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Guo J.-H.,Harbin Institute of Technology | Wang S.-Y.,Beijing University of Technology | Zheng Y.-N.,Beijing University of Technology | Peng Y.-Z.,Harbin Institute of Technology | And 3 more authors.
Harbin Gongye Daxue Xuebao/Journal of Harbin Institute of Technology | Year: 2010

The shift of nitrifier population within a partial nitrification reactor was investigated using fluorescence in-situ hybridization (FISH) techniques and the floc morphology was observed using scan electron microscope (SEM). Partial nitrification to nitrite was achieved quickly by using real-time aeration duration control when domestic wastewater was treated in a lab-scale sequencing batch reactor (SBR). The average nitrite accumulation ratio was above 93%. The morphology photographs observed using SEM indicated that the sludge showed a shift towards spherical and small rod-shaped clusters from the diverse morphology. FISH analysis showed that ammonia-oxidizing bacteria (AOB) gradually out-competed nitrite-oxidizing bacteria (NOB). AOB population percentage increased from 3.5% (during the start-up period) to 8.5% (after achieving nitritation for 102 days), while NOB population percentage decreased from 3.1% to less than 0.5%. Accordingly, the long-term operation with the use of real-time aeration duration control was not only favorable for AOB community optimisation, but also for the achievement of partial nitrification in practice. Source

Ye L.,Beijing University of Technology | Wang S.,Beijing University of Technology | Liu Y.,China Water Holdings Pte. Ltd. | Liu Z.,China National Petroleum Corporation | And 2 more authors.
Huagong Xuebao/CIESC Journal | Year: 2010

In order to find out the reason of the filamentous sludge bulking in salt-tolerant sludge during saline wastewater treatment, a lab-scale nutrient removal activated sludge system, based on the modified MUCT configuration, was used to identify the occurrence process of filamentous sludge bulking. The sludge was acclimated for a long period at 10 g·L-1 salinity in the MUCT process and was observed to have plenty of filamentous organisms under low dissolved oxygen concentration condition. Different operation strategies were used to control the filamentous sludge bulking. The pollutants removal efficiencies during each control periods were compared as well. The results indicated that filamentous sludge bulking in salt-tolerant sludge occurred at a low DO concentration. Increased salinity inhibited sludge bulking quickly and efficiently. Limited filamentous sludge bulking could be maintained for a long time when ρ(DO2) was controlled at 1.0 mg·L-1 and ρ(DO1) was controlled at 2.0 mg·L-1. The value of sludge volume index (SVI) varied between 190 ml·g-1 and 210 ml·g-1. During this period, the effluent turbidity decreased significantly due to the filtering effect of filamentous bacteria. It could be an option to solve the turbidity problem of saline wastewater treatment. © All Rights Reserved. Source

Peng Y.-Z.,Beijing University of Technology | Wang L.,Beijing University of Technology | Ma J.,Beijing University of Technology | Wang S.-P.,Beijing University of Technology | And 2 more authors.
Beijing Gongye Daxue Xuebao/Journal of Beijing University of Technology | Year: 2012

This study investigates the effects of continuous-feeding and step-feeding patterns on the nitrogen removal performance and the aeration rate under the anoxic/aerobic(A/O) condition of cyclic activated sludge technology (CAST) process treating low ρ COD/ρ TN wastewater, and analyzes the profiles of pH, DO and ORP under the step-feed mode. Results show that the average removal rate of ρ TN is 75.1% and SVI is 229 mL/g when the system runs under the continuous feeding mode, and activated sludge bulking occurs because of the operation under long-term condition of a low influent load. However, the average removal rate of ρ TN increases to 81.5% and the average SVI decreases when the system runs under the step-feeding mode. Meanwhile, the aeration rate of the continuous-feeding mode is 0.56 m 3/h but 0.24 m 3/h under the step-feeding mode when the removal rate of ρ(NH 4 +-N) is above 99%. Consequently, the operation cost can be significantly reduced by using the step-feeding mode. Furthermore, pH, DO, ORP curves have an observe variation during a cycle under the step-feed, which also have a better correlation with the variation of contamination in the system. Source

Peng Z.-X.,Harbin Institute of Technology | Peng Y.-Z.,Harbin Institute of Technology | Peng Y.-Z.,Beijing Institute of Technology | Wang S.-Y.,Beijing Institute of Technology | And 3 more authors.
Beijing Gongye Daxue Xuebao/Journal of Beijing University of Technology | Year: 2011

Inhibiting filamentous sludge bulking by using reagent is expensive and easy to recurrence after reagent is stopped adding. In order to solve this problem. This experiment investigate the feasibility of inhibiting filamentous sludge bulking through adjusting process parameters alone by using SBR. The inhibition effect of organic loading rate, dissolved oxygen (DO), feeding pattern and some other common operation parameters on filamentous sludge bulking were investigated systematically. The results show that, it is difficult to inhibit filamentous sludge bulking through increasing organic loading rate alone (>0.40 d-1). However, if aerobic time and aeration rate are not set up properly, viscosity sludge bulking is prone to happen; The effect of inhibiting filamentous sludge bulking through increasing ρDO (4-6 mg/L) alone is not obvious, meanwhile, excessive aeration could make negative impact on phosphorus removal performance; Although impulse feeding pattern could enhance storage selective function, It makes little effect on inhibiting filamentous sludge bulking; setting up proposed anoxic(anaerobic) phase is an effective method to inhibit filamentous sludge bulking. Source

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