title: Hydraulic properties, hydraulic efficiency and nitrate removal of organic carbon media for use in denitrification beds

authors: Cameron, Stewart Graham

subjects: Denitrification bed

abstract: Denitrification beds, utilising fragmented wood particles as the carbon source, have been successfully used to remove nitrate from point source discharge. Other more labile carbonaceous solids have provided higher short-term nitrate removal rates than wood in laboratory scale trials, but the longevity of these media is unproven. In addition, the nitrate removal rate of a bed is indicated to be temperature dependent. Improving the hydraulic efficiency of a denitrification bed, by reducing short-circuit flow, may also provide for increased long-term nitrate removal rate and reduced bed size and lower installation cost. In this study, we compared the hydraulic properties and hydraulic efficiency of nine carbon media, including five grain sizes of wood particles, in 0.2 m3 barrels, at two temperatures (14 °C and 23.5 °C). The relationship between hydraulic efficiency and nitrate removal of the different media was also investigated. We found that carbon substrate and temperature were more influential on nitrate removal rate than hydraulic efficiency of the media. While larger grain-sizes of wood media were less hydraulically efficient than smaller grain-sizes, the difference in hydraulic efficiency was small. We also found that primary porosity of the wood media increased with temperature, which may have been caused by contraction of the wood particles with increasing temperature due to loss of water from the cellulose to the liquid phase. While hydraulic properties and hydraulic efficiencies varied between carbon media, the variation did not cause significant difference in nitrate removal rate. The results indicate that future work on improving nitrate removal performance of denitrification beds should focus on carbon availability of the substrate and increasing bed temperature, rather than on identifying more hydraulically efficient media.

text: Hydraulic properties, hydraulic efficiency and nitrate removal of organic carbon media for use in denitrification beds Denitrification beds, utilising fragmented wood particles as the carbon source, have been successfully used to remove nitrate from point source discharge. Other more labile carbonaceous solids have provided higher short-term nitrate removal rates than wood in laboratory scale trials, but the longevity of these media is unproven. In addition, the nitrate removal rate of a bed is indicated to be temperature dependent. Improving the hydraulic efficiency of a denitrification bed, by reducing short-circuit flow, may also provide for increased long-term nitrate removal rate and reduced bed size and lower installation cost. In this study, we compared the hydraulic properties and hydraulic efficiency of nine carbon media, including five grain sizes of wood particles, in 0.2 m3 barrels, at two temperatures (14 °C and 23.5 °C). The relationship between hydraulic efficiency and nitrate removal of the different media was also investigated. We found that carbon substrate and temperature were more influential on nitrate removal rate than hydraulic efficiency of the media. While larger grain-sizes of wood media were less hydraulically efficient than smaller grain-sizes, the difference in hydraulic efficiency was small. We also found that primary porosity of the wood media increased with temperature, which may have been caused by contraction of the wood particles with increasing temperature due to loss of water from the cellulose to the liquid phase. While hydraulic properties and hydraulic efficiencies varied between carbon media, the variation did not cause significant difference in nitrate removal rate. The results indicate that future work on improving nitrate removal performance of denitrification beds should focus on carbon availability of the substrate and increasing bed temperature, rather than on identifying more hydraulically efficient media.

year: 2012

title: Matamata Piako District: Socio-Demographic Profile 1986-2031

authors: Jackson, Natalie

subjects: New Zealand

abstract: Matamata-Piako District has a larger proportion of those of European/New Zealand/Other ethnicity than either the Waikato Region or Total New Zealand, and a smaller proportion of both Maori and Pacific Island than the Waikato. Matamata-Piako also has substantially fewer people of Asian origin. In all cases, the number in each ethnic group has grown except for European/NZ/other. This group saw a small decline in its number in the 1996-2006 period, while Maori grew by 8 per cent, accounting for approximately 34 per cent of Matamata-Piako District’s growth, compared with 16 per cent of the Waikato’s.

text: Matamata Piako District: Socio-Demographic Profile 1986-2031 Matamata-Piako District has a larger proportion of those of European/New Zealand/Other ethnicity than either the Waikato Region or Total New Zealand, and a smaller proportion of both Maori and Pacific Island than the Waikato. Matamata-Piako also has substantially fewer people of Asian origin. In all cases, the number in each ethnic group has grown except for European/NZ/other. This group saw a small decline in its number in the 1996-2006 period, while Maori grew by 8 per cent, accounting for approximately 34 per cent of Matamata-Piako District’s growth, compared with 16 per cent of the Waikato’s.

year: 2013-03

title: The Critical Juncture in Aotearoa New Zealand and The Collective Future: Policy Issues in Settler/Invader Colonial Zombiism Found in “Biculturalism”

authors: Simon, Hemopereki

abstract: This theoretical Kaupapa Māori writing inquiry study seeks to explore the settler colonial nature of Aotearoa New Zealand. The research finds that biculturalism, as a neo-liberal and settler-colonial construct does not provide for either tino rangatiratanga or mana motuhake. Indeed, biculturalism fails to provide for indigenous inclusion and actively suppresses the recognition of mana motuhake. Biculturalism is found to fit Beck’s definition of Zombie Concepts. These are social concepts that are dead and yet kept alive in their use by scholars and society to describe the growing fiction of traditional social institutions and in being kept alive maintain, in this case, settler colonial and colonial power structures. The main argument is that Biculturalism is neoliberal and settler colonial public discourse, that needs to be unpacked and then discarded because it does not provide for tino rangatiranga or mana motuhake.

text: The Critical Juncture in Aotearoa New Zealand and The Collective Future: Policy Issues in Settler/Invader Colonial Zombiism Found in “Biculturalism” This theoretical Kaupapa Māori writing inquiry study seeks to explore the settler colonial nature of Aotearoa New Zealand. The research finds that biculturalism, as a neo-liberal and settler-colonial construct does not provide for either tino rangatiratanga or mana motuhake. Indeed, biculturalism fails to provide for indigenous inclusion and actively suppresses the recognition of mana motuhake. Biculturalism is found to fit Beck’s definition of Zombie Concepts. These are social concepts that are dead and yet kept alive in their use by scholars and society to describe the growing fiction of traditional social institutions and in being kept alive maintain, in this case, settler colonial and colonial power structures. The main argument is that Biculturalism is neoliberal and settler colonial public discourse, that needs to be unpacked and then discarded because it does not provide for tino rangatiranga or mana motuhake.

year: 2022