Premium
Influence of backwash regime on biofilter performance in drinking water treatment
Author(s) -
Ikhlef Sarra,
Basu Onita D
Publication year - 2017
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/jctb.5178
Subject(s) - backwashing , biofilter , dissolved organic carbon , filtration (mathematics) , chemistry , water treatment , pulp and paper industry , environmental chemistry , water quality , filter (signal processing) , total organic carbon , environmental engineering , nutrient , environmental science , ecology , mechanical engineering , statistics , mathematics , computer science , computer vision , engineering , inlet , biology , organic chemistry
BACKGROUND Drinking water biofiltration has the advantages of reducing the dissolved organic load in a drinking water treatment plant at a downstream process, such as membrane filtration and disinfection, as well as contributing to the continuity of water distribution. This study examines a series of backwash operational steps, including extended terminal subfluidization ( ETSW ) on dissolved organic carbon ( DOC ) and particulate removal, and additionally examines water with a low C:N:P ratio (considered non‐ideal for carbon removal), and water with an ideal C:N:P ratio for improved carbon removal. RESULTS Results showed that under nutrient limited conditions, collapse pulsing improved DOC removal by approximately 10% compared with a water‐only backwash condition. Bed expansions of 20% and 30% under improved nutrient conditions led to DOC removals of about 35% but further bed expansion to 40% decreased DOC removals (24%). The biofilter biomass concentrations, as measured by phospholipids and adenosine tri‐phosphate ( ATP ) showed no correlation with DOC removal. However, dissolved oxygen ( DO ) uptake showed a direct correlation with DOC removals. The addition of the ETSW had no impact on % DOC removals and successfully eliminated the filter ripening sequence. CONCLUSION The backwash method employed had an observable influence on biofiltration organic carbon removal. While air scour improved DOC removal, too high a bed expansion decreased removal levels. Thus an optimal level of backwashing exists in biofiltration that appears more stringent than requirements for conventional filtration alone. © 2016 Society of Chemical Industry