Waste Stabilization Ponds (WSPs) are used to treat wastewater largely in developing countries, though their ecology is not well understood. Past studies have used taxonomic microscopy methods to assess the photosynthetic organisms vital for WSPs functioning. There has been little use of molecular methods based on evolutionary classification in this field. This thesis sets out to develop molecular methods to study the ecology of these systems. Efficient, non-biased DNA extraction is vital for reliable molecular analysis. Commercially available DNA extraction kits were tested for efficiency when used on WSP samples. Qiagen’s Blood and Tissue kit was recommended for use. The proportion of non-photosynthetic to photosynthetic organisms making up the WSP community was investigated. Fluorescence in Situ Hybridisation (FISH) and flow cytometry based methods were devised to this end. FISH had low efficiency due to variable algal cell wall permeability. Flow cytometry proved to be an effective way to sort photosynthetic organisms from non-photosynthetic, though fixation of samples reduced efficiency. Flow cytometric counting and a PCR and DGGE approach optimised to assess microalgae and cyanobacteria were used in two case studies. The first showed a significant difference between the community found in two pond systems in Brazil, one fed with domestic wastewater and the other with mixed industrial - domestic wastewater. The second assessed the effects of engineered baffles on communities in facultative ponds (in Colombia) across the diurnal cycle. The baffled pond had lower diversity, but more of the species identified were photosynthetic. The PCR-DGGE based method was compared to traditional microscopy techniques with the help of a taxonomic specialist. Little agreement between the methods was seen at species level. The molecular analysis, including the primers chosen and the available database sequences favoured the Chlorophyceae and the cyanobacteria, the microscopy methods favoured the larger Euglenophyceae and other microalgae with morphologically distinct characteristics.

Pharmaceuticals and their metabolites are known to enter the environment from the effluent of wastewater treatment plants. From statistical analysis on the usage of pharmaceuticals, and their effects on the environment, five pharmaceuticals were selected for this study (Metronidazole, Trimethoprim, Sulphamethoxazole, Paracetamol and Ranitidine). Trace concentrations of pharmaceuticals were determined using a sensitive analytical method, comprising solid phase extraction (SPE) and liquid chromatography with a mass spectrometry detector (LC- MS),operating in selected ion monitoring (SIM) mode. It was found that Metronidazole, Trimethoprim, Sulphamethoxazole, Paracetamol and Ranitidine were detected at the highest levels in the wastewater entering the Sulaibiya WWTP Kuwait, with concentrations of up to 58 ng.L , 1814 ng.L , 1669 ng.L , 2086 ng.L and 2009 -1 ng.L , respectively. High removal efficiencies of these pharmaceuticals were found in the Sulaibiya WWTP. One year study was conducted to investigate the occurrence, persistence and fate of a range of these pharmaceuticals at different sampling points at the Sulaibiya WWTP. The treatment processes consisted of screening, grit removal and diffused air activated sludge treatment (primary and secondary treatment), followed by microfiltration (MF), reverse osmosis (RO), and chlorine oxidation (tertiary treatment). During primary and secondary treatment, Metronidazole, Trimethoprim, Sulphamethoxazole, Paracetamol and Ranitidine were removed efficiently with average removals efficiencies of 83.4%, 86.1%, 77.5%, 97.5% and 77.5%, respectively. The RO system lowered these pharmaceuticals further, giving overall removal efficiencies of 97%, 99%, 99%, 100% and 100% for Metronidazole, Trimethoprim, Sulphamethoxazole, Paracetamol and Ranitidine, respectively. All selected pharmaceuticals were tested in laboratory scale reactors to assess their -1 removal by chlorination and ozonation, and results showed that 10 mg.L of chlorine -1 removed these pharmaceuticals better than 15 mg.L of ozone. Lab-scale aerobic reactors (2 L), seeded with activated sludge inoculum from the Sulaibiya WWTP and fed with different concentrations of pharmaceuticals (0.1, 1 and -1 10 mg.L ), spiked individually into a synthetic wastewater showed that the TOC could be removed efficiently without inhibition by these pharmaceuticals. The fate of Metronidazole, Trimethoprim, Sulphamethoxazole, Paracetamol and Ranitidine was investigated in a membrane bioreactors (MBR), and a sequencing batch reactors (SBR), operating under strictly aerobic, and anoxic/aerobic conditions at different concentrations of a pharmaceutical mixture (PM) of the same -1 -1 -1 pharmaceuticals (1 µg.L , 1 mg.L and 10 mg.L ). The COD and TOC removal -1 efficiency decreased when the PM concentration was increased to 10 mg.L . The removal of Metronidazole and Trimethoprim was moderately effective, and similar in all the reactors. Sulphamethoxazole and Paracetamol were removed efficiently, but -1 this decreased when the PM was increased to 10 mg.L for most of the reactors, whilst Ranitidine experienced high removal rates at all concentrations in all the reactors. Analysis of the microbial diversity in laboratory reactors treating pharmaceuticals wastewater showed decreases in microbial community diversity when the PM concentration was increased. Pure cultures of bacteria isolated on selected pharmaceutical growth media were also detected in the microbial communities of reactor sludge by performing polymerase chain reaction–denaturing gradient gel electrophoresis (PCR-DGGE).

No description available.

The increasing carbon footprint of the water and organic waste sectors has led to water utilities to voluntarily include carbon mitigation approaches within their strategic plans and to an increase in research aimed at mitigating carbon dioxide (CO2) emissions. Injection of CO2 in anaerobic digesters (ADs) for its bioconversion into methane (CH4) has been identified as a potential solution. However, previous literature provided limited knowledge of the carbon benefits obtainable and presented conflicting information regarding the mechanisms of CO2 utilisation. This thesis investigated the potential of injecting exogenous CO2 into ADs for its bioconversion into CH4 to reduce CO2 emissions from water and organic waste facilities. Batch laboratory scale and continuous pilot-scale ADs enriched with CO2 were operated. A substrate dependant response to exogenous CO2 was reported for the first time and potential CO2 savings of up to 34% and 11% were estimated for sewage sludge and food waste batch ADs, respectively, injected with CO2 before the digestion process. Higher benefits in CH4 production were observed in sewage sludge ADs than in food waste units. An up to 2.4 fold increase in CH4 production during the 24 hours following saturation with CO2 was obtained in sewage sludge units, while benefit was limited to 1.16 fold in food waste ADs. Microbial community analyses were performed to elucidate CO2 fate mechanisms. An increase of up to 80% in the activity of Methanosaetaceae (obligate acetoclastic methanogen) was observed in sewage sludge ADs periodically enriched with CO2. Methanosaetaceae was scarce (4.3±1.7%) in food waste units, which was attributed to an inhibitory concentration of ammonia (4 gL-1 NH4-N). Based on Archaea analyses and on monitoring hydrogen (H2) and volatile fatty acids (VFA) speciation dynamics in a pilot-scale AD, it was proposed that exogenous CO2 is reduced by homoacetogenesis (Wood-Ljungdahl mechanism) and the acetate generated by this route is converted to CH4 by acetoclastic methanogenesis. Gas to liquid mass transfer was identified as limiting of the amount of dissolved CO2 loaded to an AD and the complex rheology of anaerobically digested media as detrimental for transfer performance. An increase of apparent viscosity (μa) from 130 to 340 cPo (typical variability of sewage sludge) reduced gas transfer efficiency (GTE) by 6 percentage points. The use of bubble columns was identified as suitable for further scaled-up units. Injection of CO2 could be performed in the digestate recirculation loop of single phase ADs or in the first phase of two phase ADs (TPADs), with CO2 sourced from off-gas of biogas upgrading technologies. It has been demonstrated that bioconversion of CO2 in ADs can reduce carbon footprint and increase CH4 production, with the possibility of becoming an on-site carbon revalorisation strategy.

The use of the pyrolysis process to obtain valuable products from biomass is amongst the technologies being investigated as a source for renewable energy. The pyrolysis process yields products such as biochar, bio-oil and non condensable gases. The main objective of this project is to increase energy recovery from sewage sludge by utilising the intermediate pyrolysis process. The intermediate pyrolysis has a residence time ranging from 5 to 10 minutes. The main product yields from sewage sludge pyrolysis are 50 wt% biochar, 40 wt% bio-oil and 10 wt% non condensable gases. The project was carried out on a pilot plant scale reactor with a load capacity of 20 kg/h. This enabled a high yield of biochar and bio-oil. The characterisation of the products indicated that the organic phase of the bio-oil had good fuel properties such as having high energy content of 39 MJ/kg, low acid number of 21.5, high flash point of 150 and viscosity of 35 cSt. An increase in pyrolysis experiments enabled large quantities of pyrolysis oil production. Co-pyrolysis of sewage sludge was carried out on laboratory scale with mixed wood, rapeseed and straw. It found that there was an increase in bio-oil quantity with rapeseed while co-pyrolysis with wood helped to mask the smell of the sludge pyrolysis oil. Engine test were successfully carried out in an old Lister engine with pyrolysis oil fractions of 30% and 50% blended with biodiesel. This indicates that these pyrolysis oil fractions can be used in similar engine types without any problems however long term effects in ordinary engines are unknown. An economic evaluation was carried out about the implementation of the intermediate pyrolysis process for electricity production in a CHP using the pyrolysis oil. The prices of electricity per kWh were found to be very high.

No description available.

There is growing evidence that even low levels of phosphorus (< 0.1mgL-1) entering natural water systems can cause eutrophication. Waste water treatment plants discharge over 23kT of phosphorus into UK surface waters per year. The Water Framework Directive requires that this be greatly reduced. Although many processes have been developed, they are often complex and energy intensive. This thesis aimed to assess how a novel process using dewatered water treatment works residuals (DWTR) could be engineered to maximize phosphorus removal from waste water treatment plant effluents while minimising system complexity and energy use. An extensive yearlong experiment was operated at two sites to investigate how phosphorus removal rates varied over time in relation to DWTR type, phosphorus concentration, hydraulic retention time (HRT) and scale. DWTR from eight different water treatment works were used in 35 experimental models of dimensions 0.1Ø x 1m and two meso scale beds 1x1x0.8m. The most significant factors effecting P removal rate were found to be DWTR type and media particle size. Total P removal varied between 58-95% for the 8 different DWTR over the year. Increasing particle size from 0.6-2 to 6-20mm reduced P adsorption capacity by 30% on average with 6 hours HRT and 5mgL-1 TP input. The key physical and chemical properties of the DWTR were measured to assess the effect of the parameters on the P removal ability of the media. No significant relationship (p < 0.05) between the amount of Al, Fe, Ca or Mg in the media and its P removal ability were found. An idealised adsorption system using DWTR as the media would operate with 2 to 3 beds in series with a minimum HRT of 6 hours and maximum particle size of 6mm and depth of 1m. Computer models of such a system predict >95% TP removal for over two years of operation.

The use of novel industrial by-products (IBPs) to remove phosphorus (P), instead of high-cost P removal techniques, is one of the sustainable solutions to protect aquatic life from excessive P discharges. One of such IBPs is dewatered drinking water treatment works sludges generating from using aluminium or iron salts as coagulant during the drinking water treatment process. Previous studies have shown that the sludges hold promise as a novel adsorbent for the removal of P from wastewaters; however, comprehensive investigation into factors affecting the P removal and the recovery is lacking. Therefore, the main aim of this study is to contribute to a mechanistic understanding of P removal and retention by dewatered water treatment sludge (DWTS), and the associated coagulant recycling and P recovery from the P-saturated sludge used as substrate in a constructed wetland system. Seventeen DWTSs were collected from different areas in the UK to study the combined effect of sludge inherent properties and solution chemistry; and the P equilibrium and kinetic adsorption behaviour using batch experiments. Results revealed that the metal content (Al, Fe, Aloxalate and Feoxalate) and specific surface area components had the most significant explanation for the variance of: (i) P-uptake at different initial P concentrations; (ii) the adsorption maxima; and (iii) the Freundlich constant. Overall, giving the combined effect of intrinsic sludge properties and solution chemistry, dewatered waterworks sludges with high reactive metal content (Al and Fe), Ca and SO42- ions, and total specific surface area, would be the best choice for P retention in practical applications. Phosphorus retention by two Al- and two Fe-DWTS were modelled under various operation conditions of hydraulic retention time and influent P concentration, using a continuous feeding system. Four design equations for P retention were developed and these successfully predicted discrete P retention, maximum P loaded to the sludge, accumulative amount of P retention, and lifespan at the required P saturation degree. The model results revealed that the lifespan of ferric sludge is about four years to reach its saturation point, if the flow rate of 190 (l/capita.d) and inflow P concentration of 5 mg/l are used. IV With regards to coagulant recycling and P recovery using electrodialysis (ED) technology, P saturation degree influenced negatively on Fe and P recovery where their percentages dropped from 70 ± 8%, 49 ± 3% to 17 ± 2, 6 ± 1% when P saturated sludge increase from 0% to 100% respectively. The normalised values of recovered Fe to permeated dissolved organic carbon (DOC) were between 29 and 290. Most of the recovered coagulants were comparable in performance with commercial coagulant in term of DOC removal (42 to 59%), Turbidity, and UV254 absorbance. Overall, the results have shown that DWTS has great potential not only for P removal but also for coagulant and P recovery. However, further research is needed before the developed models can be applied at field scale, and also to enhance the ED recovery for further benefits.

This study evaluated the application of magnetised powdered activated carbons and biochars, in the removal of typical pollutants encountered in refinery and other wastewaters. Phenol, pharmaceuticals and heavy metals were chosen as representatives of priority pollutants, organic micropollutants and metals. In the sorption of the organics, there existed a strong correlation (Pearson correlation R up to 0.9990) between isotherm models’ capacity parameters and sorbents’ capacity influencing properties. In the case of the metals, the sorbents’ capacities are not dependent upon surface area and micropore volume. In some instances, the biochars have on the average about 20.45% higher uptake of the metals than the activated carbons. A general decrease in phenol uptake on the biochars with increase in pH was recorded, due to electrostatic repulsion between like charged surface and sorbates. For the activated carbons, peak phenol sorption was found within the vicinity of the pKa and point of zero charge when there is maximum electrostatic attraction between the opposite charged surface and sorbates. For the micropollutants, ibuprofen was negatively affected by an increase in pH while diclofenac sorption was not sensitive to changes in pH. Sorption of metals was found to increase with an increase in pH. Synthetic wastewater (SWW) did not have a significant impact on the sorption of the phenol and heavy metals. In the case of phenol, the highest impact, an average of just 6.15% for all sorbents was recorded. For the micropollutants, according to the linear model, there is, on the other hand, about 92 and 96% less uptake of diclofenac and ibuprofen respectively due to competition. Finally, in an equimolar solution, due to its high solubility, Zn2+ was outcompeted by Cu2+ and Pb2+ for binding to available sorption sites.

Biofilms are sessile microbial communities attached to a surface, and offer a multitude of benefits to various biotechnological applications, such as anaerobic digestion. Therefore, engineering systems to promote biofilm formation is becoming increasingly desirable in the biotechnology sector. This thesis aimed to promote biofilm formation from the robust model methanogen, Methanosarcina barkeri, onto polymer support materials as a strategy for optimising the anaerobic digestion of domestic wastewater in peri-urban areas. A first step in this direction was to understand the effect of the support material on the biofilm-forming capabilities of M. barkeri. Various techniques were used throughout this thesis to show that the choice of support material was an important environmental factor in triggering different physiological responses from M. barkeri during biofilm formation. DLVO modelling, surface characterisation and static adhesion assays revealed the important role of the physicochemical surface properties of M. barkeri and the six support materials for initial microbial adhesion. M. barkeri was shown to exhibit different abilities to attach to the support materials, with the type of material strongly influencing the extent of initial attachment. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, zeta potential analysis and fluorescence microscopy suggested that significant modifications to the cell surface occurred in response to attachment to a favourable support material (PVC), with increased levels of cell surface polysaccharides detected in biofilms attached to PVC compared to PETG. Furthermore, microbial attachment to PVC caused a significant higher relative abundance of proteins involved in methanogenesis, metabolism, cell wall biogenesis and EPS production compared to biofilms attached to PETG. The results from this thesis suggest that M. barkeri showcases different physiological responses for biofilm formation depending on the support material. Therefore, the choice of support material is an important design parameter for retaining microbial biomass within AD reactors, and should be considered in future design frameworks for high rate anaerobic digestion.