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Journal of Environmental Quality Abstract -

Sewage Sludge Proteins: II. Extract Characterization


This article in JEQ

  1. Vol. 22 No. 3, p. 625-629
    Received: Sept 5, 1991

    * Corresponding author(s):
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  1. R. N. Lerch *,
  2. P. Azari,
  3. K. A. Barbarick,
  4. L. E. Sommers and
  5. D. G. Westfall
  1. C ropping Systems and Water Quality Research Unit, USDA-ARS, Columbia, MO 65211;
    D ep. of Biochemistry, Colorado State Univ., Ft. Collins, CO 805223;



The characterization of sewage sludge proteins is necessary to better understand their degradation by microbial populations when sludges are utilized for land application. The objective of this study was to characterize the molecular weights of extractable sewage sludge proteins by dialysis partitioning and polyacrylamide gel electrophoretic (PAGE) separation. Sewage sludges obtained from seven municipalities were extracted using H2O and 1 M NaOH followed by purification and concentration to facilitate molecular weight determinations. Dialysis partitioning of proteins showed that the majority of these compounds had molecular weights < 14 000 (i.e., they were not retained by dialysis membrane). The separation of proteins by PAGE also showed that the bulk of H2O and 1 M NaOH soluble proteins were of low molecular weight (< 17 000). This indicated considerable proteolysis during waste treatment processing. Thus, the extractable sludge proteins appeared to be primarily poly- and oligopeptides rather than intact proteins. Based on these findings, sludge proteinaceous materials would be expected to degrade rapidly in soil due to the many soil microorganisms capable of utilizing protein degradation products.

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