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The use of functionalised biochar to enhance phosphorus removal in woodchip bioreactors. The integration of mātauranga Māori to enhance the cultural aspects of woodchip bioreactors.

Nutrient pollution, resulting from excessive releases of nitrogen (N) and phosphorus (P) into waterways, poses a significant threat to aquatic ecosystems worldwide. Elevated nutrient levels can result in eutrophication, which can have detrimental effects on the health of waterbodies and their biota. Woodchip bioreactors are effective, edge-of-field technologies that can help mitigate nutrient pollution by lowering nutrient concentrations in agricultural drainage systems known to carry leached N and P into waterways. However, one limitation to their design is their ineffectiveness at removing P. The inclusion of functionalised biochar is one potential solution to enhance P removal in woodchip bioreactors. There is a growing need to mitigate nutrient pollution in New Zealand that does not depend on a western-centric perspective only. Integration of mātauranga Māori and western science into the design and operations of a woodchip bioreactor is one approach to incorporate both knowledge systems to the goal of mitigating nutrient pollution. In this dissertation, a column experiment was used to compare the P removal efficiencies of two treatments of functionalised biochar, and one treatment of woodchips when subjected to stream water spiked with P. Subsequently, a single phosphate extraction was done to determine the phosphate absorption capacities of each treatment. The results showed that the two functionalised biochar treatments had the highest efficacy in reducing P concentrations in the P-spiked stream water compared to the woodchip-only treatment. Both treatments also showed higher P absorption, evidenced from the Fe-P/Feox ratio, within the phosphate extraction experiment. A wānanga was organised at Matahuru Marae, Lake Waikare, to share mātauranga Māori on how to culturally enhance woodchip bioreactors from a Te Ao Māori perspective. Participants recommended that native woodchips be incorporated into woodchip bioreactors because of their inherent association to the land and people. Overall, the results implied that functionalised biochar is an effective solution to enhance P removal in woodchip bioreactors due to their biophysical properties to absorb and retain P. Secondly, incorporating native woodchips into woodchip bioreactors systems potentially offers a sustainable and culturally respected alternative to conventional wood chips, aligning with Māori values and tikanga
Type of thesis
The University of Waikato
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