Coupling hydraulic and biological measurements highlights the key influence of algal biofilm on infiltration basin performance

Abstract

International audienceInfiltration basins are increasingly used in urban areas for flood protection, groundwater recharge and storm water disposal. However, their operation is often affected by clogging, leading to degraded infiltration. The aim of this work was to evaluate the respective influences of sediment deposition and biofilm biomass on the deterioration of hydraulic performances in two infiltration basins used for groundwater recharge. Samples were collected by coring in the two basins. Grain size distribution (with and without organic matter), bacterial and algal biomasses, and microbial activity were measured at three depths from the soil surface (0-1cm, 2-3cm and 10-14cm). In parallel, in situ single-ring infiltration tests were performed before and after removal of the top layer (0-1cm). The results showed considerably reduced permeability due to clogging of the top sedimentary layer in the two basins. The highest reduction of permeability was measured in the basin colonized by the largest algal biomass. The proportions of fine mineral particles (<63 mu m) were comparable in the two basins and could not explain their differences in saturated hydraulic conductivities. In addition, the relationships between biological and hydraulic parameters highlighted a threshold effect of algal biomass on the structure of the pore network, possibly explaining the decrease in infiltration. This original link between hydraulic and microbial characteristics suggests that algal biofilm growth had a major impact on the hydraulic performance of the infiltration basins. Copyright (c) 2013 John Wiley & Sons, Ltd

Influence of tubificid worms on sediment structure, benthic biofilm and fauna in wetlands: A field enclosure experiment

“…We measured nutrient concentrations in the water column of the wetland during the course of the experiment (36 days) to characterise the trophic conditions of surface water at a weekly interval. As in previous experiments (Gette‐Bouvarot et al., , ), oligotrophic–mesotrophic conditions were found in the basin with concentrations of NO 3 − , NH 4 + , PO 4 3− and dissolved organic carbon (DOC) of 338 ± 71 μg/L, 16.7 ± 15.2 μg/L, 12.6 ± 3.7 μg/L and 4.05 ± 1.08 mg/L, respectively.…”

“…Total organic carbon and TN of the 0–1 cm sedimentary layer were measured as estimators of the sedimentary biofilm biomass (Gette‐Bouvarot et al., ). TOC and TN were determined by high‐temperature combustion of in situ pre‐acidified dry samples (60°C, 48 hr) and subsequent measurement of CO 2 and N 2 by thermal conductometry using an elemental analyser (FlashEA, Thermo Electron Corporation).…”

Water infiltration in an aquifer recharge basin affected by temperature and air entrapment

“…Clogging was one of the first factors to be evidenced and studied (Bouwer, 2002). The effect of clogging on water infiltration may be dramatic and endanger the operation of infiltration basins (Gette-Bouvarot et al, 2014;Greskowiak et al, 2005;Kildsgaard and Engesgaard, 2001;Okubo and Matsumoto, 1979;Schuh, 1990Schuh, , 1988Tu et al, 2011). To prevent clogging, practitioners usually embed a top layer of sand in infiltration basins and replace it from time to time when the sand gets clogged (Bouwer, 1999).…”

“…This study aims at investigating experimentally the effects of temperature and air entrapment on water infiltration at the scale of infiltration basins, the effects of clogging having already been investigated (Gette-Bouvarot et al, 2014). Water infiltration experiments were performed in one of the infiltration basins of the water supply pumping site of Crépieux-Charmy that provides Lyon with drinking water.…”

EPS solubilization treatment by applying the biosurfactant rhamnolipid to reduce clogging in constructed wetlands

“…To test the dispersion effect of solubilization treatment on clogging matter, block particle size distribution was analyzed using an automatic laser particle size analyzer (Mastersizer 2000). Three groups of treatments were carried out, each using 8 g of sample material; one group applied solubilization treatment at the optimal dose, one group removed OM by treatment with sodium hypochlorite (Gette-Bouvarot et al, 2014), and the third was a control group. After treatment, all the sample add deionized water to 40 ml to prepare for particle size analysis.…”