Land-based systems for the remediation of landfill leachate have the potential to provide a low-cost, low-tech alternative for dealing with the consequences of the long-term generation of polluted water from a body of municipal solid waste. However, assessing the sustainability of these systems is hampered by limited long-term monitoring under controlled and field conditions and its impact upon soil chemical quality. Despite these limitations, landfill leachate has been successfully irrigated to a range of vegetation communities. Three vegetation-based trials and a computer-modelling exercise were conducted in an attempt to assess the sustainable management for dealing with leachate from the Penhesgyn landfill site in north Wales.

Biochar from biomass pyrolysis offers a geotechnical solution to the major global issues of climate change, soil degradation and food shortage . The focus of this study is to generate stable and nitrogen enriched biochars and high quality bio oils from co -pyrolysis of biomass with bone matter at low temperatures. The biochar can act as a fertilizer because of its mineral contents while at the same time promotes carbon sequestration when used as soil amender. By improving the use of biochar, it may be possible to also utilize the bio oil for renewable generation. Currently, the biochar production process suffers from the draw backs such as the use of high temperature of up to 500°C, low biochar yield and poor bio oil quality which as rendered its applications beyond solid fuels. This work has focused on the co-pyrolysis of bone matter (BM) with pistachio (PS), Pine wood (PW), and Wheat straw (WS) at low temperatures to produce carbon and nitrogen rich biochar and improved bio oil. A prototype tubular reactor was designed and commission for pyrolysis of BM in the temperature range of 150°C to 600°C and mixing BM from 2.5wt% to 20wt%. The analysis of the biochar product showed that the addition of BM to the biomass increased their biochar yields with up to 10wt% BM addition. This was linked to the ability of the BM to interact with the biomass and retain condensable compounds at temperatures between 300°C and 350°C. Addition of BM above 10wt% was found to reduce the overall biochar yield from the biomass and promote gasification. At 10wt% bone addition, the carbon and nitrogen contents of the biochars were both increased compared with the biomass on its own, while the oxygen content decreased.

The coal-fired power generation industry is responsible for a large portion of the CO2 emission to the atmosphere. In many countries, Carbon Capture and Storage (CCS) is suggested as a long-term solution for CO2 mitigation. Oxy-coal combustion, one of the CO2 capture processes in the CCS, with Recycled Flue Gas (RFG) can be applied to the conventional coal combustion plants with modifications. However, based on the · preliminary investigations and laboratory-scale data, technical challenges have to be undertaken before oxy-coal combustion reaches the demonstration phase. In this thesis, prediction of the performance of an oxy-coal Combustion Test Facility (CTF) with RFG, and defining the challenges, are the main objectives. Technical challenges of the oxy-coal combustion are addressed, combustion physical submodels are discussed and challenges regarding modelling of the oxy-coal combustion are addressed. State-of-the-art char combustion models, along with a comprehensive set of microscopic studies (SEM, EOX and XRO) of the fly ash from air- and oxy-coal combustion tests, are discussed. Following that, a requirement for revision of the standard char burnout models for application to oxy-coal combustion is presented. An updated gas-phase mercury chlorination mechanism is presented and validated with the unbiased experimental data. In parallel, the solid-phase mercury retention and oxidation processes on the fly ash are investigated. Furthermore, an empirical correlation for the prediction of mercury speciation in the NOx removal unit is suggested. Following the development of a combined homogeneous-heterogeneous mechanism, recommendations regarding a global model for predicting the mercury transformation through the power plant are addressed. The 1 MWth CTF of interest is modelled using advanced numerical simulation (CFO) methods. The geometry set up, the boundary conditions and the approach for grid independency and optimization are discussed. Two variations of turbulence modelling techniques for simulation of air- and oxy-coal combustion have been used to assess the CFO modelling predictions. Finally a techno-economic analysis of the oxy-coal combustion process is given in detail. This includes a comparison of the thermodynamics and the costs of typical air-coal, post-combustion and oxy-coal combustion processes in the UK and China.

This thesis aims to investigate the production of electrochemically activated solution via electrolysis of diluted NaCI solution using a commercial electrochemical system (STEL device), characterise the activated solution, and evaluate the potential application of this solution in the treatment of water containing organic compounds. The research shows that the electrolytic cell in the STEL device consists of a titanium based metal oxide (Ir02, Sn02, and Ti02) coated anode, a tubular titanium cathode, and a tubular ceramic diaphragm that separates the anode and cathode. A model electrolytic cell using STEL anode material was designed and constructed for investigating reaction mechanisms occurring at the electrode and identifying the oxidising species generated at the anode during the electrolysis of NaCI solution. Experimental results show that chlorine and oxygen were two main oxidants contained in the anolyte, indicating that the generation of chlorine and oxygen are involved in the electrode reactions. The evolutions of chlorine and oxygen were found to be achieved via the formation of a series of adsorbed intermediates such as OHad, Oad on the anode surface during electrolysis. Evidences for the occurrence of the intermediates were obtained by several electrochemical observations. It is suggested that the evolution reaction of chlorine involves a mechanism in which an intermediate of OClad is formed instead of Clad. The adsorbed intermediates may also be released from the anode surface to form chlorine free radicals and hydroxyl radicals when the electrolysis is carried out at higher potentials. This was investigated using the electro-oxidation of salicylic acid (SA). It was found that in a buffer solution containing chloride ions, the oxidation processes of SA were dependent on the potential applied on the anode. At + l.5V, the reaction product was 2,4,6-trichlorophenol, indicating that chlorine free radicals were generated. At +2.5V, the obtained products included 2,5-dichloro-l,4-benzoquinone, indicating that a hydroxyl group is introduced to the benzene ring of SA. These results suggest chlorine free radicals were generated at + l.5 V while hydroxyl radicals were generated at +2.5V. The operating conditions of the STEL device were optimised with respect to the redox potential, pH, and chlorine concentration of the generated ECAS. Anolyte produced from the STEL system, using a 100/0 NaCI solution under optimised electrolysis conditions, is an acidic solution (PH 2.2) containing a mixture of oxidants with a redox potential of 1190 m V and an available free chlorine concentration of 280 mgIL. The catholyte solution is a reductive basic solution with a pH of 12.6 and a redox potential of -950m V. The anolyte solution can maintain the oxidation ability up to 6 days when it is stored in an air tight container. However, it will lose its oxidation ability in 30 min if is purged by nitrogen or in 60 min if is stirred in the atmosphere. The anolyte solution can degrade trace amounts of aromatic compounds in aqueous solution. The degradation products are dependent on the concentration and chemical nature of the reagents. Usually, 10-4M SA can be converted to ring opened compounds, while 10·3M SA can only be converted to quinonic compounds. A subsequent dechlorination step is required when using anolyte for treating aqueous solution containing organic compounds as the by products include chlorinated compounds.

Mixtures of polycyclic aromatic hydrocarbons (PARs) and heavy metals are of major concern in contaminated soil. The aim of this project was to investigate the impact of heavy metals and PAHs on microbial activity, concentrating on the mineralisation of PAHs and partitioning of phenanthrene in the presence of metals. Naphthalene and phenanthrene were used as model PAHs and Zn, Cu, Al and Fe were used as model heavy metals. 14C_ Naphthlene and 14C-phenanthrene mineralisation were followed in soil with varying concentrations of Zn, Cu, Al and Fe; a sequential aqueous\solvent extraction scheme was also used to assess the partitioning of phenanthrene in the presence of these metals. Zn and Cu (50 and 100 mg/kg) stimulated (p < 0.05) 14C-naphthalene mineralisation, but had no impact on 14C-phenanthrene mineralisation. Zn (500 and 1000 mg/kg) had no impact on 14C-phenanthrene mineralisation (p > 0.05), but Cu (500 and 1000 mg/kg) significantly reduced (p < 0.05) phenanthrene catabolism, particularly in aged Cu. Zn and Cu mixtures (500 and 1000 mg/kg) inhibited 14C-phenanthrene catabolism. 14C-Glucose mineralisation (maximum rates) and incorporation into the microbial biomass were significantly reduced at higher Zn and Cu concentrations (500 and 1000 mg/kg). Al and Fe (50 and 100 mg/kg) stimulated (p < 0.05) both 14C-naphthalene and phenanthrene mineralisation, however, Al (500 mg/kg) significantly reduced (p < 0.05) mineralisation of both PAHs. Fe (500 mg/kg) stimulated both 14C-naphthalene and phenanthrene mineralisation. Cu and Al (500 mg/kg) significantly increased (p < 0.05) 14C-phenanthrene extractable CaCh and HPCD fractions, this could be because of their great affinity for the organic and mineral soil components. The impact of metals on the biodegradation of PAHs depends on the type and concentrations of the metals, as well as the incubation time. Studies on metal-P AH impact in soil facilitates the assessment of risk, hazard and bioremediation potential at sites contaminated with both contaminants.

Global soils have the capacity to act as a sink for polycyclic aromatic hydrocarbons (PAHs) and subsequently as a secondary source making soil/PAH interactions important to environmental PAH levels. A number of physical, chemical and biological processes determine P AH fate in soil but microbial degradation is the most important. Biodegradation depends on bioavailability, soil organic matter, water and nutrient content, temperature and previous exposure to PAHs. Globally, environments differ and soils from different geographic regions differ in their properties and PAH concentrations. While the importance of diffuse P AH contamination of soils is widely acknowledged in literature, most studies on P AH biodegradation in soils have been conducted on soils contaminated from a P AH point source. The aims of this project were to investigate the indigenous biodegradation of PAHs in pristine soils from different geographic locations as well as what environmental factors are most significant in the development of PAH biodegradation potential in pristine soils. Pristine soils used include soils from Antarctica, Norway, UK and Tibet. Levels of PAHs in all the soils were low and properties like soil organic matter, nutrients and water content were different. P AH degrading bacteria were present in all the soils studied irrespective of low PAH concentrations. Temperature was found to affect both the rates and extents of P AH degradation in the Antarctic soils. Results also suggest that the effect of temperature on adaptation of indigenous microbes to PAH degradation might be more important than that of lack of exposure. Further works suggested include the identification of individual P AH -degrading bacteria in these background soils and investigating the effect of increasing soil P AH-contact time in low organic matter background Antarctic soils.

Atmospheric particulate matter, along with gaseous and precipitation pollutants, were collected close to three historic buildings; Lincoln Cathedral, Bolsover Castle and Wells Cathedral, in order to estimate the amount of sulphur and nitrogen deposited onto each. Results obtained showed that the gaseous dry deposition of both sulphur and nitrogen was the main deposition pathway at Lincoln and Bolsover, whereas as a result of high precipitation amounts the wet deposition pathway was the most significant at Wells. At each sampling site the amount of sulphur and nitrogen deposited as dry particulate matter was relatively insignificant. Estimated washout values for both SO² and SO²⁻, indicated that the former provided approximately 80% of the sulphur in precipitation arriving at the building surfaces. The important role of the gas was reinforced by the significant correlation between the sulphur level in precipitation and sulphur dioxide. The concentration of sulphur in precipitation was found to decrease at high precipitation volumes, whereas the nitrogen concentration was unaffected by precipitation volume. A high sulphate to sulphur dioxide concentration ratio during the summer months was indicative of photochemical oxidation processes. Conversely, during the winter months the relatively low sulphate to sulphur dioxide concentration ratio suggested that sulphate and sulphur dioxide were released from common sources. Multivariate statistical techniques, comprising principal component analysis and multiple regression analysis, were used to infer characteristics about the origin of the constituent parts of the collected particulate matter. In general, three sources of material; secondarily formed particulate matter, sea-salt and crustal material, were estimated to contribute to the collected particulate matter.

The seasonal variations of a number of plant nutrients, pH, spoil moisture and temperature and groups of microorganisms concerned with the recycling of nitrogen were investigated in ameliorated and untreated spoils at two colliery spoil heaps of contrasting spoil pH situated in West Yorkshire.

No description available.

Contamination of soil with arsenic (As) is a global environmental concern because As is toxic and carcinogenic. Ochre, a waste generated from mine water processing, has great potential for the remediation of As contaminated soils due to its high iron (Fe) oxyhydroxides content. Iron oxyhydroxides have large reactive surface areas for As adsorption. This research investigated the potential of ochre to adsorb As in solution and in contaminated soils and also assessed the possibility of using ochre to eliminate As exposure transport pathways (leaching to groundwater, plant uptake and soil ingestion).