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Struvite causes maintenance, and operational problems due to fouling in wastewater and sludge treatment systems. Struvite formation was initially investigated using a series of jar tests on real and synthetic sludge liquors. A computer model predicting struvite precipitation potential was compared to the results generated. Struvite formation was found to be closely linked to pH with increasing pH resulting in decreasing struvite solubility. Further studies analysed the relationship between a solutions' supersaturation ratio, material and the scaling rate. Tests were undertaken at 3 supersaturation ratios with 3 different materials: stainless steel, Teflon and acrylic. Acrylic and Teflon coupons were scientifically roughened to show the influence that surface roughness has on a materials' scaling propensity. The control of struvite precipitation was investigated using a range of chemical inhibitors and chelating agents. Experiments using the same materials used previously were performed with a range of scale inhibitors and chelating agents. The scale inhibitors did not prevent struvite from forming, with only one product, Polystabilis, showing a reduction in the mass of scale formed on the impellers. Of the chelating agents tested, EDTA was the most effective even in alkaline conditions and was shown to have the ability to re-dissolve struvite previously formed on materials.

Traditional methods of ammonium removal from municipal wastewaters rely on naturally occurring biological processes, where ammonium is converted into less harmful substances before being released into the environment. These processes are extremely effective at nitrogen removal but are less responsive to shock loads, in which case they can fall short of achieving the required effluent quality. In recent years research has been conducted into the possibility of using ion exchange technology as a complementary process for the. removal of ammonium from wastewater streams. Much of the research has been concerned with the performance of naturally occuring materials, zeolites, with much of the work being undertaken at laboratory scale using synthetic solutions. This study investigates the performance of the modified media, MesoLite, using real and synthetic solutions, at both laboratory and pilot scale, in the presence of competing cautions. Initial studies were performed under batch conditions to assess the effect of a number of parameters such as contact time, solution ammonium concentration and pH on the uptake of ammonium on to MesoLite. This was followed by a investigation into a number of design parameters under dynamic conditions, leading to a pilot scale examination of the potential of the process to be used for the application of removing ammonium from low concentration wastewater treatment works effluents. Subsequent experiments were performed pilot scale to investigate the benefit of using the ion exchange process for ammonium removal from high strength liquors arising from the sludge dewatering process. Results indicate that a range of parameters affects the performance of the media and optimum performance is observed at high ammonium concentrations with increased contact time at pH 6-7. Results also show that MesoLite was successful in removing ammonium from high concentration sludge liquors, giving a total capacity of 47-51 g + -1 + -1 NH4 N kg and a operational capacity of 27 36 g NH4 N kg . The treatment of low concentration effluents return a total capacity of 19 g NI-14+-N kg`1 and a operational capacity of 9.5 g NI-14+-N kg`1. However, this reduced capacity is offset by the significant increase run time, from 1.5 to 22 days, and a increase in the amount of liquid treated from 140 bed volumes to in excess of 6000 bed volumes.