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See detailSludge digestion instead of aerobic stabilisation – a cost benefit analysis based on experiences in Germany
Gretzschel, Oliver; Schmitt, Theo G.; Hansen, Joachim UL et al

in Water Science & Technology (2014)

As a consequence of a worldwide increase of energy costs, the efficient use of sewage sludge as a renewable energy resource must be considered, even for smaller wastewater treatment plants (WWTPs) with ... [more ▼]

As a consequence of a worldwide increase of energy costs, the efficient use of sewage sludge as a renewable energy resource must be considered, even for smaller wastewater treatment plants (WWTPs) with design capacities between 10,000 and 50,000 population equivalent (PE). To find the lower limit for an economical conversion of an aerobic stabilisation plant into an anaerobic stabilisation plant, we derived cost functions for specific capital costs and operating cost savings. With these tools, it is possible to evaluate if it would be promising to further investigate refitting aerobic plants into plants that produce biogas. By comparing capital costs with operation cost savings, a break-even point for process conversion could be determined. The break-even point varies depending on project specific constraints and assumptions related to future energy and operation costs and variable interest rates. A 5% increase of energy and operation costs leads to a cost efficient conversion for plants above 7,500 PE. A conversion of WWTPs results in different positive effects on energy generation and plant operations: increased efficiency, energy savings, and on-site renewable power generation by digester gas which can be used in the plant. Also, the optimisation of energy efficiency results in a reduction of primary energy consumption. [less ▲]

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See detailTowards exposure of elusive metabolic mixed-culture processes: the application of metaproteomic analyses to activated sludge
Wilmes, Paul UL; Bond, P. L.

in Water Science & Technology (2006), 54(1), 217-226

4th IWA Activated Sludge Population Dynamics Conference (ASPD4) Location: Gold Coast, AUSTRALIA Date: JUL 17-20, 2005 Sponsor(s): IWA Specialist Grp Activated Sudge Populat Dynam; Adv Wastewater ... [more ▼]

4th IWA Activated Sludge Population Dynamics Conference (ASPD4) Location: Gold Coast, AUSTRALIA Date: JUL 17-20, 2005 Sponsor(s): IWA Specialist Grp Activated Sudge Populat Dynam; Adv Wastewater management Ctr; Australian Water Assoc Abstract: Protein expression is a direct reflection of specific microbial activities in any ecosystem. In order to assess protein expression in mixed microbial communities, the feasibility of applying proteomic techniques to activated sludge samples has recently been demonstrated. We report the application of metaproteomics to two activated sludges from a laboratory-scale sequencing batch reactor with dissimilar phosphorus removal performances. Fluorescence in situ hybridization (FISH) revealed that the sludge with good enhanced biological phosphorus removal performance (EBPR) was dominated by Betaproteobacteria (65% of EUBMIX binding cells) and gave positive signals for the Rhodocyclus-type PAO specific probe (59%). The non-EBPR sludge was dominated by tetrad-forming Alphaproteobacteria (75%). With regard to the proteomic investigation, 630 individual protein spots were matched across the replicate groups of the anaerobic and aerobic phases of the EBPR sludge with 9.4% of all spots being statistically different between the two phases. The non-EBPR metaproteomic maps exhibited 590 matched spots with 14.7% statistical differences between the two phases. Overall, the non-EBPR sludge expressed around 30% more significant differences than the EBPR sludge. The comparison of protein expression in the two sludges showed that their metaproteomes were substantially different and this was reflected in their microbial community structures and metabolic transformations. [less ▲]

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