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Numerical simulation of a horizontal sedimentation tank considering
sludge recirculation 总被引:1,自引:0,他引:1
Most research conducted on the concentration distribution of sediment in the sedimentation tank does not consider the role of the
suction dredge. To analyze concentration distribution more accurately, a suspended sediment transportation model was constructed and
the velocity field in the sedimentation tank was determined based on the influence of the suction dredge. An application model was then
used to analyze the concentration distribution in the sedimentation tank when the suction dredge was fixed, with results showing that
distribution was in accordance with theoretical analysis. The simulated value of the outlet concentration was similar to the experimental
value, and the trends of the isoconcentration distribution curves, as well as the vertical distribution curves of the five monitoring sections
acquired through simulations, were almost the same as curves acquired through experimentation. The di erences between the simulated
values and the experimental values were significant. 相似文献
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Taking the distributing calculation of velocity and concentration as an example,the paper established a series of governing equations by the vorticity-stream function method, and dispersed the equations by the finite differencing method.After figuring out the distribution field of velocity, the paper also calculated the concentration distribution in sedimentation tank by using using the two-dimensional concentration transport equation.The validity and feasibility of the numerical method was verified through comparing with experimental data.Furthermore,the paper carried out a tentative exploration into the application of numerical simulation of sedimentation tanks. 相似文献
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IntroductionInwatertreatmenttechnology ,themostcommonlyusedmethodofsolidliquidseparationisgravitationalsedimentation .Fromstatistics,onequarterofthetotalinvestmentofthewastewatertreatmentplantisusedforsedimentationtanks (Swamee ,1 996) .Withthedevelopmentofc… 相似文献
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With the development of activated sludge model, the simulation software for the design and operation of wastewater treatment plant (WWTP) was produced and has been widely used. The dynamic change of the quality and flow of influent are major factors causing the unstable operation of wastewater treatment process. As a basic model, ASMI model was used for the simulation of activated sludge process, and double exponential model was selected for the simulation of secondary sedimentation tank. The influences of influent change to the aeration tank and secondary sedimentation tank were investigated, and the relationship among influent change, the quality of effluent and the level of sludge blanket in secondary sedimentation tank was established. On the basis of the simulation results, the operation of the WWTP could be adjusted under the dynamic change of the influent. Furthermore, the controlling strategy combined the feed-forward on the influent flow and the feedback on the level of sludge blanket in the secondary sedimentation tank was studied. 相似文献
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正方形沉淀池内部水流运动模拟及设计应用 总被引:1,自引:1,他引:0
针对江苏新纪元环保有限公司自主研发的上下全截面正方形沉淀澄清池进行水流运动模拟及分析。正方形沉淀澄清池的水力特性对其沉淀效果有很大影响,在沉淀池水力设计中应通过对池型以及各种几何参数的优化,使其池内回流区范围尽可能减小,并且尽量使池内垂直断面上流速均匀平稳,研究中主要利用模型模拟正方形沉淀澄清池在不同进水流速和不同挡板布置形式下的水流流场,经过分析比较出较为合理的沉淀池运行工况以及较为合适的挡板布置形式,进而提高沉淀池的运行效率。 相似文献
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斜管沉淀池是指在沉淀区内设有斜管的沉淀池。在平流式或竖流式沉淀池的沉淀区内利用倾斜的平行管或平行管道分割成一系列浅层沉淀层,被处理的和沉降的沉泥在各沉淀浅层中相互运动并分离。根据其相互运动方向分为逆(异)向流、同向流和逆向流三种不同分离方式。每两块平行斜板间相当于一个很浅的沉淀池。辐流式沉淀池半桥式周边传动刮泥活性污泥法处理污水工艺过程中沉淀池的理想配套设备适用于一沉池或二沉池,主要功能是为去除沉淀池中沉淀的污泥以及水面表层的漂浮物。一般适用于大中池径沉淀池。辐流式沉淀池采用机械排泥,运行较好,设备较简单,排泥设备已有定型产品,沉淀性效果好,日处理量大,对水体搅动小,有利于悬浮物的去除。本研究通过掌握斜管沉淀池的构造功能及沉淀原理、通过改变运行因素来验证斜管沉淀池的处理效率。 相似文献
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有关斜管沉淀池的上升流速讨论 总被引:1,自引:0,他引:1
文章从理论上了分析斜管沉淀池上升流速对沉淀池处理效果的影响,及原水特性与斜管沉淀池上升流速取值的关系。讨论分析斜管沉淀池设计时,应根据原水特性不同选择不同的斜管沉淀池上升流速。 相似文献
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作者认为,高浓度泥水沉淀(浓缩)池的模型律,应建立在以下过程相似的基础上:(1)池内浑水异重流发生相似;(2)池内泥水的沉淀浓缩过程相似。文中讨论了原泥水或配制泥水进行试验、试验为正常负荷或超负荷、采用正态模型或变态模型等各种情况下的模型律以及不能满足相似条件的情况。文中介绍了在两个几何相似的模型中对模型律进行试验检验的结果。 相似文献
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某城市污水A~2/O处理过程中重金属去除率分析 总被引:1,自引:0,他引:1
以A2/O法污水处理厂的城市污水实际处理过程中重金属的变化为研究对象,分析了六种重金属(Cu、Zn、Pb、Cd、Cr、Hg)在处理过程中的去除率。研究结果表明:A2/O法对城市污水中重金属总的去除率是比较高的,都在78%以上,但在处理过程中受其存在状态、污水pH和本身的沉降、吸附、交换性质的影响,各种金属去除率并不完全相同的,总的去除率的大小顺序是:Zn>Hg>Cu>Cr>Cd>Pb。一级处理由于在同一pH、Eh下,不同的重金属以颗粒态和胶体存在的量不同,由高到低的顺序是:Cr>Cu>Zn>Hg>Pb>Cd。不同的金属离子与其配位基团的配位能力、离子交换能力和吸附能力不同,生化处理去除效果不同。从设计处理能力和重金属监测结果来看:一级处理水的主要控制项目多数达不到《城镇污水处理厂污染物排放标准》GB18918-2002的要求,应加大二级处理和深度处理能力,减轻陆源污染物对海域的污染负荷,提高中水的回用率。 相似文献
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以长沙市某污水处理厂二沉池为例,采用多相流混合物模型与k-ε湍流模型结合对辐流式二沉池内速度场和污泥浓度场进行了数值模拟.以出水口悬浮物浓度(SS)为响应目标,对影响二沉池沉淀效果的3个影响因素(进水口流速、颗粒污泥粒径、挡板的淹没深度)进行中心复合设计(central composite design,CCD),并经响应表面法分析得到影响出水SS的二次回归模型,确定了二沉池沉降的最佳条件:进水口流速为0.03m·s-1,颗粒污泥粒径为220.41μm,挡板的淹没深度为3.45m,采用数值仿真模拟实验得到出水口悬浮物浓度值为2.4mg·L-1,较优化之前的仿真结果一周平均值6.7mg·L-1相比,其处理效率提高了64.2%.采用数值仿真和响应表面法结合对二沉池工艺条件进行优化研究,可以加速寻优过程,是工艺优化的辅助工具. 相似文献
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城市污水处理厂污水处理工艺对VOCs挥发特征影响 总被引:1,自引:0,他引:1
对广州市某污水处理厂入厂原水进行了现场水样采集,用吹扫捕集-气相色谱质谱法测定了水样中VOCs含量.在污水处理厂入水口中共检出20种VOCs,浓度范围为0.1789~21.89μg/L.基于实测数据和构筑物结构参数,对该厂4种不同的污水处理工艺流程(包括A-B工艺,UNITANK工艺,改良A2/O脱氮除磷工艺和改良A2/O 高效沉淀工艺)利用WATER9模型计算了各工艺主要构筑物VOCs的挥发速率和挥发总量.挥发速率最大工艺为A-B工艺,其值为0.2318g/s;构筑物加盖的改良A2/O高效沉淀工艺挥发速率最小为0.0426g/s.各个工艺中挥发速率最大的单元有生物处理池和沉淀池,主要成分有苯、甲苯、三氯甲烷、四氯乙烯.根据VOCs挥发速率和污水处理量计算了VOCs在构筑物加盖和不加盖情况下的排放因子,并估算了珠江三角洲地区污水处理厂VOCs的总排放量,发现构筑物加盖可大大减少城市污水处理厂的排放率,削减率可达到74.72%. 相似文献
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MBR处理微污染河水试验 总被引:1,自引:0,他引:1
采用絮凝沉淀+缺氧/膜生物反应器(Anoxic/Membrane Bioreactor,A/MBR)工艺对劣Ⅴ类微污染河水的处理进行了中试研究,探讨了该工艺对低碳高氮磷河水处理效果的保证措施. 结果表明:系统处理规模为10 m3/d,在曝气量为8 m3/h,平流沉淀池、缺氧池和膜池水力停留时间分别为25 min,0.8 h和2.5 h,污泥ρ(MLSS)为6.0~6.5 g/L的运行条件下,向缺氧池投加约为理论量2倍的甲醇,在平流沉淀池与膜池分别投加10和5 mg/L的聚合氯化铝(PAC),出水ρ(CODCr),ρ(BOD5),ρ(NH3-N)和ρ(TP)达到《地表水环境质量标准》(GB3838—2002)Ⅲ类水体标准,ρ(TN)<15 mg/L. 相似文献
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