Prevalence of Nitrosomonas cluster 7 populations in the ammonia-oxidizing community of a submerged membrane bioreactor treating urban wastewater under different operation conditions.

A pilot-scale ultrafiltration membrane bioreactor (MBR) was used for the aerobic treatment of urban wastewater in four experimental stages influenced by seasonal temperature and different sets of operation conditions. The structure of the ammonia-oxidizing bacteria (AOB) community was profiled by temperature gradient gel electrophoresis (TGGE), based on the amplification and separation of partial ammonia-monoxygenase subunit A (amoA) genes. Canonical correspondence analysis revealed that temperature, hydraulic retention time and percentage of ammonia removal had a significant effect on the fingerprints of AOB communities.

Structure of archaeal communities in membrane-bioreactor and submerged-biofilter wastewater treatment plants.

A cultivation independent approach (PCR-TGGE) was used to evaluate the occurrence of Archaea in four wastewater treatments based on technologies other than activated sludge, and to comparatively analyze their community structure. TGGE fingerprints (based on partial archaeal 16S-rRNA amplicons) were obtained from sludge samples taken from a pilot-scale aerated MBR fed with urban wastewater and operated under two different sets of conditions (MBR1 and MBR2 treatments), and also from biofilms sampled from two pilot-scale submerged biofilters (SBs) consisting of one aerated and one anoxic column each, fed with urban (USB treatment) or industrial (ISB treatment) wastewater, respectively. Analysis of TGGE fingerprints revealed clear and significant differences of the community structure of Archaea between the wastewater treatments studied, primarily according to wastewater origin and the type of technology.

Microbial enzymatic activities in a pilot-scale MBR experimental plant under different working conditions.

Phosphatases, glucosidase, protease, esterase and dehydrogenase activities in a MBR (membrane bioreactor) system equipped with ultrafiltration membranes for the treatment of real urban wastewater were measured at different volatile suspended solid (VSS) concentrations, total suspended solid (TSS) concentrations, hydraulic retention times (HRT), temperatures and inflow rates. The results showed the capacity of the MBR system to remove COD and BOD(5) at TSS between 7200 and 13,300 mg/L; HRT values of 8.05 and 15.

Microbial community structure and dynamics in a pilot-scale submerged membrane bioreactor aerobically treating domestic wastewater under real operation conditions.

A pilot scale submerged ultra-filtration membrane bioreactor (MBR) was used for the aerobic treatment of domestic wastewater over 9 months of year 2006 (28th March to 21st December). The MBR was installed at a municipal wastewater facility (EMASAGRA, Granada, Spain) and was fed with real wastewater. The experimental work was divided in 4 stages run under different sets of operation conditions.

Biodiesel: an alternative fuel.

Biodiesel is an alternative energy source and could be a substitute for petroleum-based diesel fuel. To be a viable alternative, a biofuel should provide a net energy gain, have environmental benefits, be economically competitive, and be producible in large quantities without reducing food supplies. Most of the sources, methods and apparatus to produce biodiesel are reviewed here.