Nogaj Thomas, Randall Andrew, Jimenez Jose, Takacs Imre, Bott Charles, Miller Mark, Murthy Sudhir, Wett Bernhard
Department of Civil and Environmental Engineering, University of Central Florida, Orlando, FL, USA.
Brown and Caldwell, 850 Trafalgar Court, Suite 300, Maitland, FL, USA E-mail:
Water Sci Technol. 2015;71(7):971-9. doi: 10.2166/wst.2015.051.
This study describes the development of a modified activated sludge model No.1 framework to describe the organic substrate transformation in the high-rate activated sludge (HRAS) process. New process mechanisms for dual soluble substrate utilization, production of extracellular polymeric substances (EPS), absorption of soluble substrate (storage), and adsorption of colloidal substrate were included in the modified model. Data from two HRAS pilot plants were investigated to calibrate and to validate the proposed model for HRAS systems. A subdivision of readily biodegradable soluble substrate into a slow and fast fraction were included to allow accurate description of effluent soluble chemical oxygen demand (COD) in HRAS versus longer solids retention time (SRT) systems. The modified model incorporates production of EPS and storage polymers as part of the aerobic growth transformation process on the soluble substrate and transformation processes for flocculation of colloidal COD to particulate COD. The adsorbed organics are then converted through hydrolysis to the slowly biodegradable soluble fraction. Two soluble substrate models were evaluated during this study, i.e., the dual substrate and the diauxic models. Both models used two state variables for biodegradable soluble substrate (SBf and SBs) and a single biomass population. The A-stage pilot typically removed 63% of the soluble substrate (SB) at an SRT <0.13 d and 79% at SRT of 0.23 d. In comparison, the dual substrate model predicted 58% removal at the lower SRT and 78% at the higher SRT, with the diauxic model predicting 32% and 70% removals, respectively. Overall, the dual substrate model provided better results than the diauxic model and therefore it was adopted during this study. The dual substrate model successfully described the higher effluent soluble COD observed in the HRAS systems due to the partial removal of SBs, which is almost completely removed in higher SRT systems.
本研究描述了一种改进的1号活性污泥模型框架的开发，用于描述高速活性污泥（HRAS）工艺中有机底物的转化。改进后的模型纳入了双溶性底物利用、胞外聚合物（EPS）产生、可溶性底物吸收（储存）和胶体底物吸附的新过程机制。对两个HRAS中试装置的数据进行了研究，以校准和验证所提出的HRAS系统模型。将易生物降解的可溶性底物细分为慢速和快速部分，以便准确描述HRAS系统中与较长固体停留时间（SRT）系统相比的出水可溶性化学需氧量（COD）。改进后的模型将EPS和储存聚合物的产生纳入可溶性底物的好氧生长转化过程以及胶体COD絮凝为颗粒COD的转化过程。吸附的有机物随后通过水解转化为缓慢生物降解的可溶性部分。在本研究中评估了两种可溶性底物模型，即双底物模型和双相生长模型。两种模型都使用两个状态变量来表示可生物降解的可溶性底物（SBf和SBs）以及单一的生物量群体。A阶段中试装置在SRT<0.13 d时通常去除63%的可溶性底物（SB），在SRT为0.23 d时去除79%。相比之下，双底物模型预测在较低SRT时去除率为58%，在较高SRT时为78%，双相生长模型预测的去除率分别为32%和70%。总体而言，双底物模型比双相生长模型提供了更好的结果，因此在本研究中被采用。双底物模型成功地描述了HRAS系统中由于SBs的部分去除而观察到的较高出水可溶性COD，而在较高SRT系统中SBs几乎被完全去除。
