AbspectroscoPY, a Python toolbox for absorbance-based sensor data in water quality monitoring
Journal article, 2022

The long-term trend of increasing natural organic matter (NOM) in boreal and north European surface waters represents an economic and environmental challenge for drinking water treatment plants (DWTPs). High-frequency measurements from absorbance-based online spectrophotometers are often used in modern DWTPs to measure the chromophoric fraction of dissolved organic matter (CDOM) over time. These data contain valuable information that can be used to optimise NOM removal at various stages of treatment and/or diagnose the causes of underperformance at the DWTP. However, automated monitoring systems generate large datasets that need careful preprocessing, followed by variable selection and signal processing before interpretation. In this work we introduce AbspectroscoPY ("Absorbance spectroscopic analysis in Python"), a Python toolbox for processing time-series datasets collected by in situ spectrophotometers. The toolbox addresses some of the main challenges in data preprocessing by handling duplicates, systematic time shifts, baseline corrections and outliers. It contains automated functions to compute a range of spectral metrics for the time-series data, including absorbance ratios, exponential fits, slope ratios and spectral slope curves. To demonstrate its utility, AbspectroscoPY was applied to 15-month datasets from three online spectrophotometers in a drinking water treatment plant. Despite only small variations in surface water quality over the time period, variability in the spectrophotometric profiles of treated water could be identified, quantified and related to lake turnover or operational changes in the DWTP. This toolbox represents a step toward automated early warning systems for detecting and responding to potential threats to treatment performance caused by rapid changes in incoming water quality.

Author

C. Cascone

IVL Swedish Environmental Research Institute

Swedish University of Agricultural Sciences (SLU)

Kathleen Murphy

Chalmers, Architecture and Civil Engineering, Water Environment Technology

H. Markensten

Swedish University of Agricultural Sciences (SLU)

J. S. Kern

Royal Institute of Technology (KTH)

C. Schleich

Vatten & Miljö i Väst AB

A. Keucken

Vatten & Miljö i Väst AB

Lund University

S. J. Kohler

Norrvatten AB

Swedish University of Agricultural Sciences (SLU)

Environmental Science: Water Research and Technology

2053-1400 (ISSN) 2053-1419 (eISSN)

Vol. In Press

Improved specificity for drinking water treatment monitoring

Formas (2017-00743), 2018-01-01 -- 2020-12-31.

Subject Categories

Water Engineering

Oceanography, Hydrology, Water Resources

Environmental Sciences

DOI

10.1039/d1ew00416f

More information

Latest update

3/14/2022