Nitrate Removal of Drainage Water with Barley Straw as a Bioreactor Filter

Abstract

Nitrate is a widespread groundwater contaminant, which can cause pollution of receiving waters. Some of the highest losses of nitrate to surface waters come from drained agricultural land. Bioreactor filters are a useful approach for removing nitrate from drainage waters, but these systems require an external carbon supply to sustain denitrification. The ability of barley straw to serve as a carbon substrate for biofilters was evaluated in a laboratory model. In this study the effect of two heads (100 and 200 cm) and two thicknesses of bioreactor (300 and 600 mm) were also evaluated. The experiment was conducted in the polyethylene columns with 90 mm internal diameter. The influent nitrate concentration was 40 mg L-1. Addition of barley straw as a carbon source decreases significantly effluent nitrate concentrations. The rate of denitrification was affected by the water velocity and decreased at velocity about 0.04 m h-1. In the columns with 300 mm height, the average nitrate reduction at 100 and 200 cm heads were 63.49% and 60.22%, respectively. The average nitrate reduction at the 600 mm height columns with 100 and 200 cm heads were 69.97% and 67.1%, respectively.

Assessment of Wood Chips and Agricultural Residues as Denitrifying Bioreactor Feedstocks for Use in the Canadian Prairies

“…Lastly, much research has been conducted in laboratory settings as it represents a step prior to pilot or full-scale trials (Tikhomirova et al, 2018). Hashemi et al (2010) showed a NO 3 -N reduction rate of 60% to 70% for laboratory bioreactors filled with barley straw. Similarly, Kouanda and Hua (2021) reported nitrate reductions of 15% for barley straw and 11% for wood in the laboratory, while Hellman et al (2021) reported NO 3 -N reductions of 42% for barley and 44% for wood in their laboratory study.…”