Call number: LD2668 .T4 1951 H67 / Master of Science

Call number: LD2668 .T4 1955 H45 / Master of Science

A detailed investigation of the kinetics of dissolution of kaolinite clay in hydrochloric acid solution has been carried out. The rate of dissolution increases with calcination temperature, calcination time, and leach temperature. For example, almost 98% of the aluminum in the clay sample roasted at 540°C for 1 h can be dissolved in 20 min. The presence of fluoride ions in the leach solution significantly enhances aluminum dissolution. Changes in the pore structure of kaolinite clay due to calcination and hydrochloric acid leaching have been studied by a gas adsorption technique. The results obtained show that the surface area, macropore volume, and micropore volume of the leached residue increase with the extent of leaching up to a leach time of 1 h and thereafter decreases. Calcination at 500-750°C appears to destroy the structure of the clay but has no significant effect on the porous nature of the clay.

Chlorosis and premature loss of pine needles was observed in the Delamere Forest, N. Cheshire in late 1992. Fears that the local environment had suffered, and was continuing to suffer, from acid rain or mist 'episodes' as a result of airborne pollutants, led to an analysis of pine needles for total foliar element concentrations in early 1994. Analysis by X-ray Fluorescence Analysis (XRF) revealed levels of foliar sulphur (0.35%) and chloride (0.32%) that suggested deposition of these chemicals as a result of emissions from nearby sources, including a local power station , Ince 'B', a scenario later confirmed by the local environment agency. A monthly programme designed to monitor tree health in Delamere Forest in relation to local levels of atmospheric S02 took place between June 1994 and April 1996, using fixed populations of Scots Pine (P. sylvestris L.) and Corsican Pine (P. nigra var. maritima (Ait.) Melville) to differentiate between short-term acute pollution events and long-term chronic ambient deposition, and to attempt to pinpoint pollution sources. The results revealed complex seasonally affected inter-relationships between atmospheric (dry deposited) sulphur dioxide, rainfall, wind direction and fluctuations in concentrations of foliar elements such as sulphur and magnesium. Average monthly atmospheric S02 levels during this programme were 20 ug/m-3 and foliar S 0.096% total dry weight. The average foliar magnesium level was low at 0.02%. Peaks of atmospheric SO2 were recorded of over 100 ug/m-3, with a maximum of 127 ug/m-3. The initial findings were used as part of a local governmental enquiry that contributed to the decision process which eventually led to the eventual closure of Ince 'B' in 1997. In order to monitor any subsequent changes in tree health as a result, further sampling took place from June 1998 to February 1999. Atmospheric sulphur dioxide levels fell significantly after the closure of of the power station (average 9l ug/m-3) and this change in air quality was reflected in a similarly significant fall in overall concentrations of foliar sulphur (average 0.064% total dry weight). Foliar Mg levels had risen during this period to 0.032%. Recent observations of continued damage to pine foliage in Delamere suggested that although the fall in atmospheric S02 in this area and the subsequent improvement in air quality had followed national trends, Delamere Forest has an ongoing health problem derived from other locally emitted atmospheric pollutants including sporadic emissions of chlorine. It is likely, due to the nature and close proximity of petro-chemical industries, that other pollutants in the immediate local atmosphere such as ozone and ammonia also influence tree health in Delamere Forest and the surrounding environment. Analysis by XRF clearly demonstrated a quick and accurate method of determining foliar element concentrations that could be used to monitor tree health affected by atmospheric pollution. This technique could successfully be used to identify local pollution sources which could prove important in the light of the reduction in local atmospheric pollution monitoring sites since 1999.

No description available.

published_or_final_version / Botany / Doctoral / Doctor of Philosophy

published_or_final_version / Biological Sciences / Master / Master of Philosophy

published_or_final_version / Civil Engineering / Master / Master of Philosophy

Acid mine drainage (AMD) at Stockton Coal Mine, located near Westport, New Zealand, is generated from the oxidation of pyrite within sedimentary overburden exposed during surface mining. The pyrite oxidation releases significant acidity, Fe, and sulphate together with trace metals to the receiving environment. Aluminium is also elevated in drainage waters due to acid leaching from overburden materials. Thirteen AMD seeps emanating from waste rock dumps, and associated sediment ponds were monitored at Stockton Coal Mine to characterise water chemistry, delineate their spatial and temporal variability, and quantify metal loads. Dissolved metal concentrations ranged from 0.05-1430 mg/L Fe, 0.200-627 mg/L Al, 0.0024-0.594 mg/L Cu, 0.0052-4.21 mg/L Ni, 0.019- 18.8 mg/L Zn, <0.00005-0.0232 mg/L Cd, 0.0007-0.0028 mg/L Pb, <0.001-0.154 mg/L As and 0.103- 29.3 mg/L Mn and the pH ranged from 2.04-4.31. Currently this AMD is treated further downstream by a number of water treatment plants employing a combination of ultra fine limestone and calcium hydroxide; however, in the interest of assessing more cost-effective technologies, passive treatment systems were investigated for their treatment and hydraulic efficacy and as potential cost-effective options. Biogeochemical reactors (BGCRs) were selected as the most appropriate passive treatment system for ameliorating AMD at Stockton Coal Mine. Results of mesocosm-scale treatability tests showed that BGCRs incorporating mussel shells, Pinus radiata bark, wood fragments (post peel), and compost increased pH to ≥6.7 and sequestered ≥98.2% of the metal load from the Manchester Seep located within the Mangatini Stream catchment. The following design criteria were recommended for BGCRs incorporating 20-30 vol. % mussel shells as an alkalinity amendment: 1) 0.3 mol sulphate /m3 substrate/day for sulphate removal (mean of 94.1% removal (range of 87.6-98.0%)); 2) 0.4 mol metals/m3/day for metal (mean of 99.0% removal (range of 98.5-99.9%)) and partial sulphate (mean of 46.0% removal (range of 39.6-57.8%)) removal; and 3) 0.8 mol metals/m3/day for metal (mean of 98.4% removal (range of 98.2-98.6%) and minimal sulphate (mean of 16.6% removal (range of 11.9- 19.2%)) removal. At the maximum recommended loading rate of 0.8 mol total metals/m3/day an average of 20.0 kg/day (7.30 tonnes/year) of metals and 85.2 kg acidity as CaCO3/day could be removed from the Manchester Seep AMD by employing BGCRs. The design hydraulic residence time (HRT) would be 3.64 days. On an acidity areal loading basis, a design criterion of 65 g/m2/day was recommended. Tracer studies conducted on the BGCRs indicated ideal flow characteristics for cylindrical drumshaped reactors and non-ideal flow conditions for trapezoidal-shaped reactors indicative of shortcircuiting, channelised flow paths and internal recirculation. Consequently, this resulted in compromised treatment performance in the trapezoidal-shaped reactors. The relaxed tanks in series (TIS) model could be successfully applied to model the treatment performance of drum-shaped reactors; however, the model was unsuccessful for trapezoidal-shaped reactors. Because most pilot and full-scaled vertical flow wetlands (VFWs) have consisted of trapezoidal-prism basins excavated into the ground, the rate-removal methods previously recommended (e.g. mol metals/m3/day) should be applied to BGCR design, evaluation and operation rather than results of hydraulic and reactor modelling. Overall, a staged passive treatment approach is recommended. The first stage should consist of a sedimentation basin to remove sediment, the second stage a BGCR to remove acidity and metals and the third an aerobic wetland to provide oxygenation and tertiary treatment of metals (primarily Fe) from BGCR effluent. Preliminary analysis indicates that BGCRs are potentially a more cost-effective means of treating AMD at Stockton Coal Mine compared with the current active lime-dosing plant by over $125/tonne of acidity ($197/tonne for BGCRs versus $324/tonne for lime dosing (60% efficient)); however, their successful implementation would need to recognise current treatment goals, required areal footprint and inherent maintenance requirements.

No description available.