title: Construction and demolition waste as low-cost materials for the removal of heavy metal ions from wastewater

authors: Ranaweera, Kavitha H.

abstract: Water pollution due to heavy metal ion contaminations and management of construction and demolition waste (CDW) are two major environmental issues faced by the world today. Exposure to heavy metal ions can cause serious health problems, and therefore, treatment of heavy metal contaminated water/wastewater to protect the environment and people is essential. The management of CDW has become a serious problem due to the large amounts generated each year. Only a small percentage of this waste is recycled, while the majority is disposed of in landfills with space running out to accommodate these materials. Repurposing CDW as low-cost materials for heavy metal ion treatment is thus a promising strategy as this not only contributes to CDW management but also to heavy metal ion remediation.
The research described in this thesis investigated the applicability of five CDW materials (particle board wood dust (PBW), medium density fiberboard (MDF) fines, biochar derived from particle board offcuts (PBB), Gibraltar board fines (GBF), and demolished concrete (DC)) for the treatment of Cd(II), Cu(II), Pb(II), and Zn(II) ions. The selected CDW materials were characterized by performing FTIR, SEM-EDX, TGA, XRD, and surface area analysis to identify the composition and nature of these materials. The effect of different parameters (metal ion type, contact time, initial metal ion concentration, pH, and material dosage) on the heavy metal ion removal process was investigated in single metal ion solution systems utilizing a batch method. All studied materials exhibited high removal efficiency for Pb(II) ions compared to the other metal ions except DC, which showed high removal efficiency towards Cu(II) ions. Therefore, Pb(II) was selected to evaluate the effect of other parameters for PBW, MDF fines, PBB, and GBF, whilst Cu(II) was used for DC. The results indicated that the main heavy metal ion removal mechanism of PBW, MDF fines, and PBB was adsorption, while DC and GBF utilized precipitation. The effect of competitive metal ions on the heavy metal ion removal
process was investigated using a Cd(II)-Cu(II) multi-metal ion system for DC and a Cd(II)-Pb(II) multi-metal ion system for other materials using a batch method. The results indicated that the presence of Cd(II) ions reduced Pb(II) ion removal efficiency for PBW, MDF fines, and PBB and Cu(II) ion removal efficiency of DC. However, Pb(II) ion removal by GBF was not affected. Experiments were carried out to investigate whether the selected CDW materials leached out any toxic substances. The results indicated that PBW and MDF fines increased TOC concentrations, while GBF increased calcium and sulfate concentrations in treated water.
Adsorption isothermal, kinetic, and adsorbent regeneration studies were carried out for CDW materials which utilized adsorption for the heavy metal ion removal. Adsorption isothermal studies were performed for single metal ion systems, and the Freundlich isotherm model fitted better with the experimental data of all studied materials. Adsorption kinetics of both single and multi-metal ion systems were evaluated, and the experimental data fitted better with either pseudo-second-order or Elovich kinetic models for all studied systems. The adsorbent regeneration studies were performed using 0.1 M HCl as a regeneration agent for three adsorption-desorption cycles for both metal ion systems. High % desorption values were obtained during the first cycle, however, the adsorption capacity was reduced in the subsequent cycles for all studied adsorption systems.
Column analyses were conducted for GBF and PBB for both single (Pb(II)) and multi-metal ion systems (Cd(II)-Pb(II)). High % removal values were obtained for Pb(II) ions in both metal ion systems for both materials. The experimental data of the PBB was fitted to column adsorption models as PBB utilized adsorption for heavy metal ion removal, and the Yan model fitted well with the experimental data of both metal ion systems. The results indicate that CDW materials have potential for heavy metal ion treatment. Further research is required to investigate the applicability of these materials in real-world applications.

text: Construction and demolition waste as low-cost materials for the removal of heavy metal ions from wastewater Water pollution due to heavy metal ion contaminations and management of construction and demolition waste (CDW) are two major environmental issues faced by the world today. Exposure to heavy metal ions can cause serious health problems, and therefore, treatment of heavy metal contaminated water/wastewater to protect the environment and people is essential. The management of CDW has become a serious problem due to the large amounts generated each year. Only a small percentage of this waste is recycled, while the majority is disposed of in landfills with space running out to accommodate these materials. Repurposing CDW as low-cost materials for heavy metal ion treatment is thus a promising strategy as this not only contributes to CDW management but also to heavy metal ion remediation.
The research described in this thesis investigated the applicability of five CDW materials (particle board wood dust (PBW), medium density fiberboard (MDF) fines, biochar derived from particle board offcuts (PBB), Gibraltar board fines (GBF), and demolished concrete (DC)) for the treatment of Cd(II), Cu(II), Pb(II), and Zn(II) ions. The selected CDW materials were characterized by performing FTIR, SEM-EDX, TGA, XRD, and surface area analysis to identify the composition and nature of these materials. The effect of different parameters (metal ion type, contact time, initial metal ion concentration, pH, and material dosage) on the heavy metal ion removal process was investigated in single metal ion solution systems utilizing a batch method. All studied materials exhibited high removal efficiency for Pb(II) ions compared to the other metal ions except DC, which showed high removal efficiency towards Cu(II) ions. Therefore, Pb(II) was selected to evaluate the effect of other parameters for PBW, MDF fines, PBB, and GBF, whilst Cu(II) was used for DC. The results indicated that the main heavy metal ion removal mechanism of PBW, MDF fines, and PBB was adsorption, while DC and GBF utilized precipitation. The effect of competitive metal ions on the heavy metal ion removal
process was investigated using a Cd(II)-Cu(II) multi-metal ion system for DC and a Cd(II)-Pb(II) multi-metal ion system for other materials using a batch method. The results indicated that the presence of Cd(II) ions reduced Pb(II) ion removal efficiency for PBW, MDF fines, and PBB and Cu(II) ion removal efficiency of DC. However, Pb(II) ion removal by GBF was not affected. Experiments were carried out to investigate whether the selected CDW materials leached out any toxic substances. The results indicated that PBW and MDF fines increased TOC concentrations, while GBF increased calcium and sulfate concentrations in treated water.
Adsorption isothermal, kinetic, and adsorbent regeneration studies were carried out for CDW materials which utilized adsorption for the heavy metal ion removal. Adsorption isothermal studies were performed for single metal ion systems, and the Freundlich isotherm model fitted better with the experimental data of all studied materials. Adsorption kinetics of both single and multi-metal ion systems were evaluated, and the experimental data fitted better with either pseudo-second-order or Elovich kinetic models for all studied systems. The adsorbent regeneration studies were performed using 0.1 M HCl as a regeneration agent for three adsorption-desorption cycles for both metal ion systems. High % desorption values were obtained during the first cycle, however, the adsorption capacity was reduced in the subsequent cycles for all studied adsorption systems.
Column analyses were conducted for GBF and PBB for both single (Pb(II)) and multi-metal ion systems (Cd(II)-Pb(II)). High % removal values were obtained for Pb(II) ions in both metal ion systems for both materials. The experimental data of the PBB was fitted to column adsorption models as PBB utilized adsorption for heavy metal ion removal, and the Yan model fitted well with the experimental data of both metal ion systems. The results indicate that CDW materials have potential for heavy metal ion treatment. Further research is required to investigate the applicability of these materials in real-world applications.

year: 2024

title: Environmental Aspects of Proteinous Bioplastic

authors: Hicks, Talia

subjects: bioplastic

abstract: During the processing of Novatein Thermoplastic Protein (NTP), volatile compounds are released which are odourous and potentially harmful. For NTP to be manufactured on a commercial scale the odour that currently arises during production must be minimised.
Literature revealed that blood components are thermally unstable under oxidising conditions and in addition, the presence of iron in bloodmeal, may catalyse the formation of various odourous compounds.
The objectives of this work were to establish an odour profile for bloodmeal and pre-extruded NTP (PNTP) and determine the effect of chemically treating bloodmeal on the resulting odour profile. In addition, the potential for NTP to be degraded by composting and effect of prolonged exposure to UV radiation was investigated.
It was found that the initial odour of bloodmeal was caused by putrefaction during the storage of whole blood prior to drying as well as the formation of other, less odourous, volatile compounds derived from lipids and proteins during drying.
The odour profile of pre-extruded NTP (PNTP) was found to change after chemical treatment of bloodmeal. Chemical treatments successfully minimised or changed the odour of the bloodmeal. Peracetic acid treatment successfully removed the characteristic bloodmeal odour resulting in decolourised bloodmeal with a mild vinegar odour. In general, removing odour from the PNTP could not be achieved without the addition of 10-20 wt% activated carbon or greater than 20 wt% natural zeolite.
Additionally, for NTP to be marketed as biodegradable as well as bio-derived plastic, it must be shown to degrade in the environment at a rate comparable with cellulose. NTP was found to undergo substantial deterioration and polymer degradation within 12 weeks of composting, for plasticised samples up to 47 % dry mass loss was observed. However, exposure to 12 weeks of ultra-violet radiation, lead to embrittlement of the plastic with very little polymer degradation occurring.

text: Environmental Aspects of Proteinous Bioplastic During the processing of Novatein Thermoplastic Protein (NTP), volatile compounds are released which are odourous and potentially harmful. For NTP to be manufactured on a commercial scale the odour that currently arises during production must be minimised.
Literature revealed that blood components are thermally unstable under oxidising conditions and in addition, the presence of iron in bloodmeal, may catalyse the formation of various odourous compounds.
The objectives of this work were to establish an odour profile for bloodmeal and pre-extruded NTP (PNTP) and determine the effect of chemically treating bloodmeal on the resulting odour profile. In addition, the potential for NTP to be degraded by composting and effect of prolonged exposure to UV radiation was investigated.
It was found that the initial odour of bloodmeal was caused by putrefaction during the storage of whole blood prior to drying as well as the formation of other, less odourous, volatile compounds derived from lipids and proteins during drying.
The odour profile of pre-extruded NTP (PNTP) was found to change after chemical treatment of bloodmeal. Chemical treatments successfully minimised or changed the odour of the bloodmeal. Peracetic acid treatment successfully removed the characteristic bloodmeal odour resulting in decolourised bloodmeal with a mild vinegar odour. In general, removing odour from the PNTP could not be achieved without the addition of 10-20 wt% activated carbon or greater than 20 wt% natural zeolite.
Additionally, for NTP to be marketed as biodegradable as well as bio-derived plastic, it must be shown to degrade in the environment at a rate comparable with cellulose. NTP was found to undergo substantial deterioration and polymer degradation within 12 weeks of composting, for plasticised samples up to 47 % dry mass loss was observed. However, exposure to 12 weeks of ultra-violet radiation, lead to embrittlement of the plastic with very little polymer degradation occurring.

year: 2010

title: ʺThree Strikesʺ sentencing: Another blow for Māori

authors: Rumbles, Wayne

abstract: On June 1, 2010 the Sentencing and Parole Reform Act 2010 amended the Sentencing Act and introduced into New Zealand the so-called “three strikes” sentencing regime. The rationale for introducing this sentencing regime was that it would protect the public, deter offenders, and improve public confidence in the criminal justice system. The stated purpose of the Act is:
• To deny parole to certain repeat offender and to offenders guilty of the worst murders.
• Impose maximum terms of imprisonment on persistent repeat offenders who continue to commit serious violent offences.
This legislative comment will argue that this regime will disproportionately impact on Māori who are already over represented in the criminal justice system at every level. The Department of Corrections has reaffirmed that amplification of Māori within the system is at least in part due to systemic factors that operate at one or more steps of the criminal justice process which make it more likely for Māori to be apprehended, arrested, charged, convicted or imprisoned, with the result that Māori “accumulate” in the system in greater numbers. Given that there is some systematic bias discernable around Māori in the criminal justice system, any habitual offender-sentencing regime will disproportionately impact on Māori, feeding a cycle of increasing Māori incarceration.

text: ʺThree Strikesʺ sentencing: Another blow for Māori On June 1, 2010 the Sentencing and Parole Reform Act 2010 amended the Sentencing Act and introduced into New Zealand the so-called “three strikes” sentencing regime. The rationale for introducing this sentencing regime was that it would protect the public, deter offenders, and improve public confidence in the criminal justice system. The stated purpose of the Act is:
• To deny parole to certain repeat offender and to offenders guilty of the worst murders.
• Impose maximum terms of imprisonment on persistent repeat offenders who continue to commit serious violent offences.
This legislative comment will argue that this regime will disproportionately impact on Māori who are already over represented in the criminal justice system at every level. The Department of Corrections has reaffirmed that amplification of Māori within the system is at least in part due to systemic factors that operate at one or more steps of the criminal justice process which make it more likely for Māori to be apprehended, arrested, charged, convicted or imprisoned, with the result that Māori “accumulate” in the system in greater numbers. Given that there is some systematic bias discernable around Māori in the criminal justice system, any habitual offender-sentencing regime will disproportionately impact on Māori, feeding a cycle of increasing Māori incarceration.

year: 2011