| Popis: |
Application of microwave (MW) radiation followed by aeration (A) for the purpose of ammonia removal from both synthetic solutions and landfill leachate was investigated in this study. Four sets of experiments: water bath (WB), microwave (MW), sequential microwave/aeration process (MW+A), and sequential water bath/aeration process (WB+A) were conducted using synthetic solution. MW and MW+A tests were applied on the landfill leachate as well. For each test, either 100 mL of synthetic solution or landfill leachate was used. All the tests were conducted with three replicates in batch scale. For both economic and safety concerns, the samples’ temperature were maintained below the boiling point. One-way ANOVA tests and T-tests were conducted to analyze the differences of ammonia removal efficiencies among different methods. Both thermal and non-thermal effects for the sequential microwave/aeration process were investigated. Factorial design and response surface methodology (RSM) were applied to evaluate and optimize the effects of pH, MW energy level and microwave power output. Results confirmed that the sequential microwave/aeration process was an effective approach for removal of ammonia from aqueous systems. Maximum ammonia removal of 81.7 % for synthetic solution and 70% for landfill leachate was achieved by applying 7.8 KJ MW energy output/L sample and 10 minutes aeration. When apply the sequential microwave/aeration process to synthetic solution, at optimum condition of pH 10.5, 7.8 KJ MW energy output/L sample and 10 minutes aeration time, the contribution of thermal process was 39%, while 61% for non-thermal processes (33% for aeration and 28% for EMF). Statistical analysis of synthetic solution tests data using RSM showed that ammonia removal efficiency strongly depended on pH and MW energy output. R square of 0.941 indicates that observed results fitted well with the model prediction. Optimum pH and MW energy output level for ammonia removal was 11 and 7.8 KJ MW energy output/L sample respectively, and under this condition, maximum ammonia removal efficiency predicted for synthetic solution was 76.3%. |
