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Despite the improvements made to deliver improved sanitation around the world, Faecal Sludge (FS) management is still a challenge affecting hundreds of millions of people. Composting is one of the well known and most preferred low-cost methods for treatment of FS in urban Africa. However, its effectiveness has not been thoroughly explored. With an aim of improving the FS composting process in terms of nutrient recovery and pathogen inactivation; this study investigated the optimum sand filtering media thickness (150 mm, 250 mm, 350 mm) for FS drying beds, as well as the effects of different bulking agent types (sawdust, coffee husks and brewery waste), turning frequency (3, 7 and 14 days) and organic solid waste types (market waste and chicken feathers) on the FS composting process. Field dewatering and composting trials were conducted in Kampala, Uganda. The investigation revealed that the media thickness had a significant effect on the removal and recovery efficiency of percolate contaminant loads, but not on the dewatering time. The dewatering time improved to 3.65 - 4.02 days resulting into 65 - 67% reduction in the land area requirement per capita (0.016 - 0.017 m2/capita) for the treatment of FS to about 37%TS. The 350 mm filtering media thickness was the most efficient, in terms of contaminant loads removal from FS. However, 150 mm media thickness had the greatest potential of optimising nutrient recovery (NPK) from FS, particularly were the resulting solids are to be composted. The results indicated that the solid loading rate of 441 kg/m2/year can be used as the design criterion for FS drying beds in urban Africa. The results showed that the bulking agent types, turning frequency and organic waste types had a significant effect on most of the key physico-chemical and biological composting parameters. Overall, sawdust was the most suitable bulking agent for co-composting with FS as it enhanced nutrient recovery. It exhibited the lowest N-losses of only 2.2% compared to coffee husk and brewery waste with 48.2% and 72.5%, respectively. The results indicated that composting with high turning frequency (3 days and 7 days) enhances pathogen inactivation efficiency, organic matter degradation and composting rate, and thus reduced the composting periods by about 33%. However, it was associated with higher N-loss of about 50.1 - 48.6% compared to 7.6% of low turning frequency (14 days). Overall, the 7 days turning frequency was the most suitable and economically feasible for use during the FS composting. On the whole, chicken feather waste was the most suitable organic waste type for co-composting with FS as it enhanced pathogen inactivation efficiency and nutrient recovery. The composting of FS with both chicken feather and market waste reduced the composting periods by 32% and enhanced pathogen inactivation rate as well as nutrient recovery through nitrogen conservation, by a factor of 3. The composting of FS with chicken feather reduced the pathogen inactivation periods by 42%. This could thus increase the capacity of FS treatment plants or reduce their required capital investment, operational costs by 42%. The study revealed that a composting period of 8 weeks with temperatures of around 50.7 - 58.7°C sustained in the piles for more than 31 days, using 7 days turning frequency, is sufficient to ensure complete inactivation of pathogens in FS. Pathogen inactivation in composting piles was not solely dependent on the temperature-time factor, but also other mechanisms such as microbial antagonistic mechanisms or antibiotic action induced by indigenous microbial, moisture content, change in pH, nutrient depletion, and toxic by-products such as NH4-N. The following indices were established for mature FS compost; NH4-N < 0.55 g/kg, C/N ratio < 12.7, NH4-N/NO3-N < 0.12, CO2-C respiration rate < 1.44 mg CO2-C-g TVS-1day, PGI > 100%, WSC < 12.3 g/kg, WSNH4-N < 0.03 g/kg and WSNH4-N/WNO3-N < 0.18. The results indicated that a composting period of 14 weeks is required to obtain both stable/ mature and pathogen free FS compost, thus co-composting can be a viable way of treating FS in urban Africa.

A novel prototype instrument was developed to measure biomass catalase activity of suspended cultures. The technology was applied to develop a batch method of measuring activity in other media (e.g. soils) and a method of measuring hydrogen peroxide concentration. The biomass catalase activity of different microbial populations was measured successfully semi-continuously on-line (activated sludge, nitrifying culture) and off-line (soils). Garden soil, soil undergoing bioremediation and a characterised soil demonstrated catalase activities between 78 and 696 catalase units g" 1 dry weight of soil. Catalase activity was linearly correlated with different weights of each soil and was an indicator of bioremediation efficiency. Nitrifying cultures (enrichment nitrifying culture and pure cultures of Nitrosomonas) were shown to have a specific activity between 79,012 and 265,965 catalase units g" 1 MLVSS. Nitrification ability of the cultures was inhibited by ATU and 3,5-DCP while catalase activity remained stable for more than one hour following inhibitor addition in continuous studies. Activated sludges taken from Cynon Sewage Treatment Works then maintained in the laboratory were shown to have a specific activity between 8,392 and 107,136 catalase units g^MLVSS. Using a 100 litre activated sludge plant operating at varying OLR (between 0.5 and 2.0 kg COD m"3 reactor day" 1 , corresponding to changes in F/M of between 0.12 and 0.65 kg COD/kg MLVSS day" 1 ) in 8 experiments lasting up to 15 days, an increase in organic loading rate was reflected by an increase in catalase activity and increased utilisation of dissolved oxygen. Starvation caused by a decrease in OLR also increased catalase activity by up to seven times within 36 hours. The catalase activity monitor provides additional knowledge of the effects of environmental changes on biological processes occurring within a wastewater treatment plant that may not be reflected by current standard methods alone.

Phosphorus and nitrogen in waste water from sewerage systems contribute to excessive nutrient enrichment of surface waters, presenting a threat to nature conservation, domestic and industrial water supplies, and recreation. The general objective of this research was to investigate phosphate and ammonium removal from waste water by constructed wetland systems (CWS), which are increasingly being used for low-cost water treatment. Phosphate (P) adsorption capacity and other properties of potential CWS substrate materials (bauxite, shale, burnt oil shale, limestone, zeolite, light expanded clay aggregates (LECA) and fly ash) were investigated. Fly ash and shale had the highest P adsorption values, which were significantly correlated with porosity and hydraulic conductivity. Longer - term experiments with shale and bauxite gave maximum P uptake values of 730 and 355 mg P kg- I, respectively. Phragmites australis (common reed) seedlings grew satisfactorily in shale, bauxite, LECA and fly ash. Shale was selected as the most suitable substrate, and used in a pilot-scale CWS in plastic tanks in a greenhouse, with and without P. australis, at two input nutrient concentrations and a loading rate of 0.02 m3 m-2 d-1. Both planted and unplanted systems removed 98 - I 00% of P from a synthetic sewage over ll months. Removal of ammonium N was also complete in the planted tanks, but only 40 - 75% was removed in the unplanted ones. Corresponding nitrate N removal was 85 - 95% and 45 - 75%. The systems performed as well at high as at low concentration for both phosphate and ammonium. The variations in P and N removal could not be attributed to differences in pH, Eh and temperature, which did not differ significantly between planted and unplanted tanks. During the experiment, P and N concentrations were determined at 3 depths and 4 positions along the length of the tanks. H2P04- - P and NH/ - N concentrations were low ( < I. 0 g m-3) at all locations in the planted systems, whereas the P concentrations were sometimes twice as high in the unplanted ones. NH4 + -N in the unplanted systems was relatively high (l 0 - 30 g m"3) throughout the experiment. N03--N concentrations were very low by comparison. P. precipitation on shale and P. australis root and rhizome surfaces was examined by X-ray fluorescence analysis, and by chemical extraction with ammonium acetate, 0.1 M HCI and 2%> citric acid. This showed that P, Fe and Al had precipitated on all these surfaces. However. it was not possible to quantify the surface deposits, and further research is necessary. The hydraulic residence time. flow characteristics and permeability of the shale was investigated by a bromide tracer. The tracer breakthrough curves showed a similar pattern in all tanks, with ca 66% of the flow occurring through the bottom zone. However, the actual hydraulic residence time (6 days) was slightly higher than the theoretical one Although there was a significant difference (p < 0.02) between the distribution of flow in planted and unplanted tanks. there was no reduction in the reactive pore volume observed in any of the tanks. This confirmed that shale has good permeability properties. Monitoring of the full-scale systems was carried out during June - September 1995. Although P removal in a planted bed was between 50-75%, the overall performance of the full-scale systems was disappointing, especially for ammonium removal. This was attributed to high loading rates, visibly non-uniform flow and clogged gabions. A bromide tracer study carried out on these systems confirmed the short hydraulic retention times and heterogeneous flow mechanisms in both the unplanted and planted systems. Results obtained from the pilot scale study do not necessarily provide a quantitative prediction of the performance of larger-scale systems. However, the potential value of a shale-based system has been demonstrated, and this opens a new direction in the design of CWS; most systems built to date in the UK use gravel as a substrate. Shale has proved to have superior properties for P removal and is cheap and readily available in Scotland. Its application as a substrate in a full-scale system remains a subject for further investigation.

Over the past forty years concerns over the presence of pharmaceuticals in the environment have grown considerably. Some pharmaceuticals can be effectively biodegraded in wastewater treatment plants but others can be sorbed onto sludges that are often subsequently used as fertilisers or disposed of to landfill. This work aimed to understand how a given pharmaceutical will be distributed between aqueous and solid phases (characterised by the sorbed:dissolved partition coefficient, Kd) within a treatment plant, which is important to be able to make accurate risk assessments. An official guideline test to measure the partitioning of a pharmaceutical in sewage sludge is available, but it is time consuming and fastidious. As activated sewage sludge is a complex matrix, commercially available solid-phase extraction (SPE) cartridges with different chemistries were used to characterise the pharmaceutical-sludge binding processes. As part of this work a new solid-phase extraction screening method has been developed to provide rapid measurements of Kd and its performance was evaluated against partition coefficients obtained with the official guideline method with a correlation coefficient of 0.93 and a r2 of 0.94. In addition, this rapid method allowed the measurement of partition coefficients for pharmaceuticals for which values were not available in the literature and these have been used to further validate new predictive models. Predictive models based on the octanol-water partition coefficient have been developed to calculate partitioning properties of compounds in soil, and these have been extended for application to sewage sludge. These models are optimised mainly for neutral organic chemicals, and only a few consider ionic substances. The work described in this thesis compared the performance of these soil-based models for a range of pharmaceuticals, including ionisable compounds, and assessed their application for the binding of ionic and non-ionic pharmaceuticals in sewage sludge. It also explored other predictive models based on molecular descriptors obtained from chemical structure. These models provided improved predictions over previous models based solely on the octanol-water partition coefficient. In this thesis, partial least squares (PLS) and Bayesian artificial neural network (ANN) models were evaluated for their accuracy in predicting the partition coefficient for neutral, basic, acidic and zwitterionic pharmaceuticals. Literature values were used to develop the models based on a range of molecular descriptors, and their predictive ability was assessed on an external test set of compounds excluded from the model-building process. The performance of the linear PLS and non-linear ANN models were discussed, and their predictive performance and interpretability were compared. Attempts to apply the method for rapid measurement of the sorption of pharmaceuticals to soils were also made to investigate potential read-across from one environmental matrix to another but the two matrices were too dissimilar to achieve this.

In Ireland many people live in homes that are rurally located and not connected to public wastewater treatment systems. Where this is the case, the treatment of the wastewater produced must be undertaken by a private on-site wastewater treatment system (OSWTS). Properly built and maintained private on-site wastewater treatment systems can treat effluent in an ecologically sound manner and return the water to the environment. Nevertheless, inappropriately designed, installed and maintained systems can lead to the contamination of ground and surface water resources (Gray 1994; Daly, 2001; Flynn & Kroger, 2003; Gray, 2004; Gill et al, 2005; EPA, 2008; Daly & Craig, 2009 & Gormley, 2009). Such contamination can lead to significant threats to human health as well environmental degradation. The very high dependence by Ireland on these OSWTS’s for domestic wastewater treatment means that it is imperative that the performance and management of the systems is effective and robust. Unfortunately however there is evidence that a huge proportion of OSWTS’s are poorly managed, maintained and operated (EU, 2008; IOWA 2012 & GSI, 2013). This poor performance and management of OSWTS’s has resulted in significant prosecutions and fines for Ireland by the EU with clear and unambiguous conditions set down for what Ireland needs to do to avoid further sanctions. The existing legislation in Ireland for OSWTS’s and some recent amendments as a consequence of the prosecutions by the EU have made it very clear that the ultimate responsility lies with the homeowner for their wastewater treatment system. Provision is made in the legislation for a new inspection reigeme that will seek to identify pollution from OSWTS’s and attempt to mitigate the contamination of ground and surface waters in accordance with the requirements of the Water Framework Directive (WFD). This new inspection reigeme and the revisions to the legislation are required for Ireland to comply with the directions of the ECJ ruling (C188-08) in relation to OSWTS’s and so that the daily fines being imposed against Ireland are suspended. There has been little time available on foot of the ECJ (2008) ruling to educate homeowners on how they should be properly managing and maintaining their OSWTS’s to ensure that they operating effectively and efficiently. Existing research has identified that even where homeowners are aware of their responsibilities towards their OSWTS that they tend not to care with an ‘out of sight out of mind attitude (Gray, 2004). Clearly therefore the issue facing Ireland is not just a knowledge deficiency towards OSWTS’s but also a beahavioural change issue where people tend not to care about how their OSWTS performs. This thesis will examine the evolution of legislation in Ireland relating to OSWTS’s and how circumstances have led to the prosecution of Ireland (ECJ, 2009) for non compliance with the relevant EU Directives. Comprehensive literature reviews will outline existing research undertaken on the contamination of water resources by OSWTS in Ireland and also on techniques that could be utilised to educate homeowners on what they need to do to ensure that their individual wastewater treatment system is compliant with the relevant legislation. The research will adopt a number of research methods such as questionnaires and interviews to collect the data that is required to determine the knowledge that homeowners require about their OSWTS and this will shape the homeowner knowledge model that is to be developed. The publication of the research findings will inform the wastewater industry and the legislature of the key areas where homeowners are deficient in knowedge and understanding towards their OSWTS. These findings will also shape the knowledge model that will seek to address the knowledge and behavioural defieiciences that have led to Ireland being in the precarious position that it now finds itself in from the pollution, contamination and health threats associated with poorly performing and managed OSWTS’s. The implication of having relevant information and a clear understanding of where Ireland currently stands in relation the homowners and their interaction with their OSWTS’s will be of benefit to a whole range of sectors such as academia, industry, local authorities and the EPA. An accurate diagnosis of the problems relating to homeowner knowledge and behaiviour towards OSWTS’s will provide a framework to develop a lasting solution that will help in addressing pollution, groundwater contamination and the associated health risks from poorly constructed, managed and functioning OSWTS’s.