【作者】 宋英伟；

【导师】 黄民生；

【作者基本信息】 华东师范大学 ， 环境科学， 2009， 博士

【摘要】 生境改善是恢复城市景观水体健康水生态系统的关键,提高水体透明度是水体生境改善的重点和难点,水体透明度也是体现城市水体景观特征的重要水质指标。城市景观水体透明度不高的原因大多是由水体中大量的浮游植物引起的,而营养盐浓度和水体流动状态对水体中浮游植物的种类和浓度有较大影响。本论文依托国家“863”课题“水体底部水平流复氧与生物膜联合生境改善技术”(2006AA06Z343),以提高水体透明度为目标,研究了降低水体中营养盐浓度和改善水体流动状态的技术方法、作用机理及工程应用效果。论文通过对实际景观水体的调查和监测,分析了北京典型景观水体的水质状况与生境特征;将凹凸棒石作为吸附剂用于降低水体中磷的浓度,在小试规模上进行了自配水和实际水的效果研究;采用推流曝气生物膜技术降低水体中的氨氮浓度和改善水体的流动状态,在中试规模上进行了0.5t实际水的多组实验槽效果比较,并对技术在工程上的应用进行了跟踪研究。通过研究得出以下主要结论:(1)什刹海与罗马湖水体中沉水植物较少,总氮浓度均处于劣V类水平,但什刹海前海东岸透明度达70cm,而罗马湖透明度却只有27cm。造成两水体透明度存在较大不同的原因是二者磷浓度存在较大差异,什刹海总磷仅为0.042mg/L,而罗马湖总磷达0.36mg/L。可见,磷的浓度是藻类生长的限制因子,与水体透明度负相关。(2)柳荫湖和罗马湖的水质均较差,磷的浓度水平均较高,但柳荫湖没有蓝藻水华现象发生,而罗马湖夏季蓝藻水华严重、透明度较低。造成两水体透明度差异的主要原因是水体的深度不同,柳荫湖平均水深仅为0.5m,小于光补偿深度,满足水生植物生长的光合作用条件,沉水植物与挺水植物生长茂盛;而罗马湖水深为1m,大于光补偿深度,沉水植物不能生长。可见,水生植物对景观水体中浮游藻类的生长有抑制作用,水下光照强度是水生植物光合作用的保障,只有在水体深度小于光补偿深度的条件下,才能形成建康的水生态系统,从而改善水体的透明度。(3)天然蛭石、凹凸棒石的除磷性能较差,酸洗改性对蛭石和凹凸棒石的除磷性能有一定的增强作用,但效果提高不大。蛭石和凹凸棒石通过煅烧改性后吸附磷的效果明显增强,但是蛭石吸附除磷后,溶液pH值有较大升高,而凹凸棒石煅烧改性后溶液pH值升高不大,因此,应优先选用煅烧改性后的凹凸棒石作为除磷吸附剂。凹凸棒石煅烧改性的最佳条件是500℃煅烧2h。(4)用煅烧改性后的凹凸棒石,对含磷浓度为0.226mg/L、pH值为8.04的清河水样进行除磷试验,投加7g/L煅烧改性的凹凸棒石时,磷的去除率为83.53%,除磷后溶液中磷浓度为0.037mg/L。(5)在水体中加入生物膜填料,在不采取推流或曝气的措施时,氨氮和COD浓度略有降低。采用推流+生物膜填料技术措施,氨氮浓度与COD浓度大幅度降低,水体透明度由24cm提高到90cm。低有机物浓度条件下,在推流+生物膜填料技术的基础上,增加曝气措施,进一步提高透明度的效果不明显。(6)推流+生物膜填料技术改变了水体的流态与流速,降低了水体中的氨氮浓度,提高了水体的透明度,其中,氨氮浓度的降低可能是抑制水体中藻类暴发的重要影响因素。(7)推流+生物膜填料技术的工程应用表明:在低浓度的氮、磷条件下,该技术对透明度的改善效果明显。水深1m、面积10000m~2的水体,治理投资为50万元,每月运行费用为1000元左右。该技术具有效果好、管理简便、运行费用低等特点。综上所述,采用煅烧方式对凹凸棒石进行改性可以有效降低景观水体中的磷,以达到控磷而提高水体透明度的目的;推流+生物膜填料技术可以降低景观水体中氨氮的浓度,改善水体的流态和流速,从而抑制藻类暴发而改善水体的透明度。更多还原

【Abstract】 Habitat improvement is the key factor to restore the healthy aqua-ecosystem of urban landscape water body,and its transparency enhancing is the emphasis and difficulty,which is one of the important indicators of urban landscapes water body. That transparency of urban-landscapes water was not high enough was due to phytoplankton over-growth.The effects of nutrient concentrations and water flow state in water on the diversity and consistency of phytoplankton in urban landscape water was remarkable.The technologies,their mechanisms and engineering application to reduce nutrient concentrations and improving water flow state in urban landscape water body were investigated in order to enhance its water transparency under supporting by national“863”project(2006AA06Z343).The water quality and habitat characteristics of typical landscape water body in Beijing were analyzed by monitoring and field study.Attapulgite was used as adsorbent to reduce phosphor(P)concentration in water by simulating water and field water at small-scale experiment condition.That the plug flow reaeration-biofilm technology was used to reduce the ammonia-nitrogen concentration and improve the flow state in water was conducted to compare their effects under medium-scale condition using 0.5 t filed water,and the application of those technologies were studied as following.According to the research,main conclusions are found as:The aquatic vegetation is few and total nitrogen concentration of water is under V level in Shishahai Lake and Luoma Lake.Transparency in eastern area of Shishahai was 70 cm,but that in Luoma Lake was only 27 cm.The difference of P concentration may be the reason that the phosphor concentration was 0.042mg/L in Shishahai and 0.36mg/L in Luoma Lake.Therefore,P concentration is the limiting factor of algae growth,which is negative correlation with transparency of water.The depth of Liuyin Lake is only 0.5 m,less than light compensation depth,the photosynthesis of aquatic vegetation is met.Hence,submerged and emerging vegetation both are flourish.However,the depth of Luoma Lake is 1 m,more than light compensation depth,the aquatic vegetation cannot be developed.Therefore,the algae growth can be controlled by aquatic vegetation,and the light intensity under water is the guarantee for aquatic vegetation photosynthesis,and water transparency is the main important factor that affects the light intensity under water.The effect of P removed by natural vermiculite and attapulgite was weak,and their capacity after modification by acid pickling also was low.However,the sorption P capacity of the natural vermiculite and attapulgite after modification increased significantly,and the best condition for calcining modification was burning for 2 hours at 700℃and 500℃.If the P in overlying water was sorbed by vermiculite calcining modification,its pH of the solution increased rapidly.However,the pH increases little for attapulgite. Therefore,using of attapulgite calcining modification is batter than vermiculite as P adsorbent.For instance,the 7g/L of attapulgite calcining modificationthe was added in overlying water with 0.226 mg/L P and pH 8.04 from Qing River.Result showed that about 83.53%P was removed and its P concentration decreased to 0.037mg/L.The concentration of ammonia nitrogen and COD in overlying water decreased little putting biofilm filler under the condition of without plugging flow and aerating, which were decreased largely under the condition of pluging flow and adding biofilm together,and their transparency of overlying water increased from 24 cm to 90 cm.So under the condition of low organic compounds concentration,the effect of transparency enhancing was not obvious by aerating on the base of pluging flow and adding biofilm together.The situation and speed of the overlying water were changed by plugging flow and adding biofilm,and the ammonia nitrogen concentration was reduced,which is maybe the reason that water transparency can be improved.Reducing of ammonia nitrogen concentration in water maybe result in algae bloom limited growth.However, this point needs to be proved in future.The application of plugging flow and adding biofilm technologies indicated that the transparency can be improved obviously under the condition of low nitrogen and phosphorus concentrations in overlying water.For the water body that its depth is 1 m and area is 10000 m~2,500,000 RMB is needed,and the run fee was about 1000 RMB per month.Management was very convenient.As the whole,the attapulgite calcining modification can be utilized to remove P from landscape water,its transparency can be enhanced and P concentration can be reduced.The ammonia nitrogen concentration and situation,flow speed of overlying water all can be improved the by using plugging flow and adding biofilm,the algae growth was limited and its transparency also was increased.更多还原