title: Electrolytic purification of water

authors: Mathieson, Grant Alexander

subjects: Electrolytic

abstract: This thesis develops the concept of an in situ electrolytic processor, a machine with electrochemical functions that purifies aqueous fluids at the point of production, whether from a bore water supply or effluent from a tannery. Where the contaminants in an effluent are useful they are separated in a specialised electrolyser for re-use in the process that produced the original effluent. The value in doing this exceeds the cost of electrolytic processing for tannery effluent. The functions of an electrolytic purifier were resolved into: flotation by bubbles, flocculation by corrosion of aluminium anodes, electrowinning by cathodic plating, disinfection, oxidation-reduction and pH modification. Improved understanding of the control of these functions has led to the ability to design better electrolysers because the functions were combined in a form that was appropriate to the required purification process. A link between extra-faradic corrosion of an aluminium anode and pH modification is postulated.

Electrochemical principles were used as the basis for development of real processor models. These models were tested using bore water, cooling tower fluid, virus contaminated water, laundry water, municipal waste water, landfill leachate and pulp mill effluent.

The most effective model, designed during the course of the project and described as the Flume, incorporated a novel corroding anode composed of thin pieces of aluminium, water flow in a cathodic flume, and a cheap water-porous membrane to separate the electrolyte into anolyte and catholyte. The novel anode was designed to improve clearance of corrosion products by maintaining a fast flow speed in proximity to the zone of anodic corrosion. The Flume model was used in an extensive test at a tannery. Greater than 90% of chromium in tannery effluent was removed by a combination of electroflocculation and electroflotation, at a lower cost than by treatment using standard chemical flocculent, using a side-stream Flume processor at a tannery. A smaller scale Flume model was used to test mechanisms of treatment in the laboratory using synthetic tannery effluent.

When treating alkaline effluent, the separating membrane in the Flume model enabled production of alkali at the cathode and production of acid at the anode. This was used for pH modification of effluent and, where the majority of the flow was anolyte, was able to produce a catholyte of pH greater than 13 from a wide range of inflow pH. The caustic catholyte is a valuable by-product of the electrolytic processing, especially when the upstream processes require net input of alkali (as is the case at a tannery or kraft pulp mill) and more generally because downstream biological treatment processes benefit from receiving neutralised effluent.

The degree of pH moderation of the whole outflow compared to the inflow was found to be controllable by adjustment of cell voltage. This effect enables treatment of effluent with variable pH.

Optimisation of an electrolyser for energy recovery, by both reduction of electrode over-potentials and electrolyte resistance, was incorporated in the full-scale designs. Based on a feasible cell voltage of 5 V, 20% recovery of the energy input is expected.

text: Electrolytic purification of water This thesis develops the concept of an in situ electrolytic processor, a machine with electrochemical functions that purifies aqueous fluids at the point of production, whether from a bore water supply or effluent from a tannery. Where the contaminants in an effluent are useful they are separated in a specialised electrolyser for re-use in the process that produced the original effluent. The value in doing this exceeds the cost of electrolytic processing for tannery effluent. The functions of an electrolytic purifier were resolved into: flotation by bubbles, flocculation by corrosion of aluminium anodes, electrowinning by cathodic plating, disinfection, oxidation-reduction and pH modification. Improved understanding of the control of these functions has led to the ability to design better electrolysers because the functions were combined in a form that was appropriate to the required purification process. A link between extra-faradic corrosion of an aluminium anode and pH modification is postulated.

Electrochemical principles were used as the basis for development of real processor models. These models were tested using bore water, cooling tower fluid, virus contaminated water, laundry water, municipal waste water, landfill leachate and pulp mill effluent.

The most effective model, designed during the course of the project and described as the Flume, incorporated a novel corroding anode composed of thin pieces of aluminium, water flow in a cathodic flume, and a cheap water-porous membrane to separate the electrolyte into anolyte and catholyte. The novel anode was designed to improve clearance of corrosion products by maintaining a fast flow speed in proximity to the zone of anodic corrosion. The Flume model was used in an extensive test at a tannery. Greater than 90% of chromium in tannery effluent was removed by a combination of electroflocculation and electroflotation, at a lower cost than by treatment using standard chemical flocculent, using a side-stream Flume processor at a tannery. A smaller scale Flume model was used to test mechanisms of treatment in the laboratory using synthetic tannery effluent.

When treating alkaline effluent, the separating membrane in the Flume model enabled production of alkali at the cathode and production of acid at the anode. This was used for pH modification of effluent and, where the majority of the flow was anolyte, was able to produce a catholyte of pH greater than 13 from a wide range of inflow pH. The caustic catholyte is a valuable by-product of the electrolytic processing, especially when the upstream processes require net input of alkali (as is the case at a tannery or kraft pulp mill) and more generally because downstream biological treatment processes benefit from receiving neutralised effluent.

The degree of pH moderation of the whole outflow compared to the inflow was found to be controllable by adjustment of cell voltage. This effect enables treatment of effluent with variable pH.

Optimisation of an electrolyser for energy recovery, by both reduction of electrode over-potentials and electrolyte resistance, was incorporated in the full-scale designs. Based on a feasible cell voltage of 5 V, 20% recovery of the energy input is expected.

year: 2006

title: The principal as learner: perceptions, beliefs and experiences of nineteen New Zealand principals

authors: Townsend, Frances Mary

abstract: The research began with a personal question about how one learnt educational management. The research participants consisted of 19 principals who were selected on the basis of distribution between primary, secondary, male and female. Two questions guided the research. How did these principals perceive that they learnt to be principals? How did they perceive that their learning impacted on their practice? A self-study paralleled the study of the principals, as a study of an educational manager who was not a principal.

The qualitative methodology applied in the study was grounded theory. The methodology and the retrospective, biographical nature of the study through interview, meant that the research was phenomenological and interpretative. The main source of raw data was the transcripts of interviews, documents and literature. 

These principals perceived that their critical learning related to educational management was learning of attitudes and values as well as knowledge and skills. This learning could be traced in the first instance to family and upbringing, to their own education and their careers in teaching and middle management. Because this learning was the foundation on which their learning as principals, was based, I called this foundational learning. The research indicated that foundational learning influenced the nature of the principalship.

The learning of principals after appointment was conceptualised as experiential and intentional. Experiential learning occurred in the contexts of initiation, dealing with crises and problems, routine management, managing change, taking part in specific events, and through the process of being a principal for an extended period. Experiential learning appeared to consist of two main types, situational and emergent. The latter comprised new learning created by learning over time from a variety of experiences. Intentional learning aimed to meet learning needs and included all the deliberate formal and informal learning activities such as gaining qualifications, attending courses and conferences, visiting other institutions and reading professional literature. Barriers and limitations to learning constituted another relevant aspect of principals’ learning.

The principals perceived that their foundational learning had a major impact on practice as the source of values, attitudes, systemic knowledge of educational management and management skills. They perceived that their experiential learning had the most direct and significant impact on their practice because it was most likely to produce practical and relevant learning. Intentional learning had a subsidiary function, supporting and growing experiential learning. In this way, intentional learning impacted on practice. Personal, systemic and external learning barriers and limitations appeared to impact on practice in idiosyncratic ways.

Foundational, experiential and intentional learning was cumulative, contextualised within particular schools and situations and inter-related through impact on practice. Consequently each principal’s story was different and unique. I concluded that each principal was a unique product of learning, accumulated over a life time and developed within schools, each of which represented a unique environment. As a result, each particular combination of principal and school represented a unique configuration in terms of learning to be and being a principal. The self-study supported these conclusions. On the basis of the findings of the research, I drew out a number of professional development implications. If heeded, the professional development implications could reorient educational management education by focusing on the unique configuration of principal as sum of foundational, experiential and intentional learning, and his or her particular school or organisation as a particularised environment of educational problems. These problems may need to be defined uniquely to be resolved.

text: The principal as learner: perceptions, beliefs and experiences of nineteen New Zealand principals The research began with a personal question about how one learnt educational management. The research participants consisted of 19 principals who were selected on the basis of distribution between primary, secondary, male and female. Two questions guided the research. How did these principals perceive that they learnt to be principals? How did they perceive that their learning impacted on their practice? A self-study paralleled the study of the principals, as a study of an educational manager who was not a principal.

The qualitative methodology applied in the study was grounded theory. The methodology and the retrospective, biographical nature of the study through interview, meant that the research was phenomenological and interpretative. The main source of raw data was the transcripts of interviews, documents and literature. 

These principals perceived that their critical learning related to educational management was learning of attitudes and values as well as knowledge and skills. This learning could be traced in the first instance to family and upbringing, to their own education and their careers in teaching and middle management. Because this learning was the foundation on which their learning as principals, was based, I called this foundational learning. The research indicated that foundational learning influenced the nature of the principalship.

The learning of principals after appointment was conceptualised as experiential and intentional. Experiential learning occurred in the contexts of initiation, dealing with crises and problems, routine management, managing change, taking part in specific events, and through the process of being a principal for an extended period. Experiential learning appeared to consist of two main types, situational and emergent. The latter comprised new learning created by learning over time from a variety of experiences. Intentional learning aimed to meet learning needs and included all the deliberate formal and informal learning activities such as gaining qualifications, attending courses and conferences, visiting other institutions and reading professional literature. Barriers and limitations to learning constituted another relevant aspect of principals’ learning.

The principals perceived that their foundational learning had a major impact on practice as the source of values, attitudes, systemic knowledge of educational management and management skills. They perceived that their experiential learning had the most direct and significant impact on their practice because it was most likely to produce practical and relevant learning. Intentional learning had a subsidiary function, supporting and growing experiential learning. In this way, intentional learning impacted on practice. Personal, systemic and external learning barriers and limitations appeared to impact on practice in idiosyncratic ways.

Foundational, experiential and intentional learning was cumulative, contextualised within particular schools and situations and inter-related through impact on practice. Consequently each principal’s story was different and unique. I concluded that each principal was a unique product of learning, accumulated over a life time and developed within schools, each of which represented a unique environment. As a result, each particular combination of principal and school represented a unique configuration in terms of learning to be and being a principal. The self-study supported these conclusions. On the basis of the findings of the research, I drew out a number of professional development implications. If heeded, the professional development implications could reorient educational management education by focusing on the unique configuration of principal as sum of foundational, experiential and intentional learning, and his or her particular school or organisation as a particularised environment of educational problems. These problems may need to be defined uniquely to be resolved.

year: 1999

title: Te Kōtihitihi: Ngā Tuhinga Reo Māori, Putanga 3

authors: Temara, Pou

abstract: Koinei te katoa o te Putanga 3 o te puka hautaka, Te Kōtihitihi.

text: Te Kōtihitihi: Ngā Tuhinga Reo Māori, Putanga 3 Koinei te katoa o te Putanga 3 o te puka hautaka, Te Kōtihitihi.

year: 2016