Releasing control of nitrogen and phosphorus from contaminated sediment covered with aluminum-zirconium modified zeolite

Abstract

In this paper, aluminum and zirconium based metal compounds were used to modify natural zeolite to produce Al-Zr modified zeolite (AZMZ). The adsorption performance, micro morphology and releasing control effect of AZMZ on nitrogen and phosphorus from sediment were tested. Test results show that the adsorption performance of natural zeolites on ammonia nitrogen and phosphate in water was significantly improved after Al-Zr modification. The adsorption model is chemical adsorption, and follows the quasi second-order kinetic equation and Langmuir model. The saturated adsorption capacity of 0.5 to 1.0 mm size of AZMZ for ammonia nitrogen and phosphate in water is 8.40 mg/g and 3.10 mg/g respectively. AZMZ has the potential to be used as in-situ covering materials to control the release of nitrogen and phosphorus from sediment. The average release rate was resduced by the increasing thickness of AZMZ. When the covering thickness of AZMZ reaches 0.5 cm, the releasing rate of nitrogen and phosphorus in the sediment can be effectively controlled. When the AZMZ thickness reaches 1.0 cm, the releasing reduction rate of nitrogen and phosphorus in the sediment are 89.1% and 75.3% respectively.