Instant whole milk powder is designed to rapidly dissolve in water, which depends on the particle size distribution (PSD). The fragile powder exiting the dryer is conveyed for packing which breaks down the particles, worsening the dissolution properties. This work investigated the effect of conveying on the final functional properties using two industrial plants with differing transport systems; a pneumatic system and bucket elevator. It was expected that the plant with the bucket elevator consistently produced powder with superior dissolution due to lower breakdown during transport. This was evaluated using the change in PSD. It was found that the plant with the bucket elevator had at least as large a change in the median particle size as the plant with the pneumatic transport system, contrary to the expectation. However, the plant with the bucket elevator had an initially larger particle size, and so the percentage of fine particles that negatively impact dissolution, remained low post transport. When quantified using the change in bulk density, having an initially low bulk density compensated for large increases in bulk density during conveying and powder with lower bulk density pre-transport showed better wettability post transport. Thus in order to produce powder with the desired functionalities the focus should be on improving the initial agglomeration and generating larger particles and lower bulk density pre-transport, as opposed to optimizing the powder transport.

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Wet oxidation is a successful process for the treatment of municipal sludge.In addition, the resulting effluent from wet oxidation is a useful carbon source for subsequent biological nutrient removal processes in wastewater treatment.Owing to limitations with current kinetic models, this study produced a kinetic model which predicts the concentrations of key intermediate components during wet oxidation. The model was regressed from lab-scale experiments and then subsequently validated using data from a wet oxidation pilot plant. The model was shown to be accurate in predicting the concentrations of each component, and produced good results when applied to a plant 500 times larger in size.A statistical study was undertaken to investigate the validity of the regressed model parameters. Finally the usefulness of the model was demonstrated by suggesting optimum operating conditions such that volatile fatty acids were maximised.

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