Environmental: in-situ reduction of fibrous sludge in a pulp mill aerated stabilization basin.

APPLICATION: This study helps identify the mechanisms by which specialty organisms are able to break down fibrous sludge in wastewater treatment systems.

Specialty microorganisms added to pulp mill aeration stabilization basins are able to reduce sludge in-situ. Laboratory work undertaken to identify the mechanism showed that a cell-free extract prepared from the microorganisms decreased the length of pulp fibers that are the principal components of primary sludge. The hemicellulosic components of the fiber degrade upon exposure. A controlled field study was also run in the secondary treatment system of a pulp mill. Primary sludge was held in vials capped with semipermeable membranes that allowed liquid and gas to flow through the vials. Vials containing sludge, to which we added microbes, were placed in the lagoon. No decrease in sludge mass was observed over seven months of exposure to the lagoon water. We propose that the sludge reduction observed in the field occurs from initial degradation of the fibrous sludge into smaller fragments that are then slowly mineralized. View this paper online at http://www.tappi.org/index.asp?pid=32224&ch=1

Sujit Banerjee is professor and Usha Hooda is assistant scientist at the School of Chemical & Biomolecular Engineering and at the Institute of Paper Science & Technology at Georgia Institute of Technology, 500 Tenth ST NW, Atlanta, GA 30332-0620. Email Banerjee at [e-mail].