bleach, sodium hypochlorite, calcium hypochlorite and ferric chloride are examples of chemicals that are effective in controlling H2S in wastewater collection systems. The aim of the study was to determine the possibility of the application of advanced oxidation process with Fenton’s reagent to the reduction of nuisance of H2S generated at putrefaction of municipal sewage. The experiment was performed at the laboratory scale. Carbon compounds transformations were observed, redox potential, H2S concentration in biogas, and rate of purification were determined. Investigations were conducted in five phases, on laboratory-scale experimental anaerobic reactor at the temperature of 20oC. The research phases varied with the type of chemical reagents supplied to the technological system. Depending on the experimental phase different substances were dosed to the analysed sewage. Ions of Fe2+, Fe3+, H2O2, and advanced oxidation systems Fe/H2O2 and Fe/H2O2 were used in the experiment. Experimental system revealed the significance of coagulation, oxidation and advanced oxidation on deodorization of tested wastewater. Technology of reduction of H2S nuisance, generated at putrefaction of municipal sewage, based on advanced oxidation, allowed to obtain effective final results in relation to all analysed parameters.The most effective reduction of odours nuisance was obtained with classic Fenton reaction. An increase of the efficiency correlated with the increase of oxidant H2O2 doses. The dosage of 0.1 g Fe2+/dm3 and 2 g H2O2 caused sewage putrefaction after 11 days. Sewage putrefaction in control sample was observed after 24 hours. Application of advanced oxidation process was more effective method than other methods tested in the experiment. The final results of sewage preparation were far better than results observed at hydrogen peroxide, Fe2+ or Fe3+ ions application alone. Presented method of odours reduction for the sake of the obtained results, easy operation, chemical reagents accessibility and economical reasons can become alternative technology of reduction of nuisance of H2S generated at putrefaction of municipal wastewater.