Characterization of Polish Sewage Sludges with Respect to Fertility and Suitability for Land Application

Abstract

Twenty-one varieties of sewage sludge from municipal, municipal-industrial and industrial areas were analysed for their suitability for agricultural purposes. The samples were taken from an agricultural area of Poland characterised by a low level of industrialisation. The sewage sludges were characterised for total organic carbon and nitrogen, pH, available phosphorous and potassium, cation exchange capacity, total exchangeable bases, the degree of base saturation, the total trace metals (such as Cd, Co, Ni, Pb, Cu, Mn, Zn, Sr, V, Cr) and the content of polycyclic aromatic hydrocarbons (16 PAHs from EPA list). The results showed that the studied sludges can potentially enhance soil's agronomic properties. However in a few cases, the pH, ratio of total organic carbon to total nitrogen (TOC/Nt) and electrical conductivity were the exceptions. Trace metal contents in the sewage sludge studied varied widely (statistical significant) as a result of the size of the sewage producing unit, and especially, the content of industrial sludge. The results obtained for PAHs in sewage sludge showed a clear differentiation in the content of PAHs, which ranged from 2039 to 36439 μg/kg. The predominant contribution of 3- and 4-ring PAHs was observed. In the case of 6 sewage sludges the PAH content twice exceeded the allowable value.

Keywords:

• Sewage sludge
• Fertility
• Heavy metals
• Polycyclic aromatic hydrocarbons
• Fertilizers

ACKNOWLEDGMENTS

The work was founded in the frame of grant No. 2 P06S 005 29 financed in 2005–2008 from the budget of Ministry of Science and Information Society Technologies. P. Oleszczuk is granted by the Foundation for Polish Science.

Notes

¹—stored 1 year;

²—stored 2 years;

³—stored 3 months;

⁴—stored 2 months.

*—cultivation of plants to compost production and non-consumer.

*—Na—naphthalene; Ace—acenaphthylene; Ac—acenaphthene; Fl—fluorene; Phen—phenanthrene; Ant—anthracene; Fluo—fluoranthene; Pyr—pyrene; BaA—benzo[a]anthracene; Ch—chrysene; BbF—benzo[b]fluoranthene; BkF—benzo[k]fluoranthene; BaP—benzo[a]pyrene; DahA—dibenz[a,h]anthracene; BghiP—benzo[ghi]perylene; Ind—indeno[1,2,3-cd]pyrene;

¹—9 sewage sludges;

²—11—sewage sludges;

³—1 industrial sewage sludge; n.d.—not detected.