Modeling geosmin removal in a full-scale filter.

Juliana A Coelho,Diana Cristina S De Azevedo,Ivanildo José Da Silva Junior,José Capelo-Neto

doi:10.1590/0001-3765202020190453

Juliana A Coelho, Diana Cristina S De Azevedo + Show 2 more

Open Access

https://doi.org/10.1590/0001-3765202020190453

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Abstract

Taste and odor compounds affect drinking water safety perception and may drive consumers to less secure water sources. Adsorption, using powered activated carbon, is the most common method to remove these compounds but greatly increases the amount of sludge generated. Another way of removing taste and odor compounds is to use filters with granular activated carbon (GAC) but little is still known on how to design them. In this work, the homogeneous surface diffusion model (HSDM) was used to model bench-scale kinetic and isotherm experiments and to simulate the removal of geosmin in a full-scale GAC filter. Geosmin adsorption isotherm was best described by the Freundlich model in all used carbons and film resistance (Kf) was more relevant to adsorption kinetics than pore diffusion (Ds). The simulation showed that in a filter with an empty bed contact time of 5 minutes and raw water with geosmin concentrations of 50, 75, and 100 ng.L-1, the effluent would exceed the trash-hold concentration (10 ng.L-1) in 98, 77, and 66 days, respectively, without considering biological removal.

Highlights

Geosmin and 2-methylisoborneol (MIB) are taste and odor (T&O) compounds produced by cyanobacteria that negatively affect drinking water aesthetics
granular activated carbon (GAC) filtration is an efficient process for the removal of MIB and geosmin, its efficiency decreases over time as the carbon adsorption sites are occupied (Mackenzie et al 2005, Elhadi et al 2006)
The methodology used in this paper may offer an option for a first approach to GAC filter projects and for planning pilot and bench-scale experiments

Summary

Introduction

Geosmin and 2-methylisoborneol (MIB) are taste and odor (T&O) compounds produced by cyanobacteria that negatively affect drinking water aesthetics. A sensitive consumer can detect geosmin and MIB at levels as low as 10 ng.L-1 (Young et al 1996). This concentration can be reached in raw water with a relatively low number of Dollicorspermum circinale cells (200 cells.mL-1), for example (Zamyadi et al 2013). Two forms of activated carbon may be used to remove metabolites such as MIB and geosmin: powder activated carbon (PAC) and granular activated carbon (GAC). Under favorable conditions, a biofilm capable of rapidly degrading MIB and geosmin may form on the GAC particles, significantly expanding its lifetime (Elhadi et al 2006, Ho et al 2012)

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