| In this paper, the ferrate solution was used for the treatment of coking wastewater and landfill leachate as an oxidant and flocculant. Environmental conditions were researched systematically, and the removal efficiency of COD and NH3-N was tested at different environmental conditions. The methods of concentration measurement and stabilization were compared and studied owing to the unstability of ferrate solution.The experimental results showed that:①The process of wastewater treatment would be simple and the cost would decrease by using of the ferrate solution as an oxidant and flocculant.②The stability of ferrate solution could be improved with NaOH, Na2SiO3 and NaClO. The higher the alkalinity was, the slower the decomposition speed of ferrate was. The decomposition speed was only 16.6% with doping 14M NaOH solution and holding 2.5h. Moreover, the stabilization of Na2SiO3 was more efficient than that of NaClO.③The disposal process of A/O-O internal-cycle was used for the wastewater in Chongqing Coking Plant. The method obviously improved the drainage water quality. However, the value of COD and NH3-N couldn't reach the standard of drainage wastewater in our country.④Alkaline condition was suitable for removing NH3-N in coking wastewater. Oxidation time was 15min. The NH3-N removal ratio could reach 59% as CFeO42-=4.1×10-3mol/dm3, pH=3 and the initial CNH3-N=187.86mg/dm3. The COD removal ratio was 55.69% if CFeO42-=4.72×10-3mol/dm3, pH=11 and the initial CCOD=4586.8mg/dm3.⑤The removal ratio was equal to 80.9% when the ferrate solution was used in dealing with the simulative coking wastewater of CCOD=370.55mg/dm3. Simultaneously, the ratio of BOD5/COD raised 0.30.8.⑥With testing the influence fators for the removal ratio of NH3-N in landfill leachate, the order was: the ferrate quantity > pH > oxidization time. The result was following: the NH3-N removal ratio could reach 64.4% when pH=11, CFeO42-=4.36×10-3mol/dm3 and oxidation time was 15min.⑦The removal ratio of COD and NH3-N could raise to 86.32% and 73.21% respectively when the CFeO42-=2.64×10-2mol/dm3 and the CNH3-N=2463.83mg/dm3 and CCOD=7051.44mg/dm3 in landfill leachate. The acidity of wastewater had great effect for getting rid of pollutant. It was found that the removal ratio of COD was 83.36% when pH=3, and that of NH3-N was 67.29% when pH=11. The pollutant removal efficiency was obviously improved and the disposal process was simple by adopting ferrate solution. Thus, it is reasonable and practicable... |
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