Hydraulic constraints on the performance of a groundwater denitrification wall for nitrate removal from shallow groundwater.

摘要: Denitrification walls are a practical approach for decreasing non-point source pollution of surface waters. They constructed by digging trench perpendicular to groundwater flow and mixing the aquifer material with organic matter, such as sawdust, which acts carbon stimulate denitrification. For efficient functioning, need be permeable flow. We examined functioning denitrification wall in an consisting coarse sands. Wells were monitored changes nitrate concentration passed through soil samples taken measure microbial parameters inside wall. Nitrate concentrations upstream ranged from 21 39 g N m(-3), 0 2 m(-3) downstream 19 44 m(-3). An initial investigation using salt tracer dilution technique showed that was less than 4% occurring aquifer. Natural gradient tests bromide Rhodamine-WT confirmed bypass under Hydraulic conductivity 0.48 m day(-1) measured wall, whereas surrounding had hydraulic 65.4 day(-1). This indicated during construction been greatly reduced, so most flowed rather rates center 0.020 0.13 day(-1), did not account removal (0.16-0.29 day(-1)) calculated monitoring concentrations. suggested rate greater at face its where it limited low While can inexpensive tool removing groundwater, they may suitable aquifers textured subsoils simple techniques result major decreases conductivity.