Journal
WATER RESEARCH
Volume 84, Issue -, Pages 315-322Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.watres.2015.07.034
Keywords
Tertiary effluent; Biodegradation; Biofilter; Trace organic compound; Nitrification; Reclaimed water
Funding
- German BMBF
- MOST from Israel
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The Shafdan reclamation project facility (Tel Aviv, Israel) practices soil aquifer treatment (SAT) of secondary effluent with hydraulic retention times (HRTs) of a few months to a year for unrestricted agricultural irrigation. During the SAT, the high oxygen demand (>40 mg L-1) of the infiltrated effluent causes anoxic conditions and mobilization of dissolved manganese from the soil. An additional emerging problem is the occurrence of persistent trace organic compounds (TrOCs) in reclaimed water that should be removed prior to reuse. An innovative hybrid process based on biofiltration, ozonation and short SAT with similar to 22 d HRT is proposed for treatment of the Shafdan secondary effluent to overcome limitations of the existing system and to reduce the SAT's physical footprint. Besides efficient removal of particulate matter to minimize clogging, coagulation/flocculation and filtration (5-6 m h(-1)) operated with the addition of hydrogen peroxide as an oxygen source efficiently removed dissolved organic carbon (DOC, to 17-22%), ammonium and nitrite. This resulted in reduced effluent oxygen demand during infiltration and oxidant (ozone) demand during ozonation by 23 mg L-1 and 1.5 mg L-1, respectively. Ozonation (1.0 -1.2 mg O-3 mg DOC-1) efficiently reduced concentrations of persistent TrOCs and supplied sufficient dissolved oxygen (>30 mg L-1) for fully oxic operation of the short SAT with negligible Mn2+ mobilization (<50 mu g L-1). Overall, the examined hybrid process provided DOC reduction of 88% to a value of 1.2 mg L-1, similar to conventional SAT, while improving the removal of TrOCs and efficiently preventing manganese dissolution. (C) 2015 Elsevier Ltd. All rights reserved.
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