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Denitrification in constructed wetlands in cold climate regions
2002 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

Nitrogen compounds are predominant pollutants in leachate. Nitrogen removal can be accomplished by biological nitrification and denitrification. A constructed wetland can serve as a denitrification step. The aim of this master thesis was to assess a potential of the organic plant material in a constructed wetland to be used as a reduction agent for the process of denitrification under cold climate conditions. Denitrification experiments were performed in laboratory scale. The examined factors include temperature, water quality, amount of sludge, C:N-quotient, kind of organic material and initial nitrate nitrogen concentration. 144 experiments were performed. Multivariate data analysis (MVDA) was used to evaluate the results. The sludge content was the factor which had the highest influence on the denitrification process. High sludge contents significantly increased the rate of the process. Methanol was the best reduction agent among the organic materials. The addition of wetland plants did not seem to have any impact on the denitrification process. It is not possible to see any difference between using dry or wet plant material as a reduction agent. The denitrification process was favoured by high C:N-quotients. The results indicate that at low C:N-quotients the intermediate product nitrite might have accumulated. Artificial water was more favourable for the denitrification process than ash and industrial leachates. The results also show that a high temperature made the denitrification process start faster. The denitrification process was favoured by low initial nitrate nitrogen concentrations. The results indicate that high nitrate nitrogen concentrations resulted in a slower process and caused an accumulation of nitrite nitrogen.

Place, publisher, year, edition, pages
2002.
Keyword [en]
Technology, denitrification, wetlands, cold climate
Keyword [sv]
Teknik
Identifiers
URN: urn:nbn:se:ltu:diva-48933ISRN: LTU-EX--02/020--SELocal ID: 65b1f9c3-b344-49e0-9667-c7e918647d1aOAI: oai:DiVA.org:ltu-48933DiVA: diva2:1022278
Subject / course
Student thesis, at least 30 credits
Educational program
Environmental Engineering, master's level
Examiners
Note
Validerat; 20101217 (root)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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