Technical note: Nutrient removal and microbial settlement in a full-scale subsurface wastewater infiltration system: Impact of varying hydraulic and organic loads and temperature

  • Yafei Sun College of Life Science, Shenyang Normal University, Shenyang, China
  • Linlin Fan College of Life Science, Shenyang Normal University, Shenyang, China
  • Deli Tong College of Life Science, Shenyang Normal University, Shenyang, China
  • Zhiqi Li College of Life Science, Shenyang Normal University, Shenyang, China
  • Fanping Zheng College of Life Science, Shenyang Normal University, Shenyang, China
  • Wanyuan Hou College of Life Science, Shenyang Normal University, Shenyang, China
  • Jing Pan College of Life Science, Shenyang Normal University, Shenyang, China
Keywords: decentralized wastewater, nitrifying bacteria, denitrifying bacteria, soil treatment system

Abstract

A series of experiments was conducted through a full-scale subsurface wastewater infiltration system (SWIS) to investigate the impact of hydraulic loading rate (HLR), organic loading rate (OLR) and underground temperature on nutrient removal and microbial settlement. Taking the hydraulic and treatment performance into consideration, HLR of 0.10 m3/(m2·d) was recommended with average NH3-N, TN, COD and TP removal rates of 82.6%, 81.5%, 80.9% and 90.9%, respectively.
Considering treatment performance, OLR of 10.4 g BOD/(m2·d) was recommended with average NH3-N, TN, COD and TP removal rates of 88.1%, 84.8%, 86.3% and 91.3%, respectively. The number of nitrifying bacteria in each layer in the matrix decreased with increasing HLR, and the number of denitrifying bacteria increased with increasing HLR, at 0.8 and 1.0 m depths. When OLR increased, the number of bacteria and denitrifying bacteria at 0.8 and 1.0 m depths increased, and the number of nitrifying bacteria decreased. Average NH3-N, TN and COD removal rates increased with underground temperature increasing. The number of bacteria, nitrifying bacteria at 0.4 and 0.6 m depths and denitrifying bacteria at 0.8 and 1.0 m depths, increased with underground temperature increasing.

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Published
2018-07-31
Section
Technical note