Evaluation of agricultural utilisation of the sludge produced at Psyttalia WWTP

Abstract

A six-month experimental study was conducted to evaluate the agricultural use of the sludge produced at Psyttalia after completion of secondary biological treatment. Based on the results obtained from a bench scale activated sludge system the average biological sludge production for the year 2000, is estimated to be approximately 111 tn DS/day. Using the values of heavy metals measured in Psyttalia primary dewatered sludge and in the biological sludge obtained from the laboratory scale unit, the approximate heavy metal concentrations of the sludge produced in Psyttalia after the construction of the Biological Treatment Plant were determined: 327 mgCu/kg DS, 4140 mgZn/kg DS, 981 mgCr/kg DS, 264 mgPb/kg DS, 228 mgNi/kg DS, 1.6 mgCd/kg DS and 7 mgHg/kg DS. According to the above results the use of sludge in agriculture is unfeasible at present given the high zinc concentrations that exceed EC Regulations, but also considering the high concentrations of other heavy metals that exceed the more stringent regulations of several European countries.

Evaluation of single chemical extractants for the prediction of heavy metal uptake by barley in soils amended with polluted sewage sludge

“…Land application of sewage sludge is a current environmental and agricultural practice for disposing of an unwanted waste product, returning valuable nutrients and organic matter to the land and reclaiming degraded soils (Bernal et al 1998;Speir et al 2003). However, this practice may lead to a risk to humans and the environment because of the presence of heavy metals that could contaminate soil and water, cause phytotoxicity, and be transferred to the food supply (Mamais et al 2000;Dolgen et al 2007).…”

Evaluation of Different Extraction Methods for the Assessment of Heavy Metal Bioavailability in Various Soils

“…Thus, the presence of heavy metals could result in soil and water contamination, phytotoxicity, transfer to the food supply, and reduction of soil biological activity (Giller et al 1998;Mamais et al 2000;Horswell et al 2003;Dolgen et al 2007;Speir et al 2007). For these reasons, it is necessary to understand the impact of the presence of heavy metals in soils and develop techniques to determine potential risks from soil contamination.…”

Phytoremediation as a Prospective Method for Rehabilitation of Areas Contaminated by Long-Term Sewage Sludge Storage: The Greek Experience

“…This is why in most cases wastewater sludge is not reused and is just left at the area of the WWTP. Thus, in Greece only 10 % of produced sludge is reused in agriculture (for example, at Rethymno WWTP (Chania, Crete) [1,2,8,16,25]), the rest 90 % is directed to landfills' disposal [18]. Wastewater sludge could be used not only as a fertilizer; dried sludge could be used in the active cement industry as a fuel substitute.…”