Biomedical subjects

P Vandevivere

Publications and source records attributed to P Vandevivere.

2 recordsLinked to original sources

PubMed2001

Solid waste digestors: process performance and practice for municipal solid waste digestion.

The most common types of anaerobic digesters for solid wastes have been compared based on biological and technical performance and reliability. Batch systems have the most simple designs and are the least expensive solid waste digesters. They have high potential for application in developing countries. Two-stage systems are the most complex and most expensive systems. Their greatest advantage lies in the equalisation of the organic loading rate in the first stage, allowing a more constant feeding rate of the methanogenic second stage. Two-stage systems with biomass accumulation devices in the second stage display a larger resistance toward toxicants and inhibiting substances such as ammonia. However, the large majority of industrial applications use one-stage systems and these are evenly split between "dry" systems (wastes are digested as received) and "wet" systems (wastes are slurried to about 12% total solids). Regarding biological performance, this study compares the different digester systems in terms of organic loading rates and biogas yields considering differences in input waste composition. As a whole, "dry" designs have proven reliable due to their higher biomass concentration, controlled feeding and spatial niches. Moreover, from a technical viewpoint the "dry" systems are more robust and flexible than "wet' systems.

Bacteria, Anaerobic↗

PubMed1992

Effect of bacterial extracellular polymers on the saturated hydraulic conductivity of sand columns.

Columns were packed with clean quartz sand, sterilized, and inoculated with different strains of bacteria, which multiplied within the sand at the expense of a continuous supply of fresh nutrient medium. The saturated hydraulic conductivity (HCsat) of the sand was monitored over time. Among the four bacterial strains tested, one formed a capsule, one produced slime layers, and two did not produce any detectable exopolymers. The last two strains were nonmucoid variants of the first two. Only one strain, the slime producer, had a large impact on the HCsat. The production of exopolymers had no effect on either cell multiplication within or movement through the sand columns. Therefore, the HCsat reduction observed with the slime producer was tentatively attributed to the obstruction of flow channels with slime. Compared with the results with Arthrobacter sp. strain AK19 used in a previous study, there was a 100-fold increase in detachment from the solid substratum and movement through the sand of the strains used in this study. All strains induced severe clogging when they colonized the inlet chamber of the columns. Under these conditions, the inlet end was covered by a confluent mat with an extremely low HCsat.

Bacteria↗