In this work, an integrated and optimized production process for 99 % pure 1,3-propanediol (PDO) from raw glycerol is presented. Glycerol fermentation is carried out applying a newly isolated strain Clostridium pasteurianum K1 under non-sterile conditions without any complex ingredients in the fermentation media. In this environment over 55 g/L PDO, yields of 0.52 g/g and space time yields over 2.3 g/(Lh) were achieved in up to 1 m(3) pilot scale. The downstream process for PDO purification consists of an ultrafiltration for biomass and protein separation, an evaporation step for concentration of PDO and a two-step rectification for final purification. For a proof of concept, process optimization and especially investigation of interactions of individual steps, the downstream process was performed in miniplant scale. A minimum salt input into the downstream process was shown to be important to overcome precipitation in evaporation as well as rectification. Thus, raw glycerol is desalinated before fermentation and the fermentation medium was minimized and complex nutrients, such as yeast extract, were avoided totally to prevent furthermore dark color formation. Furthermore, by titration of fermentation with ammonia instead of sodium hydroxide, the later separation of the major by-products, organic acids, in the evaporation step was significantly enhanced.

A production process, using upshock fermentation and osmotic downshock, for the effective production/excretion of mannosylglycerate (MG) by the trehalose-deficient mutant of the strain Thermus thermophilus RQ-1 has been developed. In the first phase of fed-batch fermentation, the knockout mutant was grown at 70 degrees C on a NaCl-free medium. After the culture reached the end of the exponential growth phase, upshift in temperature and NaCl concentration was applied. The temperature was increased to 77 degrees C, and NaCl was added up to 3.0% and kept constant during the second phase of fermentation. Although this shift in cultivation parameters caused a dramatic drop of cell density, a significant improvement in accumulation of MG up to 0.64 micromol/mg protein compared to batch fermentations (0.31 micromol/mg protein) was achieved. A total yield of 4.6 g MG/l of fermentation broth was obtained in the dialysis bioreactor with a productivity of 0.29 g MG l(-1) h(-1). The solute was released from the harvested biomass by osmotic downshock using demineralized water at 70 degrees C. More than 90% of the intracellularly accumulated solute was recovered from the water fraction. The process was very efficient, as hyperosmotic shock, release of the solute, and reiterative fed-batch fermentation could be repeated at least four times.

The heterologous production of a thermoactive alcohol dehydrogenase (AdhC) from Pyrococcus furiosus in Escherichia coli was investigated. E. coli was grown in a fed-batch bioreactor in minimal medium to high cell densities (cell dry weight 76 g/l, OD600 of 150). Different cultivation strategies were applied to optimize the production of active AdhC, such as lowering the cultivation temperature from 37 to 28 degrees C, heat shock of the culture from 37 to 42 degrees C and from 37 to 45 degrees C, and variation of time of induction (induction at an OD600 of 40, 80 and 120). In addition to the production of active intracellular protein, inclusion bodies were always observed. The maximal activity of 30 U/l (corresponding to 6 mg/l active protein) was obtained after a heat shock from 37 to 42 degrees C, and IPTG induction of the adhC expression at an OD600 of 120. Although no general rules can be provided, some of the here presented variations may be applicable for the optimization of the heterologous production of proteins in general, and of thermozymes in particular.

An overview is given over different types of gas storages and their pressure/level relationship, which is crucial for the design of the plant's gas system. It focuses on the design of air‐inflated double‐membrane gas storages, their blowers, and pressure control valves. During the design phase of a biogas plant, the responsible engineer must calculate the pressure gradient for several scenarios to ensure it is fully functional and safe, even outside normal operation. Methods for the design of cascading flow and ring flow of biogas through the biogas plant are summarized, and a technique of managing the gas storages in a way that the full storage capacity can be used is provided. The findings of this paper are illustrated with examples of two large‐scale industrial biogas plants.

The mass balances of countercurrent gas permeation modules for the separation of multicomponent gas mixtures are formulated as a boundary value problem, using the ideal gas law and isobaric isothermal stages. The balances are extended for the common three‐stage gas permeation process for the upgrading of biogas. The solution is calculated with MATLAB's BVP4C boundary value solver. The process is optimized by means of the FMINCON SQP‐algorithm towards lowest power consumption. Parameter variations are conducted, highlighting the impact of product and lean‐gas quality setpoints, biogas composition, membrane surface and selectivity, permeate compression, and choice of compressor model on the energetic optimum.