污染物在铝污泥雨水生物滞留系统中去除迁移特性

发布时间：2018-07-23 18:42

【摘要】：雨水径流中所携带的污染物会对水生态系统以及水环境产生严重的影响。给水厂剩余铝污泥对磷等多种径流污染物具有很强吸附性,将铝污泥用作生物滞留系统填料以去除雨水径流中的污染物,具有实用性和经济性,这不仅发挥了铝污泥对水体污染物优良的吸附和滞留作用,同时这也是对铝污泥的一种资源化利用。铝污泥基质生物滞留系统是一种极具应用前景的雨水管理技术。本课题首先对典型水厂的铝污泥性质进行了检测,通过XRD、XRF、BET等方法探讨了其组分和内部结构特征,确定了铝污泥成分、内部孔隙率和孔径分布以及其比表面积等物理特性。同时在25oC的条件下对铝污泥吸附磷的性能进行了等温吸附试验,以探究铝污泥对磷的吸附特征。铝污泥改良雨水生物滞留系统试验通过设置两组滞留系统模拟柱,分别装砂土和添加质量分数为10%的铝污泥砂土两种填料,通过监测生物滞留系统内不同填料层出水污染物浓度指标的变化情况,更直观的了解污染物在生物滞留系统中的去除和迁移。另外设计四套生物滞留模拟箱装置,分别考察了砂土基质和砂土铝污泥基质生物滞留系统在有无种植植物的条件下对污染物的去除状况,以了解生物滞留系统中植物对污染物去除的影响。通过一系列试验得到以下结论。(1)铝污泥的XRF分析表明试验所取铝污泥中铝铁含量较高(Al、Fe的含量分别为6.74%和15.9%),P的本底值很底,仅占0.0691%,铝污泥比面积为126.44m~2/g,平均孔径为5.02 nm,内部孔隙主要以介孔为主。铝污泥对P饱和吸附量为19.01mg/g。铝污泥对磷具有优秀的吸附去除能力,其吸附量和吸附亲和力均优于一般雨水生物滞留填料。(2)铝污泥改良后的生物滞留系统在整个运行阶段均表现出持续、高效的除磷能力,在试验期间,进水磷浓度为3.0-7.0mg/L,进水总量约2600L,从距填料层上端20cm处开始,出水TP浓度基本能保持在0.01-0.04mg/L之间,上端20cm填料层处对TP的平均去除率已达到95%左右。相比之下砂土基质生物滞留系统对P的吸附能力显得不足,试验开始后填料由上往下对P的吸附逐渐饱和。可见,使用20cm厚砂土铝污泥基质可以达到理想的TP去除效果(3)生物滞留系统对雨水径流的NH_4~+-N去除机理主要有填料吸附,硝酸菌的硝化作用和植物的吸收作用等,在本试验中,生物滞留系统通过硝化作用对NH_4~+-N的去除所占的比例在22.5%-30%之间。砂土和砂土铝污泥两组生物滞留系统进水流经填料后,从距填料层上端20cm处径流内NH_4~+-N基本被完全去除,最终,砂土基质生物滞留系统对NH_4~+-N的平均去除率为98.8%,稍高于砂土铝污泥系统的94.4%。砂土生物滞留系统和砂土铝污泥生物滞留系统对NO_3~--N的平均去除率分别为27%和24.9%。系统对NO_3~--N的去除效果较差,效果不稳定,其浓度的减小主要发生在生物滞留模拟柱的下部40-60cm处。两生物滞留系统对TN的去除率也相对较低,在27.8-39.5%之间,从试验结果看,由于填料粒径的关系,与砂土生物滞留系统相比,铝污泥的加入并没有对TN的去除起到明显的积极作用。(4)试验进水COD浓度为140-200mg/L,随着填料深度的增加COD的去除率随之增大。两种生物滞留系统种植土层对COD的去除率均在15%上下,砂土铝污泥填料和砂土填料生物滞留系统生物滞留系统底部的取水口处两系统的最终出水COD平均浓度分别为38.6mg/L与17.1mg/L,平均COD去除率分别达到78.7%与90.5%,可见砂土填料生物滞留系统对COD的去除效果优于砂土铝污泥生物滞留系统。与砂土生物滞留系统相比,铝污泥的加入同样没有对COD的去除起到明显的积极作用。(5)在实际应用中,使用20cm厚砂土铝污泥填料可以达到理想的TP去除效果。但从TN和COD去除的角度考虑,填料层越深去除效率越高。同时,由于粒径的影响,在砂土填料中添加铝污泥可能导致COD、TN去除率稍微降低。(6)生物滞留模拟箱模拟结果表明,砂土铝污泥基质生物滞留系统,种植植物后种植土层对TP的平均去除率提高6%左右,对于最终出水,两者相差不明显,这是因为砂土铝污泥对TP的吸附固定能力强且稳定。对砂土生物滞留系统来说,不种植物与种植植物后种植土层对TP的平均去除率同样提高6%左右,对于最终出水,与不种植物砂土生物滞留系统相比,最终出水TP去除率提高4%左右。(7)砂土铝污泥生物滞留系统和砂土生物滞留系统种植植物后种植土层对NH_4~+-N平均去除率提高5%-10%左右,但砂土铝污泥系统的最终出水NH_4~+-N去除率的提高不足1%,砂土系统最终出水NH_4~+-N去除率的提高2%左右,可见种植植物在种植土层对NH_4~+-N的最终去除率有小幅度提高作用,但对最终出水的强化作用不明显。两系统中,种植植物后种植土层对NO_3~--N平均去除率均提高3%左右,最终出水砂土铝污泥生物滞留系统对NO_3~--N去除率的提高1%左右,砂土生物滞留系统提高2%左右。对两生物滞留系统,种植植物后种植土层和最终出水对TN平均去除率均提高5%左右,可见,植物对TN的去除增强5%左右。(8)进水COD浓度为140-220 mg/L,砂土铝污泥系统在不种植植物的情况下,种植土层COD平均去除率为11.0%,种植植物时,种植土层COD平均去除率为15.4%,无植物时,底部系统COD平均出平均去除率为70.6%,种植植物时,系统底部COD平均去除率为75%,可见砂土铝污泥系统中,种植植物后种植土层和最终出水对COD平均去除率提高5%左右。砂土生物滞留系统种植植物后种植土层和最终出水对COD平均去除率均也提高5%左右。种植植物后生物滞留系统对COD平均去除率均提高5%左右。(9)植物、微生物和基质在生物滞留中相互协同去除磷和其他污染物,植物在生物滞留系统中是不可或缺的部分,生物滞留系统中的植物不止有美化作用,还对雨水中各种污染物均有不同程度的促进作用。
[Abstract]:The pollutants carried in the rainwater runoff have a serious effect on the water ecosystem and the water environment. The remaining aluminum sludge of the water plant has a strong adsorbability to a variety of runoff pollutants such as phosphorus. It is practical and economical to use aluminum sludge as a biological retention system filler to remove the pollutants in the rainwater runoff. Sludge has a good adsorption and retention effect on water pollutants, and it is also a resource utilization of aluminum sludge. The aluminum sludge matrix biological retention system is a very promising rain management technology. Firstly, the properties of the aluminum sludge in the typical water plant were detected, and its components were discussed by XRD, XRF, BET and other methods. The physical characteristics of the aluminum sludge composition, internal porosity and pore size distribution and its specific surface area were determined. At the same time, the adsorption of phosphorus on the aluminum sludge was tested under the condition of 25oC, in order to explore the adsorption characteristics of the aluminum sludge on the phosphorus. The experiment of the biological retention system for the modified rainwater of the aluminum sludge was set up by two The simulation column of the group retention system is loaded with sand and two kinds of filler in the aluminum sludge sand with 10% mass fraction respectively. By monitoring the change of the pollutant concentration index of the effluent in the biological retention system, the removal and migration of pollutants in the biological retention system are more intuitively understood. In addition, four sets of biological retention simulation boxes are designed. In order to understand the removal of pollutants in the biological retention system, the effects of plants on the removal of pollutants in the biological retention system were investigated. The following conclusions were obtained by a series of experiments. (1) XRF analysis of aluminum sludge showed that aluminum in the sludge was taken from the aluminum sludge. The content of iron is higher (Al, Fe content is 6.74% and 15.9%), the background value of P is only 0.0691%, the specific area of aluminum sludge is 126.44m~2/g, the average pore size is 5.02 nm, the inner pore is mainly mesoporous. The saturated adsorption capacity of aluminum sludge to P is 19.01mg/g. aluminum sludge with excellent adsorption and removal capacity, its adsorption capacity and adsorption affinity. (2) the biological retention system after the improvement of aluminum sludge showed continuous and efficient phosphorus removal ability during the whole operation stage. During the experiment, the concentration of influent phosphorus was 3.0-7.0mg/L and the total amount of water was about 2600L. From the 20cm of the top end of the packing layer, the TP concentration of the effluent could be kept at 0.01-0.04mg/L basically. The average removal rate of TP at the upper end 20cm filling layer has reached about 95%. In contrast, the adsorption capacity of P by the sand matrix biological retention system appears insufficient. After the experiment, the adsorption of the filler from the upper to the lower P is gradually saturated. Thus, the ideal TP removal effect (3) biological retention system can be achieved by using the 20cm thick sandy soil sludge matrix. The NH_4~+-N removal mechanism of rainwater runoff mainly consists of packing adsorption, nitrification of nitrate bacteria and absorption of plants. In this experiment, the proportion of the removal of NH_4~+-N in the biological retention system by nitrification is between 22.5%-30%. The sand soil and the sand soil sludge two raw material retention systems flow through the filler and from the filler. At the upper end of 20cm, the NH_4~+-N in the runoff was completely removed. Finally, the average removal rate of NH_4~+-N was 98.8%, which was slightly higher than the 94.4%. sand biological retention system of the sands aluminum sludge system and the average removal rate of NO_3~--N by 27% and 24.9%. system to NO_3~--N, respectively. The removal efficiency is poor and the effect is unstable. The decrease of the concentration is mainly in the lower 40-60cm of the biological retention simulation column. Two the removal rate of TN is relatively low in the biological retention system. From the experimental results, the addition of the aluminum sludge is not to the TN because of the relationship between the particle size of the filler and the sand soil retention system. (4) the concentration of COD is 140-200mg/L, and the removal rate of COD increases with the increase of filling depth. The removal rate of COD in the soil layer of the two kinds of biological retention system is 15%, and the water intake at the bottom of the biological retention system of the sandy soil sludge packing and the biological retention system is at the two lines. The average COD concentration of the final effluent is 38.6mg/L and 17.1mg/L, respectively, and the average COD removal rate is 78.7% and 90.5%, respectively. It is obvious that the removal efficiency of the biological retention system to COD is better than that of the sand soil sludge biological retention system. Compared with the sandy soil biological retention system, the addition of aluminum sludge is also not obvious to the removal of COD. Positive effect. (5) in practical application, the use of 20cm thick sand aluminum sludge packing can achieve the ideal TP removal efficiency. But from the angle of TN and COD removal, the deeper the removal efficiency is, the higher the removal efficiency is. At the same time, adding aluminum sludge in the sand filling may lead to the reduction of COD and TN slightly. (6) biological retention simulation. The simulation results showed that the average removal rate of TP was increased by about 6% after planting, and the difference was not obvious for the final effluent. This was because the adsorption and fixation of TP was strong and stable. The average removal rate of TP increased by about 6%. For the final effluent, the removal rate of TP was increased by about 4%. (7) the average removal rate of NH_4~+-N was increased by about 5%-10% after the planting soil of the sand soil sludge biological retention system and the soil biological retention system. The increase of the NH_4~+-N removal rate of the final effluent of the sands aluminum sludge system is less than 1%, and the removal rate of NH_4~+-N in the final effluent of the sand soil system is increased by about 2%. It can be seen that the final removal rate of NH_4~+-N in the planting soil layer has a small increase, but the strengthening of the final effluent is not obvious. Two in the system, planting soil after planting. The average removal rate of NO_3~--N increased by about 3%, and the removal rate of NO_3~--N was improved by about 1%, and the biological retention system of sandy soil increased by about 2%. For two biological retention system, the average removal rate of TN was increased by 5% after planting and final effluent, so the plant to TN Except for the increase of 5%. (8) the influent COD concentration was 140-220 mg/L, the average removal rate of COD in the soil layer was 11%, the average removal rate of COD in the planting soil was 15.4% when the plant was not planted, and the average average removal rate of COD at the bottom system was 70.6% when the plant was no plant. When the plant was planted, the COD average of the bottom of the system went to the average. The average removal rate of COD in the sand soil sludge system was 75%. The average removal rate of the planting soil and the final effluent increased by 5% in the sand soil sludge system. The average removal rate of COD in the planting soil and the final effluent of the soil biological retention system were also increased by about 5%. The average removal rate of COD after the planting plant increased by 5% left. Right. (9) plants, microbes and substrates are coordinated to remove phosphorus and other pollutants in biological retention. Plants are an indispensable part in the biological retention system. Plants in the biological retention system not only have the effect of beautifying, but also have different degrees of promotion on various pollutants in the rainwater.
【学位授予单位】：北京建筑大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X52

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