Yu-Xia Song

The Increasing Interest of ANAMMOX Research in China: Bacteria, Process Development, and Application

Nitrogen pollution created severe environmental problems and increasingly has become an important issue in China. Since the first discovery of ANAMMOX in the early 1990s, this related technology has become a promising as well as sustainable bioprocess for treating strong nitrogenous wastewater. Many Chinese research groups have concentrated their efforts on the ANAMMOX research including bacteria, process development, and application during the past 20 years. A series of new and outstanding outcomes including the discovery of new ANAMMOX bacterial species (Brocadia sinica), sulfate-dependent ANAMMOX bacteria (Anammoxoglobus sulfate and Bacillus benzoevorans), and the highest nitrogen removal performance (74.3–76.7 kg-N/m3/d) in lab scale granule-based UASB reactors around the world were achieved. The characteristics, structure, packing pattern and floatation mechanism of the high-rate ANAMMOX granules in ANAMMOX reactors were also carefully illustrated by native researchers. Nowadays, some pilot and full-scale ANAMMOX reactors were constructed to treat different types of ammonium-rich wastewater including monosodium glutamate wastewater, pharmaceutical wastewater, and leachate. The prime objective of the present review is to elucidate the ongoing ANAMMOX research in China from lab scale to full scale applications, comparative analysis, and evaluation of significant findings and to set a design to usher ANAMMOX research in culmination.

Partial nitrification in an air-lift reactor with long-term feeding of increasing ammonium concentrations

The partial nitrification (PN) performance under high ammonium concentrations was evaluated in an airlift reactor (ALR). The ALR was operated for 253days with stepwise elevation of ammonium concentration to 1400mg/L corresponding nitrogen loading rate of 2.1kg/m(3)/d. The ammonium removal rate was finally developed to 2.0kg/m(3)/d with average removal efficiency above 91% and nitrite accumulation percentage of 80%. Results showed that the combined effect of limited DO, high bicarbonate, pH and free ammonia (FA) contributed to the stable nitrite accumulation substantially. The biomass in the ALR was improved with the inception of granulation. Precipitates on biomass surface was unexpectedly experienced which might improve the settleability of PN biomass. Organic functional groups attached to the PN biomass suggested the possible absorbability to different types of pollutant. The results provided important evidence for the possibility of applying an ALR to treat high strength ammonium wastewater.

Start-up characteristics of a granule-based anammox UASB reactor seeded with anaerobic granular sludge.

The granulation of anammox sludge plays an important role in the high nitrogen removal performance of the anammox reactor. In this study, anaerobic granular sludge was selected as the seeding sludge to start up anammox reactor in order to directly obtain anammox granules. Results showed that the anammox UASB reactor was successfully started up by inoculating anaerobic granular sludge, with substrate capacity of 4435.2 mg/(L·d) and average ammonium and nitrite removal efficiency of 90.36% and 93.29%, respectively. During the start-up course, the granular sludge initially disintegrated and then reaggregated and turned red, suggesting the high anammox performance. Zn-Fe precipitation was observed on the surface of granules during the operation by SEM-EDS, which would impose inhibition to the anammox activity of the granules. Accordingly, it is suggested to relatively reduce the trace metals concentrations, of Fe and Zn in the conventional medium. The findings of this study are expected to be used for a shorter start-up and more stable operation of anammox system.

Study on the mechanism of copper–ammonia complex decomposition in struvite formation process and enhanced ammonia and copper removal

Heavy metals and ammonia are difficult to remove from wastewater, as they easily combine into refractory complexes. The struvite formation method (SFM) was applied for the complex decomposition and simultaneous removal of heavy metal and ammonia. The results indicated that ammonia deprivation by SFM was the key factor leading to the decomposition of the copper-ammonia complex ion. Ammonia was separated from solution as crystalline struvite, and the copper mainly co-precipitated as copper hydroxide together with struvite. Hydrogen bonding and electrostatic attraction were considered to be the main surface interactions between struvite and copper hydroxide. Hydrogen bonding was concluded to be the key factor leading to the co-precipitation. In addition, incorporation of copper ions into the struvite crystal also occurred during the treatment process.

Two-sectional struvite formation process for enhanced treatment of copper–ammonia complex wastewater

Abstract Mg2+ and PO43+ were added into the synthetic wastewater, leading to the dissociation of the complex ions in the wastewater, and resulting in removal of copper and ammonia therein. The effects of agents addition amount, pH, and reaction time on the removal efficiency of copper and ammonia were investigated. In particular, two-sectional struvite formation (TSSF) process was established for copper and ammonia removal. MgCl2 and Na2HPO4 were added by following 90% addition in the first section and remained 10% in the second during the TSSF process. Compared with one sectional struvite formation, TSSF possessed much better performance. Under condition of n(NH3-N):n(Mg):n(P)=1:1.2:1.5 (molar ratio), pH=9, and reaction time of 30 min, the removal efficiencies of copper and ammonia were 98.9% and 99.96%, respectively. The enhanced performance of TSSF is explained by the competition of ammonia by copper–ammonia complexes and struvite. The dissociation of copper–ammonia complexes is further demonstrated by thermodynamic equilibrium analysis, on the basis of calculations and establishment of predominance phases diagram. Moreover, XRD and EDS analyses further confirmed the formation of struvite and precipitation of copper, which prove the transmission of copper and ammonia from liquid phase into solid phase.

Corrigendum to “Start-Up Characteristics of a Granule-Based Anammox UASB Reactor Seeded with Anaerobic Granular Sludge”

[This corrects the article DOI: 10.1155/2013/396487.].