Evaluation of partial nitrification efficiency as a response to cadmium concentration and microplastic polyvinylchloride abundance during landfill leachate treatment

The partial nitrification efficiency response to the presence of cadmium (Cd2+) and microplastics was investigated. Microplastics polyvinylchloride (PVC) abundance was 0-10,000 particles/L, and Cd2+ concentration was 0-10 mg/L. Cd-only inhibited the NH4+-N oxidation rate 1.21, 1.23, and 1.18 times with concentrations at 1, 5, and 10 mg/L, respectively. PVC-only inhibited NH4+-N oxidation rate 1.01, 1.21 and 1.05 times with PVC abundance at 1000, 5000 and 10,000 particles/L, respectively. The ammonia oxidation rate was improved with the co-existence of PVC and Cd2+ at the conditions PVC1000 and PVC5000, which could be attributed to the PVC. PVC at 1000 particles/L could act as carrier and mitigate the negative effect of Cd2+ to the partial nitrification process. Moreover, the partial nitrification process was largely inhibited with PVC abundance at 10,000 particles/L. First-order kinetic models could simulate the NH4+-N, NO2-N, and NO3--N changes in the partial nitrification process. (C) 2020 Elsevier Ltd. All rights reserved.