Simultaneous removal of odourous and organic compounds in septic tanks using an electrolytic oxidation system

Odour, which is emitted from septic tanks treating excrement and manure, has become public concerns. Reduced sulphur compounds, such as hydrogen sulphide, are the main sources of the malodour, and readily degradable organics play an important role in the production of the reduced sulphur compounds u...

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Bibliographic Details
Published in:Desalination and water treatment 2014, Vol.52 (4-6), p.929-936
Main Authors: Kim, Jin-Sung, Nam, Yun-Ki, Yu, JeongWhon, Song, JiHyeon
Format: Article
Language:English
Subjects:
Electrolytic oxidation
Excrement
Hydrogen sulphide
Odour
Septic tank
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Summary:Odour, which is emitted from septic tanks treating excrement and manure, has become public concerns. Reduced sulphur compounds, such as hydrogen sulphide, are the main sources of the malodour, and readily degradable organics play an important role in the production of the reduced sulphur compounds under anaerobic conditions. In this study, an electrolytic batch reactor was applied to reduce both organics and odourous sulphur compounds in excrement slurry. In the reactor, direct currents at fixed voltages of 10, 20 and 30 V were applied to a Ti/IrO2 anode and a stainless steel cathode, both submerged into the slurry. The predominant chemical reaction at the surface of the anode was the production of HOCl, resulting in the simultaneous oxidation of the odourous and organic compounds and the increase in oxidation/reduction potential. At the applied voltages greater than 20 V, the concentration of H2S in the headspace of the reactor exponentially dropped within initial 30 min period. In addition, the chemical oxygen demand (COD) in the slurry was gradually declined at all the voltage conditions, and a rapid removal of the COD was observed only when the fixed voltage of 30 V and corresponding current density of 150 A/m2 was applied. Energy consumptions expressed as kWh/kg-H2S and kWh/kg-COD varied greatly, and they need to be experimentally evaluated depending on wastewater characteristics. Consequently, the electrolytic oxidation can be applied to effectively control odours emitted from the excrement slurry, and an appropriate current density and energy consumption as a threshold value should be selected to optimize the system for the simultaneous removals of organics and reduced sulphur compounds.
ISSN:1944-3986
1944-3986
DOI:10.1080/19443994.2013.827317