Improvement of Industrial-scale Anaerobic Digestion by Enzymes Combined with Chemical Treatment

The effect of a new developed process for biogas boosting was studied at a municipal wastewater treatment plant in industrial scale over the period of three years. After pre-selection studies in the lab and short industrial setups, four hydrolytic enzymes and sodium citrate were combined and tested for a two-year period. The year 2007 was picked as reference year. In February 2008, the dosage was started. Some immediate changes in the digestion system could be observed like gas production increase and sludge volume reduction. Yet the adaption to the chemical dosage took several months. A stable production was achieved about 6 months after the start of the dosage. In 2009 it was assumed that the system had adapted to the chemical dosages and that stable running parameters were achieved. Mainly the results from the years 2007 as reference and 2009 as resulting year are compared, showing clearly positive effects on process stability, increased gas production by 16% and minimized sludge volumes by 13%

Artificial carrier for oxygen supply in biological systems

Several poly (dimethylsiloxanes) (PDMS) copolymers of dimethylsiloxane (DMS) with ethylene or propylene oxide were tested as artificial carriers for the delivery of oxygen to biological systems. Copolymers with a DMS content of 33% or lower enhanced glucose oxidation by 200% in contrast to the 25% increase produced by the same concentration of perfluorodecalin. When 0.05% of the copolymer with 18% DMS was included in the growth media of Bacillus thuriginensis, the biomass (growth rate) increased 1.5-fold. With 0.1% of this copolymer, actinorhodin production by Streptomyces coelicolor A3 (2) occurred in half the normal time and with an increased yield. In conclusion, these PDMS copolymers are a good alternative to perfluorodecalin as oxygen carriers in biotechnological processes