title: Influence of alkali fiber treatment and fiber processing on the mechanical properties of hemp/epoxy composites

authors: Islam, Mohammad Saiful

subjects: hemp fiber

abstract: Industrial hemp fibers were treated with a 5 wt % NaOH, 2 wt % Na₂SO₃ solution at 120°C for 60 min to remove noncellulosic fiber components. Analysis of fibers by lignin analysis, scanning electron microscopy (SEM), zeta potential, Fourier transform infrared (FTIR) spectroscopy, wide angle X-ray diffraction (WAXRD) and differential thermal/thermogravimetric analysis (DTA/TGA), supported that alkali treatment had (i) removed lignin, (ii) separated fibers from their fiber bundles, (iii) exposed cellulose hydroxyl groups, (iv) made the fiber surface cleaner, and (v) enhanced thermal stability of the fibers by increasing cellulose crystallinity through better packing of cellulose chains. Untreated and alkali treated short (random and aligned) and long (aligned) hemp fiber/epoxy composites were produced with fiber contents between 40 and 65 wt %. Although alkali treatment generally improved composite strength, better strength at high fiber contents for long fiber composites was achieved with untreated fiber, which appeared to be due to less fiber/fiber contact between alkali treated fibers. Composites with 65 wt % untreated, long aligned fiber were the strongest with a tensile strength (TS) of 165 MPa, Young's modulus (YM) of 17 GPa, flexural strength of 180 MPa, flexural modulus of 9 GPa, impact energy (IE) of 14.5 kJ/m², and fracture toughness (KIc) of 5 MPa m1/2

text: Influence of alkali fiber treatment and fiber processing on the mechanical properties of hemp/epoxy composites Industrial hemp fibers were treated with a 5 wt % NaOH, 2 wt % Na₂SO₃ solution at 120°C for 60 min to remove noncellulosic fiber components. Analysis of fibers by lignin analysis, scanning electron microscopy (SEM), zeta potential, Fourier transform infrared (FTIR) spectroscopy, wide angle X-ray diffraction (WAXRD) and differential thermal/thermogravimetric analysis (DTA/TGA), supported that alkali treatment had (i) removed lignin, (ii) separated fibers from their fiber bundles, (iii) exposed cellulose hydroxyl groups, (iv) made the fiber surface cleaner, and (v) enhanced thermal stability of the fibers by increasing cellulose crystallinity through better packing of cellulose chains. Untreated and alkali treated short (random and aligned) and long (aligned) hemp fiber/epoxy composites were produced with fiber contents between 40 and 65 wt %. Although alkali treatment generally improved composite strength, better strength at high fiber contents for long fiber composites was achieved with untreated fiber, which appeared to be due to less fiber/fiber contact between alkali treated fibers. Composites with 65 wt % untreated, long aligned fiber were the strongest with a tensile strength (TS) of 165 MPa, Young's modulus (YM) of 17 GPa, flexural strength of 180 MPa, flexural modulus of 9 GPa, impact energy (IE) of 14.5 kJ/m², and fracture toughness (KIc) of 5 MPa m1/2

year: 2010-10

title: Use of high-rate filamentous algal ponds for primary municipal wastewater treatment

authors: Novak, Indira

abstract: High-rate filamentous algal pond (HRFAP) systems offer a promising alternative to conventional municipal wastewater treatment. Research on selecting filamentous algal species for municipal wastewater bioremediation is currently limited. Chapter 2 introduces a screening protocol aimed at identifying robust cultivars suitable for HRFAP monoculture systems. Evaluating eleven cultivars under local seasonal ambient and extreme conditions played a crucial role in cultivar selection. Based on their consistent biomass productivity and bioremediation performance across ambient and extreme conditions, Klebsormidium sp. (KLEB B), Stigeoclonium sp. (STIG A) and Ulothrix sp. were identified as target cultivars for nutrient bioremediation of primary municipal wastewater.

The identification of target cultivars has previously been based on laboratory conditions, which are insufficient for practical applications. Chapter 3 assessed the biomass productivity and nutrient bioremediation performance of three cultivars - Klebsormidium flaccidum, Oedogonium calcareum, and Oedogonium sp. – in outdoor HRFAP mesocosms. K. flaccidum had the highest biomass productivity and bioremediation performance, while O. calcareum had complete die-off. Competition experiments at varying stocking densities highlighted K. flaccidum dominance at lower densities (0.25 and 0.5 g FW L-1), positioning it as the preferred cultivar for nutrient bioremediation in primary municipal wastewater within HRFAP systems.

Effective management of operational parameters is crucial for optimising wastewater treatment in HRFAP systems. Therefore, in Chapter 4 the effects of hydraulic retention time (HRT), stocking density, and harvest frequency on the growth and nutrient bioremediation performance of K. flaccidum in primary municipal wastewater in outdoor HRFAPs were examined during summer and winter. Seasonal conditions impacted biomass productivity, which was 48.3% higher in summer compared to winter. A HRT of 4 days was optimal for both seasons based on bioremediation of total ammoniacal-nitrogen (TAN). Lower stocking densities of 0.25 and 0.5 g FW L-1 demonstrated enhanced bioremediation efficiency, while higher densities were preferable during slower growth periods to mitigate potential toxicity risks from primary wastewater. Harvest frequencies of two, four and six days did not significantly affect nutrient removal rates across different treatments and seasons. These results highlight the importance of seasonal optimisation of HRFAP systems to maximise biomass production and nutrient bioremediation. 

Wastewater treatment plants (WWTPs) are major sources of per- and polyfluoroalkyl substances (PFAS) pollution entering the environment. Certain algal species have demonstrated the ability to bioaccumulate PFAS compounds, indicating their potential for removing PFAS from wastewater. Therefore, in Chapter 5 a laboratory study was conducted to assess the ability of K. flaccidum to reduce concentrations of PFAS and PFAS precursors in primary municipal wastewater under two HRTs. K. flaccidum maintained stable productivity in the wastewater. Removal rates of PFAS and PFAS precursors, however, varied considerably. Specifically, reductions were observed in three individual PFAS and in all measured PFAS precursors present in the wastewater. Despite these reductions, PFAS was not detected in the algal biomass of K. flaccidum, making it suitable for a range of biomass applications provided it remains free of other contaminants.

Overall, this thesis has demonstrated that HRFAP systems are an effective alternative treatment for nutrient reduction in primary municipal wastewater. Application of the screening protocol to select target species, and seasonal optimisation of HRFAP operating parameters will enable more consistent and effective year-round nutrient bioremediation and algal biomass productivity to be achieved.

text: Use of high-rate filamentous algal ponds for primary municipal wastewater treatment High-rate filamentous algal pond (HRFAP) systems offer a promising alternative to conventional municipal wastewater treatment. Research on selecting filamentous algal species for municipal wastewater bioremediation is currently limited. Chapter 2 introduces a screening protocol aimed at identifying robust cultivars suitable for HRFAP monoculture systems. Evaluating eleven cultivars under local seasonal ambient and extreme conditions played a crucial role in cultivar selection. Based on their consistent biomass productivity and bioremediation performance across ambient and extreme conditions, Klebsormidium sp. (KLEB B), Stigeoclonium sp. (STIG A) and Ulothrix sp. were identified as target cultivars for nutrient bioremediation of primary municipal wastewater.

The identification of target cultivars has previously been based on laboratory conditions, which are insufficient for practical applications. Chapter 3 assessed the biomass productivity and nutrient bioremediation performance of three cultivars - Klebsormidium flaccidum, Oedogonium calcareum, and Oedogonium sp. – in outdoor HRFAP mesocosms. K. flaccidum had the highest biomass productivity and bioremediation performance, while O. calcareum had complete die-off. Competition experiments at varying stocking densities highlighted K. flaccidum dominance at lower densities (0.25 and 0.5 g FW L-1), positioning it as the preferred cultivar for nutrient bioremediation in primary municipal wastewater within HRFAP systems.

Effective management of operational parameters is crucial for optimising wastewater treatment in HRFAP systems. Therefore, in Chapter 4 the effects of hydraulic retention time (HRT), stocking density, and harvest frequency on the growth and nutrient bioremediation performance of K. flaccidum in primary municipal wastewater in outdoor HRFAPs were examined during summer and winter. Seasonal conditions impacted biomass productivity, which was 48.3% higher in summer compared to winter. A HRT of 4 days was optimal for both seasons based on bioremediation of total ammoniacal-nitrogen (TAN). Lower stocking densities of 0.25 and 0.5 g FW L-1 demonstrated enhanced bioremediation efficiency, while higher densities were preferable during slower growth periods to mitigate potential toxicity risks from primary wastewater. Harvest frequencies of two, four and six days did not significantly affect nutrient removal rates across different treatments and seasons. These results highlight the importance of seasonal optimisation of HRFAP systems to maximise biomass production and nutrient bioremediation. 

Wastewater treatment plants (WWTPs) are major sources of per- and polyfluoroalkyl substances (PFAS) pollution entering the environment. Certain algal species have demonstrated the ability to bioaccumulate PFAS compounds, indicating their potential for removing PFAS from wastewater. Therefore, in Chapter 5 a laboratory study was conducted to assess the ability of K. flaccidum to reduce concentrations of PFAS and PFAS precursors in primary municipal wastewater under two HRTs. K. flaccidum maintained stable productivity in the wastewater. Removal rates of PFAS and PFAS precursors, however, varied considerably. Specifically, reductions were observed in three individual PFAS and in all measured PFAS precursors present in the wastewater. Despite these reductions, PFAS was not detected in the algal biomass of K. flaccidum, making it suitable for a range of biomass applications provided it remains free of other contaminants.

Overall, this thesis has demonstrated that HRFAP systems are an effective alternative treatment for nutrient reduction in primary municipal wastewater. Application of the screening protocol to select target species, and seasonal optimisation of HRFAP operating parameters will enable more consistent and effective year-round nutrient bioremediation and algal biomass productivity to be achieved.

year: 2024

title: The Impact of Colonisation on the Maori community: An exploration of the attitudes and perspectives held by Maori in relation to the active reclamation of Maori sovereignty/tino rangatiratanga.

authors: Baty, Tina Amy

subjects: Maori

abstract: Whāia te iti kahurangi ki te tūohu koe me he maunga teitei
Seek the treasure you value most dearly: If you bow your head, let it be to a lofty mountain
The purpose of my research was twofold. I first sort to explore the attitudes and perspectives held by Māori in relation to the active reclamation of Māori sovereignty, tino rangatiratanga. I further wanted to know how Māori sovereignty, tino rangatiratanga could lead to the improvement of Māori health.
My research collected information pertinent to these two inquiries from current literature and from interviews I conducted with five Māori individuals from different iwi, hapu groups. All whom were actively engaged with the Māori community in some form. My research data found that colonisalism has and continues to negatively impact the Māori community. This negative impact manifests in a variety of behaviours that effect Māori health and leads to poor outcomes for Māori. Māori sovereignty, tino rangatiratanga was thought of as the solution to overcome and neutralise the negative effects of colonialism experienced by Māori. Māori sovereignty, tino rangatiratanga was found to be related with Māori idenity and instrumental in all things pertinent to the Māori communities.
My research found that Māori sovereignty, tino rangatiratanga can be identified as existing on a philosophical level, governance-structural level, and on a day-to-day basis. This research found that the reclamation of Māori sovereignty, tino rangatiratanga is a process that is currently in motion. Finally, the exercising of Māori sovereignty, tino rangatiratanga in relation to Māori health provides a well-established argument that it can produce positive health benefits to the Māori community, because it is responsive to Māori and better meets the needs of our Māori community simply because it is a Māori way of being, doing and knowing.

text: The Impact of Colonisation on the Maori community: An exploration of the attitudes and perspectives held by Maori in relation to the active reclamation of Maori sovereignty/tino rangatiratanga. Whāia te iti kahurangi ki te tūohu koe me he maunga teitei
Seek the treasure you value most dearly: If you bow your head, let it be to a lofty mountain
The purpose of my research was twofold. I first sort to explore the attitudes and perspectives held by Māori in relation to the active reclamation of Māori sovereignty, tino rangatiratanga. I further wanted to know how Māori sovereignty, tino rangatiratanga could lead to the improvement of Māori health.
My research collected information pertinent to these two inquiries from current literature and from interviews I conducted with five Māori individuals from different iwi, hapu groups. All whom were actively engaged with the Māori community in some form. My research data found that colonisalism has and continues to negatively impact the Māori community. This negative impact manifests in a variety of behaviours that effect Māori health and leads to poor outcomes for Māori. Māori sovereignty, tino rangatiratanga was thought of as the solution to overcome and neutralise the negative effects of colonialism experienced by Māori. Māori sovereignty, tino rangatiratanga was found to be related with Māori idenity and instrumental in all things pertinent to the Māori communities.
My research found that Māori sovereignty, tino rangatiratanga can be identified as existing on a philosophical level, governance-structural level, and on a day-to-day basis. This research found that the reclamation of Māori sovereignty, tino rangatiratanga is a process that is currently in motion. Finally, the exercising of Māori sovereignty, tino rangatiratanga in relation to Māori health provides a well-established argument that it can produce positive health benefits to the Māori community, because it is responsive to Māori and better meets the needs of our Māori community simply because it is a Māori way of being, doing and knowing.

year: 2018