Reducing natural organic matter and disinfection by-product precursors by alternating oxic and anoxic conditions during engineered short residence time riverbank filtration: A laboratory-scale column study

• Published in: The Science of the total environment Vol. 565; pp. 616 - 625
• Main Authors: Liu, Peng, Farré, Maria José, Keller, Jurg, Gernjak, Wolfgang
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15-09-2016
• Subjects: Bioreactors; Disinfection - methods; Disinfection by-product precursors; Engineered riverbank filtration; Natural organic matter; Oxidation-Reduction; Oxygen - chemistry; Rivers - chemistry; Short residence time; Water Pollutants - analysis; Water Pollutants - chemistry; Water Purification - methods; Water Quality; C-DBPs; UV254; DBP FP; BDOC; TCNM; TBNM; DO; HK2; HKs; WTP; DBP; Short residence time; 1,1,1-TCP; HOBr; RBF; GC-ECD; DOC; THM4; THMs; BIF; TBM; TDN; CH; SEC-UV-OCD; HAAs; HNM2; EEM; HNMs; NOM; Natural organic matter; SUVA254; BCAN; HOCl; BDCM; DCAN; DBAN; N-DBPs; 1,1-DCP; Disinfection by-product precursors; DBCM; TCAN; Engineered riverbank filtration; HAN4; HANs; TCM
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2016.05.061

Riverbank filtration (RBF) with days to months of residence time has been successfully used as treatment or pre-treatment process to improve water quality for decades. However, its feasibility depends on the local hydrogeological conditions. Therefore, for sites unsuitable to traditional RBF, a smaller engineered RBF may be an option. This study evaluates the performance of engineered short residence time RBF on improving water quality, focusing on the removal of natural organic matter (NOM) and the reduction of precursors of carbon and nitrogen disinfection by-products (DBP).
Lab-scale experiments were conducted with surface feed water from a drinking water plant. The results showed that within 6days hydraulic retention time (HRT), 60–70% dissolved organic carbon (DOC) and 70–80% ultraviolet absorbance at 254nm (UV254) could be removed. During the whole filtration process, biodegradation was responsible for the removal of organic matter, and it was found that alternating redox condition between oxic and anoxic was beneficial for the overall performance of the RBF. Dissolved oxygen (DO) had a substantial impact on the removal of DBP precursors. For carbon-containing DBP (C-DBP) precursors' removal, re-aeration after a sequence of oxic and anoxic conditions could further increase the removal efficiencies from 50%, 60%, and 60% to 80%, 90%, and 80% for trihalomethanes (THMs), chloral hydrate (CH), and haloketones (HKs). Prolonged anoxic conditions were however beneficial for the removal of nitrogen-containing DBP (N-DBP) precursors.
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•Engineered river bank filtration was tested with 6days retention time.•Organic matter and disinfection by-product precursor removal ranged from 40 to 90%.•Alternating oxic and anoxic conditions increased overall performance.•High dissolved oxygen availability favours C-DBP precursor removal.•Prolonged anoxic phases favour N-DBP precursor removal.