| The desulfurization wastewater produced in the flue gas desulfurization process of coal-fired power plants has the characteristics of high salt content and hardness,strong corrosiveness and complex composition.At present,the triple-tank process（flocculation-precipitation-neutralization）is widely used in domestic power plants to treat desulfurization wastewater,but there are limitations in the complicated processes and high chemical consumption.To overcome the limitations of traditional desulfurization wastewater treatment,one-step treatment of desulfurization wastewater based on biomass materials was proposed for the first time in this research.In this method,sodium alginate was cross-linked in situ in the desulfurization wastewater to form hydrogels and simultaneously flocculate and adsorb the desulfurization wastewater.Then the waste hydrogels after the treatment of desulfurization wastewater were used as carbon sources for carbonization,and they were prepared as porous carbon material adsorbents to realize the resource utilization of hydrogels waste generated after wastewater treatment.Therefore,this research mainly carried out the following two aspects of work:（1）The removal rate of heavy metals from target wastewater by alginate increased with the increase of dosage and reaction time and the modified sodium alginate could improve the treatment on desulfurization wastewater.The results demonstrate that the optimum treatment effect was obtained using ethylenediamine at 0.02 g·L-1,alginate dosage of 12 g·L-1 and a reaction time of 3 h,with removal rates of 71.13、39.63、42.86、64.43、66.67、63.16、89.47and 80.00（%）for Ca、Mg、Ni、Zn、As、Cd、Pb and Cr,respectively.EEM results showed that the content of humic acid and fulvic acid in the wastewater were significantly reduced after treatment by ethylenediamine modified sodium alginate hydrogel.The formed hydrogels had a denser structure and the analysis of EDS showed that the surface of the material was composed of a variety of heavy metals.The mechanism showed that the covalent cross-linking reaction between the amino group of ethylenediamine and the carboxyl group of sodium alginate improved the ability of the material to complex heavy metals in desulfurization wastewater and the treatment effect of desulfurization wastewater.On this basis,the process of one-step process of modified alginate in-situ gelation for desulphurization wastewater treatment was explored.The results show that the method is better than the triple-tank process in the process and removal rate.And we developed a new integrated treatment system for desulphurization wastewater,which provided technical support for the treatment of short flow and low agent in the desulfurization wastewater.（2）Alginate based porous carbon aerogels were prepared by carbonization of sodium alginate based wastewater gel formed after treatment of desulfurized wastewater.The material had a rich pore structure,and the specific surface area was 52.37 m2·g-1.At the same time,the effects of adsorption time and initial p H value of the solution on the tetracycline and PFOA in the carbon aerogel adsorption solution were investigated,and the adsorption process was in accordance with the quasi two stage kinetic model（R2 is 0.8257 and 0.9665,respectively）.The adsorption process could be well described by the Freundlich adsorption isothermal model,（R2is 0.9798）,and as the p H value of the solution increases,the adsorption capacity and removal rate of the carbon aerogel to pollutants gradually decreased.The maximum removal rate of tetracycline could reach 83.1%,the maximum removal rate of PFOA could reach 95.6%,indicating that the sodium alginate-based porous carbon aerogel prepared from the hydrogels waste of desulfurization wastewater was good in removing antibiotics and organic pollutants in the water environment,and had realized the resource utilization of the waste hydrogels for desulfurization wastewater treatment. |
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