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: Improving Collaborative Drawing using HTML5

authors: Huang, Yu-Hsin (Amigo)

subjects: HTML5

abstract: This research looks into improving online web-based collaborative drawing using HTML5. Although many systems have been developed over a number of years, none of the applications released have been satisfactory for many artists; the core drawing experience was too different from a stand-alone drawing applications. Stand-alone drawing applications have better freedom of control with functions like undo and allow artists to work efficiently with hotkeys. The advent of the HTML5 Canvas Element and Websockets in recent browsers has provided new opportunities for collaborative online interaction. 
This research used an incremental development approach to build a prototype HTML5 drawing application providing new functionality for online collaborative drawing. The project was supported by two experienced artists throughout investigation, design, implementation and testing. The project artists helped validate design decisions and evaluate the implementation. 
As a result, a robust HTML5 collaborative drawing application was built. The prototype contains core drawing functionality that existing applications did not. Features include: undo and redo, free canvas transformation, complex hotkey interaction, custom canvas size support, colour wheel, and layers. All these features work smoothly in a fully synchronized network environment under a client-server model. The collaboration system uses an authoritative server structure with local prediction and re-synchronization to hide latency. 
Although the result is only a prototype, the evaluations from the project artists were very positive. Once more functionality targeted towards social interaction is built, the prototype will be ready for mass public testing. Although there are some issues caused by the immaturity of HTML5 technology, this project affirms its capability for collaborative web applications.

text: Improving Collaborative Drawing using HTML5 This research looks into improving online web-based collaborative drawing using HTML5. Although many systems have been developed over a number of years, none of the applications released have been satisfactory for many artists; the core drawing experience was too different from a stand-alone drawing applications. Stand-alone drawing applications have better freedom of control with functions like undo and allow artists to work efficiently with hotkeys. The advent of the HTML5 Canvas Element and Websockets in recent browsers has provided new opportunities for collaborative online interaction. 
This research used an incremental development approach to build a prototype HTML5 drawing application providing new functionality for online collaborative drawing. The project was supported by two experienced artists throughout investigation, design, implementation and testing. The project artists helped validate design decisions and evaluate the implementation. 
As a result, a robust HTML5 collaborative drawing application was built. The prototype contains core drawing functionality that existing applications did not. Features include: undo and redo, free canvas transformation, complex hotkey interaction, custom canvas size support, colour wheel, and layers. All these features work smoothly in a fully synchronized network environment under a client-server model. The collaboration system uses an authoritative server structure with local prediction and re-synchronization to hide latency. 
Although the result is only a prototype, the evaluations from the project artists were very positive. Once more functionality targeted towards social interaction is built, the prototype will be ready for mass public testing. Although there are some issues caused by the immaturity of HTML5 technology, this project affirms its capability for collaborative web applications.

year: 2014

title: Making sense of Te Whāriki a te Kōhanga Reo through toi Māori: A whānau approach

authors: McMillan, Hoana

abstract: The involvement of whānau in the teaching and learning process is important at every juncture of a child’s educational journey. Rich understanding of the curriculum enables whānau to make deep and meaningful contributions to discussions about their child’s development. It also presents an interesting challenge for educational settings to create opportunities for whānau to increase their knowledge of the curriculum. This article outlines the benefits of a toi Māori approach to support whānau understanding.

text: Making sense of Te Whāriki a te Kōhanga Reo through toi Māori: A whānau approach The involvement of whānau in the teaching and learning process is important at every juncture of a child’s educational journey. Rich understanding of the curriculum enables whānau to make deep and meaningful contributions to discussions about their child’s development. It also presents an interesting challenge for educational settings to create opportunities for whānau to increase their knowledge of the curriculum. This article outlines the benefits of a toi Māori approach to support whānau understanding.

year: 2023