Coal-generated acid mine drainage (AMD) is characterized by low-pH waters with excessive loads of dissolved species such as SO4, Fe, Al and Mn along with other elements of environmental concern (i.e. Cd, As, Cr, Ni, Pb, Se and Cu). To mitigate this problem, anaerobic sulfate reducing bioreactors (ASRB) have been implemented as a technology for passive treatment systems that utilize low-cost organic substrates to stimulate biologically enhanced contaminant sequestration. Previous work has identified the establishment of diverse microbial communities in which a hierarchal chain of substrate degradation processes is essential in developing sustainable environments to produce long-lived sulfate-reducing microbial (SRM) populations. In this study, to determine the optimal mixture of substrate types, alternating ratios of herbaceous (ie. leaves, grass, spent brewing grains) and ligneous (i.e. maple wood chips and saw dust) reactor matrices were tested. Five bioreactors along with one control reactor containing only limestone were constructed at the Tab-Simco abandoned mine land (AML) site in southern Illinois, USA. The field experiments were monitored over ~ one year (377 days) to evaluate the physical, geochemical and microbiological parameters which dictate ASRB efficiency in remediation of AMD contaminants. Results from this experiment documented contaminant removal in all reactors. However, the bioreactors established SRM populations that contributed to enhanced removal of SO4, Fe, and trace metals (i.e. Cu, Cd, Zn, Ni). Geochemical assessment of the aqueous environments established within the bioreactors suggested multiple pathways of contaminant sequestration. This included the formation of Fe-oxyhydroxide precipitates, adsorption, co-precipitation (e.g. Zn/Ni-Ferrites) and bio-induced sulfide mineralization. Activity of the SRMs was dependent on temperature, with bioreactors exhibiting decreases in both effluent sulfide concentrations and 34S-depletion of sulfate during low-T months (i.e. T < 10°C). Overall, maximum remediation of dissolved constituents SO4, Fe, Al and Mn was obtained in the predominantly herbaceous bioreactors. Extrapolation of our results to the full-scale Tab-Simco bioreactor indicated that, over the course of one year, the herbaceous bioreactors would remove ~75,600 kg SO4, 21,800 kg Fe, 8000 kg Al, and 77 kg Mn. This represents a 21.7 wt%, 41.5 wt%, 9.4 wt% and 81.8 wt% increase in SO4, Fe, Al and Mn removal over dominantly ligneous bioreactors, respectively. Although the overall Fe removal within the limestone control reactor reached 44.5 mol%; removal of 19.5 mol% SO4 and 36.9 mol% Al from influent AMD were significantly less when compared to the bioreactors. These results imply that ASRB technologies are promising in remediation of coal-generated AMD and increasing herbaceous content of bioreactors can significantly enhance contaminant sequestration. However, geochemical results also displayed seasonal variation in redox gradients within our field ASRB's which may induce dissolution of the redox sensitive phases produced within bioreactors. Furthermore, optimal microbial-mediated sulfate reduction may be inhibited by the high surface areas of the abundant Fe/Al-oxyhydroxides which dominate the system. Therefore, to enhance ASRB remediation capacity, future designs must optimize not only the organic carbon substrate but also include a pretreatment phase in which the bulk of dissolved Fe/Al-species are removed from the influent AMD prior to entering the bioreactor.

Sustainable animal production on pasture planted on rehabilitated mine land will only be possible if the optimal stocking rate for animal and pasture production is determined. A grazing trial was conducted on tall fescue, established on rehabilitated mine land and irrigated with mine waste water. The aims of this study were to quantify: a) animal performance and nutritive value at different levels of nitrogen (N) fertilization during pasture establishment, and b) intake, animal performance (defined as average daily gain; ADG) and nutritive value when different stocking rates were applied. This study was done during two seasons: season one in winter (6 June -16 July 2008) and season two in spring (28 Aug – 6 Nov 2008). In terms of post mining land use this study supplied valuable information on potential livestock production. The higher level of N fertilization applied during the winter of 2007 at pasture establishment resulted in a significantly (P < 0.05) higher crude protein (CP) concentration a year later compared to the lower levels of N fertilization. During the winter grazing season the pasture contained an average of 83.4 g CP kg-1 dry matter (DM), 601.9 g NDF kg-1 DM, 6.2 g Ca kg-1 DM and 1.7 g P kg-1 DM, the average in vitro organic matter digestibility (IVOMD) was 642.2 g kg-1 OM and the average leaf: stem ratio was 88:12. The ADG of crossbred weaner calves grazing the low N fertilization (LN), low stocking rate (LS) paddock (229.1 g day-1) was significantly (P < 0.05) lower than the ADG of weaner calves grazing the LN, high stocking rate (HS) and the high N (HN), LS respectively. The ADG of the animals in the HN, LS paddock was 482.7 g day-1 and in the LN, HS paddock was 310.6 g day-1. The low ADG for the LS treatment was due to the low CP concentration of this paddock, with values as low as 55.1 g CP kg-1 DM recorded during the winter grazing period. Low pasture nutritive value during winter can potentially limit animal production.spring grazing season the pasture contained an average of 101.0 g CP kg-1 DM, 639.1 g NDF kg-1 DM, 8.9 g Ca kg-1 DM and 2.1 g P kg-1 DM. The average leaf: stem ratio was 85:15, IVOMD was 717.5 g kg-1 OM and effective DM degradability (in situ) was 56.1 %. The average OM digestibility estimated with the alkane method varied between 720.8 to 768.3 g kg-1 depending on the alkane used and weather a correction was made for the faecal recovery of the alkane used. On average the forage available in the paddock with the LS had a significantly (P < 0.05) higher CP concentration, leaf: stem ratio and IVOMD, with a significantly (P < 0.05) lower NDF concentration than the HS paddock. This is probably due to the fact that in the HS paddock forage with a high nutritive value was removed at a higher rate. Irrespective of the calculation used, digestibility calculated by the alkane method did not differ significantly (P > 0.05) between paddocks at any time period. The average intake in the paddock with medium grazing stocking rate (MS) was significantly (P < 0.05) higher than the average for the other paddocks. The paddock with the MS was managed to supply a pasture DM allowance of 2.5 % body weight (BW). The DM intake over the spring season was 2.2 % BW. The MS treatment supplied sufficient plant material without resulting in large accumulation of plant material. The ADG for the spring season was 110.5 g day-1 and averages for each paddock did not differ significantly (P > 0.05) from each other. During the / Dissertation (MSc Agric)--University of Pretoria, 2013. / gm2014 / Animal and Wildlife Sciences / unrestricted

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Die Arbeit fängt mit einer Beschreibung des Zustands der Kohlenbergbauindustrie weltweit und des zukünftigen Bedarfes für Kohle an. Danach folgt eine allgemeine Beschreibung des Restrukturierungsprozesses des Kohlenbergbaus in Rumänien und eine vertiefende Untersuchung der Situation im Schiltal infolge des Umstrukturierungsprozesses. Die schwierige sozioökonomische Lage im Schiltal braucht konkrete Lösungen; das Potenzial der Region bietet die Möglichkeit für zukünftige Entwicklungen. Eine vollständige, umfangreiche Analyse und ein Entwicklungskonzept wurden durchgeführt bzw. entwickelt. Es werden sowohl die Entwicklung von alternativen Wirtschaftstätigkeiten, als auch die Modernisierung und Rentabilisierung des traditionellen Bergbaus begründet.