【作者】 于淼；

【导师】 李圭白；

【作者基本信息】 哈尔滨工业大学 ， 土木工程， 2022， 硕士

【摘要】 含盐废水会使水环境恶化,导致土地盐碱化,危害生态环境,阻碍经济发展,影响人类健康。已有的理化处理方法普遍具有能耗高、操作成本高、具有二次污染等缺点,因此寻找经济有效的含盐废水处理措施是现在的热点问题。重力流膜生物反应器(Gravity-driven membrane bioreactor,GDMBR)采用超低压重力驱动,具有低能耗、低维护的特点,在污水处理与回用领域具有很好的应用前景。然而,含盐废水中的盐度会抑制微生物作用,降低GDMBR对污染物的去除效能。本文在GDMBR工艺中引入弱电场作用,以调控生物作用、强化对污染物的去除效能及控制膜污染。首先考察了弱电场介导的GDMBR工艺处理含盐废水长期运行过程中的通量变化规律及对污染物的去除效能,并探究了不同电压强度对工艺效能影响。结果表明,引入弱电场可以提高GDMBR对污染物的去除效能,对COD和氨氮的去除率分别提升至59.81%和77.01%,且阳极(泡沫镍电极)电解出的镍离子和进水中的Na~+、Cl~-在电场的作用下发生电絮凝作用,可强化对TP的去除效果,平均去除率高达97.88%。弱电场介导作用有利于滤饼层产生疏松多孔结构,缓解膜污染,提升GDMBR工艺运行通量,且最佳电压为0.75V。其次探究了不同电极(如泡沫镍电极和碳毡电极)对弱电场介导的GDMBR工艺运行效能和膜污染的影响。结果表明,相比于泡沫镍电极,耦合工艺中阳极采用碳毡电极对污染物的去除效能更高,反应器运行更加稳定;且阳极选用碳毡电极更有利于缓解膜污染,从而缓解膜通量的下降,而阳极选用泡沫镍电极时膜表面被阳极析出的金属镍覆盖,易诱发新的膜污染,导致通量较低。为了进一步强化导电效果并为微生物的生长提供载体,考察了投加电气石粉对弱电场介导的GDMBR工艺通量稳定性和污染物去除效能的影响,并探究了不同粒径对工艺效能的影响。结果表明,投加电气石粉有利于耦合工艺的稳定运行和污染物去除效能的提高,相比于325目电气石粉,8000目电气石粉效果更好。但投加的电气石粉易沉积在滤饼层内,导致滤饼层颜色较深且结构致密,并导致滤饼层内微生物丰度降低,EPS(如多糖与蛋白质等)含量增加,致使膜通量有所下降。本研究开发了弱电场介导的重力流膜生物反应器耦合工艺,并优化了工艺运行条件,有助于提升GDMBR对含盐废水中污染物的去除效能和缓解膜污染,为低能耗、低维护的含盐废水处理工艺提供技术支持。更多还原

【Abstract】 Saline wastewater will worsen the water environment,lead to land salinization,harm the ecological environment,hinder economic development and affect human health.The existing physical and chemical treatment methods generally have the shortcomings of high energy consumption,high operating cost,secondary pollution and so on.Therefore,it is a hot issue to find economic and effective measures to treat saline wastewater.Gravity-Driven membrane bioreactor(GDMBR)adopts ultra-low pressure Gravity to drive and has the characteristics of low energy consumption and low maintenance,and has a good application prospect in the field of sewage treatment and reuse.However,high salinity in saline wastewater inhibits microbial action and reduces the removal efficiency of pollutants by GDMBR.In this paper,the effect of weak electric field was introduced in THE GDMBR process to regulate biological effects,strengthen the removal efficiency of pollutants and control membrane fouling.The flux variation law and pollutant removal efficiency of GDMBR process mediated by weak electric field in the long-term operation of saline wastewater treatment were investigated,and the effects of different voltage intensities on process efficiency were explored.The results show that the introduction of weak electric field can improve the removal efficiency of pollutants by GDMBR,and the removal rates of COD and ammonia nitrogen are increased to 59.81% and 77.01%,respectively.Moreover,the electrocoagulation of Nickel ions electrolyzed by anode(nickel foam electrode)and Na+ and Cl-in water will occur under the action of electric field,which can strengthen the removal effect of TP.The average removal rate was 97.88%.The mediating effect of weak electric field is beneficial to the cake layer to produce loose porous structure,alleviate membrane pollution and improve the operating flux of GDMBR process,and the optimal voltage is 0.75 V.The effects of different electrodes(such as nickel foam electrode and carbon felt electrode)on the operation efficiency and membrane fouling of GDMBR mediated by weak electric field were investigated.The results show that compared with the nickel foam electrode,the carbon felt electrode is more effective in removing pollutants and the reactor runs more stably.In addition,carbon felt electrode is more conducive to alleviating membrane pollution and thus alleviating the decrease of membrane flux.However,when nickel foam electrode is used for anode,the membrane surface is covered by metal nickel precipitated from anode,which is easy to induce new membrane pollution and lead to low flux.In order to further strengthen the conductive effect and provide a carrier for the growth of microorganisms,the effects of tourmaline powder on flux stability and pollutant removal efficiency of weak electric field-mediated GDMBR process were investigated,and the effects of different particle sizes on process efficiency were explored.The results show that the addition of tourmaline powder is beneficial to the stable operation of the coupling process and the improvement of pollutant removal efficiency.Compared with 325 mesh tourmaline powder,the effect of 8000 mesh tourmaline powder is better.However,tourmaline powder is easily deposited in the filter cake layer,resulting in dark color and dense structure of the filter cake layer,and resulting in decreased microbial abundance in the filter cake layer,increased EPS content(such as polysaccharide and protein,etc.),resulting in a decrease in membrane flux.In this study,the coupling process of gravity flow membrane bioreactor mediated by weak electric field was developed,and the operating conditions of the process were optimized,which helped to improve the removal efficiency of pollutants in saline wastewater by GDMBR and alleviate membrane pollution,and provided technical support for the treatment process of saline wastewater with low energy consumption and low maintenance.更多还原