Effect of influent COD/SO42− ratios on biodegradation behaviors of starch wastewater in an upflow anaerobic sludge blanket (UASB) reactor

Published Date
August 2016, Vol.214:175–183, doi:10.1016/j.biortech.2016.04.100

Title 
Effect of influent COD/SO₄²⁻ ratios on biodegradation behaviors of starch wastewater in an upflow anaerobic sludge blanket (UASB) reactor

• Author 

• Xueqin Lu ^a
• Guangyin Zhen ^b
• Jialing Ni ^a
• Toshimasa Hojo ^a
• Kengo Kubota ^a
• Yu-You Li ^a,c,,

• aDepartment of Civil and Environmental Engineering, Graduate School of Engineering, Tohoku University, Sendai, Miyagi 980-8579, Japan
• bNational Institute for Environmental Studies, Onogawa 16-2, Tsukuba, Ibaraki 305-0053, Japan
• cGraduate School of Environmental Studies, Tohoku University, Sendai, Miyagi 980-8579, Japan

Received 9 March 2016. Revised 10 April 2016. Accepted 20 April 2016. Available online 22 April 2016.

Highlights

• •
  Sulfidogenesis was essential to the UASB operation and process stability.
• •
  Reactor showed the high stability at COD/SO₄²⁻ ratios ⩾2 with efficient removal of COD and sulfate.
• •
  Sulfidogenesis promoted propionate degradation and acetoclastic methanogenesis.
• •
  Excessive sulfidogenesis suppressed methanogenesis, deteriorating bioenergy conversion.

Abstract

A lab-scale upflow anaerobic sludge blanket (UASB) has been run for 250 days to investigate the influence of influent COD/SO₄²⁻ ratios on the biodegradation behavior of starch wastewater and process performance. Stepwise decreasing COD/SO₄²⁻ratio enhanced sulfidogenesis, complicating starch degradation routes and improving process stability. The reactor exhibited satisfactory performance at a wide COD/SO₄²⁻ range ⩾2, attaining stable biogas production of 1.15–1.17 L L⁻¹ d⁻¹ with efficient simultaneous removal of total COD (73.5–80.3%) and sulfate (82.6 ± 6.4%). Adding sulfate favored sulfidogenesis process and diversified microbial community, invoking hydrolysis–acidification of starch and propionate degradation and subsequent acetoclastic methanogenesis; whereas excessively enhanced sulfidogenesis (COD/SO₄²⁻ ratios <2) would suppress methanogenesis through electrons competition and sulfide inhibition, deteriorating methane conversion. This research in-depth elucidated the role of sulfidogenesis in bioenergy recovery and sulfate removal, advancing the applications of UASB technology in water industry from basic science.

Graphical abstract

Keywords

• Upflow anaerobic sludge blanket (UASB)
• Starch
• Sulfate reduction
• Methane
• Energy conversion

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Supplementary data

• ⁎ 
  Corresponding author at: Department of Civil and Environmental Engineering, Graduate School of Engineering, Tohoku University, Japan.

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