Using upstream oxidants to minimize surface biofouling and improve hydraulic performance in GAC biofilters

WATER RESEARCH

卷:148

Article

de Vera, Glen Andrew¹  Lauderdale, Chance²  Alito, Christina L.³  Hooper, Jennifer⁴  Wert, Eric C.¹ 

[1] Southern Nevada Water Author, Appl Res & Dev Ctr, POB 99954, Las Vegas, NV 89139 USA

[2] HDR Engn Inc, 5426 Bay Ctr Dr,Suite 400, Tampa, FL 33609 USA

[3] HDR Engn Inc, 2650 Pk Tower Dr,Suite 400, Vienna, VA 22180 USA

[4] CDM Smith, 14432 SE Eastgate Way 100, Bellevue, WA 98007 USA

关键词: Biofiltration;    Biological Filtration;    Granular Activated Carbon (GAC);    Filter clogging;    Head loss;    Oxidants;   

DOI  :  10.1016/j.watres.2018.10.085

来源: Elsevier

【 摘 要 】

The combination of biological growth and particle loading can adversely affect hydraulic performance in drinking water biofilters. In this study, upstream oxidant addition was used to distribute biologically derived filter clogging in granular activated carbon (GAC) biofilters. Oxidant penetration was assessed during pilot-scale operation and backwashing of dual media (GAC/sand) and multimedia (GAC/anthra-cite/sand) biofilters. Influent chlorine (HOCI), monochloramine (NH2CI), and hydrogen peroxide (H2O2) residuals were optimized to react with the GAC surface in the upper portion of the filter media bed (depth < 0.5 m) to attenuate biomass development. As the oxidant residual was quenched by surface mediated reaction with the filter media, biomass growth was promoted deeper in the filter bed (depth > 0.5 m). The oxidant-induced effects on biomass and hydraulic performance were monitored through measurements of adenosine triphosphate (ATP) and head loss accumulation at different media depths. Addition of oxidants (e.g., 0.6 mg Cl-2/L HOCI) could decrease terminal head loss by 20% in dual media filters and 40% in multimedia filters. These hydraulic benefits were achieved without significantly affecting removal of assimilable organic carbon (AOC), total organic carbon (TOC), turbidity, and particle counts. Oxidant type, residual concentration, media type, media age, and media depth influenced the passage of oxidant residuals and distribution of filter biomass. When oxidants were added during backwashing, oxidant residual was quenched through the bed depth from a combination of reactions with GAC media and biofilm degradation. This attenuation of residual oxidant may prevent the oxidant residual from penetrating the entire bed depth, potentially compromising backwashing objectives. (C) 2018 The Authors. Published by Elsevier Ltd.

【 授权许可】

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