The current paper recycling processes are surveyed pointing out the major stages and the variety of chemical/mechanical treatments the fibres undergo. The reduction or replacement of chemical/mechanical treatments presents possible advantages in prolonging fibre life. The results from recycled office waste which has been treated with ultrasound show a change in the particle size distribution of toner particles - making these particles easier to remove using established flotation techniques. Particle size distributions were measured using image analysis on thin (20gsm) paper handsheets. To establish the affect of sonication on fibres, a variety of virgin fibres were obtained from UK Paper, Sittingbourne. Results from virgin fibres which have been treated using ultrasound indicate an absence of cutting compared to conventional techniques. Fibres were found to have the same average length (0.6mm) after ultrasound treatment as the control sample, refined fibres were reduced to approximately 0.3 mm in length. Freeness decreased in both virgin sonicated and refined sonicated samples. The decrease in freeness was accompanied by an increase in the strength properties of both categories of fibres. Experiments with a prepared office waste furnish showed that ultrasonic treatment could decrease the size distribution of fused toner particles. The control sample had an average size of 80.9 um, after 1 minute sonication this was decreased to 54.9) um, decreasing further to 46.8)um after 2 minutes sonication. After demonstrating that ultrasound could decrease the particle distribution of the prepared office waste a more realistic and variable furnish was used. The experiments were conducted at room temperature, 50°C and 75°C. These temperatures were chosen to study the behaviour of fused toners as it approaches and exceeds its glass transition point, essentially the melting point of an amorphous polymer. It was found that the toner is easier to remove as the glass transition temperature is approached. Ultrasound is effective in breaking up large toner particles and detaching particles smaller than 25 microns in diameter.

Many countries in the world today have reached the point of full utilization of their forest resources, to satisfy their need for lumber and pulp and paper products. Others have reached the point where their consumption is far in excess of the capacity their domestic forest stands can sustain and they are net importers of these products. Still fewer have developed the practice of recycling these products to any appreciable extent. Canada and United States are approaching full utilization and have only accomplished a recycling rate of approximately 20% of paper and paperboard products. On the other hand conservationists are calling for more efficient utilization of resources, ecologists are calling for less waste and less pollution, while the burden on city garbage collection facilities, 50% of which is paper products, is increasing exponentially. In this thesis the technical processes required to make first quality newsprint from recycled newspaper are shown to be available. The economics of such a plant is examined in detail leading to the judgment that it is economically sound. The conclusion is reached that a 300 ton/ day newsprint mill can be entirely supported by locally generated waste newspaper in a city of three million population or over. Furthermore, it is concluded that if the collection and transportation of waste newspapers is not impeded by governmental regulations or unanticipated competition in the feeder cities, such a plant is still economically feasible after allowing for water barge transportation of the raw materials as far as 200 miles. / Business, Sauder School of / Graduate

Thesis (M.S.)--University of Wisconsin--Madison, 1996. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 106-108).

This thesis investigated the technological economics of waste paper recovery and recycling in UK. The major problem in waste paper recycling is still the removal of contraries, although technological developments have so far been able to remove some of them. The costs incurred by the local authorities in recovering waste paper were investigated. Local authority costing was found to be inconsistent and many of them did not include all the relevant indirect costs and savings, so that many local authorities claimed to be making heavy losses in their operations. Full accounting incorporating all the relevant indirect costs and savings have shown that most local authorities incurred much smaller losses and in some cases profited from their waste paper recovery operations. A general computer model was developed to allow local authorities to check the viability of their on-going operations and another computer model was developed for an investment appraisal of a proposed waste paper recovery operation. Multiple regression models were developed to forecast the demand of waste paper in the short term and the long term. The cost to the mill in recycling waste paper was also examined. Waste paper recycling can only be increased by improving demand for waste paper based products. Various alternatives for diversifying the markets for waste paper were investigated, particularly those outside the paper and board industry. The government's role in helping to inc~ease waste paper recovery and recycling was examined and some government actions that could be taken were proposed.

Mondi Ltd. operates a deinking plant at its Merebank mill. The plant recycles 85 000 tons per annum of flat news and magazine to produce a furnish for its newsprint papermachines. A review of the relevant pulping and flotation chemistry literature revealed that the role played by sodium silicate appears to be multi-faceted and in some dispute. Sodium silicate has an undisputed role in pH buffering, hydrogen peroxide stabilisation and the prevention of fibre yellowing. However, its role in deinking is said to be that of an ink collector or alternatively an ink dispersant. The mill's own experience has shown that the sodium silicate plays a vital role in the deinking process. Sodium silicate's ability to disperse ink, both alone and in the presence of calcium ions and fatty acid soaps, was investigated using a model ink system. A representative newsprint ink base was dispersed in the laboratory under conditions similar to those encountered in a deinking pulper. The resultant dispersions were studied using turbidity and particle size analysis. The morphology of the ink particles was determined using a scanning electron microscope. Sodium silicate proved to be a poor disperser of ink particles, but nevertheless appeared to greatly influence the dispersing properties of the soap in the presence of calcium ions. The nature of the interactions between sodium silicate, calcium ions and the collector soap were studied in an attempt to elucidate the role of sodium silicate. A model system consisting of the sodium salt of collector soap, calcium ions and sodium silicate was studied under the conditions that prevail in a typical newsprint deinking pulper. It was found that the soap and the sodium silicate compete for the calcium ions, and sodium silicate showed a measurable chelating e:ffect on calcium ions. Thus, increasing levels of sodium silicate lead to an increase in the concentration of sodium soap in solution. It was hypothesised that this effect would lead to better dispersion of ink particles and improved deinking performance. This chelating effect was evaluated in laboratory deinking studies. Samples of newsprint were pulped in a 251 Lamort laboratory pulper under a variety of conditions, viz. with fresh water, with an excess of soap, with an excess of calcium, with and without sodium silicate. The pulps were floated in a 201 flotation cell. The brightness and colour of the unfloated and floated pulps were measured. The level of the final brightness after flotation was taken as a measure of deinking efficiency. The highest final brightness was achieved when there was an excess of sodium soap and a low Ca hardness in the pulper. Softening the water used in pulping without adding excess sodium soap did not significantly improve pulp brightness. The lowest final brightness occurred in the presence of an excess of calcium in the pulper. Calcium in the pulper in the presence of sodium silicate did not result in a significantly lower final brightness. The results support the hypothesis that sodium silicate sequesters the soluble calcium in a pulping system, thereby increasing the sodium soap concentration and the resultant deinking performance. Apart from sodium silicate's chief role as a peroxide stabiliser, the sequestering action on calcium appears to be its main mechanism of action in a deinking system. An appreciation of this role will facilitate the optimisation of deinking systems with respect to calcium hardness and silicate concentration. To this end it was recommended that the Merebank deinking plant should evaluate the use of water with a low calcium ion concentration and the addition of some soap into the pulper to improve their deinking plant performance. / Thesis (M.Sc.)-University of Natal, Durban, 2003.

The greatest appreciation is extended to all who contributed valuable time to assist with this project. In particular, Barry Messer, from the Recycling Education Project at Portland State University, who recommended study ideas and provided integral information; Bruce Walker, from the City of Portland, who granted many interviews and was always willing to answer questions; Steve Apotheker, from Resource Recycling, who invited me to use the office library and spent time discussing current recycling issues; Deborah Adams, from Metro, who furnished me with essential data; and Wess Brenner, from the Academic Computing Center, who contributed substantial time to help in the analysis of the data. Additionally, Mara Tableman, from the Mathematical Sciences Department and Dr. Robert Fountain, from the Statistics Consulting Laboratory provided considerable advise about statistical procedures. I also deeply thank my parents, Rob Allerman, Jennifer Wheelan, and other friends and family who supported me throughout the completion of this document. Joel Freedman particularly, provided continual encouragement, unending patience and sound counsel. From the Geography department, I extend my sincere gratitude to Carolyn Perry and my committee, Joseph Porascky, Thomas Harvey and most importantly, my advisor, Dr. Teresa Bulman.

Unexpectedly, it was found that when a waterborne polyacrylate adhesive was placed on carbon steel it was not tacky; this was not the case for the same adhesive placed on stainless steel. It was determined that the surface energy, as measured with liquid contact angles, of the adhesive films is significantly different between the two films, with the non-tacky film having a higher surface energy. Atomic force microscopy (AFM) showed that the non-tacky surface has a higher roughness which minimizes the contacting area between the film and a contacting surface. Analysis of the heating of the carbon steel coupon with infrared thermography shows a non-uniform temperature profile at the surface. This experimental data is corroborated using a 2-D heat transfer model that incorporates the heat transfer characteristics of the various components of carbon steel. Surface driven flow, or Marangoni convection, can develop from temperature gradients and are known to cause increased roughness in polymer films. IR thermography measurements of the adhesive film during drying shows larger temperature differences for the films on carbon steel than on stainless steel. These larger temperature differences induce greater Marangoni convection, which result in the rougher surfaces on carbon steel that were measured with AFM. The effect of lowering the tack of a polyacrylate film has significant impact in the dryer section of a paper machine. This effect was quantified using the Web Adhesion Drying Simulator, which is a laboratory-scale apparatus that measures the energy required to pull the sheet from a metal surface. By substituting the adhesive-on-stainless steel with the less-sticky adhesive-on-carbon steel surface, the energy required to pull the sheet from the metal surface was reduced significantly and the picking associated with the test was nearly eliminated.

The interest in this study was initiated by the rapid global transition of paper usage to digital systems in teaching and learning at tertiary institutions, particularly those that are signatories to the Talloires Declaration, which include Rhodes University (RU). It was discovered that there are two earlier studies (Leslie et al. 2009; Amutenya et al. 2009) that investigated and proposed recommendations towards sustainable paper usage at Rhodes University (RU). This study then investigated the response of RU to the proposed recommendations of the above mentioned studies and evaluated the conditions that promote and constrain sustainable paper usage in teaching and learning, and the attitudes of users thereof.

Every year, millions of tons of paper are diverted from landfills and recycled. Newspaper constitutes a large portion of total paper recycled, providing a cheap source of raw material for the paper industry and helping sustainable forestry. The recycling of newsprint paper involves the separation of ink from the newsprint, which is done either by flotation or washing. Conventional flotation processes for separating ink are not adequate for newsprint printed using flexography printing technique and with water-based ink. The removal of these flexographic water-based inks by washing is a better alternative. However, one drawback of washing is that it has lower yield. In addition, the subsequent wash filtrate is difficult and costly to decontaminate. The overall goal is to develop a combination of processes that can remove ink from a feedstock that contains up to 100% flexographic ink newsprint; in the context of process variables with known effects. In the present work the objectives are to (1) demonstrate that incorporating an electric field into a conventional deinking process improves deinking efficiency, (2) propose a mechanism of how incorporating an electric field helps to improve deinking efficiency, (3) demonstrate that an electric field can decontaminate water containing flexographic inks and identify the mechanism behind electric field clarification of water, and (4) demonstrate that by incorporating electric fields into both the flotation deinking stage and water decontamination, the target deinking efficiency can be achieved.

There is a significant problem for the paper recycling industry known as “stickies”. “Stickies” are tacky species, present in recycled paper and coated broke, derived from coating formulations, adhesives, etc. They impact negatively on paper quality and cause web runnability problems by deposit build-up. To sustain recycling, stickies are controlled by adsorbing them onto minerals added to the recycled stock. So the aim of the project was to characterise non-porous and porous minerals suitable for paper-making, and then use the knowledge gained to improve the adsorption of stickies. The pore level properties of the minerals used to control stickies are highly relevant in regulating adsorption of the stickies. Levels of pore architecture were investigated by characterising filter media with porosimetry, porometry, electron microscopy and modelling the combined results. Seven samples were studied, with pore size distributions ranging from simple unimodal to complicated bimodal. Porometry, porosimetry and SEM, individually can only determine primary pore architecture. A combination of experimental and modelling techniques allows a full characterisation of pore architecture from primary to quaternary levels. Calcium carbonates can be modified to change the pore architecture, which affects properties such as wetting. Their pore architecture was investigated to understand why some modified calcium carbonates do not show two distinct wetting rates. The investigation implied a significant surface area could be attributed to nano rugosity. The nano rugosity was responsible for the enhanced wetting of a sample. A zero length column was used to study diffusion and desorption of benzene with calcium carbonate. Desorption and diffusion coefficients for calcium carbonate systems were calculated from the corrected concentration versus time measurements. They showed how the pore architecture affects diffusion and desorption. By comparing the experimental results with a pore network simulation, it was possible to deduce the relative effect of surface diffusion. The adsorption of stickies onto different mineral grades was investigated using a novel proxy method to determine equilibrium constants and adsorption isotherms. The results were then used to understand the influence of particle size on the adsorption behaviour, with three mechanisms proposed. The equilibrium constant and adsorption isotherm data also allowed comparisons between hydrophilic and hydrophobic adsorption onto grades of talc. Recommendations are made for the optimum use of minerals for the removal of stickies, and for in-situ methods for monitoring and optimising removal.