A pilot bioretention system with commercial activated carbon and river sediment-derived biochar for enhanced nutrient removal from stormwater

Abstract

Bioretention is an effective technology for urban stormwater management, but the nutrient removal in conventional bioretention systems is highly variable. Thus, a pilot bioretention column experiment was performed to evaluate the nutrient control of systems with commercial activated carbon and river sediment-derived biochar. Significant chemical oxygen demand (COD) and total phosphorus (TP) leaching were found with the addition of activated carbon and biochar, but total nitrogen (TN) leaching was significantly improved when activated carbon was used as the medium. During a semi-synthetic runoff experiment, the bioretention systems containing two types of fluvial biochar showed relatively better COD and TN control (average mass removal efficiencies and cumulative removal efficiencies) than commercial activated carbon. However, the average TP mass removal efficiency with commercial activated carbon (95% ± 3%) was significantly higher than biochar (48% ± 20% and 56 ± 14%). The addition of biochar in the media increased the nitrogen removal efficiency, and the addition of activated carbon significantly increased the phosphorous removal efficiency. Therefore, both biochar and activated carbon are effective materials for bioretention, and fluvial biochar provides an alternative approach to comprehensively utilize river sediment.

Assessing global urban CO2 removal

“…Beneficial effects of urban vegetation can be further amplified by the addition of biochar to urban substrates, fostering soil fertility and thus the prosperity of street trees and green roofs in an otherwise harsh growing environment 75,78,126 . Biochar's ability to filter pollutants from contaminated aqueous solutions also contributes to enhancing not only air but also water quality in urban areas [127][128][129][130] . In addition, thriving vegetation can also support biodiversity conservation efforts in cities [131][132][133] .…”

Filter media for storm water treatment in sustainable cities: A review

“…Different types of organic matter can be used as feedstock in the pyrolysis process along with differences in the pyrolysis process (temperature and duration of the process), which means that the biochar has different properties (Xie et al, 2021). Biochar has been investigated regarding its removal capacities for various pollutants in laboratory experiments with promising results (Mohanty et al, 2014;Afrooz and Boehm, 2017;Sang et al, 2019;Biswal et al, 2022;Kaya et al, 2022). Some researchers have also performed pilot-scale experiments in the laboratory.…”

Biofilters and bioretention systems: the role of biochar in the blue-green city concept for stormwater management

“…Most bioretention studies were conducted in laboratories using synthetic and semi-synthetic stormwater. 117,147 The use of controlled environmental conditions and simplified stormwater compositions may limit the applicability of these findings in practical field scenarios. Thus further research using more realistic and diverse stormwater compositions is necessary to validate the performance of biocharincorporated bioretention systems.…”