Backwashing conditions of novel bio-amended sands and its enhanced filtration efficiency

摘要

Novel amended sands enveloped in bio- film ( B- NAS) were employed to treat the ammonium-nitrogen ( NH4+ -N) in raw water. The backwashing conditions, treatment efficiency, and morphological characteristics of the B- NAS were investigated via bio- filtration experiments. The bare quartz sands ( BQS) and NAS exhibited biomass levels of 24.32 nmol- P g- sand (-1) and 83.71 nmol- P g-sand-(1), respectively. B- NAS was most effective when air alone ( at a strength of q(air),(I) = 7 L s-(1) m-(2) for t(air, I) = 6 min), a combination of air - water (at strengths of (qair, II) = 7 L s-(1) m-(2) and q(water, II) = 5 L s-(1) m-(2) for tairwater, II D 6 min), and water alone ( at a strength of qwater, III D 7 L s- 1 m- 2 for twater, III D 4 min) were employed alternately for flushing. The proposed B- NAS with nano- pores surface effectively ( 1) resisted the shock produced by high NH4 C- N concentrations ( 4 mg L- 1), ( 2) exhibited removal rate of 96%, and ( 3) a high capturing capacity indicated by a high head loss ( 126.5 cm) for 72 hr.