Greenhouse gas emissions from stabilization ponds in subtropical climate.

Waste stabilization ponds (WSPs) are a cost-efficient method to treat municipal and non-toxic industrial effluents. Numerous studies have shown that WSPs are a source of greenhouse gas (GHG). However, most reports concerned anaerobic ponds (AP) and few have addressed GHG emissions from facultative (FP) and aerobic/maturation ponds (MPs). In this paper, GHG emissions from three WSP in series are presented. These WSPs were designed as anaerobic, facultative and aerobic/maturation and were treating agricultural wastewater. CH4 fluxes from 0.6 +/- 0.4 g CH4 m(-2) d(-1) in the MP, to 7.0 +/- 1.0 g CH4 m(-2) d(-1) in the (AP), were measured. A linear correlation was found between the loading rates of the ponds and CH4 emissions. Relatively low CO2 fluxes (0.2 +/- 0.1 to 1.0 +/- 0.8 g CO2 m(-2) d(-1)) were found, which suggest that carbonate/bicarbonate formation is caused by alkaline pH. A mass balance performed showed that 30% of the total chemical oxygen demand removed was converted to CH4. It has been concluded that the WSP system studied emits at least three times more GHG than aerobic activated sludge systems and that the surface loading rate is the most important design parameter for CH4 emissions.

Biofiltration of methanol in an organic biofilter using peanut shells as medium.

Biofiltration consists of a filter-bed of organic matter serving both as carrier for the active biomass and as nutrient supply, through which the polluted gas passes. The selection of a suitable medium material is of major importance to ensure optimum biofilter efficiency. Peanut shells are an agricultural byproduct locally available in large quantities at a low price in most tropical and sub-tropical countries. A previous study showed that peanut shells are physically and chemically suitable for biofiltration. This paper presents the results obtained during a six month biofiltration experiment using peanut shells as medium and methanol as air pollutant. It is shown that peanut shells are potentially suitable as biofiltration medium, since degradation rates of up to 30 kg MeOH/m(3)d with an empty bed residence time of 19s was obtained. The biofilter showed a good resistance to shock load and no operational problems were observed.

Establishment and characterization of porcine aortic endothelial cell cultures with prolonged replicative lifespan by a non-enzymatic method.

The aim of this work was the establishment and characterization of porcine aortic endothelial cell cultures with prolonged lifespan. Endothelial cells where isolated from porcine thoracic aorta and established in primary culture; after sub cultivation, the cells showed typical morphology of endothelial phenotype with cobblestone appearance and growth in monolayer; they were positive against anti-CD31 and anti-CD54 immunostaining and Ac-LDL-Dil uptake. The cells were able to migrate in culture and showed a normal growth curve. The phenotype of our in vitro model of endothelial cells was stable through subcultivation; so, it should be a valuable tool for diverse studies of the endothelial response against physiological and pathological stimulus, particularly it could be useful to study interactions of endothelium with pathogenic bacteria causing diseases in pigs, as they are difficult to study in vivo.