Removal of Hydrogen Sulfide in Septic Tanks for Treating Black Water via an Immobilized Media of Sulfur-Oxidizing Bacteria.

Jeong-Hee Kang,Sung Soo Yoo,Jeong-Il Cho,Bong-Jae Lee,Hyon Wook Ji,Hyeong-Gyu Namgung

doi:10.3390/ijerph17030684

Abstract

In South Korea, the installation of septic tanks for treating black water (STBW) is regulated even in sewage treatment areas to prevent the black water deposition in combined sewers. STBWs in which black water is anaerobically decomposed generate high concentrations of hydrogen sulfide (H2S). In this study, an immobilized media of sulfur-oxidizing bacteria (SOB) was used to remove the H2S. SOB media was prepared by using activated sludge collected from a wastewater treatment plant. Prior to field application, an appropriate cultivation period and aeration rate for SOB activation were estimated through a laboratory-scale test. The SOB was activated after a 23-day cultivation period and an aeration rate of 0.25 L-water/L-air/min. Moreover, the maximum H2S removal efficiency was observed at a cultivation period of 43 days and an aeration rate of 0.38 L-water/L-air/min. Then, the SOB media was installed on STBWs of various capacities. The H2S removal efficiency was compared between with and without SOB media. The maximum H2S elimination capacity with SOB media was 12.3 g/m3/h, which was approximately three times higher than without SOB media. Furthermore, the energy efficiency and oxidation rate were also three times higher with SOB, demonstrating the applicability of SOB for H2S removal in STBW.

Highlights

Septic tanks are on-site private sewage treatment facilities often employed in rural areas where it is difficult to send domestic wastewater to wastewater treatment plants (WWTP)
Black water remains in the septic tank for treating black water (STBW) for a long residence time of 2–3 days, during which various contaminants are decomposed by anaerobic bacteria [3]
Even though oxygen was supplied through a blower, it would have been unreasonable to expect an immediate increase in sulfur-oxidizing bacteria (SOB) activity

Summary

Introduction

Septic tanks are on-site private sewage treatment facilities often employed in rural areas where it is difficult to send domestic wastewater to wastewater treatment plants (WWTP). Due to the poor conditions of the sewage system in South Korea, installing a septic tank for treating black water (STBW) is regulated in areas with combined sewers to avoid deposition of wastewater solids, odors, and hygienic problems caused by the direct discharge of black water into the sewage system. Black water remains in the STBWs for a long residence time of 2–3 days, during which various contaminants are decomposed by anaerobic bacteria [3]. In this process, the sulfur and nitrogen compounds in the water are decomposed together with organic matter, and various

Methods

Results

Conclusion