ASM simulation optimization and practical application on upgrading of urban sewage treatment plant in cold region
LIU Mengmeng1,2,3,, CHEN Meixue1,2, QI Rong1,2, WEI Yuansong1,2,3,,, DU Haizhou4, HU Yanming4, ZHANG Xin5 1.State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China 2.Department of Water Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China 3.University of Chinese Academy of Sciences, Beijing 100049, China 4.Zhangjiakou Xishan Wastewater Treatment Co. Ltd., Zhangjiakou 076250, China 5.Zhangjiakou Wanquan Sewage Purification Research Center, Zhangjiakou 076250, China
Abstract:In order to guide and support the upgrading of the sewage plant in cold region, the upgrading model for CASS process in a sewage treatment plant of Hebei province was constructed by using the ASM1 model with GPS-X software. In this study, the sludge reflux ratio (RS), the reaction volume ratio (RV), the decant ratio (λ), the operating cycle time (T) and CASS operation strategy at different water temperatures were numerically simulated and optimized. Based on simulation results, the optimal operation strategy for upgrading this sewage plant was provided and put into practice. Results of the CASS performance in the winter clearly showed that the effluent COD, ${\rm{NH}}_4^ + $-N and TN concentrations of the modified CASS process were (23.23±2.76), (1.16±0.76), (9.83±1.4) mg·L?1, respectively, and stably met with requirements of the first grade A discharge standard of the Discharge standard of pollutants for municipal wastewater treatment plant (GB 18918-2002). Key words:cyclic activated sludge system/ activated sludge model/ wastewater treatment plant/ upgrading and rebuilding/ low temperature.
图1污水厂CASS工艺流程及模拟示意图 Figure1.Flow and simulation diagram of CASS process
图3回流比、体积比对出水COD, ${\bf{NH}}_4^ + $-N和TN的影响 Figure3.Effect of sludge reflux ratio and reaction zone volume ratio on the COD, ${\rm{NH}}_4^ + $-N and TN in effluent
WU X, YANG Y, WU G, et al. Simulation and optimization of a coking wastewater biological treatment process by activated sludge models (ASM)[J]. Journal of Environmental Management, 2016, 165(4): 235-242.
[8]
FENU A, GUGLIELMI G, JIMENEZ J, et al. Activated sludge model (ASM) based modelling of membrane bioreactor (MBR) processes: A critical review with special regard to MBR specificities[J]. Water Research, 2010, 44(15): 4272-4294. doi: 10.1016/j.watres.2010.06.007
[9]
KIM H, LIM H, WIE J, et al. Optimization of modified ABA2 process using linearized ASM2 for saving aeration energy[J]. Chemical Engineering Journal, 2014, 251(5): 337-342.
GIROU é, SPANJERS H, PATRY G, et al. Dynamic modelling for operational design of a respirometer[J]. Water Science & Technology, 1996, 33(1): 297-309.
[16]
KARLIKANOVAITE-BALIKCI A, YAGCI N. Determination and evaluation of kinetic parameters of activated sludge biomass from a sludge reduction system treating real sewage by respirometry testing[J]. Journal of Environmental Management, 2019, 240: 303-310.
1.State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China 2.Department of Water Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China 3.University of Chinese Academy of Sciences, Beijing 100049, China 4.Zhangjiakou Xishan Wastewater Treatment Co. Ltd., Zhangjiakou 076250, China 5.Zhangjiakou Wanquan Sewage Purification Research Center, Zhangjiakou 076250, China Received Date: 2019-06-14 Accepted Date: 2019-08-20 Available Online: 2020-05-06 Keywords:cyclic activated sludge system/ activated sludge model/ wastewater treatment plant/ upgrading and rebuilding/ low temperature Abstract:In order to guide and support the upgrading of the sewage plant in cold region, the upgrading model for CASS process in a sewage treatment plant of Hebei province was constructed by using the ASM1 model with GPS-X software. In this study, the sludge reflux ratio (RS), the reaction volume ratio (RV), the decant ratio (λ), the operating cycle time (T) and CASS operation strategy at different water temperatures were numerically simulated and optimized. Based on simulation results, the optimal operation strategy for upgrading this sewage plant was provided and put into practice. Results of the CASS performance in the winter clearly showed that the effluent COD, ${\rm{NH}}_4^ + $-N and TN concentrations of the modified CASS process were (23.23±2.76), (1.16±0.76), (9.83±1.4) mg·L?1, respectively, and stably met with requirements of the first grade A discharge standard of the Discharge standard of pollutants for municipal wastewater treatment plant (GB 18918-2002).
2)模型设置。工艺模型主要由进水流、水流分离器、缺氧池、SBR池、水流汇合器及出水排放单元组成。GPS-X软件可按照用户自身需求对SBR池的每阶段运行时间(进水、混合、曝气、沉淀、滗水、排泥、回流等)、回流量、排泥量等进行设置。在研究中，回流阶段可作为独立阶段，也可与其他运行阶段同时进行。出水方式采用顶部滗水。 3)模型选择与校正。以国际水协会(International Water Association, IWA)的活性污泥1号模型(ASM1)作为工艺模拟的数学模型(只关注除碳和脱氮)。确定模拟分析所要求的数据，主要包括池容、污水流量、泥龄、温度、污水进水组分数据等。通过呼吸速率方法[15-16]测定进水水质组分(见表2)，该厂进水COD组分质量分数如下：溶解性可生物降解有机物SS为8.80%，溶解性不可生物降解SI为8.50%，颗粒性可生物降解有机物XS为59.25%，颗粒性不可生物降解有机物XI为15.99%，异养微生物XH为7.47%。
综合图3模拟结果来看，根据污水厂现有的缺氧区/好氧区体积比条件(RV=12.8%)，使回流比增加到200%，仍然不能满足出水TN一级A排放标准。因此，须针对当前情况，对其充水比和运行周期进行模拟优化。 2)充水比对处理效果的影响。充水比(λ)是影响CASS工艺处理效果的重要因素，它直接影响CASS工艺的抗冲击负荷能力[19-20]。在CASS工艺周期性地不断进出水过程中，每个周期未处理进水被池内处理后剩余污水所稀释，理论上，λ越大，稀释作用越小，水力负荷越大，更易引起出水水质不稳定；λ越小，稀释作用越大，水力负荷越小，出水水质越稳定。但是，较低的λ会降低CASS池的体积利用率，导致处理规模下降和运行成本提高[17]。因此，针对CASS池充水高度分别为0.5、1.0、1.25、1.5和2.0 m 5种情况，设定RS为200%，RV为12.8%的条件，以表3所示的运行周期进行模拟，探究了影响污染物削减的最佳充水比。如图4所示，随着λ的增加，进入系统内的COD总量有所提升，水力负荷增大，导致COD更难被去除；另一方面，λ增大，可导致进入系统内的水量增大，CASS工艺对水质水量的调节能力变差。在几种充水比条件下，氨氮浓度基本上都能满足出水排放标准，并且较小的λ更有利于硝化反应的进行；对总氮而言，随着λ的增加，出水总氮浓度升高，系统去除能力变弱。主要原因在于，较小的充水比可增加污水在池内的停留时间，进而增强反硝化效果。但在5种充水比条件下，出水总氮均未达到一级A排放标准。因此，须对当前运行周期进行优化，以调整反硝化和硝化时间，使污染物达标排放。
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