Nitrification in multistage horizontal flow treatment wetlands for landfill leachate treatment
[Display omitted] •Feasible alternative solution for landfill leachate treatment.•Nitrification was achieved with reduced hydraulic retention time without aeration.•Influent COD:N ratio showed negative correlation with NH4+-N removal rates.•Nitrate accumulation and inorganic carbon consumption as ev...
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| Published in: | The Science of the total environment Vol. 704; p. 135376 |
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| Main Authors: | , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
Netherlands
Elsevier B.V
20-02-2020
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| Subjects: | |
| Online Access: | Get full text |
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| Summary: | [Display omitted]
•Feasible alternative solution for landfill leachate treatment.•Nitrification was achieved with reduced hydraulic retention time without aeration.•Influent COD:N ratio showed negative correlation with NH4+-N removal rates.•Nitrate accumulation and inorganic carbon consumption as evidence of nitrification.•pH adjustment of wastewater considerably increased COD removal efficiency.
One of the key challenges in landfill leachate treatment is removing organic matter (OM) and ammonium nitrogen (NH4+-N) at a low cost. To evaluate the feasibility of treatment wetlands for diluted (3:10) landfill leachate treatment with OM and NH4+-N oxidation, a lab-scale shallow subsurface horizontal flow system (HF wetland) comprised of two units operated in series was assessed as post-treatment of partial ammonia stripping system. A HF wetland planted with Heliconia psittacorum (HP) and an unplanted HF wetland (control) were supplemented with micronutrients and monitored under the influence of hydraulic retention time (HRT), pH, and the plant presence on performance. With an HRT above 4 days, mean chemical oxygen demand removal for both HP and the control was less than 20%, without complete mineralization, probably due to the recalcitrance of OM. For NH4+-N, the mean global removal efficiencies with and without influent pH adjustment were, respectively, 74% and 54% for HP and 56% and 43% for the control, resulting in mean concentrations between 36 and 93 mg L−1. The NH4+-N removal was correlated with inorganic carbon consumption followed by NO3− production, which suggests that nitrification was the major route of removal. For both systems, nitrification was significantly higher in one of the units, when biodegradable OM was already consumed and competition between heterotrophic and autotrophic bacteria for dissolved oxygen was likely minimized. By balancing the organic load and availability of dissolved oxygen within each unit in series, a reduced HRT necessary for NH4+-N oxidation was achieved, an essential aspect for the design of high performance constructed wetlands for full scale landfill leachate treatment. |
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| Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
| ISSN: | 0048-9697 1879-1026 |
| DOI: | 10.1016/j.scitotenv.2019.135376 |