Recovery of EDTA and metal precipitation from soil flushing solutions

Treatment and recovery of contaminated railway ballast

“…In the view of a future optimization of the washing conditions, this should be taken into account and a final washing with water is required before reuse or disposal of the stones, as generally required after chelant-assisted washing of contaminated soil and sediments [19,25].…”

“…A substantial excess of EDTA is thus generally adopted, increasing the cost of the whole remediation treatment, unless recovery of EDTA from the spent solution is realized [18,19].…”

Bioremediation of agricultural solid waste leachates with diverse species of Cu (II) and Cd (II) by periphyton

“…Cu and Cd) from agricultural solid waste leachate, physical and chemical methods, such as evaporation and reverse osmosis, were the predominant techniques, (Di Palma et al, 2003), with electrochemical treatment (Iskander et al, 2016), photocatalysis (Fabbri et al, 2009), selective adsorption by activated carbon (Ahn et al, 2008) or biochar (Regmi et al, 2012) also being used. Nevertheless, most of these methods are costly in terms of maintenance and operation because special apparatus and reagents are required (Fedje et al, 2013).…”

Recovery of toxic metal ions from washing effluent containing excess aminopolycarboxylate chelant in solution

“…An electrochemical reduction treatment followed by membrane separation (Juang and Wang, 2000a;Arévalo et al, 2002), a precipitation treatment with zero-valent metals (Lee and Marshall, 2002) or the addition of suitable reagents (e.g., NaOH, Ca(OH) 2 , Na 2 S, FeSO 4 , FeCl 3 , NaH 2 PO 4 , Na 2 HPO 4 , or diethyldithiocarbamate) (Tünay and Kabdasli, 1994;Chang, 1995;Steele and Pichtel, 1998;Hong et al, 1999;Kim and Ong, 1999;Xie and Marshall, 2001;Di Palma et al, 2003;Lim et al, 2005) are potential techniques proposed for the recovery of metal ions from metal-chelant solutions. Operational problems, such as membrane fouling, membrane degradation, considerable costs or the inherent stability of metal-chelant complexes in solution, are some drawbacks of the proposed separation techniques (Kim and Ong, 1999;Di Palma et al, 2003;Lim et al, 2005). Most of the proposed separation techniques are also based on equimolar solutions of metals and APCs (Chang, 1995;Kim and Ong, 1999;Juang and Wang, 2000a), while washing effluents from metal-contaminated solid-waste treatment processes are often characterized by a large excess of free APCs in solution or APCs that are combined with 5 other competitive ions in the waste (Di Palma et al, 2003;Leštan et al, 2008).…”

“…Operational problems, such as membrane fouling, membrane degradation, considerable costs or the inherent stability of metal-chelant complexes in solution, are some drawbacks of the proposed separation techniques (Kim and Ong, 1999;Di Palma et al, 2003;Lim et al, 2005). Most of the proposed separation techniques are also based on equimolar solutions of metals and APCs (Chang, 1995;Kim and Ong, 1999;Juang and Wang, 2000a), while washing effluents from metal-contaminated solid-waste treatment processes are often characterized by a large excess of free APCs in solution or APCs that are combined with 5 other competitive ions in the waste (Di Palma et al, 2003;Leštan et al, 2008). A technique that ensures the effortless selective separation of metal ions and recycling of processed water, including APCs, may therefore be economically beneficial (Lim et al, 2005;Leštan et al, 2008).…”