Key Laboratory for Resource Exploitation and Environmental Disaster Control Engineering in Southwest China

Chongqing, China

Key Laboratory for Resource Exploitation and Environmental Disaster Control Engineering in Southwest China

Chongqing, China
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Zhang D.,Chongqing University | Zhang D.,Key Laboratory for Resource Exploitation and Environmental Disaster Control Engineering in Southwest China | Guo L.,Chongqing University | Xu D.,Tianjin Academy of Environmental Science | Chen Y.,Chongqing University
Environmental Engineering Science | Year: 2010

A model designed to couple a sludge-wastewater turbulence model (SWTM) with an activated sludge model 2 (ASM2) through a three-dimensional (3D) advection-dispersion equation (ADE) was developed to simulate 3D pollutant concentration fields in a reactor. SWTM is a hydrodynamic model of 3D two-phase turbulent flow. In this model, the sludge settling velocity (SSV) function was modified by the turbulence effect and coupled to a traditional mixture turbulence model to separate sludge movement from mixture. The coupled SWTM-ASM2 model was then integrated into a simplified wastewater treatment plant (WWTP) modeling system based on a real Carrousel-type WWTP located in Fengdu, Chongqing, China, and calibrated using the dynamic effluent data from this plant. Concentration fields of an oxidation ditch simulated using the coupled SWTM-ASM2 model were then validated by comparison of the measured concentrations in the full-scale oxidation ditch of the WWTP evaluated in this study and found to be satisfactory. According to the simulation results and measured dissolved oxygen (DO) concentrations, the ditch was divided into a nitrification, denitrification, and transition zone. Overall, the results of this study indicate that this novel coupled SWTM-ASM2 model could be used to simulate 3D component distributions in a reactor with a complex hydrodynamic structure and to investigate its treatment process through identification of bioreaction zones. © 2010, Mary Ann Liebert, Inc.


Zhang X.,Chongqing University | Zhang D.,Chongqing University | Zhang D.,Key Laboratory for Resource Exploitation and Environmental Disaster Control Engineering in Southwest China | Lu P.,Chongqing University | And 2 more authors.
Water Science and Technology | Year: 2011

Based on the structure of the hybrid respirometer previously developed in our group, a novel implementation for titrimetry was developed, in which two pH electrodes were installed at the inlet and outlet of the measuring cell. The software capable of digital filtering and titration time delay correction was developed in LabVIEW. The hardware and software of the titrimeter and the respirometer were integrated to construct a novel system of respirometry- titrimetry. The system was applied to monitor a batch nitrification process. The obtained profiles of oxygen uptake rate (OUR) and hydrogen ion production rate (HPR) are consistent with each other and agree with the principle of the biological nitrification reaction. According to the OUR and HPR measurements, the oxidized ammonium concentrations were estimated accurately. Furthermore, the endpoint of ammonium oxidation was identified with much higher sensitivity by the HPR measurement. The system could be potentially used for on-line monitoring of biochemical reactions occurring in any kind of bioreactors because its measuring cell is completely independent of the bioreactor.


Lu P.,Chongqing University | Zhang X.,Chongqing University | Zhang D.,Chongqing University | Zhang D.,Key Laboratory for Resource Exploitation and Environmental Disaster Control Engineering in Southwest China
Water Science and Technology | Year: 2010

The guidelines of Activated Sludge Model (ASM) can make the use of modeling more straightforward and systematical. Therefore, this paper aims to develop a guideline for wastewater COD characterization. Four physical-chemical methods were compared experimentally for wastewater characterization in this paper and flocculation + 0.45 μm membrane filtration combining respirometry was selected to determine soluble inert COD. Simultaneous determination of readily and slowly biodegradable COD through respirometric measurement of raw wastewater was proved feasible. In addition, two methods were evaluated to determine heterotrophic biomass. In light of these investigations, an integrated system for characterizing wastewater COD fractions defined in ASM1 was proposed and then applied to characterize influent COD of a treatment plant. By following this guideline, a detailed and practical COD characterization can be obtained. Moreover, this study could also provide an example for the development of more widely accepted guidelines. © IWA Publishing 2010.


Zhang D.,Chongqing University | Zhang D.,Key Laboratory for Resource Exploitation and Environmental Disaster Control Engineering in Southwest China | Cai Q.,Chongqing University | Zu B.,Chongqing University | And 3 more authors.
Water Science and Technology | Year: 2010

Ammonia oxidizing bacteria-enriched sludge was obtained in a sequencing batch reactor with synthetic wastewater. Batch tests of ammonia oxidation were carried out with the sludge, in the presence of only trace NO2 and in the presence of O2 and trace NO2, respectively. The Andrews model is used to describe NO2-dependent ammonia oxidation. The maximum ammonia oxidation rate of 139.11 mg N·(g sludge COD h) -1, occurred in the presence of 21% O2 and 100 ppm NO 2, which was 3 times higher than the aerobic ammonia oxidation rate without NO2. The kinetic model of ammonia oxidation in the presence of O2 and trace NO2 is developed, and the function of NO2 apparently enhancing ammonia oxidation is suggested. The maximal nitrogen removel of 34.19% occurred at the 21% O2 and 100 ppm NO 2 in the mixed gases. Nitrogen removal principally depended on the denitrification activity and NO2-dependent ammonia oxidation activity of ammonia-oxidizing bacteria (AOB). © IWA Publishing 2010.

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