Optimization of phytoremediation of industrial wastewater with water hyacinth plant using response surface methodology

Abstract

Phytoremediation of simulated wastewater by using water hyacinth plant and the optimization of uptake process have been investigated. In this project, response surface methodology (RSM) was used to study the relationship of initial heavy metal concentration and contact time on pH changes, and also heavy metal uptake efficiency. The experiment was designed by using central composite design and 23 full factorial design with one centre point. From the result, the optimum condition for phytoremediation process was determined via RSM. The overall removal efficiency of copper decreased from 98.94 % to 91.57 % as the copper concentration increased from 1 mg/L to 5 mg/L. The lead removal efficiency decreased from 73.64 % to 30.95 %. For optimization of copper removal, the uptake condition toward pH changed along 28 days of experiments at initial copper concentration of 3.66 mg/L and contact time of 16 days. For optimization of copper uptake capacity, the optimum uptake condition toward uptake capacity along 28 days of experiments was at initial copper concentration of 3.80 mg/L and contact time of 25.28 days for leaf, whereas for stem, the initial concentration was 5.0 mg/L. For root part, the optimum copper uptake condition toward uptake capacity happened at contact time of 18.54 days with initial concentration of 3.89 mg/L. For optimization of lead removal, the optimum uptake condition toward pH changed along 28 days of experiments at initial lead concentration of 727.43 mg/L and contact time of 16.76 days. The optimum lead uptake condition toward uptake capacity along 28 days of experiments was at initial lead concentration of 674.16 mg/L and contact time of 19.05 days for leaf, whereas for stem, at initial concentration of 926.94 mg/L and contact time of 18.54 days. For root part, the optimum copper uptake condition toward uptake capacity for root was at contact time of 17.22 days with initial concentration of 750 mg/L.