Full-Scale Manipulation of the Empty Bed Contact Time to Optimize Dissolved Organic Matter Removal by Drinking Water Biofilters
Journal article, 2021

A study was conducted at a water treatment plant to optimize parallel rapid gravity biofilters for dissolved organic matter (DOM) removal. The biofilters treat urban and agriculturally impacted river water using a commercial non-adsorptive, expanded-clay filter medium. The study aimed to locate the optimal operating conditions via experimental manipulation of the biofilter empty bed contact time (EBCT) during full-scale operation at the plant. During a two-month experiment, contact times in four parallel biofilters were switched to and maintained at 15, 30, 50, and 80 min by manipulating the hydraulic loading on each filter. The removal efficiency of organic matter fractions increased with EBCT for dissolved organic carbon (DOC) and microbial humic-like (F290/420) and protein-like (F280/340) fluorescent organic matter. Other DOM fractions were largely unaffected by biofiltration, or at slightly higher concentrations in the effluent. Protein-like fluorescence is associated with labile organic matter fractions, which are known to be removed poorly by drinking water treatment barriers apart from biological filters. The results suggest that long contact times (>30 min) have advantages for the operation of some biological filters, especially if placed ahead of barriers that are sensitive to biofouling, e.g., membranes.

parallel factor analysis (PARAFAC)

drinking water

dissolved organic matter (DOM)

fluorescence spectroscopy

biological filter



Nashita Moona

Chalmers, Architecture and Civil Engineering, Water Environment Technology

Andrew Holmes

Kungälvs kommun

Urban J. Wunsch

Technical University of Denmark (DTU)

Thomas Pettersson

Chalmers, Architecture and Civil Engineering, Water Environment Technology

Kathleen Murphy

Chalmers, Architecture and Civil Engineering, Water Environment Technology


2690-0637 (eISSN)

Vol. 1 5 1117-1126

Improved specificity for drinking water treatment monitoring

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

Subject Categories

Water Engineering


Water Treatment



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