Azotobacter vinelandii biomass production from olive-mill wastewaters for heavy metal recovery

Sixteen litres of olive-mill wastewaters (OMW) diluted to 5% organic matter (d.w.) were inoculated in a fermentor (T=30°C, air FLOW=161min−1, STIRRING=100 rpm) with a strain of Azotobacter vinelandii. After 2 weeks the bacterial biomass was separated by centrifugation and capsular polysaccharide (CPS) and exopolysaccharides were extracted. The apparent molecular weight of CPS was determined by gel filtration. The CPS was entrapped in polyvinyl alcohol membranes which were used to adsorb cadmium and lead ions from a liquid stream.