Metal fractionation of atmospheric aerosols via sequential chemical extraction: a review

Chemical Speciation & Bioavailability

Pöykiö

et al. 2008

Paper mills produce large amounts of paper mill sludge in the treatment of process water. According to overburden studies, the hydraulic conductivity of the paper mill sludge originating from a paper mill in Northern Finland at a pressure of 30 kPa was 4.4610 À 10 m s À 1 , and 1.7610 À 10 m s À 1 at a pressure of 100 kPa. These values well meet the generally required values of between 1.0610 À 7 m s À 1 and 1.0610 À 9 m s À 1 for a geological barrier in landfill base and sides at landfills in the European Union. Paper mill sludge can also be used in the artificially constructed geological barrier layer of landfill cover structures. The angle of internal friction of the paper mill sludge was 34.8 and the cohesion of interparticle adhesion 23 kPa, which are important measures for assessing the shear strength of paper mill sludge and thus the stability of the landfill layer in which it is used. During a 28-day period, the biodegradability of the paper mill sludge in soil was ca 0.4% and in ground water under 1%, whereas according to the OECD 301F standard concentrations (BOD 28 ), it was ca 8%. For the determination of total element concentrations in the paper mill sludge, the dried sample was digested using USEPA method 3052. A five-stage sequential leaching procedure was also used to fractionate trace elements in the paper mill sludge between the water-soluble (H 2 O), exchangeable (CH 3 COOH), easily reduced (HONH 3 Cl), oxidizable (H 2 O 2 þ CH 3 COONH 4 ), and (5) the residual (HF þ HNO 3 þ HCl) fractions. This paper covers also examples of case studies how paper mill sludge is utilized in Finland.

Section: Resultsmentioning

confidence: 99%

Chemical and leaching properties of paper mill sludge

Kuokkanen

Chemical Speciation & Bioavailability

Pöykiö

et al. 2008

“…24 From the environmental and utilization point of view, the low levels of organic matter in ash is a favorable phenomenon since, if present, the organic matter may form complexes with toxic heavy metals; the absence of such complexes prevents toxic heavy metals from migrating into the soil. 24 However, according to Smichowski et al, 25 the organic fraction released in the oxidizable step is not considered to be very mobile or available. In the coal fl y ash, 16.8% of the molybdenum was found in this fraction, whereas the proportion of other heavy metals in this fraction varied between 1.9% and 8.1%.…”

Section: Elementmentioning

confidence: 99%

Concentrations of heavy metals in fly ash from a coal-fired power plant with respect to the new Finnish limit values

Dahl

Pöykiö²,

J Mater Cycles Waste Manag

2008

In Finland, the new limit values for heavy metals in fertilizers used in agriculture and in forestry came into force in March 2007, and for materials used as earth construction agents, in June 2006. From the utilization point of view, it was notable that the total heavy metal concentrations (Cd, Cu, Pb, Cr, Mo, Zn, As, Ni, Ba, and Hg) in fl y ash from a coal-fi red power plant were lower than those limit values. The concentrations of the easily soluble elements Ca, Mg, Na, P, and Zn in the fl y ash were between 3.5 and 35 times higher than those found in the coarse mineral soils of Finland. Fly ash is a potential agent for soil remediation and for improving soil fertility. If inorganic materials and by-products are utilized in earthworks, the content of harmful compounds must be low and the harmful components must be tightly bound to the matrix. Therefore, a fi ve-stage sequential extraction procedure was used to evaluate the extractability of different elements in fl y ash into the following fractions: (1) the water-soluble fraction, (2) the exchangeable fraction (CH 3 COOH), (3) the easily reduced fraction (NH 2 OH-HCl), (4) the oxidizable fraction (H 2 O 2 + CH 3 COONH 4 ), and (5) the residual fraction (HF + HNO 3 + HCl).

“…However, according to the total organic carbon (TOC) value of 1.4 mg kg À 1 (d.w.), the amount of organic matter in the slaker grits is negligible (Table 1), and it is therefore not likely that the degradation of organic matter under oxidizing conditions can lead to significant release of the metals bound to these organic components. According to Smichowski et al (2005), the organic fraction released in the oxidizable step is not considered to be very mobile and available. From a utilization point of view, the low level of organic matter in the slaker grits is a favourable phenomenon since, if present, the organic matter may form complexes with toxic heavy metals.…”

Section: The Results Inmentioning

confidence: 99%

Total and extractable heavy metal, phosphorous and sulfur concentrations in slaker grits from the causticizing process of a pulp mill for use as a soil amendment

Chemical Speciation & Bioavailability

Pöykiö

Watkins

et al. 2010

The utilization of solid residues allows industry to reduce and recycle waste materials and produce beneficial by-products. The total heavy metal concentrations in slaker grits originating from the chemical recovery process of a pulp mill are lower than the current Finnish statutory limit values for fertilizers used in agriculture and in forestry. In addition, slaker grits are strongly alkaline pH (13.1), have elevated total calcium concentration (331 g kg; d.w.), contain calcite (CaCO 3 ), as well as a neutralizing value of 39.4% (Ca equivalents, d.w.). Thus, 0.96 tonnes of slaker grits would be required to replace 1 tonne of a commercial ground limestone product. This indicates that slaker grits have great potential as an industrial residue-based fertilizer and liming agent for use in agriculture and forestry. Since, before such use, it is necessary to assess the mobility of elements in the grits, the three-stage BCR sequential extraction procedure was carried out. Results from sequential extractions showed that the partitioning of Mn (47%), Co (47.1%), Ni (43.1%) and S (94%) was highest in the exchangeable fraction, in which acetic acid (CH 3 COOH) is used as extractant. The partitioning of Fe (96.5%) and Ti (75.6%) was highest in the easily reduced fraction, in which hydroxylamine hydrochloride (NH 2 OH -HCl) is used as extractant. The partitioning of Cr (90.8%), V (75.4%), Zn (78.3%), Ba (62.1%), Al (99.4%) and P (99.8%) was highest in the oxidizable fraction, in which hydrogen peroxide (H 2 O 2 ) is first applied to a heated medium (i.e. 85 C) for dissolving organic matter, after which ammonium acetate (NH 4 COOH) is used as extractant.