秸秆生物炭在废水脱氮中的应用研究

发布时间：2018-09-01 10:22

【摘要】：地表水中氮磷导致的富营养化和地下水硝酸盐超标是环境中的两大问题。对此,本文以秸秆生物炭为吸附剂和碳源,开展了对二级出水和地下水脱氮效果研究。研究内容为秸秆生物炭作为吸附剂对废水中氨氮和硝态氮的吸附效果、生物炭作为反硝化碳源去除二级出水中硝态氮以及地下水中常见离子对生物炭在地下水脱氮应用中的影响。通过一系列的研究得出以下结论:(1)通过颗粒与粉末生物炭对废水中氨氮和硝态氮吸附差异研究,得出颗粒生物炭对氨氮的吸附效果优于粉末生物炭,但两者对硝态氮的吸附不明显,且会产生一定量的NO3--N。粉末生物炭通过FeCl3和CaCl2改性后,可以有效的吸附硝态氮,且FeCl3改性效果优于CaCl2改性效果。(2)未改性的粉末和颗粒生物炭对氨氮吸附的吸附等温线符合Freundich吸附模型;未改性的粉末生物炭对氨氮吸附的吸附动力学符合准二级动力学方程,未改性的颗粒生物炭对氨氮吸附的吸附动力学符合准一级动力学方程。改性后的粉末生物炭对硝态氮吸附的吸附等温线符合Langmuir吸附模型,动力学方程符合准二级动力学方程。(3)改性粉末生物炭对二级出水中的硝态氮(17.5mg/L)、氨氮(5.0mg/L)和总磷(2.9mg/L)有很好的吸附效果。FeCl3改性粉末生物炭对硝态氮、氨氮和总磷的去除率分别为54.40%、31.75%和80.25%,CaCl2改性粉末生物炭对硝态氮、氨氮和总磷的去除率分别为41.18%、26.46%和30.18%。(4)通过从中国矿业大学污水处理站分离得到三种反硝化细菌WS、PYS、YS,且均属于Pseudomonas.,通过反硝化菌反硝化能力实验得出反硝化效果最佳的是PYS。以PYS为反硝化菌,颗粒生物炭为反硝化碳源和填料,应用于二级出水中去除硝态氮的摇床实验和连续实验中,均得到很好的反硝化效果,且无亚硝态氮的累积。(5)通过地下水中常见离子对颗粒生物炭去除地下水硝态氮的影响实验,结果显示离子类型及浓度影响硝酸盐去除的效果。其中,SO42-具有明显的抑制作用,且造成大量的亚硝酸盐累积;Ca2+、Na+、HCO3-均处于促进作用,但浓度越低促进效果越明显;Cl-在高浓度(600 mg/L)时为抑制作用,在低浓度时为促进作用,且浓度越低促进效果越好。
[Abstract]:Eutrophication caused by nitrogen and phosphorus in surface water and nitrate in groundwater are two major problems in the environment. In this paper, the nitrogen removal effect of secondary effluent and groundwater was studied with straw biochar as adsorbent and carbon source. The adsorption effect of straw biochar on ammonia nitrogen and nitrate nitrogen in wastewater was studied. Removal of nitrate nitrogen from secondary effluent by biochar as a carbon source for denitrification and the effects of common ions in groundwater on the application of biochar in denitrification of groundwater. Through a series of studies, the following conclusions are drawn: (1) the adsorption effect of granular biochar on ammonia-nitrogen and nitrate nitrogen in wastewater is better than that of powdered biochar through the study of the difference of adsorption of ammonia nitrogen and nitrate nitrogen between granular and powdered biochar. But the adsorption of nitrate nitrogen is not obvious, and a certain amount of NO3--N. will be produced. After modified by FeCl3 and CaCl2, powder biochar can effectively adsorb nitrate nitrogen, and the modification effect of FeCl3 is better than that of CaCl2. (2) the adsorption isotherm of ammonia nitrogen adsorbed by unmodified powder and granular biochar accords with Freundich adsorption model. The adsorption kinetics of unmodified powder biochar accords with quasi second order kinetic equation, while that of unmodified granular biochar accords with quasi first order kinetic equation. The adsorption isotherm of the modified powder biochar for nitrate nitrogen is in accordance with the Langmuir adsorption model. The kinetic equation accords with the quasi second-order kinetic equation. (3) modified powdered biochar has a good adsorption effect on nitrate nitrogen (17.5mg/L), ammonia nitrogen (5.0mg/L) and total phosphorus (2.9mg/L) in secondary effluent. The removal rates of ammonia nitrogen and total phosphorus were 54.40% and 80.25% respectively. The removal rates of ammonia nitrogen and total phosphorus were 41.18% and 30.18% respectively. (4) three denitrifying bacteria (WS,PYS,YS,) were isolated from wastewater treatment station of China University of Mining and Technology and all belong to Pseudomonas.,. Through denitrification ability experiment of denitrifying bacteria, the best denitrification effect was obtained by PYS.. Using PYS as denitrifying bacteria and granular biochar as carbon source and filler for denitrification, a good denitrification effect was obtained in the shaking bed experiment and continuous experiment of removing nitrate nitrogen in secondary effluent. And no accumulation of nitrite nitrogen. (5) the effects of common ions in groundwater on the removal of nitrate nitrogen from groundwater by granular biochar were studied. The results showed that the type and concentration of ions affected the effect of nitrate removal. So _ 42- had obvious inhibitory effect, and caused a large amount of nitrite to accumulate Ca ~ (2 +) ~ (2 +) Na ~ (2 +) HCO3-, but the lower the concentration, the more obvious the inhibitory effect was at high concentration (600 mg/L), and the latter at low concentration. And the lower the concentration, the better the promotion effect.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703

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