Removal of heavy metals in sludge via joint EDTA-acid treatment: Effects on seed germination.

Heavy metals (Cu, Pb, Zn, Ni, Cr, and Cd) were removed from sludge via joint treatment with ethylene diamine tetraacetic acid (EDTA) and three organic acids (citric acid, glutamic acid, or aspartic acid) at optimal EDTA-acid concentration ratios of 1:1, 1:2 and 2:1, respectively. Heavy metal removal rates and post-treatment nutrient retention in sludge was then analyzed. The effects of different proportions sludge and soil mixes on the germination of Chinese white cabbage (Brassica campestris L.