No description available.

No description available.

The aim of this research was to investigate the application and effects of pressure on an aerobic biological wastewater treatment process. For the purpose of the investigation two specially designed, identical, laboratory-scale rotating biological contactor (RBC) units were constructed. One of these was held in a steel pressure vessel while the reference unit was operated open to the atmosphere. The treatment capabilities of the pressurized unit, as compared to those of the reference unit, were determined for a variety of organic loadings at increasing pressures up to a limit of 6 bar. During the investigation, the substrate employed was a synthetic wastewater made up frequently in the laboratory. Most of the analytical work was carried out on composite druly samples of the feed wastewater and of the two effluents produced, both filtered and nonfiltered. In addition, sludge samples from both units were regularly tested for a variety of sludge parameters. The water quality parameters investigated were the 5-day Biochemical Oxygen Demand (BOD5), the Chemical Oxygen Demand (COD), Suspended Solids, pH, Temperature, Ammoniacal Nitrogen and Total Oxidized Nitrogen (TON). The yield of sludge produced and certain characteristics of sludge i.e. Specific Stirred Volume Index (SSVl). Specific Resistance to Filtration, were also obtained. The quantity of air required for the pressurized treatment unit was also investigated. The pressurized treatment unit has demonstrated the capability of operating with a high level of carbonaceous oxidation and nitrification at organic loadings of up to 13 g BOD5/ m2 of disc area per day. In comparison with the identical reference unit operated at atmospheric pressure, the pressurized unit demonstrated slightly improved BODs and COD removal efficiencies, a greatly improved level of nitrification and a substantially lower sludge production. All these characteristics improved with increasing pressure.Of particular importance the sludge yield coefficient was always significantly lower for the pressurized unit than for the reference unit and results such as 0.12 kg dry solids/ kg BOD5 removed at 6 bar pressure are highly signif1cant with regard to the requirements of the modern wastewater treatment industry. Additional investigations were carried out to determine the cost of a proposed full-scale pressurized treatment unit with a design based upon the findings of this investigation. These were compared with the costs of a conventional biological treatment process capable of treating an equivalent wastewater loading. The comparison between the pressurized unit and the selected processes were made for three populations (500, 1,000 and 3,000 persons). The sludge disposal costs of the pressurized unit were appreciably lower than those for the other processes. The results indicated that the cost of the pressurized unit (present value for a twenty-year period) and the costs of activated sludge and conventional RBC processes were found to be similar for the smaller populations. However a substantial saving could be obtained with the pressurized unit for the larger populations. In addition there is an indication that the land requirement of the pressurized treatment unit decreases appreciably as the flow rate increases.

No description available.

No description available.

No description available.

No description available.

Subsurface oil and surface seep samples from the Niger Delta Nigeria, Tano and Cape Three Points Basins in Ghana, and the Orcadian Basin in Scotland were analysed using an organic geochemistry approach. Source organofacies, oil thermal maturity and the effect of alteration processes were evaluated, with the aim of developing a better understanding of the origin, nature and type of petroleum present. Biomarker analyses suggested that undegraded oils are found with biodegraded oils with a range of levels of biodegradation in the Niger Delta. On the commonly used Peters and Moldowan scale of biodegradation, the samples rank between PM level 0 and 7. The Ghanaian and Scottish oils and seeps showed a range of biodegradation levels between PM level 2 and 7. Biodegradation appeared to be the major control on the composition and physical properties of the oils and seeps from Niger Delta and Ghana while there is evidence that a stage of water washing was important for the Scottish seeps. Key aspects of the biodegradation process were reflected in the variable occurrence of hopanoids and other biomarkers. 25-Norhopanes were detected in all samples biodegraded in subsurface reservoirs but absent in seeps degraded at surface conditions. This was observed for both the Ghanaian and Nigeria samples. The inverse relationship of hopane to 25- norhopanes in the Niger Delta is presented for the first time. This evidence supports the hypothesis that 25-norhopanes are a product of hopane demethylation. Furthermore a pathway for the formation of 25-norhopane from 25-norhopanoic acid by decarboxylation is evidence by nature of the covariation in relative concentration of these compounds. Seeps from Scotland show that only moderate levels of biodegradation (PM 3) have significantly reduced monoaromatic and triaromatic steroids abundances. The most likely cause for this is by water washing at surface conditions. Reservoir temperature and oil charge histories appeared to have had a significant influence on the extent of biodegradation in the Niger Delta. The late migration of oil from deeper hotter subsurface regions to shallow reservoirs accounts for the presence of undegraded oils amidst the biodegraded oils in the Niger Delta.

A field study was carried out at Ardross forest, northern Scotland where heavy metal contaminated sewage sludge had been applied to a peaty podzol at rates of 500 (low) and 1000 (high) kg N ha-1 before tree (Sitka spruce) planting. Nitrogen mineralisation rates determined by field incubation of sealed cores ranged from 3.7 to 4.5 and 7.3 to 9.4 kg N h-1 over the growing season (May to September, 1991) in soils amended with low and high rates of sludge respectively. For the control soil, to which no sludge had been added, mineralisation rates ranged from 2.4 to 2.9 kg N ha-1. Mineralisation of residual sludge was estimated to be 0.56&'37 and 1.14&'37 in 1991, 8 years after sludge application at the low and high rates, respectively. Soils brought back to the laboratory and repacked according to the field profile enabled microcosm studies to be carried out to further investigate possible changes caused to N-cycling processes in coniferous forest soil due to application of heavy metal contaminated sewage sludge, and to consider possible mechanisms of any such changes. In the microcosm study, the two rates of application of sewage sludge increased N mineralisation. A linear relationship was apparent between N mineralisation and the rate of sludge application. Increased N mineralisation was associated with an increase in active fungal mycelium, biomass N and soil animal population densities. The availability of Cd, Cu, Mn, Pb and Zn was found to be related to the time of the year, with highest availability in Spring and Summer, and lowest availability in Winter. There was no evidence of any adverse effects in terms of heavy metals on the studied biological parameters and mineralisation rates in the field and microcosm studies. Total N, pH and moisture also increased due to sludge application.

The work in this thesis relates to understanding the potential effects of using surface liming of upland soils to ameliorate water acidification. Effects on vegetation, soil, and drainage water chemistry are considered. Part I of this thesis reviews the environmental conditions of British Uplands (climate, soils and vegetation), and the relevant literature on water acidification in North-East Scotland. In Part II, each chapter deals with materials, methods used, discussion of the results and conclusion for one of a series of individual experiments. This pattern is followed for a number of laboratory, greenhouse and field studies. Liming of different organic soils significantly increased only the surface layer pH of the soils. The consequence of surface liming should be highly beneficial in terms of water quality, since most of the precipitation in the catchment under consideration (Glendye) during heavy storms, when river acid episodes occur, drains near or over the surface. The effect of lime on pH below the surface should be considered after a year or more. Liming on the other hand increased the mineralisation of organic N and released NH4+ and NO3-. The balance between N mineralization and immobilization by vegetation and microbial biomass should be considered carefully for each individual soil and site. If the mobile NO3- reaches the river or streams and increases the NO3- to beyond an acceptable limit, this could be considered an adverse effect of liming. Although within the timescale of this project there was no adverse effect noticed on the heather under field conditions, the long term effects should be considered carefully in terms of changing vegetation pattern as a result of liming, which will favour growth of grass.