Evaluation of hydrogen sulphide concentration and control in a sewer system

Department of Civil and Environmental Engineering, The University of Texas at San Antonio, San Antonio, TX, USA.
Environmental Technology (Impact Factor: 1.56). 06/2012; 33(10-12):1207-15. DOI: 10.1080/09593330.2011.618932
Source: PubMed


This study focused on monitoring hydrogen sulphide (dissolved and atmospheric) generation and wastewater volumetric flow in a 21.4 km sewer line of the City of San Antonio, Texas. The results were used to evaluate daily and seasonal trends of atmospheric and dissolved sulphide, and to better apply sulphide control using ferrous sulphate to prevent odour and sewer pipe deterioration. As part of this study, the evaluation of a cost-effective dosing strategy with ferrous sulphate was performed to better control the sulphide contents in wastewater. Dosing studies were performed in the laboratory to find the required ratio of ferrous sulphate for acceptable sulphide removal. The results indicate a 1.25 mole ratio requirement, to reduce sulphide by 93%. Over a typical daily diurnal cycle, necessary dosing rates to maintain sulphide concentrations below 2mg varied between 0 and 36,777 mold(-1) with a daily average rate of 14,438 mol d(-1). If, instead of dosing at the maximum required rate, dosing was matched over the diurnal cycle, chemical savings would amount to 22,339 mold(-1) while achieving sulphide control. The approximate cost of the ferrous sulphate solution dosed is $0.14 per mol and this amount of chemical savings translates into roughly $2923 per day. Actual dosing cost for the hypothetical average day will be $1889 per day. These cost savings can easily recoup the required instrumentation costs to achieve this diurnal dose matching.

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    • "[2] It is known that the degradation of sewer systems can be primarily attributed to corrosion induced by biogenic sulphuric acid attack, which causes severe structural deterioration and ultimate structural collapse.[3] [4] [5] [6] [7] There are many cases in which sewer pipes designed to last 50–100 years have failed due to hydrogen sulphide (H 2 S) corrosion after only 10–20 years of service life. Such problems are rarely brought to the attention of the public until a catastrophic failure occurs. "
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    ABSTRACT: Millions of dollars are being spent worldwide on the repair and maintenance of sewer networks and wastewater treatment plants. The production and emission of hydrogen sulphide has been identified as a major cause of corrosion and odour problems in sewer networks. Accurate prediction of sulphide build-up in a sewer system helps engineers and asset managers to appropriately formulate strategies for optimal sewer management and reliability analysis. This paper presents a novel methodology to model and predict the sulphide build-up for steady state condition in filled sewer pipes. The proposed model is developed using a novel data-driven technique called evolutionary polynomial regression (EPR) and it involves the most effective parameters in the sulphide build-up problem. EPR is a hybrid technique, combining genetic algorithm and least square. It is shown that the proposed model can provide a better prediction for the sulphide build-up as compared with conventional models.
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