Nitrifyers in constructed wetlands treating landfill leachates

Landfill leachate is produced many years after a landfill site closes. Hence, treatment by “natural methods”, as e.g. constructed wetlands, with low management requirements is attractive. Constructed wetlands usually provide both shallow and deep areas with aerobic and anaerobic zones, which is suitable for nitrification followed by denitrification of the ammonium-rich leachates. Full-scale treatment systems are influenced by climatic variables that affect the microbial community. Also, the operational strategy can have a considerable impact on both activity and composition of the microorganisms. Many studies have measured inflow/outflow water quality in treatment systems. Such “black box” studies describe the treatment efficiency but add little to an increased understanding of theorganisms performing the treatment or the spatial distribution of their activities and treatment processes. In this thesis we investigated seasonal and annual changes in potential nitrification and denitrification, and in the corresponding bacterial communities in constructed wetlands treating landfill leachates…


1. Nitrogen as an environmental problem
2. Aim of this thesis
3. Nitrogen-rich emissions
3.1 Landfill leachate
3.2 Wastewater
4. Nitrification
4.1. Ammonia- and nitrite-oxidising bacteria
5. Denitrification
5.1 Denitrifying bacteria
6. On-site treatment – Constructed wetlands
6.1 Overland flow areas
6.2 Compact constructed wetlands
7. Methods
7.1 Potential activity
7.2. Molecular methods used to investigate the “black box”
7.3. Investigating bacterial communities using conventional PCR
This work
Site description
Environmental sampling
Potential ammonia oxidation
The ammonia oxidising bacterial communities
Potential denitrification
Denitrifying bacterial communities
Future work

Author: Sundberg, Carina

Source: Linköping University

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