Potential of anaerobically digested poultry wastewater for metal biosorption by Rhodobacter blasticus and Rhodobacter capsulatus

Abstract

The aim of this research was to assess the elimination efficiency of heavy metals from poultry wastewater using the two bacterial species Rhodobacter capsulatus and Rhodobacter blasticus. In this research, the wastewater of breeder hens of Birjand city was used and in all the experiments the used bacterial amount was mixed with wastewater sample in a volumetric ratio of 1:10. The optimal bacterial mixture rate and pH were assessed. The results showed that the concentration of zinc and copper in the poultry wastewater constantly reduces with the lapse. R. blasticus had the highest elimination percent of heavy metals copper and zinc up to 72 hours, whereas eventually the two bacterial species mixture (1:1 ratio) together eliminated 84% and 90 % of zinc and copper respectively, but there was no significant difference between different bacterial treatments, period and residual concentration of zinc and copper (p>0.5). The elimination efficiency of zinc and copper was higher when pH level was between 7 and 9 (zinc was equivalent to 75% and 68% and copper was equivalent to 88% and 82% respectively) in comparison to the other pH’s. Therefore, neutral pH is suitable for the wastewaters treated via bacteria. With the dilution of poultry wastewater, the elimination percent of zinc and copper increases and this indicates that the metals concentration present in poultry wastewater does not have a negative effect on the elimination. So, these bacterial types are able to grow in poultry wastewaters and treat them.