Premium
Predicting manganese and iron precipitation in drinking water biofilters
Author(s) -
Earle Martin R.,
Breda Inês L.,
Stoddart Amina K.,
Gag Graham A.
Publication year - 2021
Publication title -
awwa water science
Language(s) - English
Resource type - Journals
ISSN - 2577-8161
DOI - 10.1002/aws2.1216
Subject(s) - manganese , biofilter , effluent , homogeneous , groundwater , environmental chemistry , water treatment , environmental science , chemistry , redox , environmental engineering , inorganic chemistry , geology , mathematics , geotechnical engineering , organic chemistry , combinatorics
Manganese is removed from drinking water because of aesthetic, health, and corrosion concerns. Like iron, manganese removal in biofilters depends on homogeneous, heterogeneous, and biological processes. This study aims to add further understanding to the importance of homogeneous processes for manganese removal in drinking water biofilters. Data collected from 10 groundwater biofilters across filter depth were analyzed using Pourbaix diagrams and thermodynamic modelling software (PHREEQC). Both methods predicted that iron would precipitate in all samples, but the predictions differed for manganese. The software approach provided a more precise look into the minerals predicted to form by homogeneous oxidation, allowing for deeper interpretation of biofilter oxidation–reduction (redox) conditions. Results suggest that multiple manganese removal mechanisms occur across biofilters, but homogeneous manganese oxidation may be essential to meet new Canadian guidelines. Utilities operating manganese removing biofilters should measure redox conditions to determine if changing biofilter pretreatment could decrease effluent manganese concentrations. Article Impact Statement Results of this study suggest that homogeneous manganese oxidation may be important for achieving the low effluent concentrations required by Canadian guidelines.