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Leaching Test with Sawdust from Different Tree Species : Appropriateness of using them as adsorption media in wastewater and in stormwater treatment

Abstract   Bio energy in form of woodchips and sawdust is today commonly stored outdoors in heaps on hardened surfaces, exposed to weather and wind. Any water leaching from these heaps have the potential to be toxic to the environment. This paper examines the quality of the water leaching from heaps of four different tree species (oak, pine, maple and beech), by analysing different parameters such as pH, conductivity, colour, COD, BOD7, tannins & lignins (T&L) and phenols. The results show significant higher leaching values of COD, phenols, T&L and colour from oak compared to the other tree species (pine, maple and beech). These leached substances from woodchips and sawdust were shown in the BOD7 tests and BOD7/COD ratio values to be hard to biodegrade and are therefore not easily removed from the water. Hence it is important that wood-based fuel storage conditions are considered in bio energy generation schemes to ensure that the environmental benefits of using woodchips and sawdust instead of traditional fuel are not offset by the potential harm of inappropriate storage. The investigation further showed that leaching of highly toxic substances such as phenols can be up to 10 times higher for one tree type (oak) than another (pine, beech and maple). This difference could potentially be found for other tree species not characterized in this study.  Therefore, it is important to consider the constitution of the heaps to be able to apply appropriate storage conditions to avoid these toxic substances in the leached water reaching sensitive watercourses. As some of these substances are hard to biodegrade the treatment applied need a long retention time. Another problem is the carbon: nutrient ratio, this water has a high carbon content compared to phosphorus and nitrogen content which might prevent an efficient biodegradation. Adjusting C:N:P ratio with low cost amendments might raise the performance of the biodegradation in for instance, a constructed wetland.
Date January 2010
CreatorsSvensson, Henric
PublisherLinnéuniversitetet, Institutionen för naturvetenskap, NV
Source SetsDiVA Archive at Upsalla University
Detected LanguageEnglish
TypeStudent thesis, info:eu-repo/semantics/bachelorThesis, text

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