Background and aims

  Formaldehyde is one of hazardous compounds that may be found in waste water of different industries. This compound is toxic and biodegradation of it is difficult. The aim of this study is determination of efficiency of isolated microorganisms from polluted effluents by formaldehyde in aerobic and suspended and attached growth.

  Methods

  In this study formaldehyde degrading microorganisms were separated from waste  water and soil in a chemical industry. Then microorganisms were isolated and separated by using special culture medias. 12 microorganisms were separated and used for biodegradation of formaldehyde. Standard method was used to evaluated of degradation value.

  Results

  The results showed that pseudomonas aeruginosa was the most effective microorganisms. COD removal efficiency of pseudomonas aeruginosa was 85% in suspended  growth and 83% in attached growth condition. Also removal kinetic parameters were calculated That μmax, K, Y, Ks and Kd coefficients were 1.44 l/d , 3.28 mg COD/mg MLSS.day, 0.44 28 mg  COD/mg MLSS. day, 1.36 mg/l and 0.04 l/day respectively.

  Conclusion

  Using aerobic conditions in this study to degrade formaldehyde and acceptable output reduction in the COD can be the advantages of aerobic exercises method in comparison  with anaerobic exercises.