[Performance and Microbial Characteristics of Ammonium-limited and Nitrite-limited ANAMMOX Systems].

The performance and microbial characteristics of ammonium-limited and nitrite-limited ANAMMOX reactors were studied in two continuously stirred tank reactors. The influent TN concentrations were controlled below 50 mg·L. The hydraulic retention time and water temperature were maintained at 2.

[Start-up and Optimization of Denitrifying Phosphorus Removal in ABR-MBR Coupling Process].

The feasibility of the denitrifying phosphorus removal process in the ABR-MBR system with no sludge reflux and high concentration of seeding activated sludge (25 g ·L, in MLSS) in the ABR was investigated. The characteristics of the microbial community in the denitrifying phosphorus removal compartment were also evaluated. The denitrifying phosphorus removal function was achieved by gradually increasing the reflux ratio () from 0% to 200%.

[Characteristics of ANAMMOX Granular Sludge and Differences in Microbial Community Structure Under Different Culture Conditions].

Anaerobic ammonium oxidation (ANAMMOX) granular sludge was cultured during different operating conditions by an expanded granular sludge bed (EGSB) reactor and up-flow anaerobic sludge bed (UASB) reactors, and the characteristics of the granular sludge and microbial community were compared. The results showed that the flocculent ANAMMOX sludge can be granulated after being operated for 384 days by the EGSB and UASB reactors. The average particle size reached 1.

[Characteristics of Organics Transformation and Sludge Morphology in an ABR for Sewage Treatment with Different HRTs].

The characteristics of organics transformation and sludge morphology of in an ABR(anaerobic baffled reactor) for sewage treatment with different HRTs were investigated based on reactor performance, particle size distribution, and scanning electron microscopy (SEM). Results showed that the COD removal rate was stably maintained above 90.0% when the HRT decreased from 15 h to 4 h.

[Realization Process of Nitritation and Changes in Sludge Characteristics in Granular Sludge Reactor for Low Strength Sewage Treatment].

The realization process of nitritation was studied in a CSTR reactor seeding with nitrification granular sludge to treat low ammonia sewage. During the operation period, the physical and chemical properties, the spatial distribution of functional microbes, and the activity of the granular sludge were also investigated to elaborate the main factors for the stability of nitritation. The results showed that nitritation can be successfully achieved and maintained by the cooperative controlling of nitrogen loading rate (NLR) and dissolved oxygen (DO) levels, and the nitrite accumulation rate was over 80%.

[Rapid Achievement of Nitrifying Micro-granular Sludge and Its Nitritation Function].

The rapid achievement of nitrifying micro-granular sludge and its nitritation function was studied in a continuously operated internal-loop airlift reactor seeding with floccular sludge. Results showed that the sludge micro-granulation was almost realized within three weeks by gradually reducing the hydraulic retention time from 5 h to 2.5 h.

[Process Control and Operation Optimization of PN-SAD Coupling Process Based on SBR-ABR].

This study uses three different operating phases for a sequencing batch reactor (SBR) combined with an anaerobic baffled reactor (ABR) to determine the effect of deep nitrogen and carbon removal by the "partial nitrification-anaerobic ammonium oxidation combined denitrification" (termed PN-SAD) reaction. The effluent of the SBR (NO-N/NH-N ratio range of 1-1.32) was accessed directly to the single compartment ABR anammox system in phase Ⅰ.

[Start-up of a Three-stage PN/A Granular Sludge Reactor for Treating Wastewater with High Concentrations of Ammonia].

In order to apply partial nitritation-ANAMMOX (PN/A) technology to treat wastewater with high concentrations of ammonia, autotrophic nitrogen-removing granular sludge was crushed and inoculated into a three-stage continuous flow reactor. The nitrogen loading rate (NLR), dissolved oxygen (DO) concentration, and free ammonia (FA) levels in each compartment of the reactor were controlled over a 106-day period. Results showed that the nitritation process occurred with the inoculated granules during the initial phase.

[Start-up Performance and Sludge Characteristics of Single-stage Autotrophic Nitrogen Removal System with Granular Sludge at Low Ammonia Nitrogen Concentration at Room Temperature].

The start-up and stable operation of single-stage autotrophic nitrogen removal process under low ammonia nitrogen substrate at room temperature appears as the premise and basis for the application in municipal wastewater treatment. In this study, the PN/A (partial nitritation and ANAMMOX) granular sludge for long-term storage was inoculated into an air-lift bioreactor to investigate the nitrogen removal performance during the start-up of single-stage partial nitritation and ANAMMOX process under the following conditions:temperature at (23±2)℃, pH at 7.7-8.

[Effect of Sludge Retention Time and pH on the Denitrifying Phosphorus Removal Process].

In this work, the effects of the sludge retention time (SRT, 35, 25, or 15 d) and pH (7.5, 8.0, 8.

[High-rate Nitrogen Removal in a Two-stage Partial Nitritation-ANAMMOX Process Under Mainstream Conditions].

A two-stage partial nitritation (PN)-ANAMMOX process was successfully carried out for low-strength NH-N (50 mg·L) wastewater treatment at ambient/low temperatures. The results show that an average total nitrogen removal rate and removal efficiency above 0.6 kg·(m·d)and 80% could be maintained, respectively, at temperatures between 20℃ and 14℃.

[Removal of Humic Acid from Water by Magnetic Chitosan-Grafted Polyacrylamide].

For high-efficiency removal of humic acid (HA), a natural organic matter in the water source, an adsorbent named magnetically modified chitosan-grafted polyacrylamide (MC-g-PAM) was developed by using an coprecipitation method. Analytical instruments, such as a Fourier transform infrared (FTIR) spectroscope, scanning electron microscope (SEM), vibrating sample magnetometer (VSM), and specific surface area tester (BET), were used to characterize and analyze this material. With the aid of batch tests, the removal efficiency and mechanism of humic acid in water samples were investigated.

[Effect of C/N and Sludge Concentration on the pH-Regulated Nitrosation System].

pH is one of the most important means of control for the realization and stability of the nitrosation system. To study the change rule of pH values of the nitrosation system and the influence of pollution removal and transformation at different pH under the conditions of different C/N (0, 1, 2, 3,4) and sludge concentrations (sludge amount:water content was 1:6, 1:3, 1:1), batch tests were conducted with tapered bottles using sodium acetate as the carbon source and inoculated with mature nitrosation sludge. The results showed that the higher the C/N, the higher the pH increment and the denitrification efficiency at the same sludge concentration.

[Carbon and Nitrogen Removal Characteristics of ABR Decarbonization-CANON Coupling Process].

If municipal wastewater can be treated by the completely autotrophic nitrogen removal over nitrite (CANON) process, it will greatly reduce the energy consumption of municipal wastewater treatment. The CANON reactor with a fiber carrier was started up by seeding nitrosation sludge and anaerobic ammonia oxidation (ANAMMOX) sludge in the continuously stirred tank reactor (CSTR). An ABR decarbonization system was added to the front of the CANON system to build the ABR decarbonization-CANON coupling process to examine carbon and nitrogen removal characteristics of the whole system.

[Start-up and Stable Operation of ABR-MBR Denitrifying Phosphorus Removal Process].

The nitrogen and phosphorus removal characteristics during the start-up and the long-term operational stability of an anaerobic/anoxic (A/A) ABR coupled aerobic MBR system treating low C/N domestic wastewater were investigated. The results showed that the denitrifying phosphorus bacteria (DPBs) were successfully enriched within 46 d by controlling the nitrate recycling ratio (increasing from 150% to 300%), with a temperature of 30℃±2℃, volume loading rate of 0.8 kg·(m·d) and sludge reflux ratio of 80% in the ABR, sludge retention time (SRT) in the denitrifying phosphorus removal functional area of 25 d, and the dissolved oxygen (DO) of 1-2 mg·L in the MBR.

[Microbial Community Characteristics of Shortcut Nitrification Start-up in Different MBR-Inoculated Sludges].

In order to clarify the microbial community characteristics of the shortcut nitrification start-up with different inoculated sludges in the membrane bioreactor (MBR), the MBR was inoculated with nitrification sludge (R1), anaerobic nitrification sludge (R2) and 1:1 mixed inoculated anaerobic nitrification and denitrification sludge (R3). The results showed that the combination of intermittent aeration and shortened hydraulic retention time (HRT) successfully achieved the shortcut nitrification by R1, R2 and R3 reactors after 46 d, 8 d and 30 d respectively, with the R2 reactor exhibiting the shortest start-up period. During stable operations, the average nitrite accumulation rates of R1, R2 and R3 reactors were 92%, 93% and 94% respectively, and the R3 reactor showed a more stable shortcut nitrification.

[Effects of Nanoscale Zero-valent Iron (nZVI) on Denitrifying Performance of an Upflow Granular Sludge Bed Reactor].

In order to examine the effects of nanoscale zero-valent iron (nZVI) on the performance of denitrifying granular sludge (DGS) in a continuous flow model, the variations of nitrogen removal efficiency in the reactor, sludge morphology, and denitrifying characteristics at different influent nZVI concentrations were investigated in an upflow sludge bed (USB). The results showed that nZVI concentrations lower than 5 mg·L did not influence the nitrogen removal performance of the reactor significantly, and the activity of DGS was improved slightly. When the influent nZVI concentration was in the range of 5 to 10 mg·L, the DGS could adapt to the biological inhibition of nZVI partially, with the increase of sludge concentration and grain size.

[Effect of Volume Loading Rate (VLR) on Denitrifying Phosphorus Removal by the ABR-MBR Process].

The effect of volume loading rate (VLR) on denitrifying phosphorus removal was investigated in a continuous-flow ABR-MBR combined process treating domestic wastewater to arrive at optimum process parameters. In the experiment, the VLR of the ABR was set at 0.76, 1.

[Effect of NO-N Recycling Ratio on Denitrifying Phosphorus Removal Efficiency in the ABR-MBR Combined Process].

Based on the coupling of the ABR process and the MBR process, a novel combined ABR-MBR process, including biophase separation, liquid circulation, and functional linkage, was developed to achieve simultaneous carbon, nutrient, and phosphorus removal when treating domestic wastewater with low carbon/nitrogen ratio and to obtain the best combination of ABR, providing a quality carbon source, and MBR, achieving shortcut nitrification by optimizing hydraulic retention time (HRT). The influence of NO-N recycling ratio on nitrogen and phosphorus removal was investigated at NO-N recycling ratios of 100%, 200%, 300%, and 400%, respectively. The experimental results under different conditions showed that the efficiency of denitrifying phosphorus removal in the ABR was found to increase with increasing NO-N recycling ratio from 100% to 300% but decreased when the NO-N recycling ratio was 400%.

[Start-up of a High Performance Nitrosation Reactor Through Continuous Growth of Aerobic Granular Sludge].

In order to examine the continuous growth capacity of the nitrosation granular sludge (NGS), the sludge was inoculated to start up the columnar sequencing batch reactor (SBR). During 130 d, the concentration of mixed liquor suspended solids (MLSS) in SBR increased from 0.1 g·L to 11.

[Effects of Influent C/N Ratios on Denitrifying Phosphorus Removal Performance Based on ABR-MBR Combined Process].

An ABR-MBR integrated reactor based on a combination of the anaerobic baffled reactor (ABR) with the microbial phase separation and membrane bioreactor (MBR) with high-effect entrapment was constructed and the circulation and interactivity of the combined process were examined by adding nitrate recycling and sludge reflux. By increasing the influent COD to adjust the COD/TN ratio, the influence of the mechanism on the denitrifying phosphorus removal performance under the condition of continuous-flow was investigated. The results showed that the average effluent concentration of soluble phosphorus under different influent C/N conditions were 0.

[Quick Start-up Performance of Combined ANAMMOX Reactor Based on Different Inoculated Sludge Types].

In order to determine the optimal sludge source of anaerobic ammonium oxidation (ANAMMOX) and the rapid formation of ANAMMOX granular sludge, two CAMBRs (combined ABR and MBR) were compared for ANAMMOX enrichment with different inoculated sludge types, the anaerobic granular sludge (R1) and flocculent denitrifying sludge (R2). The results showed that ANAMMOX was successfully initiated after 45 d (R1) and 60 d (R2) in both reactors, respectively. The enrichment processes are divided into three different phases, lag phase, activity elevation phase, and stationary phase but the removal rules of nitrogen in each phase were different.

[Fast Start-up of Shortcut Nitrification in a CSTR and an MBR].

In order to achieve fast start-up of shortcut nitrification, a continuous stirred tank reactor (CSTR) and a membrane bioreactor (MBR) were selected for a comparative study about the start-up characteristic of shortcut nitrification. The differences in three aspects of the two reactors were investigated, namely start-up time, nitrogen transformation, and sludge performance. The results showed that the start-up of shortcut nitrification was successfully achieved in the CSTR and MBR after 44 and 56 days of operation, respectively, with influent C/N=1, temperature around 30℃±1℃, pH of 7.

[Start-up and Characteristics of the Microbial Community Structure of ANAMMOX].

An anaerobic ammonium oxidation (ANAMMOX) reactor was successfully started up in 17 days, with the up-flow anaerobic sludge blanket (UASB) reactor being seeded with mixed anaerobic sludge from laboratory cultures with an ANAMMOX function and aerobic activated sludge from a municipal sewage treatment plant in a volume ratio of 1:2. The processes could be divided into two phases of hydrolysis, enhanced and steady. Anaerobic ammonium oxidation bacteria (AAOB) were enriched by improving the reactor volume load gradually after the steady phase.