Multi-view confocal microscopy enables multiple organ and whole organism live-imaging.

Understanding how development is coordinated in multiple tissues and gives rise to fully functional organs or whole organisms necessitates microscopy tools. Over the last decade numerous advances have been made in live-imaging, enabling high resolution imaging of whole organisms at cellular resolution. Yet, these advances mainly rely on mounting the specimen in agarose or aqueous solutions, precluding imaging of organisms whose oxygen uptake depends on ventilation. Here, we implemented a multi-view multi-scale microscopy strategy based on confocal spinning disk microscopy, called Multi-View confocal microScopy (MuViScopy). MuViScopy enables live-imaging of multiple organs with cellular resolution using sample rotation and confocal imaging without the need of sample embedding. We illustrate the capacity of MuViScopy by live-imaging Drosophila melanogaster pupal development throughout metamorphosis, highlighting how internal organs are formed and multiple organ development is coordinated. We foresee that MuViScopy will open the path to better understand developmental processes at the whole organism scale in living systems that require gas exchange by ventilation.

Prequalification of flotation sludge for a sustainable increase in biogas production and in regard of demand-driven feeding strategy.

Co-substrates can increase gas production in a digester significantly. The characteristic properties of substrates, depending on the amounts added, influence the processes in the digester reactor. As a consequence, they can have an impact on the buffer capacity, pH value, C:N ratio, dewaterability of the digested sludge and introduce contaminants to the digester among others. In the future, a discontinuous digester feeding could contribute to the demand-driven energy supply by WRRFs. Due to the increasing instability caused by fluctuating organic load, higher demands are placed on the selection of co-substrates. This study examined to what extent flotation sludge from dairy companies is suitable for a sustainable co-digestion. In addition, it should be evaluated whether flotation sludge is applicable for demand-driven feeding strategies. It was shown that flotation sludge has positive effects on the reactor as well as a significant increase in biogas production and a high degree of degradation of at least 80%. Even at high organic loads pH remained at a high level at around 7.5 due to the high alkalinity of the substrate. Nonetheless, addition of more than 20 w-% flotation sludge lead to a significant decrease of the dewaterability of the digested sludge.

Digesters as heat storage: Effects of the digester temperature on the process stability, sludge liquor quality, and the dewaterability.

Variation of the digester temperature during the year enables the operation of digesters as seasonal heat storage contributing to a holistic heat management at water resource recovery facilities. Full- and lab-scale process data were conducted to examine the effect of the digester temperature on process stability, sludge liquor quality, and dewaterability. Both full- and lab-scale digesters show a stable anaerobic degradation process with a hydraulic retention time of more than 20 days and organic load rates up to 2.2-kg COD/(m3 ·day) at temperatures between 33 and 53°C. The concentrations of soluble COD and ammonium-nitrogen in the sludge liquor digested at 53°C are 2.6 to 5.8 times and 1.3 times higher, respectively, than in the sludge liquor digested at 37°C. Dewatering tests show an enhancement of the dewaterability but a clear increase in the polymer demand at increased digester temperature. PRACTITIONER POINTS: Digesters can operate as seasonal heat storage within mesophilic and thermophilic temperatures Stable anaerobic degradation process for HRT above 20 days Maintenance of process stability as well as quantity and quality of biogas Increase of soluble COD in sludge liquor at higher temperatures Better dewaterability but higher demand for polymers with increasing temperature.

Residues from the dairy industry as co-substrate for the flexibilization of digester operation.

Water resource recovery facilities (WRRF) can make an important contribution to increase the share of renewable energies in Germany. In this context, it is important to utilize unused digester capacities on WRRF. In addition, a demand-orientated biogas production could synchronize electricity demand and electricity generation and improve the overall energetic balance of the WRRF. As part of the project "Water Resource Recovery Facilities in interaction with the waste and energy industry: A German-Austrian Dialogue - COMITO," the influence of residues from the dairy industry on the digestion process was examined as well as the suitability for the flexibilization of digester gas production. Four reactors were fed with different amounts of flotation sludge from the dairy industry for several months. The difference in the feed resulted in organic loading (OLR) rates between 3.2 kg COD/(m3  day) and 6 kg COD/(m3  day). The reactors were fed with a daily shock load. The investigations showed that volumetric loads up to 4.4 kg COD/(m3  day) did not lead to an accumulation of organic acids. Organic loading rate of 6 kg COD/(m3  day) showed a significant accumulation of organic acids higher than 2,500 mg/L oHAc. Nevertheless, the reactor could be operated with a degradation rate of 71% with a corresponding biogas yield with a methane content of 71%. With increasing flotation sludge content, a higher concentration in ammonium of up to 2.000 mg/L NH4 -N could be detected in the effluent of the digester. Despite higher phosphorus concentration in the flotation sludge, the concentration of PO4 -P remained constant for all reactors fluctuating between 20 and 40 mg/L PO4 -P. Dewatering worsened significantly with increasing levels of flotation sludge. PRACTITIONER POINTS: Main purpose of the research is to flexibilize digester operation on WRRF using flotation sludges from the dairy industry. Flexibilization of the digester using flotation sludge is possible up to an organic load of 6 kg COD/(m3  day). Higher NH4 -N concentration in the effluent of the digester must be accepted when using higher amounts of flotation sludge. Phosphate concentration in the effluent of the digester remained on a low level despite higher phosphorus content in the flotation sludge. High levels of organic acids (mainly acetic acid) can be tolerated and can be recovered within a short time after reducing the load.