Microalgae as biological treatment for municipal wastewater - effects on the sludge handling in a treatment plant.

A mix of microalgae and bacteria was cultivated on pre-sedimented municipal wastewater in a continuous operated microalgae-activated sludge process. The excess material from the process was co-digested with primary sludge in mesophilic and thermophilic conditions in semi-continuous mode (5 L digesters). Two reference digesters (5 L digesters) fed with waste-activated sludge (WAS) and primary sludge were operated in parallel. The methane yield was slightly reduced (≈10%) when the microalgal-bacterial substrate was used in place of the WAS in thermophilic conditions, but remained approximately similar in mesophilic conditions. The uptake of heavy metals was higher with the microalgal-bacterial substrate in comparison to the WAS, which resulted in higher levels of heavy metals in the digestates. The addition of microalgal-bacterial substrate enhanced the dewaterability in thermophilic conditions. Finally, excess heat can be recovered in both mesophilic and thermophilic conditions.

Anaerobic co-digestion of sludge and microalgae grown in municipal wastewater - a feasibility study.

In this study a natural mix of microalgae grown in wastewater of municipal character was co-digested with sewage sludge in mesophilic conditions, in both batch and semi-continuous modes. The semi-continuous experiment was divided into two periods with OLR1 (organic loading rate) of 2.4 kg volatile solids (VS) m-3 d-1 and HRT1 (hydraulic retention time) of 15 days, and OLR2 of 3.5 kg VS m-3 d-1 and HRT2 of 10 days, respectively. Results showed stable conditions during both periods. The methane yield was reduced when adding microalgae (from 200 ± 25 NmL CH4 g VSin-1, to 168 ± 22 NmL CH4 g VSin-1) but VS reduction was also decreased by 51%. This low digestibility was confirmed in the anaerobic batch test. However, adding microalgae improved the dewaterability of the digested sludge. The high heavy metals content in the microalgae resulted in a high heavy metals content in the digestate, making it more difficult to reuse the digestate as fertilizer on arable land. The heavy metals are thought to originate from the flue gas used as a CO2 source during the microalgae cultivation. Therefore the implementation of CO2 mitigation via algal cultivation requires careful consideration regarding the source of the CO2-rich gas.

Differences in regulatory T-cell and dendritic cell pattern in decidual tissue of placenta accreta/increta cases.

INTRODUCTION: Primary infertility, miscarriage, and preeclampsia have been correlated with reduced numbers of regulatory T-cells (Treg) suggesting that decreased extravillous trophoblast (EVT) invasion originates from inadequate EVT tolerance. In contrast increased numbers of Treg-cells may be responsible for over-invasion of EVT. As the maturation status of dendritic cells (DC) influences T-cell behavior (tolerance or immune activation), altered relation between immature and mature DCs may also influence EVT invasion. METHOD: Paraffin-embedded specimens of placenta accreta/increta (Pc; n = 11) and healthy intrauterine pregnancy (IUG; n = 18) were double-stained for cytokeratin and CD45, CD68, CD56, CD20, CD3, or CD8 as well as FoxP3/CD4 and FoxP3/CD8 and single-stained for CD4, CD25, FoxP3, CD209, Dec205 and CD83. Quantification of the leukocyte subpopulations was performed for decidua parietalis and basalis as characterized by cytokeratin-positive EVT. Statistical analysis was performed by using the Mann-Whitney test. RESULT: There were significantly fewer CD4(+) cells in Pc than in IUG. Concerning the Treg-markers, FoxP3(+) cells are significantly increased. CD25(+) cells showed a small non-significant increase in Pc in comparison to IUG. Concerning dendritic cells, immature non-activated CD209(+) DCs were significantly decreased in Pc while immature activated CD205(+) DCs were slightly but non-significantly increased. Mature activated CD83(+) DC were non-significantly decreased in IUG vs Pc. DISCUSSION AND CONCLUSION: The increased number of Treg-cells in Pc suggests significance for these cells in the regulation of trophoblast invasion. Their adequate interaction with other lymphocyte populations (e.g. adequately maturated dendritic cells) may be one mechanism to assure controlled EVT invasion.