Nitrogen removal from sewage and septage in constructed wetland mesocosms using sand media amended with biochar

No Thumbnail Available
File version

Accepted Manuscript (AM)

Author(s)
de Rozari, P
Greenway, M
El Hanandeh, A
Griffith University Author(s)
Primary Supervisor
Other Supervisors
Editor(s)
Date
2018
Size
File type(s)
Location
Abstract

Biochar has been identified as a media amendment to improve nutrient removal from wastewater, and N retention and plant growth in agroforestry. It therefore has the potential for treating domestic wastewater. The aim of this research was to compare nitrogen removal and plant growth in pure sand and sand amended with biochar, in wetland mesocosms (240 L) receiving sewage. There were seven media treatments based on the proportions of biochar in the sand media (100% sand, sand and coir peat, 5, 10, 15, 20, 25% biochar). The plant species were Paperback tree (Melaleuca quinquenervia) and Lemongrass (Cymbopogon citratus). The mesocosms were continuously loaded for 8 months with secondary clarified wastewater (SCW) (16 L/day). Septage was then intermittently loaded (20 L/2 days) for a further 8 months. Inflow and outflow samples were monitored for TN, NH4-N, and NOx-N.

All treatments showed good nitrogen removal efficiency. Average removal efficiencies of TN, NOx-N and NH4-N in the mesocosms loaded with SCW ranged from 71 to 87%, 81 to 93% and 65 to 79%, for 100% Sand to 25% Biochar respectively. For septage, the removal efficiencies ranged from 63 to 81%, 69 to 87% and 66 to 81%, for 100% Sand to 25% Biochar respectively. Significant differences of nitrogen outflow concentrations were observed between pure sand and sand amended with biochar. Physical chemical properties of the biochar would have facilitated microbial processes and adsorption. Strong positive correlations were observed between biochar content in the media and nitrogen removal rates. The increased nitrogen removal may be attributed to higher mineralisation of organic nitrogen and NH4-N, especially in the case of septage where strong correlation was observed between BOD5 and TN removal. Total N biomass in the plants harvested after 21 months ranged from 13.4–14.0 g N. The addition of biochar did not increase plant N biomass in either species.

Journal Title

Ecological Engineering

Conference Title
Book Title
Edition
Volume

111

Issue
Thesis Type
Degree Program
School
Publisher link
Patent number
Funder(s)
Grant identifier(s)
Rights Statement
Rights Statement

© 2018 Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International Licence (http://creativecommons.org/licenses/by-nc-nd/4.0/) which permits unrestricted, non-commercial use, distribution and reproduction in any medium, providing that the work is properly cited.

Item Access Status
Note
Access the data
Related item(s)
Subject

Earth sciences

Environmental sciences

Engineering

Other engineering not elsewhere classified

Persistent link to this record
Citation
Collections