Land application of sewage sludge: A soil columns study

Abstract

A column study was conducted to assess the potential Cr, Ni, Cu, Zn, Cd and Pb movement through a reconstructed soil profile to which surface composted sewage sludge was applied. Sewage sludge was mixed into the top 100 mm of each column at the rates of 357 (H), 223 (M) and 22 Mg·ha -1 (L). Treatment H was calculated according to the critical soil concentration and treatments M and L were calculated according to the amount of metals which may be added to agricultural land on 10 yr average (M) and 1 yr (L) according to European legislation. Soil columns were leached with 5 000 mℓ of water. After leaching, soil columns were sampled at depth intervals of 0 to 100, 100 to 300, 300 to 500 and 500 to 840 mm. Metal balance accounted for over 97% of metals and over 86% of metals were retained in the first 100 mm of the column. The average percentage of metals leached decreased in the order Cd (0.04%) > Cu (0.02) ~ Ni (0.02) ~ Zn (0.02) > Pb (0.01) ~ Cr (0.01). The maximum metal concentration in leachates was lower than the limit value for irrigation water but metal concentrations exceeded the drinking water levels for Pb and Ni in all treatments. Thus, harmful health effects may result from the application of sewage sludge.

The effect of acid treatment on the pyrolysis behavior of sewage sludges

“…Humic substances possess a variety of functional groups such as carboxylic, phenolic-alcoholic and amine groups which provide binding sites for metals. Indeed, this result is according to other studies that have shown that Cu, Ni and Zn have a great affinity to organic matter [3]. Fig.…”

“…Combustion of sewage sludges need rigid controls on the volatile pollutants generated [1,2] and farmland application is limited by the potential pollution of the metals present in the sewage sludges [3]. Landfill has been a major option in disposal of sewage sludge for a long time, but it is not sustainable due to the increasing competition for landfill space, higher costs and more stringent environmental standards applied, especially in the European countries [4].…”

“…The conventional uses of sewage sludges include industrial utilization, landfill, individual combustion [1] or with coal [2] and composting for farmland utilization [3]. Combustion of sewage sludges need rigid controls on the volatile pollutants generated [1,2] and farmland application is limited by the potential pollution of the metals present in the sewage sludges [3].…”

Chemical and leaching properties of paper mill sludge

“…According to the criteria of the Ministry of Agriculture and Forestry in Finland, the organic matter content of compost (expressed as LOI), has to be at least 20% (dry weight) for it to be classified as a soil improver. Furthermore, a high organic matter content in sludge is reported to have favourable effects on the physical, chemical and microbiological properties of soil, to improve soil structure as well as the infiltration rate, soil crusting, run-off and pore-size distribution and aggregate stability to raindrop impact, and to improve the water holding capacity of the soil (Cabral et al, 1998;Gascó et al, 2005). However, it has been found that, when the amount of organic material in paper mill sludge decreases due e.g.…”

Environmental risk assessment of heavy metal extractability in a biosludge from the biological wastewater treatment plant of a pulp and paper mill

“…Thus, the biosludge from Stora Enso Oyj Veitsiluoto Mills fulfils this criterion. A high organic matter content in sludge is reported to impart favourable effects on soil physical, chemical and microbiological properties and to improve soil structure as well as the infiltration rate, soil crusting, run-off and pore-size distribution and to aggregate stability to raindrop impact and improve the water holding capacity of the soil (Cabral et al, 1998;Gascó et al, 2005).…”