Variable Nature of Chemical Composition of Sewage Sludges
1976
Sommers, L. E. | Nelson, D. W. | Yost, K. J.
Sewage sludge samples were collected over a 2-year period from eight Indiana cities and analyzed for C, N, P, K, Ca, Mg, Fe, Cd, Zn, Cu, Ni, and Pb. The sludges contained approximately 50% organic matter and 1–4% inorganic C. Organic and inorganic C, organic N, inorganic P, and Ca and Mg were found to be present in a given sludge at a relatively constant concentration with respect to sampling time. Inorganic N, organic P, K, and all metals were found to be quite variable with time for sewage sludge produced by a given city. In general, organic N and inorganic P constituted the majority of total N and P, respectively, in sludges. The largest deviations between the mean and median were found for Cd, Zn, Cu, Ni, and Pb. Variable nature of inorganic N and metal contents of sludges indicates that a sound sampling and analysis program is essential prior to formulating recommendations for rates of sewage sludge applications on soils used for crop production.
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