The objective of the present study was to compare the potential accumulation capacity of Cr, Cu and Zn in Zea mays and Populus deltoides Marsh. The study was conducted in an area in a wastewater treatment plant in Birjand for a period of 120 days. The soil sample and selected parts of Z. mays and P. deltoides Marsh were collected monthly and treated with hydrochloric acid and nitric acid. The results showed that the highest mean concentrations of Cu (1.78 ± 0.93 mg kg−1) and Zn (2.65 ± 1.37 mg kg−1) were observed at Z. mays in September. The results indicated that the concentrations of Cu and Zn in Z. mays and P. deltoides Marsh shoots irrigated with wastewater were higher than tap water. In addition, both the plants comparatively showed a significant increase in total metal amount when treated with wastewater (p < 0.001). The study of BCF and TF demonstrated that Z. mays was suitable for phytoextraction of Cu, but unsuitable for both phytoextraction and phytostabilization of Zn and Cr, whereas P. deltoides Marsh was unsuitable for both phytoextraction and phytostabilization of Zn, Cu and Cr.