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Speciation of heavy metals during co-composting of livestock manure

Gul S., Naz A., Fareed I., Khan A., Irshad M.

Polish Journal of Chemical Technology

2015

Vol. 17, nr 3

19--23

Heavy metals determination in manures provides beneficial information to predict the availability and the potential contamination of environment. Therefore, a study was carried out to investigate heavy metals changes in livestock manure during a co-composting process. The metals were stepwise fractionated into exchangeable, adsorbed, organically bound, carbonate precipitated and residual forms by extracting with 0.5M KNO3, de-ionized water, 0.5M NaOH, 0.05M Na2EDTA and 4M HNO3, respectively. During the extraction process, the amount of metals remained highly dependent on an extraction method and stage of manure composting. Extractions released heavy metals contents in the final composted manure as Zn > Cu > Pb > Cr > Ni > Cd. Irrespective of the days of composting, extracting agents differed in the order HNO3 > Na2EDTA > NaOH > KNO3 > H2O for all heavy metals. Higher concentrations of heavy metals were observed during the early stages of composting. Conversely, there was a progressive increase in the concentrations of K, Ca and Mg during composting of manure. Total C in the manure reduced with composting days.

Invariant approximations noncommuting maps and strongly M-starshaped metric spaces

Naz A.

Demonstratio Mathematica

2003

Vol. 36, nr 4

893--898

In this paper, we obtain some results on invariant approximations in strongly M-starshaped metric spaces, which extend some known results.