Figure 2(a) shows that the absolute abundances of the tested seven eARGs and iARGs in the raw sludge were 10^2.37–10^5.21 and 10^5.30–10^8.64 copies/mL, respectively. Conditioning of the sludge using TAP significantly increases the absolute abundances of eARGs by 1.06–1.90 log copies and reduced the absolute abundances of iARGs by 0.21–1.43 log copies, respectively. A previous study revealed that sludge with ZVI/ reduced the abundance of iARGs effectively, but eARGs were accumulated in sludge (Lu et al. 2020b). Figure 2(b) shows that the absolute abundances of the intracellular and extracellular intI1 in the raw sludge were 10^8.44, 10^5.00 copies/mL and 16S rDNA were 10^10.46, 10^6.16 copies/mL. After TAP treatment, intracellular intI1 and 16S rDNA decreased by 0.99 and 1.01 log copies, and extracellular intI1 and 16S rDNA increased by 1.43 and 2.04 log copies, respectively. Table 1 shows that the abundance of seven ARGs had significant correlations with intI1 and 16S rDNA, and the previous study observed that the abundance of ARGs showed positive correlations with intI1 (Mao et al. 2015). The intI1 was one of the main mobile gene elements of ARGs during horizontal gene transfer (Partridge et al. 2009). In order to reduce the dissemination risk of ARGs, it was necessary to control the abundance of intI1 effectively.