This thesis is concerned with phosphorus management in grassland agriculture in Ireland and the impact it has on catchment chemical water quality. It reports three inter-related studies which assess changes in phosphorus concentration in the soils and streams of two 5km2 grassland sub-catchments, Co.Tyrone (Northern Ireland) and Co. Monaghan (Republic of Ireland) of the cross-border River Blackwater following the implementation of mitigation measures. The first study assessed the changes in soil phosphorus status after five years of recommended zero phosphorus application to high phosphorus status soils. This study found that in the Co. Tyrone sub-catchment, where phosphorus had not been applied to soils with originally agronomically optimum or excessive phosphorus status, a significant mean reduction in Olsen-phosphorus concentration of 4.5 mg l-1 was achieved. The reduction was more pronounced (7.2 mg rl) when only excessive soil phosphorus status was considered. However, despite receiving the same advice in Co. Monaghan, the fields with optimum or excessive phosphorus status had a significant overall increase of 4.5 mg rl . Excessive fields had a mean increase of 4.9 mg l-1. In both catchments there were significant increases in low to moderate phosphorus status fields of 5.96 and 7.1mg rl (Co. Tyrone and Co. Monaghan, respectively). Application of a soil phosphorus decline model on the fields which demonstrated a decrease in the excessive soil phosphorus status estimated that the phosphorus deficit for these ranged between -0.1 and -30 kg ha-1, which is agronomically realistic for grassland management. Analysis of a five year high resolution phosphorus and discharge dataset showed that, although discharge from the Co. Tyrone and Co. Monaghan streams were not significantly different from 2006 to 2010, totalling 3170 mm and 3694 mm respectively, the phosphorus loads in Co. Tyrone were less than half of those in Co. Monaghan; 7.26 and 14.94 kg ha-1, respectively. Analysis of the extent of critical source areas in each catchment revealed that 3.75 % of the 19.3 8 km of stream network in Co. Tyrone had bankside fields of excessive phosphorus status while in Co. Monaghan the percentage was almost double that of Co. Tyrone with 7% of the 36.85 km of the stream network impacted by bankside excessive phosphorus fields. Analysis of change in phosphorus concentration at medium to high discharge percentiles showed that, in both catchments, there had been a significant increase in concentration between 2006-2010 at Q5-QIO , 0.152 to 0.280 mg l-1 in Co. Tyrone and in 0.228 to 0.391 mg l-1 in Co. Monaghan. When annual loads were calculated for each catchment, the largest load from both catchments was in 2009, 2.12 and 3.98 kg ha-1 , in Co. Tyrone and Co. Monaghan, respectively. This year, however, did not have the highest rainfall, which happened in 2006 (1299mm) compared with 2009 (l123mm). When analysis of the timing of rainfall events was conducted it was revealed that 2009 had continuous rainfall events throughout the year but 2006 had all but one storm event during the winter period. Analysis of extreme baseflows in both years (Q9S) revealed that 2009 had less than 20% of Q9S discharges compared with any of the other years which suggested than the continuous rainfall maintained the soil in a persistently wet state throughout the year and increased the potency of subsequent storm events for phosphorus transfer thereby increasing phosphorus load loss.

Due to increasingly stringent legislation covering the discharge of hazardous chemicals into the environment, existing wastewater treatment processes need to be upgraded for their removal. This thesis explores the removal of a diverse range of hazardous chemicals during secondary wastewater treatment with the overall aim of enhancing their removal simultaneously by activated sludge. Previous research in this field has made the broad comparison of full-scale activated sludge plants (ASPs) which receive varying influent sewage compositions and flow. Consequently, assessing the direct impact of process operation to hazardous chemical removal has been difficult. In this study, the independent impact of the process variables solids retention time (SRT) and hydraulic retention time (HRT) were examined using a pilot-scale ASP. To measure ASP resilience for the removal of a wide range of hazardous chemicals of varied chemistry and preferred removal pathways steroid estrogens, nonylphenolic surfactants and metals were monitored. Cont/d.

The treatment of phosphorus at small sewage works requires alternative approaches to the traditional chemical precipitation and biological removal pathways, as such approaches do not align well to the requirements at such a scale in relation to the use of chemicals, increased energy demands and/or increased sludge production. At small sewage works, constructed wetlands are often used as a tertiary treatment for solid removal and some associated biological degradation. The current work aims to assess the potential to upgrade such systems for phosphorus removal by replacing the traditional media with a reactive alternative. This was accomplished through a series of laboratory and pilot trials to establish the most appropriate media and understand the underlying mechanisms. Determination of key properties, such as retention capacity, mechanical strength and regeneration potential, identified steel slag and phosfate™ as media that were suitable for in depth investigation. Both were shown to be effective at phosphorus removal if sufficient contact time was provided such that 1 mg L- 1 effluent concentrations was achieved when an empty bed contact time of 48 hours was used. A detailed investigation of the media revealed that steel slag worked through a two-step process where initially calcium was dissolved into the water from the surface of the media and then precipitated with the phosphorus to form calcium phosphate. The presence of alkalinity in steel slag bed inhibited the precipitation of phosphorus through calcium, as carbonates were precipitated instead. There was also a risk associated with the leachability of aluminum and flushing of retained phosphorus during the treatment of wastewater with very low phosphorus concentrations from the bed. In the case of Phosfate™ , the binding agent resulted in very high effluent pH and the formation of colloidal phosphates that needed to be filtered out to enable low effluent phosphorus concentrations to be achieved. The results indicated that both media have the potential to remove phosphorus from tertiary effluents, but the issues of leachability of aluminum from steel slag bed and the release of retained phosphorus should be investigated further before full scale trials. The colloidal phosphorus observed escaping effluent from phosfate™ bed and that the elevated effluent pH should be solved before full scale trials.

The thesis is focused on the study of the microbiology of groundwater contaminated by diesel with three main goals. Firstly, to characterize the natural attenuation process, secondly, to increase knowledge of the role of microorganisms in the remediation of polluted environments and thirdly, to evaluate the efficacy of molecular biology methods to assess the in situ biodegradation potential of the microorganisms in such contaminated areas. This study includes the metagenomic characterization of the microbial community through the exploitation of next-generation sequencing techniques and the quantification of key biodegrative genes as biomarkers. Moreover, several strategies were put in place to understand the role of an uncultivated bacterial phylum (the OD1 candidate division) in the biodegradation of organic pollutants. These included the design of primer sets for the amplification of a functional gene specific for OD1 and the phylogenetic analysis of 16S rRNA sequences assigned to OD1 from several studies and a public database. A main outcome has been the characterization of the natural attenuation process in the site. A network of fermentative syntrophic bacteria and methanogenic archaea are the likely the protagonists of this process. The role of OD1 in the fermentation process was proposed. A thorough analysis of OD1 distribution has been carried out and phylogenetic cluster of ODl clades involved in this complex trophic network of fermentative bacteria and methanogens was identified.

Algae-based wastewater treatment technologies are gaining popularity because of their sustainable treatment capabilities, coupled with their ability to capture carbon and consequently reduce the carbon footprint of the overall treatment process. Research was undertaken to develop a low-cost hybrid mixed microalgae-activated sludge municipal wastewater treatment system coupled with CO2 sequestration. Red light-emitting diodes were used as light source to illuminate 1 L and 21 L microalgal photobioreactors. Three phases of laboratory experiments (I, II and III) were conducted to treat real or synthetic municipal wastewater using batch and continuous modes of operation, either with or without CO2 addition. Phases I and II experiments were conducted in batch mode using a mixed microalgae-bacteria culture as inoculum, while Phase III was conducted in continuous mode using a mixture of microalgae and activated sludge as inoculum. The added gas in Phases I and II had O2 supplementation whereas the gas in Phase III had no O2 but a substantial amount of CO2. Average ‘optimal’ irradiance (582.7 μmol.s-1.m-2) was used in Phases II and III, while Phase I investigated a range of lower light regimes (i.e. 25.3 to 234.3 μmol.s-1.m-2). Results showed high wastewater treatment efficiency, in terms of soluble chemical oxygen demand (SCOD) and ammonium-nitrogen (NH4-N) removal. SCOD removal efficiency greater than 70% was achieved in all the three experimental phases. Furthermore, NH4-N removal efficiencies greater than 90, 70 and 40%, were achieved in Phases I, II and III, respectively. However, nitrite accumulation was observed in Phases I and II, indicating that NH4-N removal was due to partial nitrification. Furthermore, low phosphate removal efficiencies were achieved in Phase III. Results confirmed that considerable reduction of operational costs could be achieved by satisfying bacterial oxygen requirement through photosynthetic oxygenation in the hybrid microalgae-activated sludge (HMAS) photobioreactors, with considerable energy savings possible whilst maintaining high levels of SCOD removal. Typically, a dissolved oxygen concentration > 2 mg.L-1 could be maintained in the HMAS photobioreactors without external aeration. Microbial analyses of samples collected from Phase II and III photobioreactors revealed a dominance of bacteria over microalgae. In order to prevent system failure, it was recommended that HMAS photobioreactors be set-up with an initial microalgae-bacteria ratio of at least 90:10, as determined by flow cytometry. Overall, this study demonstrated the potential for achieving high treatment efficiency by coupling wastewater treatment with carbon capture in HMAS photobioreactors. The potential for realising cost savings in wastewater treatment through use of HMAS photobioreactors at full-scale are discussed.

The increasing worldwide contamination of aquatic environment with pollutants introduced by anthropogenic sources has become of great concern. Although present at low concentration, many of these pollutants have considerable long-term impacts on the ecosystem, such that extremely challenging legislative limits on their concentration in effluents are being proposed. This has led to the examination of membrane bioreactor (MBR) technology for wastewater treatment, since it offers the best and most consistent treated water quality of all biotreatment processes. However, both a review of the literature and experimental study reveals that MBRs appear to offer insufficient benefit over conventional processes to make their implementation for this duty viable, given their significantly higher cost. Notwithstanding this, the fate of micropollutants in MBR processes represents the most rapidly growing research topic in the general MBR subject area. Despite the wide range of products commercially available, the majority are hollow fibre (HF) products based on polyvinylidene difluoride (PVDF) or polyethersulfone (PES) and almost all are in the pore size range between 0.04 and 0.4 μm. Whilst differences in module design across the whole range of products constrains their interchangeability, the increased acceptance of and confidence in this technology is reflected in the increased rate of implementation of large installations and the overall exponential growth in the market of 11-13% per year. However, there appears to be a dysfunction between the needs of the industry and the primary research area within the academic community, with practitioners identifying clogging as the main impediment to sustainable operation while 31% of all research papers published to end 2009 were based on fouling and less than 1% on clogging. Experimental study of operation of an MBR to treat municipal wastewater based on a new HF material has revealed that studies based on aeration step provide a more realistic indication of critical operation than classical flux step experiments, since the latter involve imposing a hydraulic shock on the membrane. Simple measured sludge fouling propensity parameters did not appear to relate to fouling rate, with a counter-intuitive relationship arising under some operating conditions.

This thesis is concerned with the production of solid recovered fuel (SRF) from municipal solid waste using mechanical biological treatment (MBT) plants. It describes the first in-depth analysis of a UK MBT plant and addresses the fundamental research question: are MBT plants and their unit operations optimised to produce high quality SRF in the UK? A critical review of the process science and engineering of MBT provides timely insights into the quality management and standardisation of SRF use in Europe. Quantitative fuel property data for European SRFs are collated and analysed statistically in a detailed examination of the fuel quality achievable from MBT-derived SRF. The experimental research herein applies statistical sampling, analytical characterisation and materials flow analysis to a new generation, fully operational SRF-producing MBT plant. To the author’s knowledge, this is the first detailed analysis of this kind for a UK plant. Individual process flows from mechanically processed waste are characterised using a series of fuel properties in line with the European product standards for SRF, and confidence limits in these properties quantified. New data on SRF quality, including biogenic content, is provided. In seeking understand the variability in waste heterogeneity and its impact on SRF production in an MBT plant, material flow analysis is applied across the MBT flowsheet to compute transfer coefficients for individual unit operations. This provides a basis for critically evaluating the performance of this specific MBT and the extent to which is it optimised for SRF production. Cont/d.

The programme was concerned with the effects of processing variables on the structure and properties of coolant reservoir tanks. The work was concentrated on the extrusion blow moulding process and on propylene polymers, following an earlier similar research in the Institute on high density polyethylene. We have worked with a company which specialises in technical blow mouldings; the work has dealt with coolant tanks which are required for high temperature, high pressure service in the presence of antifreeze. It soon became apparent that the application made severe demands on polypropylene in that failure was possible by a variety of mechanisms, including environmental stress cracking and ductile blow-out failure. Additionally, the shaping process by extrusion blow moulding was not being carried out in the optimum way, either with respect to process economics or to product properties. Investigation of the surface texture of corn mercial tanks revealed that shrinkage from the mould occurred frequently due to inadequate holdon pressure; this loss of contact gives poor surface finish and retarded cooling. This phase of the research was supported by a programme carried out on the Bradford University equipment and by providing appropriate thermal data for the Bradford mathematical model for cooling. To reduce the cooling cycle time, the efficacy of internal cooling techniques, including forced air cooling and liquid carbon dioxide, was studied. Further, the possibility of shaping polypropylene in the supercooled region was investigated and a double extruder system was developed to examine the shear viscosity of supercooled polymers. The main concern has been failure caused by stress cracking and environmental stress cracking, especially of development grades of propylene polymers. The structures of various ethylene-modified polypropylenes have been elucidated, as have the relationship of structure' to processing history and its relevance to the severe stress cracking encountered. A new method for determining ethylene content of ethylene- propylene systems has been developed, as this is one of the important characteristics of ethylene modified polypropylene. The available processes of manufacturing the coolant reservoir tanks have been considered; in particular, competing methods of manufacture of extrusion blow moulding and injection moulding/welding have been compared. The design of coolant tanks, in particular the wall thickness required, has been examined. Stress analysis, supported by tensile failure and relaxation data, has been carried out to provide background to the failures encountered in practice. Finally, possible new candidate material for the coolant tank application, polypropylene-linear low density polyethylene (ethylene-octene copolymer) blends have been investigated.

The sustainability of a large pilot-scale hollow fibre immersed membrane bioreactor (HF iMBR) has been investigated with specific reference to membrane surface fouling and membrane channel clogging. Studies were conducted at normal sludge solids concentration of around 8 g/L and were also extended to concentrations more associated with thickening processes (around 32 g/L). A review of mechanically- moved membranes was conducted with a view to exploring a low energy means of sustaining operation through suppressing clogging. Methods were devised to quantify the amount of clogged solids within the membrane fibre bundle, either through their separation and gravimetric analysis or in-situ gravimetic estimation of the clogged solids without their removal from the membrane HF bundle. Outcomes generally revealed clogging to be as important a contributor to suppression of permeability as fouling, the key differentiator being that chemical cleaning had no sustained impact on permeability recovery when clogging took place. It was further substantiated that the operating permeability of membranes, once they had been clogged, could not be returned to that of the preclogged state despite declogging (i.e. mechanical removal of the solids) followed by the repeated application of chemically-enhanced backwashing. This was attributed to membrane pore plugging. Cont/d.

Consumption of unsafe water in developing countries results in considerable number of illnesses and deaths annually. The World Health Organization and the International Water Association are promoting the use of water safety plans (WSPs), a risk management approach aimed at attaining water safety. This study investigated how culture impacts on the implementation of WSPs in these countries. Combining interpretive and critical paradigms resulted in the choice of qualitative methodologies utilizing multiple-case studies. Cases from India, Uganda, and Jamaica are each embedded with three units of analysis: promoters of WSPs, water utilities and their customers. Thematic analysis of data generated from semi-structured interviews, field observations and documents revealed eleven cultural factors impacting on the implementation of WSPs. Analyses of these factors led to various groupings and the subsequent development of a taxonomy categorizing these factors as being either enabling, limiting, or neutral in relation to WSPs. Findings show all the limiting factors to be deviations from the values and principles on which they are built. The findings have also led to the development of a culturally adapted risk management framework. This four-step cyclical & iterative framework is designed to address the impact of culture on the implementation of WSPs. The implementation of WSPs will take time and will require continuous improvement to the process. The successful management of drinking water risks in developing countries will require a broad institutional approach and a concerted effort that involves institutions beyond the water utilities. As such, targeted recommendations are first made towards achievement of good governance. Activities that will lead to the embracement of WSP by stakeholders along with suggestions to attain its institutionalization are also put forward. Recommendations towards addressing negative cultural factors include suggestions on dealing with: pollution causing rituals, bettering storage related practices, addressing excessive water use in rituals, counteracting belief that water should be free, fighting corruption and improving compliance, changing deliver-first safety-later attitude, and improving knowledge management practices.