title: Wetland biodiversity in Aotearoa New Zealand: an eDNA perspective on exotic and non-exotic species

authors: Bird, Starsha

abstract: Invasive species threaten biodiversity in Aotearoa New Zealand. In wetlands − significant sites that provide an array of ecosystem and cultural services but represent <10% of their original extent − invasive species can affect hydrological function, nutrient regimes and overall ecological functionality. Environmental DNA (eDNA) has emerged as a valuable biomonitoring technique for cataloguing biodiversity and detecting biological incursions, but little is known about how biodiversity varies in wetlands over fine and broad spatial scales. Here, we examined the publicly available eDNA database of Wilderlab New Zealand, retrieving data from 26 sites across the country to characterise taxonomic diversity patterns, including the extent of exotic and non-exotic (native and endemic) species. We found significant spatial variation in biodiversity–even among neighbouring sites–and a pattern whereby all sites had ≥50% exotic species in their total species tally. Our results provide new information on the current state of wetland biodiversity in Aotearoa New Zealand and highlight the value of eDNA databases for generating new insights from publicly shared data. They also emphasise an urgent need for greater resource allocation to conservation and restoration initiatives in Aotearoa New Zealand that will ensure the persistence of treasured native and endemic wetland species.

text: Wetland biodiversity in Aotearoa New Zealand: an eDNA perspective on exotic and non-exotic species Invasive species threaten biodiversity in Aotearoa New Zealand. In wetlands − significant sites that provide an array of ecosystem and cultural services but represent <10% of their original extent − invasive species can affect hydrological function, nutrient regimes and overall ecological functionality. Environmental DNA (eDNA) has emerged as a valuable biomonitoring technique for cataloguing biodiversity and detecting biological incursions, but little is known about how biodiversity varies in wetlands over fine and broad spatial scales. Here, we examined the publicly available eDNA database of Wilderlab New Zealand, retrieving data from 26 sites across the country to characterise taxonomic diversity patterns, including the extent of exotic and non-exotic (native and endemic) species. We found significant spatial variation in biodiversity–even among neighbouring sites–and a pattern whereby all sites had ≥50% exotic species in their total species tally. Our results provide new information on the current state of wetland biodiversity in Aotearoa New Zealand and highlight the value of eDNA databases for generating new insights from publicly shared data. They also emphasise an urgent need for greater resource allocation to conservation and restoration initiatives in Aotearoa New Zealand that will ensure the persistence of treasured native and endemic wetland species.

year: 2024-06-05

title: Landfill leachate treatment: Using sequencing batch reactor technology to remove high ammonium concentration

authors: Lu, Philip Andrew

subjects: landfill leachate

abstract: Landfilling requires various consents and regulations in order to operate most effectively and cause minimal environmental issues to its immediate surroundings. The contaminated liquid produced from precipitation seeping through the layers of waste in landfills are generally called landfill leachate or leachate. Sequencing batch reactors (SBR) are fill-and-draw activated sludge systems that facilitate wastewater treatment in a singular reactor, while utilizing a sequence of different phases to create aerobic, anoxic, and sometimes anaerobic conditions. Multiple studies have been done that demonstrate the capacity of SBRs to treat wastewater for varying strengths of wastewater and concentration of contaminants, including ammonium. The objectives of the research are to: 1. run a lab-scale sequencing batch reactor to treat ammonium concentrations similar to that of landfill leachate; 2. design a full-scale sequencing batch reactor for landfills based on the bench-scale reactor’s ammonium removal potential; and 3. analyse the viability and economic feasibility of a SBR for treating landfill leachate.

Two lab-scale SBRs are used in the experiment. SBR 1 was run for 250 days of operation, while SBR 2 was run for only 130 days. These achieved ammonium removal at influent ammonium loading as high as 720 mg/L, and the SBR achieved ammonium removal efficiency of 90% to 100% with a TSS of 17 to 18 g/L during this most stable period of operation. pH control was required at higher influent ammonium loadings above 300 mg/L. Removal rates over the stable periods of operation are calculated to be at 1.65 and 1.55 mg NH4+ removed/g TSS/ per cycle for SBR 1 and 2, respectively. An ammonium removal rate of 0.0508 mg NH4+/L/min is calculated based on measurements using an ammonium ISE probe. Inhibition in ammonium removal due to low pH is observed. With extended aeration and pH control the ammonium removal continued as long as pH is maintained above 6.5. The oxygen consumption rate is also found to be at 0.01 mg DO/L/min, while the average mass transfer coefficient of O2 at 0.0144 min-1, and the percentage of oxygen transferred from gas to the mixed liquor calculated to be at 14.8%.

The full-scale SBR design is based on rates calculated from the experimental set-up and approximate leachate flow rate, based on precipitation, in the Waikato region. An area of 49 hectares landfilled is considered, which is similar to one of the class 1 municipal sanitary landfills in the region. A landfill leachate ammonium concentration range of 600 to 1500 mg/L is considered for the full-scale SBR design. The full-scale SBR is calculated to require a working volume of 8168 m3. The capital and operating cost of which shows high economic feasibility, and is estimated to be cost-effective compared to the cost of offsite treatment.

text: Landfill leachate treatment: Using sequencing batch reactor technology to remove high ammonium concentration Landfilling requires various consents and regulations in order to operate most effectively and cause minimal environmental issues to its immediate surroundings. The contaminated liquid produced from precipitation seeping through the layers of waste in landfills are generally called landfill leachate or leachate. Sequencing batch reactors (SBR) are fill-and-draw activated sludge systems that facilitate wastewater treatment in a singular reactor, while utilizing a sequence of different phases to create aerobic, anoxic, and sometimes anaerobic conditions. Multiple studies have been done that demonstrate the capacity of SBRs to treat wastewater for varying strengths of wastewater and concentration of contaminants, including ammonium. The objectives of the research are to: 1. run a lab-scale sequencing batch reactor to treat ammonium concentrations similar to that of landfill leachate; 2. design a full-scale sequencing batch reactor for landfills based on the bench-scale reactor’s ammonium removal potential; and 3. analyse the viability and economic feasibility of a SBR for treating landfill leachate.

Two lab-scale SBRs are used in the experiment. SBR 1 was run for 250 days of operation, while SBR 2 was run for only 130 days. These achieved ammonium removal at influent ammonium loading as high as 720 mg/L, and the SBR achieved ammonium removal efficiency of 90% to 100% with a TSS of 17 to 18 g/L during this most stable period of operation. pH control was required at higher influent ammonium loadings above 300 mg/L. Removal rates over the stable periods of operation are calculated to be at 1.65 and 1.55 mg NH4+ removed/g TSS/ per cycle for SBR 1 and 2, respectively. An ammonium removal rate of 0.0508 mg NH4+/L/min is calculated based on measurements using an ammonium ISE probe. Inhibition in ammonium removal due to low pH is observed. With extended aeration and pH control the ammonium removal continued as long as pH is maintained above 6.5. The oxygen consumption rate is also found to be at 0.01 mg DO/L/min, while the average mass transfer coefficient of O2 at 0.0144 min-1, and the percentage of oxygen transferred from gas to the mixed liquor calculated to be at 14.8%.

The full-scale SBR design is based on rates calculated from the experimental set-up and approximate leachate flow rate, based on precipitation, in the Waikato region. An area of 49 hectares landfilled is considered, which is similar to one of the class 1 municipal sanitary landfills in the region. A landfill leachate ammonium concentration range of 600 to 1500 mg/L is considered for the full-scale SBR design. The full-scale SBR is calculated to require a working volume of 8168 m3. The capital and operating cost of which shows high economic feasibility, and is estimated to be cost-effective compared to the cost of offsite treatment.

year: 2024-02-20

title: 'Waitangi and indigenous rights: Revolution, law and legitimacy' by F.M. Brookfield

authors: Melbourne, Hirini

subjects: indigenous rights

abstract: 'Waitangi and Indigenous Rights: Revolution, Law and Legitimacy' book review by Hirini Melbourne.

text: 'Waitangi and indigenous rights: Revolution, law and legitimacy' by F.M. Brookfield 'Waitangi and Indigenous Rights: Revolution, Law and Legitimacy' book review by Hirini Melbourne.

year: 2000-10