title: Studies of anodising sludge and its uses

authors: Patel, Purvesh Vinodbhai

subjects: Anodising alum waste

abstract: Anodising is an important finishing technique used to produce controlled oxide coating on aluminium extrusions which impart aesthetic finish, longer life and resistance to corrosion and abrasion. The anodising process however leads to generation of significant amounts of acid and alkaline waste containing mainly aluminium. Normally these wastes are neutralised producing aluminium hydroxide sludge the disposal of which is problematic. Finex is New Zealand's most recently developed anodising plant established in Hamilton in 2004. During the first period of operation the company was faced with a costly sludge disposal problem. The present project was devised to study their production plant and wastewater treatment plant. A brief study of the sludge showed that even under optimum conditions and with use of polyelectrolyte, gravity settling produced excessive volumes of sludge. The decision was made to install a plate and frame filter press. With the reduction of its bulk by dewatering, the problem of sludge disposal was essentially solved. However the 12 tonnes per week of dewatered sludge production still posed the challenge of devising a way of using the material beneficially. The characteristics of the sludge were determined and routes to commodity products were investigated.
Commodity alum was produced in good yield at 4 C by treatment of the sludge with sulphuric acid followed by crystallisation with anhydrous potassium sulphate. The product was very similar to the commercial product. Under basic conditions, sodium aluminate was produced by adding stoichiometric amount of OH-. Under acid conditions at the H+/Al(OH)3 stoichiometric ratio of 3, 95% of the aluminium was recovered as aluminium salt solution. When acid addition was less than the stoichiometric ratio of 3, the polyelectrolyte containing sludge showed little tendency to re-suspend. A variety of mechanical and thermal methods was used in an attempt to disaggregate and re-suspend the sludge. These included ultrasonic treatment at 80 C at frequency 14 kHz for 6 hours, autoclaving the sludge in electrical furnace at 150 C for 6 hours, homogenisation at 3000 rpm for 30 minutes at 20 C and mechanical grinding using mortar and pestle at 20 C. The ultrasonic treatment was effective in re-suspending 30% of the sludge. The other treatments were largely ineffective. On comparing the heavy metal concentration present in the original anodising sludge with the heavy metal concentration in the recovered commodity products, it was found that heavy metal content reduction was achieved with the alum crystallisation process. On producing aluminate, Cd, Mg and Ni were reduced through the removal of insoluble hydroxides. Minimal reduction of heavy metal content was achieved in the acidic aluminium chloride solution. The acidic and alkaline products prepared from anodising sludge were tested for their usefulness as coagulation agents. Critical coagulation concentrations for kaolin suspensions for all products were determined to be 5 mg/L. For all systems except the ultrasonic re-suspended sludge, clear solutions of low turbidity resulted after 1 hour standing. An analysis of the cost recovery of various commodity products from waste sludge indicated that recovery of acid aluminium chloride solution was most cost effective while the recovery of alum produces the purest product. Assuming that the acid aluminium chloride solution could be substituted for and sold at the same per kg of aluminium price as polyaluminium chloride, a 52% margin over consumables cost allows the possibility of a modest profit. The main benefit to Finex from proceeding with a sludge recovery program however is likely to be enhancement of the companies green credentials.

text: Studies of anodising sludge and its uses Anodising is an important finishing technique used to produce controlled oxide coating on aluminium extrusions which impart aesthetic finish, longer life and resistance to corrosion and abrasion. The anodising process however leads to generation of significant amounts of acid and alkaline waste containing mainly aluminium. Normally these wastes are neutralised producing aluminium hydroxide sludge the disposal of which is problematic. Finex is New Zealand's most recently developed anodising plant established in Hamilton in 2004. During the first period of operation the company was faced with a costly sludge disposal problem. The present project was devised to study their production plant and wastewater treatment plant. A brief study of the sludge showed that even under optimum conditions and with use of polyelectrolyte, gravity settling produced excessive volumes of sludge. The decision was made to install a plate and frame filter press. With the reduction of its bulk by dewatering, the problem of sludge disposal was essentially solved. However the 12 tonnes per week of dewatered sludge production still posed the challenge of devising a way of using the material beneficially. The characteristics of the sludge were determined and routes to commodity products were investigated.
Commodity alum was produced in good yield at 4 C by treatment of the sludge with sulphuric acid followed by crystallisation with anhydrous potassium sulphate. The product was very similar to the commercial product. Under basic conditions, sodium aluminate was produced by adding stoichiometric amount of OH-. Under acid conditions at the H+/Al(OH)3 stoichiometric ratio of 3, 95% of the aluminium was recovered as aluminium salt solution. When acid addition was less than the stoichiometric ratio of 3, the polyelectrolyte containing sludge showed little tendency to re-suspend. A variety of mechanical and thermal methods was used in an attempt to disaggregate and re-suspend the sludge. These included ultrasonic treatment at 80 C at frequency 14 kHz for 6 hours, autoclaving the sludge in electrical furnace at 150 C for 6 hours, homogenisation at 3000 rpm for 30 minutes at 20 C and mechanical grinding using mortar and pestle at 20 C. The ultrasonic treatment was effective in re-suspending 30% of the sludge. The other treatments were largely ineffective. On comparing the heavy metal concentration present in the original anodising sludge with the heavy metal concentration in the recovered commodity products, it was found that heavy metal content reduction was achieved with the alum crystallisation process. On producing aluminate, Cd, Mg and Ni were reduced through the removal of insoluble hydroxides. Minimal reduction of heavy metal content was achieved in the acidic aluminium chloride solution. The acidic and alkaline products prepared from anodising sludge were tested for their usefulness as coagulation agents. Critical coagulation concentrations for kaolin suspensions for all products were determined to be 5 mg/L. For all systems except the ultrasonic re-suspended sludge, clear solutions of low turbidity resulted after 1 hour standing. An analysis of the cost recovery of various commodity products from waste sludge indicated that recovery of acid aluminium chloride solution was most cost effective while the recovery of alum produces the purest product. Assuming that the acid aluminium chloride solution could be substituted for and sold at the same per kg of aluminium price as polyaluminium chloride, a 52% margin over consumables cost allows the possibility of a modest profit. The main benefit to Finex from proceeding with a sludge recovery program however is likely to be enhancement of the companies green credentials.

year: 2008

title: Extracting information from time series data from rechargable batteries

authors: Wilson, Marcus T.

abstract: In practical applications such as electric vehicles, mobile phones, etc, rechargable batteries are continually charged and discharged, resulting in time-varying voltages and currents. The relationship between voltage and current depends on the properties of the battery and analysis of the time-series can yield useful information about battery performance. However, analysis is complicated because the charge-discharge cycles are not periodic or regular.  For example, in an electric vehicle the battery might undergo intensive periods of discharge and charge, corresponding to acceleration and regenerative braking respectively, while the vehicle is in use, followed by long periods of inactivity.  There is structure on the timescales of seconds through to days. We have recorded voltage, current and temperature of several batteries in a laboratory as they have been continually cycled over many months using both regular and irregular cycles, the latter mimicking cycles experienced in practical applications. We have used established methods of time-series analysis such as the Hilbert Transform to investigate the relationships between voltage and current, and have shown that results agree with more sophisticated but less practical methods of battery characterisation such as electrical impedance spectroscopy. The relationships imply that several different processes occur, depending on time-scale.

text: Extracting information from time series data from rechargable batteries In practical applications such as electric vehicles, mobile phones, etc, rechargable batteries are continually charged and discharged, resulting in time-varying voltages and currents. The relationship between voltage and current depends on the properties of the battery and analysis of the time-series can yield useful information about battery performance. However, analysis is complicated because the charge-discharge cycles are not periodic or regular.  For example, in an electric vehicle the battery might undergo intensive periods of discharge and charge, corresponding to acceleration and regenerative braking respectively, while the vehicle is in use, followed by long periods of inactivity.  There is structure on the timescales of seconds through to days. We have recorded voltage, current and temperature of several batteries in a laboratory as they have been continually cycled over many months using both regular and irregular cycles, the latter mimicking cycles experienced in practical applications. We have used established methods of time-series analysis such as the Hilbert Transform to investigate the relationships between voltage and current, and have shown that results agree with more sophisticated but less practical methods of battery characterisation such as electrical impedance spectroscopy. The relationships imply that several different processes occur, depending on time-scale.

year: 2023-09-15

title: Integrating mātauranga Māori into community resilience frameworks for the built environment

authors: Dunlop, Ezra

abstract: Efforts to improve community resilience have seen universal efforts to grow capabilities in disaster management for the built environment. Although comprehensive frameworks exist, the perspective used to derive these frameworks fails to address marginalised communities' vulnerabilities, including the Indigenous Māori people. Colonisation and socio-economic deprivation of Māori mean community response frameworks fail to reflect their values and specific needs when preparing and responding to natural disasters.
The nature of Māori culture and values presents an opportunity to reimagine the scope of community resilience for an inclusive framework. The Māori history has resilient practices weaved into the very fabric of their culture through the oral transmission of waiata, whakataukī, whakairo, and pūrākau. The practice of community resilience amongst ancient Māori was not consigned to singular events but is a holistic perspective bound to their manner of living. Sourcing and qualifying this information from people aligned and immersed in nature is the knowledge required to improve the frameworks to respond to natural disasters while expanding the literature on community resilience.
This study collaborated with Ngāti Toa to represent the Māori worldview using tikanga Māori and Kaupapa Māori methodology in an action-based participatory research approach. The research analyzed traditional Māori resilience through wānanga and korero kanohi-ki-te-kanohi and evaluated various mātauranga, tikanga, and kaupapa that relate to the resilient nature of Ngāti Toa. Modern Māori perspectives of community resilience were compared to this information using a realistic earthquake scenario in the Wellington region. This led to expanding community resilience to be more inclusive of Māori communities and informed measures to enhance their resilience and address their unique needs following a disaster.
This study found that the Ngāti Toa community employs traditional resilience practices dating back to their migration to Aotearoa from Hawaiki. These practices are community-led and grounded in unity, with resilience being viewed as a collective responsibility. The study identified various Te Ao Māori resilience principles by translating traditional resilience principles into corresponding Te Ao Māori principles. A response and recovery plan was developed for Ngāti Toa in response to a realistic earthquake scenario. This plan includes a vulnerability matrix and a community resilience calculator to inform Ngāti Toa of their vulnerability level and needs following a disaster.
The community resilience frameworks developed for the Wellington region in response to the 7.5 magnitude earthquake were found to be economically dependent and did not utilize the response capabilities and strengths of Ngāti Toa. The frameworks lacked proper representation from Ngāti Toa and failed to address the needs of the Māori community in Wellington, resulting in inequitable outcomes. To rectify this,
Page | iii
community resilience frameworks for Māori should adopt a principle-based approach that supports collaborative engagement and integrates Māori cultural values. Unity is a crucial strength underpinning Māori resilience. Technological mediums such as retrofitting Marae should be developed to enhance Māori response capabilities and harness the strengths of Te Ao Māori resilience.

text: Integrating mātauranga Māori into community resilience frameworks for the built environment Efforts to improve community resilience have seen universal efforts to grow capabilities in disaster management for the built environment. Although comprehensive frameworks exist, the perspective used to derive these frameworks fails to address marginalised communities' vulnerabilities, including the Indigenous Māori people. Colonisation and socio-economic deprivation of Māori mean community response frameworks fail to reflect their values and specific needs when preparing and responding to natural disasters.
The nature of Māori culture and values presents an opportunity to reimagine the scope of community resilience for an inclusive framework. The Māori history has resilient practices weaved into the very fabric of their culture through the oral transmission of waiata, whakataukī, whakairo, and pūrākau. The practice of community resilience amongst ancient Māori was not consigned to singular events but is a holistic perspective bound to their manner of living. Sourcing and qualifying this information from people aligned and immersed in nature is the knowledge required to improve the frameworks to respond to natural disasters while expanding the literature on community resilience.
This study collaborated with Ngāti Toa to represent the Māori worldview using tikanga Māori and Kaupapa Māori methodology in an action-based participatory research approach. The research analyzed traditional Māori resilience through wānanga and korero kanohi-ki-te-kanohi and evaluated various mātauranga, tikanga, and kaupapa that relate to the resilient nature of Ngāti Toa. Modern Māori perspectives of community resilience were compared to this information using a realistic earthquake scenario in the Wellington region. This led to expanding community resilience to be more inclusive of Māori communities and informed measures to enhance their resilience and address their unique needs following a disaster.
This study found that the Ngāti Toa community employs traditional resilience practices dating back to their migration to Aotearoa from Hawaiki. These practices are community-led and grounded in unity, with resilience being viewed as a collective responsibility. The study identified various Te Ao Māori resilience principles by translating traditional resilience principles into corresponding Te Ao Māori principles. A response and recovery plan was developed for Ngāti Toa in response to a realistic earthquake scenario. This plan includes a vulnerability matrix and a community resilience calculator to inform Ngāti Toa of their vulnerability level and needs following a disaster.
The community resilience frameworks developed for the Wellington region in response to the 7.5 magnitude earthquake were found to be economically dependent and did not utilize the response capabilities and strengths of Ngāti Toa. The frameworks lacked proper representation from Ngāti Toa and failed to address the needs of the Māori community in Wellington, resulting in inequitable outcomes. To rectify this,
Page | iii
community resilience frameworks for Māori should adopt a principle-based approach that supports collaborative engagement and integrates Māori cultural values. Unity is a crucial strength underpinning Māori resilience. Technological mediums such as retrofitting Marae should be developed to enhance Māori response capabilities and harness the strengths of Te Ao Māori resilience.

year: 2023