Search

The operating parameters of membrane biological reactors (MBRs) differ significantly from those of conventional activated sludge (CAS) reactors, especially with regard to solids retention time (SRT) and food-to-mass ratio. This has an impact on the structure of the activated sludge biocenosis and its susceptibility to seasonal variations. The aim of this research was to find out the structure and variability of the activated sludge biocenosis in a small wastewater treatment plant using MBR reactors situated in southern Poland. The results were compared with the results obtained from a CAS wastewater treatment plant with a similar capacity and showed that the sludge biocenosis in MBRs differs significantly from that in CAS reactors. There was a noticeable difference in the ratio of attached to crawling ciliates in the sludge from MBRs and CAS, and it was also shown that the MBR biocenosis, despite the long SRT, undergoes stronger seasonal changes during the year, with a clear deterioration of the biocenosis structure in the autumn and winter period and a visible improvement in the spring. Despite this, no noticeable impact of changes in the MBR biocenosis structure was found with regards to the technological efficiency of the wastewater treatment process. [ABSTRACT FROM AUTHOR]

The main objective of this study is to examine the developments of political and economic relations between Poland and Sub‑Saharan Africa. The article is written from the Polish perspective. The author is fully aware that the perception of Sub‑Saharan Africa as a homogeneous region must result in multiple oversimplifications. However, an analysis of the Polish “African discourse” indicates that political and business elites are not aware of the heterogeneity of the continent and the latter is perceived as a “single unit”. The article demonstrates that after the eastward enlargement of the European Union in 2004 Poland realized its principal goal of foreign policy and did not attempt to redefine its role and place in international relations in terms of its potential and assets. Since 2013, the relations between Poland and Sub‑Saharan states have been intensified, but it is everything but clear whether it will become a permanent trend. [ABSTRACT FROM AUTHOR]

Copyright of Africa Spectrum is the property of Sage Publications Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)