Quantitative monitoring of an activated sludge reactor using on-line UV-visible and near-infrared spectroscopy

Mafalda C. Sarraguça, Ana Paulo, Madalena M. Alves, Ana M.A. Dias, João A. Lopes, Eugénio C. Ferreira

Research output: Contribution to journalArticlepeer-review

64 Citations (Scopus)

Abstract

The performance of an activated sludge reactor can be significantly enhanced through use of continuous and real-time process-state monitoring, which avoids the need to sample for off-line analysis and to use chemicals. Despite the complexity associated with wastewater treatment systems, spectroscopic methods coupled with chemometric tools have been shown to be powerful tools for bioprocess monitoring and control. Once implemented and optimized, these methods are fast, nondestructive, user friendly, and most importantly, they can be implemented in situ, permitting rapid inference of the process state at any moment. In this work, UV-visible and NIR spectroscopy were used to monitor an activated sludge reactor using in situ immersion probes connected to the respective analyzers by optical fibers. During the monitoring period, disturbances to the biological system were induced to test the ability of each spectroscopic method to detect the changes in the system. Calibration models based on partial least squares (PLS) regression were developed for three key process parameters, namely chemical oxygen demand (COD), nitrate concentration (N-NO 3 - ), and total suspended solids (TSS). For NIR, the best results were achieved for TSS, with a relative error of 14.1% and a correlation coefficient of 0.91. The UV-visible technique gave similar results for the three parameters: an error of ∼25% and correlation coefficients of ∼0.82 for COD and TSS and 0.87 for N-NO 3 - . The results obtained demonstrate that both techniques are suitable for consideration as alternative methods for monitoring and controlling wastewater treatment processes, presenting clear advantages when compared with the reference methods for wastewater treatment process qualification.
Original languageEnglish
Pages (from-to)1159-1166
Number of pages8
JournalAnalytical and Bioanalytical Chemistry
Volume395
Issue number4
DOIs
Publication statusPublished - Oct 2009
Externally publishedYes

Keywords

  • Activated sludge process
  • Chemometrics
  • Near-infrared
  • On-line monitoring
  • UV-visible
  • Wastewater treatment

Fingerprint

Dive into the research topics of 'Quantitative monitoring of an activated sludge reactor using on-line UV-visible and near-infrared spectroscopy'. Together they form a unique fingerprint.

Cite this