Performance of a Woodchip Bioreactor for the Treatment of Nitrate-Laden Agricultural Drainage Water in Northeastern Germany

Environments

Lennart Gosch¹  Bernd Lennartz¹  Haojie Liu¹ 

[1] Faculty of Agricultural and Environmental Sciences, University of Rostock, Justus-von-Liebig-Weg 6, 18059 Rostock, Germany;

关键词: woodchip bioreactor;    nitrate;    denitrification;    tile drainage;    nutrient removal;   

DOI  :  10.3390/environments7090071

来源: DOAJ

【 摘 要 】

Reactive barriers, such as denitrifying bioreactors, have been identified as a clean-up
option for nutrient-laden agriculture runoff. Here we tested a 20 m long, 3.75 m wide and 2.2 m
deep woodchip bioreactor receiving tile drainage water from a 5.2 ha field site, aiming at testing the
hydraulic functioning of a dual-inlet system and quantifying its impact on nutrient loads (nitrogen,
reactive phosphorus, organic carbon) in a region with a drainage season taking place in the
hydrological winter (November to April). The hydraulic conditions in the dual-inlet bioreactor
system developed differently than expected; asymmetric flow rates led to long average hydraulic
retention times and a highly dispersed residence time distribution, which was revealed by a
bromide tracer test. With a nitrate load reduction of 51 to 90% over three drainage seasons, the
woodchip bioreactor proved at the same time to be very effective under the winter conditions of
northeastern Germany. The bioreactor turned from an orthophosphate source in the first year of
operation into an orthophosphate sink in the second and third year, which was not expected because
of anoxic conditions (favorable for denitrification) prevailing within the woodchips. Besides an
efficient nutrient retention, the woodchip bioreactor contributed to the total organic carbon load of
receiving waters, which impairs the overall positive role of bioreactors within intensively
agriculturally used landscapes. We consider this promising low-maintenance biotechnology
particularly suitable for single drainage pipes with high discharge and high nitrate concentrations.

【 授权许可】

Unknown