Send to

Choose Destination
Ecotoxicol Environ Saf. 2018 Oct 30;162:296-303. doi: 10.1016/j.ecoenv.2018.06.096. Epub 2018 Jul 11.

Comprehensive assessment of microbial aggregation characteristics of activated sludge bioreactors using fuzzy clustering analysis.

Author information

Department of Water & Soil Sciences, China Agricultural University, Beijing 100193, China.
Department of Civil Engineering, Hefei University of Technology, Hefei 230009, China.
Department of Plant & Soil Sciences, University of Delaware, Newark, DE 19716, USA.
Nanjing Hydraulic Research Institute, Nanjing 210029, China.
Department of Civil Engineering, Hefei University of Technology, Hefei 230009, China; State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing 210098, China. Electronic address:


Understanding microbial aggregation dynamics in response to the often violent environmental fluctuations is important for activated sludge wastewater biotreatment practice, yet remains poorly understood. We investigated microbial aggregation process of an activated sludge reactor in response to various operating conditions of resource limitations, disinfectant and pH stresses, and quantified aggregation characteristics by employing a fuzzy clustering analysis (FCA) method. The results revealed that the FCA provided a means for comprehensive assessment of microbial aggregation dynamics of the bioreactor relying solely on simple parameter estimation. Proper disinfectant stress (of NaClO 1.00% or 2.00%) is a promising strategy to improve the comprehensive performance of microbial aggregation and sludge settleability. Nitrogen- (of C/N ratio > 40) and dissolved oxygen-limitations (of DO < 0.2 mg/L) had medium influence on the comprehensive performance of the activated sludge system, while little impacts for acidic and alkaline conditions. These quantitative estimations offer insights into the underlying bio-physicochemical processes of an activated sludge bioreactor in response to practical fluctuations that is often beyond typical assessment practice. In addition, it may represent a step towards uncoupling the complex biophysical interactions that is essential for optimized designing and proper engineering practice of biological wastewater treatment reactors.


Activated sludge; Comprehensive assessment; Environmental stress; Fuzzy clustering analysis

[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center