Hi all…for those of you dealing with biological filtration for drinking water treatment, a paper entitled “Biodegradable organic matter and rapid-rate biofilter performance: A review” has just been published in the journal Water Research. The authors examined 100 or more studies on biological filtration (biofiltration) and reported the median biodegradable organic carbon (BDOC) and assimilable organic carbon (AOC) percentages with and without pre-ozonation. They also reported on removals through biofiltration: “For all operation conditions (n = 117), biofilters (12 min average EBCT) removed 12% (median) of the influent TOC with higher removals for ozonated waters, 15% (median), compared to nonozonated waters, 10% (median). As temperature increased from ≤10 °C to ≥20 °C, TOC removal increased from 10% to 17% (median).”

They conclude that “Biofiltration can be an efficient treatment technology to remove the biodegradable portion of organic matter from the influent water, but should be optimized to achieve maximum removal. EBCT, temperature, oxidant conditions, and backwash strategies, among others, can impact biofilter efficacy and should be carefully chosen or taken into consideration in the design and operation of biofilters.”

Ontario research was well represented with about 20 papers being cited.

Bill

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Biodegradable organic matter and rapid-rate biofilter performance: A review
Leigh G. Terry*, R. Scott Summers
Water Research
Volume 128, 1 January 2018, Pages 234–245
http://www.sciencedirect.com/science/article/pii/S0043135417308023
https://doi.org/10.1016/j.watres.2017.09.048 

Abstract

“Biodegradable organic matter (BOM), found in all surface waters, is a challenge for drinking water utilities because it can lead to distribution system bio-regrowth, react to form disinfection by-products, or be a specific compound of concern. A critical review of BOM (occurrence and oxidant effects) and rapid-rate biofiltration performance (preozonation, backwashing with an oxidant, empty bed contact time (EBCT) and temperature) was carried out. An extensive literature data analysis (n = 100) found total organic carbon (TOC) in nonozonated water is comprised of 20% (median) biodegradable organic carbon (BDOC) and 3% (median) assimilable organic carbon (AOC). For ozonated waters (n = 103), these values increased to 30% (median) BDOC and 9% (median) AOC. For all operation conditions (n = 117), biofilters (12 min average EBCT) removed 12% (median) of the influent TOC with higher removals for ozonated waters, 15% (median), compared to nonozonated waters, 10% (median). As temperature increased from ≤10 °C to ≥20 °C, TOC removal increased from 10% to 17% (median). This review demonstrates biofiltration can be an efficient treatment technology to remove a portion of the BOM from the filter influent and should be optimized to achieve maximum removal.”