Emissions of greenhouse gases carbon dioxide and methane from duckweed systems for stormwater treatment
No Thumbnail Available
Authors
Meeting name
Sponsors
Date
Journal Title
Format
Thesis
Subject
Abstract
This study determined the greenhouse gas emission from lab-scale duckweed treatment systems that were used for stormwater treatment. By using the static chamber technique, the fluxes of CO2 emission from the duplicate duckweed systems were 1472 -- 721 and 626 -- 234 mg m-2 d-1, respectively. After the complete removal of duckweeds, CO2 emission from the systems decreased to 492 -- 281 and 395 -- 53 mg m-2 d-1, respectively. A thin-film model was successfully applied to predict the increasing CO2 concentrations approaching saturation in the static chamber. In contrast, the concentrations of methane in the closed chamber fluctuated a lot with time, which were attributed to complex methane production and consumption reactions at the soil-water interface. The CH4 flux from the two duckweed systems were 299 -- 74 mg m-2 d-1 and 180 -- 91 mg m-2 d-1, respectively. After the removal of duckweeds, the flux were 559 -- 215 mg m-2 d-1 and 328 -- 114 mg m-2 d-1, respectively. The higher CO2 emission in the duckweed systems was linked to more biomass debris formation on the soil surface due to duckweed growth and decay. As a result of duckweed growth, the duplicated duckweed systems removed 54 -- 13 % COD, 94 -- 4 % NH4 + -N, 87 -- 7 % NO3- -N, 34 -- 7 % PO4 3- -P at the hydraulic retention time of 10 days. When the duckweeds were removed, the nutrient removal efficiencies decreased significantly: 68 -- 3 % for NH4 + -N, 43 -- 7 % for NO3 - -N, 10 -- 6 % for PO4 3- -P. The COD removal efficiency without duckweeds was 47 -- 6 %, which did not change significantly.
Table of Contents
DOI
PubMed ID
Degree
M.S.