Journal of Environmental Biology

Fate of dissolved organic nitrogen during biological nutrient

removal wastewater treatment processes

Bing Liu^1,2, Huirong Lin²*, Guozhong Yu¹, Shenghua Zhang²?and Chengmei Zhao¹

1School of Urban and Environmental Science, Xinyang Normal University, Xinyang, 464 000, China

2Key laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences,
Xiamen, 361021, China

*Corresponding Author email : hrlin@iue.ac.cn

Publication Data

Paper received:

12 June 2012

Revised received:

12 August 2012

Accepted:

29 August 2012

Abstract

Due to its potential to form toxic nitrogenous disinfection byproducts (N-DBPs), dissolved organic nitrogen (DON) is considered as one of the most important parameters in wastewater treatment plants (WWTP). This study describes a comprehensive investigation of variations in DON levels in orbal oxidation ditches. The results showed that DON increased gradually from 0.71 to 1.14 mg l^-1?along anaerobic zone, anoxic zone, aerobic zone 1 and aerobic 2. Molecular weight fractionation of DON in one anaerobic zone and one aerobic zone (aerobic zone 2) was performed. We found that the proportion of small molecular weight (<6 kDa) decreased and large molecular weight (>20 kDa) showed opposite trend. This variation may have been caused due to the release of different types of soluble microbial products (SMPs) during biological processes. These SMPs contained both tryptophan protein-like and aromatic protein-like substances, which were confirmed by three-dimensional excitation-emission matrix (EEM) analysis.

Key words

Wastewater treatment plant, Dissolved organic nitrogen, Soluble microbial products,
Orbal oxidation ditch

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