A preliminary cost-effectiveness analysis of denitrifying bioreactors in the Lower Burdekin

Abstract

A cost-effectiveness (CE) analysis was undertaken to assess the cost per kilogram of nitrate-nitrogen ($/kg N) removed by denitrifying bioreactor beds in a sugarcane production system in Queensland. The preliminary analysis evaluates the CE of a 34m3 bioreactor bed trialled on a sugarcane farm in the lower Burdekin delta district, conducted as part of the Bioreactors for GBR Project, funded through the Queensland Reef Water Quality Program. The aim of the project was to investigate the nitrate removal performance of bioreactor beds receiving run-off from sugarcane farms in the lower Burdekin. In addition, the CE of a hypothetical 100m3 bioreactor scenario is also explored.
The project trialled and monitored three bioreactor beds in the lower Burdekin. Of the three trials, one produced a more comprehensive dataset compared to the others that had experienced significant blockages during the trial period. Data from this trial was therefore utilised in the CE analysis. High-frequency water quality monitoring was undertaken over 12 months (May 2019 - April 2020) with nitrate concentration, woodchip saturation and water flow analysed to enable calculation of the nitrogen removal rate (NRR).