HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by Rodgers, M. Articles by Healy, M. G. Search for Related Content PubMed Articles by Rodgers, M. Articles by Healy, M. G. GeoRef GeoRef Citation Agricola Articles by Rodgers, M. Articles by Healy, M. G. Related Collections Animal Waste Hydraulic Conductivity/Relative Permeability Water Retention/Capillary Pressure Laboratory Column Studies Nutrients Time Domain Reflectometry, TDR Hydraulic Conductivity

Division S-1—Soil Physics

Surface Clogging in an Intermittent Stratified Sand Filter

Dep. of Civil Engineering, National Univ. of Ireland, Galway, Ireland

^* Corresponding author (markgerardhealy{at}hotmail.com)

Accumulation of biomass and deposition of suspended solids at the surface of a sand filter can lead to clogging of the filter media. A laboratory intermittent sand filter column, which included three sand strata, was operated for a period of 806 d before failure occurred through surface clogging. Upon dismantling the column, the cause and effects of the surface clogging were investigated. The main mechanism responsible for sand clogging appeared to be biomass buildup. Maximum loss on ignition of filter media samples was 2.35%, and it occurred in the upper 0.01 m of the sand. There was a reduction in field-saturated hydraulic conductivity in the top 0.01 m of the upper sand stratum from a value of 1.9 x 10^–3 ± 1.7 x 10^–4 m s^–1 (for virgin sand with an effective size, d₁₀, of 0.45 mm) to 3.5 x 10^–5 ± 7.5 x 10^–6 m s^–1. The soil-water characteristic curve, which relates the volumetric water content (_v) to the soil suction, also reflected the changes in the filter media due to clogging. The water-holding capacity greatly increased as biomass accumulated in the filter media. Scanning electron microscopy (SEM) confirmed the existence of a clogging organic layer on the surface of the top sand layer.

Abbreviations: (h), soil-water characteristic curve • _v, volumetric water content • C_u, uniformity coefficient, d₁₀, effective size • K_fs, field-saturated hydraulic conductivity • SEM, scanning electron microscopy