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The main goal of this study was to develop a cost-efficient biological method for the removal of sulfate from mining effluents in cold conditions. A consortium of cold-tolerant sulfate-reducing bacteria (SRB) was tested at 6 °C regarding the utilization of economically viable, low-cost carbon sources, i.e., whey, conditioned sewage sludge, and peat, in the removal of sulfate from synthetic mining water. Succinate was used as a reference carbon source. Of all the studied low-cost carbon sources, conditioned sewage sludge proved to be the most efficient. Nuclear magnetic resonance (NMR) spectroscopy revealed that sewage sludge contained propionic acid, which proved to be utilizable by SRB under cold conditions. Peat both adsorbed the sulfate and acted as a nutrient source in the sulfate reduction process. When whey was used as a carbon source, only a slight decrease in sulfate concentration was detected. Succinate was found to work in a truly predictable and efficient way as a carbon source in biological sulfate reduction, even at the lowest concentration tested. The use of conditioned sewage sludge increased the bacterial diversity in liquid cultivations significantly. However, the number of SRB was highest in the succinate cultivations. HIGHLIGHTS Cold-tolerant sulfate-reducing bacteria (SRB) were successfully cultivated using low-cost carbon sources.; Kemicond-treated sewage sludge was the most efficient low-cost carbon source.; Simultaneous sulfate adsorption and reduction were observed with natural peat.; Organic compounds utilized and produced by the bacteria were characterized by nuclear magnetic resonance (NMR).; Synthetic mining water was treated to model real water pollution control.;

Boreal peatlands with low iron availability are a potential, but rarely studied, source for the isolation of bacteria for applications in metal sorption. The present research focused on the isolation and identification of Actinobacteria from northern Finland, which can produce siderophores for metal capture. The 16S rDNA analysis showed that isolated strains belonged to Firmicutes (Bacillus sp.) and Actinobacteria (Microbacterium sp.). The culture most efficiently producing siderophores in the widest array of the media was identified as Microbacterium sp. The most appropriate media for siderophore production by the Microbacterium strain were those prepared with glucose supplemented with asparagine or glutamic acid, and those prepared with glycerol or fructose supplemented with glutamic acid. The microorganism obtained and its siderophores were used to develop Sphagnum moss-based hybrid biosorbents. It was showed that the hybrid sorbent could bind nickel ions and that the nickel removal was enhanced by the presence of siderophores. Bacterial cells did not have a significant effect on sorption efficiency compared to the use of siderophores alone. The microbial biosorbent could be applied in the final effluent treatment stage for wastewater with low metal concentrations.

This work highlights the system specific characteristics encountered when considering a distillation-based separation strategy for levulinic acid (LA) and the by-product formic acid (FA) in the presence of water and water-miscible sulfolane or ?-valerolactone (GVL) solvents. Simulation using Aspen Plus® was applied to identify the presence of distillation boundary surfaces and tangent pinches resulting from the non-ideal behaviour of the mixtures in question. In the applied feed composition regions, the separation performance of the GVL solvent system in particular is limited by these restricting conditions. Minimum energy requirements for the separation of valuable components are presented as the conceptual design performance indicators, allowing the benchmarking of separation strategies. Sidedraw column configurations offer advantages in enriching the dilute valuable compounds from the feed and performing difficult separations at lower solvent quantities. This is especially advantageous for the sulfolane system where both LA and FA are intermediate-boiling.

Hydrolysis is a reaction to produce sugars from lignocellulosic raw materials for biochemical production. The present study elucidates the hydrolysis of cellulose and formation of glucose decomposition products catalyzed by 5% to 20% (w/w) formic acid at 180 to 220 °C with an initial cellulose concentration of 10 to 100 g/L. Microcrystalline cellulose was used as a model compound. The experimental findings indicated that cellulose hydrolysis follows first-order kinetics in formic acid. A side reaction from cellulose to non-glucose products was required to explain the experimental results. A kinetic model was developed for the hydrolysis of microcrystalline cellulose in formic acid, based on a rate constant expression in accordance with the specific acid catalysis. The model showed good agreement with the experimental data. This study demonstrates how kinetic parameters can be fitted in a case-specific manner for the hydrolysis part of the kinetic model, while the well-established glucose decomposition model is utilized directly from literature.

In this paper, the thermally coupled side-rectifier and side-stripper configurations are studied in the separation of component sets with a curved distillation boundary. A solving procedure is introduced that can be used in the determination of the minimum total energy consumption for the studied complex separation structures. The results show that thermally coupled side-column configurations enable distillation boundary crossing with high product flow purities. In fact, the achievable purities are higher than is possible with conventional column sequences. It is also noted that in some methanol/ethanol/water separations the energy consumption of the thermally coupled side-stripper configuration may partly decrease with increasing methanol distillate purity. [ABSTRACT FROM AUTHOR]

In this paper, the benefits of intermediate heat exchangers situated in thermally coupled side-column configurations are examined in the separation of component sets having a curved distillation boundary. The simulation results indicate that by incorporating an intermediate heat exchanger the distillation boundary crossing can be enhanced. In consequence, pure product flows may be achieved with decreased total energy requirement. It is also found that thermally coupled side-column configurations having an intermediate heat exchanger require less energy to carry out the desired separation than do the corresponding conventional direct and indirect column schemes. Regardless of the increased complexity and possibility for multiple steady states, intermediate heat exchangers always improve thermodynamic efficiency and widen the potential for heat integration. This paper complements the study started in Part 1 [Malinen, I.; Tanskanen, J. Thermally coupled side-column configurations enabling distillation boundary crossing. 1. An Overview and a solving procedure. Ind. Eng. Chem. Res.2009, 48, DOI: 10.1021/ie800817n] of this series of papers. [ABSTRACT FROM AUTHOR]