The chemistry and microbiology of circum-neutral polluting mine waters and other ferruginous discharges were studied with particular reference to the effects of these factors on the rate of iron(II) oxidation. The studies were aimed at furthering the understanding of processes occurring in mine waters from a fundamental and applied perspective. A literature review detailed the mechanisms of the known chemical and microbiological involvement in mine waters.
Throughout the study appropriate analytical techniques were modified to minimise and/or account for interference with iron.
The microbiology of mine water sediments was studied by both classical techniques and 16S rDNA phylogenetic studies. These studies revealed that characterised iron bacteria were not the predominant species present. The phylogeny of the dominant species implied the major bacterial species present may be methylotrophic bacteria, ammonia oxidisers and purple non-sulphur photosynthetic bacteria. Potential niches for these bacteria were suggested from a knowledge of the chemistry of the system.
A specially designed system was developed for the accurate measurement of the rate constant for iron(II) oxidation. Kinetic studies indicated that the rate constant of iron(II) oxidation in mine waters was indistinguishable in magnitude from that in synthetic solutions.
Indigenous concentrations of micro-organisms were shown not to significantly affect iron oxidation. The addition of large amounts of ochre was shown to dramatically increase the rate of reaction.
The levels of seasonal pollution of the Sheephouse Wood mine drainage system were found to be highly variable. This variation was attributed to changes in flow rate, which were correlated to rainfall data, affecting the buffering of the system. The pH of the system was found to rise with time, which was accounted by degassing of C 0 2. Suggestions as to the implications of the results with regard to treatment systems of neutral mine waters were discussed.