Nitrogen removal over nitrite by aeration control in aerobic granular sludge sequencing batch reactors

Int J Environ Res Public Health. 2014 Jul 8;11(7):6955-78. doi: 10.3390/ijerph110706955.

Abstract

This study investigated the potential of aeration control for the achievement of N-removal over nitrite with aerobic granular sludge in sequencing batch reactors. N-removal over nitrite requires less COD, which is particularly interesting if COD is the limiting parameter for nutrient removal. The nutrient removal performances for COD, N and P have been analyzed as well as the concentration of nitrite-oxidizing bacteria in the granular sludge. Aeration phase length control combined with intermittent aeration or alternate high-low DO, has proven to be an efficient way to reduce the nitrite-oxidizing bacteria population and hence achieve N-removal over nitrite. N-removal efficiencies of up to 95% were achieved for an influent wastewater with COD:N:P ratios of 20:2.5:1. The total N-removal rate was 0.18 kgN·m-3·d-1. With N-removal over nitrate the N-removal was only 74%. At 20 °C, the nitrite-oxidizing bacteria concentration decreased by over 95% in 60 days and it was possible to switch from N-removal over nitrite to N-removal over nitrate and back again. At 15 °C, the nitrite-oxidizing bacteria concentration decreased too but less, and nitrite oxidation could not be completely suppressed. However, the combination of aeration phase length control and high-low DO was also at 15 °C successful to maintain the nitrite pathway despite the fact that the maximum growth rate of nitrite-oxidizing bacteria at temperatures below 20 °C is in general higher than the one of ammonium-oxidizing bacteria.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aerobiosis
  • Air Pollutants / metabolism
  • Bacteria / classification
  • Bacteria / genetics
  • Bacteria / metabolism
  • Biological Oxygen Demand Analysis
  • Bioreactors*
  • DNA, Bacterial / analysis
  • Nitrates / metabolism*
  • Nitrites / metabolism*
  • Nitrogen / metabolism*
  • Nitrous Oxide / metabolism
  • RNA, Ribosomal, 16S / genetics
  • Sewage
  • Waste Disposal, Fluid
  • Water Pollutants, Chemical / metabolism*

Substances

  • Air Pollutants
  • DNA, Bacterial
  • Nitrates
  • Nitrites
  • RNA, Ribosomal, 16S
  • Sewage
  • Water Pollutants, Chemical
  • Nitrous Oxide
  • Nitrogen