The aim of this research is to evaluate the potential of low energy wastewater treatment processes to meet UK performance requirements, with respect to an increasingly strict regulatory framework This research proposes the implementation of double filtration trickling filters (TF) operating in series without the requirement for intermediate settlement. Performance data is analysed and presented to demonstrate how a 50-80% biological offload of organic carbon (BOD) using a primary plastic media TF can enhance nitrification of existing conventional TFs. This configuration is capable of providing 97.4%, ammoniacal nitrogen (NH4-N) removal with effluent concentrations as low as 1.2mg/L. Process performance data from 120 TF wastewater treatment works (WWTW) are analysed in order to evaluate the relative nitrification performance of TF WWTWs, both with and without aerated tertiary nitrifying processes. Multivariate regression analysis whilst considering flow, temperature and infiltration determines that tertiary nitrification contributes to a significantly higher risk of NH4-N consent being exceeded during colder winter periods. This directly challenges the current strategy of adopting tertiary processes for enhancing nitrification on TF WWTWs. A decentralised facultative aerated lagoon (FAL) system with novel mixing and point source aeration is investigated and evaluated to determine its suitability for offloading existing WWTWs. Computational fluid dynamics (CFD) modelling describes the systems complex hydrodynamics and is validated with an experimental tracer study. Overall, this study showed that low energy mixing is capable of preventing hydraulic short circuiting and thermal stratification, which are notorious for reduced performance in traditional waste stabilisation pond variants.

Human activities unintentionally add pollutants to water bodies. This research has focused on the removal of trace elements from sources of water pollution (point and non-point), using a mineral based by-product (Blueguard® solids). The materials were characterised to identify the mineralogy, structure, porosity, and composition using different techniques including X-ray Fluorescence Spectrometry, X-ray Powder Diffraction and Brunauer–Emmett–Teller gas sorption methods. The results showed that the main compounds of the Blueguard® materials are alteration products of Mg-rich silicates. Three different types of contaminated water originating from different sources were prepared and analysed. These samples included (a) a multi-element solution prepared from trace element stock solutions; (b) rain water contaminated with motorway dust, and (c) contaminated water taken from an industrially polluted site (Cranleigh Brickworks, Surrey). Trace element analysis was undertaken by inductively coupled plasma mass spectrometry. Using a batch equilibrium procedure with optimised conditions of 0.25 g material in 50 ml solution for 5 min contact time, the mixing of the Blueguard® materials with a multi-element solution showed an effective removal of various trace elements under pH 4 to 9 conditions. These materials were then used to treat contaminated rainwater mixed with digested motorway dust. Trace element removal occurred from 80% for manganese up to 100% for lead. Analysis of surface water samples collected from the Cranleigh Brickworks showed that the levels of zinc and manganese were above the World Health Organisation (WHO) guidelines for drinking water. The most contaminated lagoon (25950 µg l-1 Zn and 2843 µg l-1 Mn) on the site was selected for laboratory and on-site testing of the Blueguard® materials. The best removal efficiency for these types of materials took place under a static design system where more than 95% of zinc and up to 97% of manganese was removed. Further investigation of the Blueguard® materials suggested the mechanism by which these materials reduce the level of trace elements in a solution was by precipitation, as a result of pH increase (through release of OH-(aq)). The results obtained for metal removal at Cranleigh has resulted in the application of these materials to remediate the site.

Current sewage treatment processes fail to protect against viral contamination of the marine environment and human enteric viruses are frequently present in sewage effluents. Chief amongst these are the Noroviruses (NoV), which are responsible for virtually all outbreaks of gastroenteritis. NoVs are non-cultivable, and molecular methods for their environmental detection are relatively new. Consequently, virtually nothing is known about their survival in the environment. This project seeks to determine the occurrence of NoVs in crude sewage effluents, their behaviour during passage through sewage treatment processes, and their subsequent survival characteristics in the marine environment. Current NoV detection methods are dependent on qualitative reverse transcription PCR (RT-PCR), however survival studies require quantitative methods. Within this study, a quantitative PCR assay for NoVs in sewage effluents has been developed using the real-time TaqMan assay. Data demonstrate that NoVs are ubiquitous in effluent samples, with higher titres present within winter months. Viruses were poorly inactivated by treatment and were still present at high titre in final (secondary) effluent. NoVs were detected in 75% of final effluents tested. In contrast, E.coli was approximately tenfold more sensitive to inactivation/removal by treatment. Sunlight was found to be an important factor in virus inactivation within seawater, whilst decreased temperature favored survival. All E.coli inactivation times were dramatically quicker than viruses, notably NoV and on average NoV demonstrated longer survival times than any organism. Overall, it was judged that conventional bacterial indicators of sewage treatment efficacy and bathing water standards do not adequately reflect the survival of viruses during treatment or in the marine environment.

The integration of the different parts of the urban wastewater system (i.e. catchment, sewer network, wastewater treatment plant and receiving waters) permits the representation of their intrinsic interactions and complexities, allowing for a more sophisticated management of stormwater and wastewater interventions. Emerging threats (e.g. climate change, population growth) and their associated future uncertainties pose an unprecedented challenge to the performance of the integrated urban wastewater system (IUWWS), which is expected to be reliable, resilient and sustainable regardless of future conditions. The aim of this thesis is to understand the performance and planning implications of catchment-scale infrastructure strategies for the improved management of the IUWWS in the face of future uncertainty. To this end, green and grey infrastructure strategies are proposed and assessed in the context of two different IUWWS models. Future uncertainties are represented by means of four future scenarios that account for a rich and ample variety of internal and external threats in the horizon 2050. A novel regret-based method is employed in order to: 1) assess the performance of the proposed strategies for multiple objectives (environmental, economic and social) and identify their main trade-offs; 2) evaluate the robustness of the proposed strategies for reliability, resilience and sustainability across future scenarios; 3) explore the dynamic compliance and adaptability of the strategies along pathways of transient scenarios. The obtained results demonstrate that end-of-pipe grey infrastructure strategies are subject to significant trade-offs that compromise their performance downstream, in spite of addressing localised issues. These operational trade-offs, along with the cost of grey schemes, importantly constrain their robustness to promote sustainability in the future, even in situations where these can become robust for reliability and resilience. In contrast, green infrastructure retrofits prove to be more consistent in their performance, delivering a wide range of performance benefits at a moderate cost. This translates into higher levels of robustness for reliability, resilience and sustainability across future scenarios when compared to their grey counterparts. Hybrid strategies combining grey and green interventions offer additional potential for robustness as they can ameliorate the unintended impacts and consequences of end-of-pipe solutions. Finally, it is also demonstrated that the robust performance of green retrofit strategies reconciles (and can help grey infrastructure alternatives to reconcile) compliance requirements in the short-term with those associated with the need to adapt to uncertain challenges in the long-term.

Anaerobic Digestion (AD) is a biologically mediated technology that is used as a method for managing and obtaining energy from organic waste materials. Through the biological action of Bacteria, Fungi and Archaea, in the absence of oxygen, the organic waste is converted to biogas, mainly methane, which can be used as a fuel source. This gas can be burned to generate electricity, heat, injected into the grid or used to fuel vehicles. I have developed a single stage, lab scale anaerobic digester that is a reflection of full-scale process systems. This model reactor facilitates the collection of samples for metagenomic sequencing, along with process data, providing an insight to the AD process. Three experiments were carried out (using the lab model) to determine (i) the dynamic changes that occur in microbial AD communities, (ii) the rate at which these communities change and (iii) if the observed changes are comparable between numerous systems run under the same conditions. The use of amplicon sequencing appears to be a common method used to study the composition of microbial communities, especially in AD, but this method is prone to inaccuracies and so alternative methods were developed, as described in this thesis. By applying the use of shotgun metagenomic sequencing, combined with various contig assemblers and a custom clustering method, more detail on the microbes present and their functions in AD is obtained compared to targeted sequencing. Pipelines to interpret large datasets generated through Next Generation Sequencing (NGS) have been developed and utilised in this project. We have identified microbes that are present within the AD system, and the time-scale of the dynamic changes. This method has also revealed novel methanogens that are important in the AD process.

No description available.

Faecal Sludge Management is regarded as an affordable and viable option for providing sanitation services in complex informal urban settlements. This thesis examines to what extent current urban sanitation planning approaches and practices are suitable frameworks for achieving sustainable Faecal Sludge Management in informal settlements. The findings are based on a mixed methodology approach where primary data was collected from household level questionnaires (N=169) and a series of key informant interviews (N=35 at city and country level, N=14 at community level) during 2013 in Lusaka, Zambia. The development of a decision support tool that allows for the modelling, costing and comparison of various Faecal Sludge Management infrastructure and technology scenarios was also completed. The findings conclude that whilst many urban sanitation planning approaches exist, adaptation is required so that sustainable Faecal Sludge Management systems can be achieved in complex informal environments. Firstly, a more in depth understanding of social structures, dominant influences and their effect on service provision is required. In particular, an understanding of the role of politics, power, trust and history was shown to be vital. Insights from various decision-making domains including household, community, city and country level representatives was shown to be essential. Application of the developed decision support tool highlighted that obtaining accurate spatio-topological information on the existing sanitation and transport infrastructure networks and on the status and capacity of the containment, removal and transportation components of the Sanitation Value Chain is critical. These are required to ensure accurate long-term cost projections can be developed for various modelled scenarios, that comparisons can be made against other sanitation technologies and where appropriate, sustainable services can be implemented. This research bridges a gap in the sanitation sector by highlighting key socio-technical factors that need to be addressed in order to achieve sustainable sanitation provision for informal settlements in Zambia and beyond.

Heavy metals are found as pollutant in many industrial waste waters. The toxicity of heavy metals has been known for many years and they belong to persistent toxic substances. Therefore, removal of these metals from industrial effluents represents an important challenge in order to avoid one of the major causes of water and soil pollution. The aim of this thesis was the efficient removal of two metal ions which are close to or more noble than hydrogen in the electromotive series (i. e. zinc and copper) from aqueous solutions that simulate industrial wastewater containing these two elements. The removal was done by employing an electrolytic reactor, provided with a 3-dimensional packed-bed cathode of carbon particles, operated in a continuous recirculation mode of flow. Firstly, the removal of copper from monometallic solution was dealt with where the effects of initial concentration of the metal, flow rate, applied current intensity and initial pH (pHo) on removal % and current efficiency of the metal removal were presented. Moreover, two experiments were performed at the same recirculation flow rate, pHo and initial concentration. In the first one the applied current was fixed at 7 A, while in the second one the applied current was decreased from 7 A to 3 A; by manually decreasing 1A every 15 minutes. The second mode of current application led to saving of 41.6 % in the electrical energy utilized for about 96 % removal of copper. Also, the removed copper could be recovered as Cu2O. Secondly, the removal of copper and zinc from bimetallic solutions - containing different mass ratios of Cu to Zn in the range from 0 - 80 % - were investigated. Experiments were carried out under galvanostatic condition. The initial pH was kept almost constant at a nominal value of 2.65 and the rate of flow of the treated solution was fixed at 0.065 L/s. It was found that: - The increase of Zn ratio did not affect the removal of copper negatively; but the presence of Cu with Zn did. - Increasing applied current intensity enhanced the removal of Cu and Zn while the current efficiency was decreased. - The effects of generation of hydrogen, anodic dissolution and IR drop are main reasons for decreasing current efficiency. Thirdly, a kinetic study was carried out in order to determine the order of the kinetics of metal-removal process and to shed light on how the operating parameters affect the value of rate constant. The study revealed that: - The removal of copper and Zn ions followed first order kinetics with respect to the concentration of the metal. - The apparent rate constant, k, of copper removal was found to depend on (F.R.), (pHo), (Co)Cu, (I) and the presence of Zn in the same solution with Cu. - The apparent rate constant, k, of Zn removal was found to be almost independent of the mass ratio of copper to zinc and increased with increasing applied current.

Over the last 18 years, different sludge pre-treatment processes have been used to improve the performance of sewage sludge anaerobic digestion efficiency. Some of these pre-treatment technologies, notably the Thermal Hydrolysis Process (THP), has significantly increased the sludge throughput and allowed more efficient utilisation of treatment assets without adversely impacting the biology of the anaerobic digestion process. However, the expected increase in Volatile Solid reduction (VSr) and the consequent increase of biogas production have not been fully realised. Specifically, to address this poor performance when the THP process is used and to overcome its limitations, its application as an Intermediate Thermal Hydrolysis Process (ITHP) was studied. The ITHP process configuration consists of a first stage conventional Mesophilic Anaerobic Digestion (MAD) followed by THP and then a second stage MAD (i.e. MAD+THP+MAD). The main aims of this research were therefore to evaluate the impact of the ITHP configuration on an already digested sludge constituents, namely, carbohydrates, proteins and lipids degradation and the extent of their conversion to biogas. The sludge constituents’ degradation as a result of thermal hydrolysis and Anaerobic Digestion (AD) followed a stepwise process where the initial faster degradation was followed by a second stage slower degradation process. The sludge constituents’ degradation kinetic rate constants showed that the use of ITHP can further enhance the already digested sludge degradation reducing the sludge mass and increasing its conversion to biogas. Furthermore, the ITHP configuration showed a significant impact on sludge Extracellular Polymeric Substance (EPS) content. The results obtained from laboratory scale experiments showed that the ITHP process configuration resulted in an overall average VSr of 62% in comparison with the THP configuration which provided a VSr of 47%. As a result, the overall biogas production from the ITHP process was found to be in excess of 478 m3/tonne dry solids (TDS) fed, compared with 345 m3/tds feed from the THP digestion configuration.

The UK water industry has huge, but as yet under-developed, potential to generate sustainable energy from the main by-product created in the treatment of wastewater. Sewage sludge is an energy rich sustainable biomass resource with a similar calorific value to woodchip. Until recently, technologies and processes for further energy recovery have not been efficient or viable for large-scale use, but this research has shown that developments and innovations are now available and can realistically be brought into use. Using a combination of detailed techno-economic analysis and data from several large scale demonstration plants this research has shown that the renewable energy produced from sewage sludge in the UK could be significantly increased. A typical conventional AD site will achieve 15% electrical conversion efficiency; this can be improved to 20% with the Thermal Hydrolysis Process (THP). Second generation THP developed during the project could boost recovery to 23% with other benefits such as reduced support fuel requirements and sludge transport volumes. By combining THP, sustainable thermal drying and pyrolysis, gross conversion efficiencies of 34% to electricity are achievable. All of the scenarios developed by the project have been proven to environmentally & economically sustainable and have been demonstrated at a large scale as part of this project. A UK wide study in conjunction the Department of Energy & Climate Change showed that an economic deployment across the UK of second generation THP, followed by drying and pyrolysis, could generate to 2,216GWh or an additional 1,310GWh pa of renewable electricity from sewage sludge.