cee200: Environmental and Water Resources Engineering Seminar

UCLA Civil & Environmental Engineering Department

Nitrate Removal by Biochar-Amended Woodchip Biofilters

Alexander Berger

Master’s Student

Civil and Environmental Engineering, UCLA

Stormwater biofilters, particularly woodchip biofilters, have been used to remove nitrate from stormwater, but their performance is expected to decrease under extreme weather conditions such as prolonged drying and high rainfall intensity, which are expected to be more frequent during climate change. The objective of this study was to examine the effect of antecedent drying conditions and rainfall intensity on nitrate removal capacity of woodchip biofilters and evaluate whether addition fo biochar would decrease the detrimental effect of high intensity rainfall on nitrate removal. Nitrate removal capacity of biochar-amended woodchip biofilters (0-20% biochar by volume) were compared at storm event with different rainfall intensities (19 to 300 mm/h) and antecedent drying duration (1 to 8 days). The results showed that addition of biochar could increase the resiliency of woodchip biofilters for denitrification during high intensity rainfall expected during climate change—the conditions at which the performance of woodchip biofilters typically deteriorates quickly. Antecedent drying duration improved nitrate removal. This improvement is attributed to changes in pore water chemistry, such as a decrease in dissolved oxygen (DO) concentration and an increase in dissolved organic carbon (DOC) trapped in pore water. The results can help stormwater engineers to optimize biofilter design to optimize the removal of nitrate during climate change.

Where:   4275 Boelter Hall

When:    11am – 12pm, Thursday, April 26