Long-Term Effects of Trace NO2 Addition on the Performance of CANON SBR

Two parallel CANON Sequencing Bach reactors were started, and 67ppm NO2 was added into Sequencing Bach Reactor 2 while nothing was added to Sequencing Bach Reactor 1. The total nitrogen removal efficiency of SBR1 was 65.5±5.0% at a removal rate of 0.198±0.023 kgN/m3/d. Meanwhile, the SBR2 with NO2 addition showed a removal efficiency of 67.5±6.2%, with a removal rate of 0.277±0.017 kgN/m3/d. The SBR2 had a higher removal efficiency and rate than the SBR1. The continuous addition of trace NO2 into the CANON Sequencing Bach Reactor allows conventional aerobic ammonia oxidation with O2 as the electron acceptor and ammonia oxidation of with NO2 as the electron acceptor to take place simultaneously, thus improving the ammonia oxidation rate and autotrophic nitrogen removal performance. China Library Classification No.: X703.1 Literature Label: A Article No.:

Influence of ammonia oxidation rate on thaumarchaeal lipid composition and the TEX86 temperature proxy

Archaeal membrane lipids known as glycerol dibiphytanyl glycerol tetraethers (GDGTs) are the basis of the TEX86 paleotemperature proxy. Because GDGTs preserved in marine sediments are thought to originate mainly from planktonic, ammonia-oxidizing Thaumarchaeota, the basis of the correlation between TEX86 and sea surface temperature (SST) remains unresolved: How does TEX86 predict surface temperatures, when maximum thaumarchaeal activity occurs below the surface mixed layer and TEX86 does not covary with in situ growth temperatures? Here we used isothermal studies of the model thaumarchaeon Nitrosopumilus maritimus SCM1 to investigate how GDGT composition changes in response to ammonia oxidation rate. We used continuous culture methods to avoid potential confounding variables that can be associated with experiments in batch cultures. The results show that the ring index scales inversely (R2 = 0.82) with ammonia oxidation rate (ϕ), indicating that GDGT cyclization depends on available reducing power. Correspondingly, the TEX86 ratio decreases by an equivalent of 5.4 °C of calculated temperature over a 5.5 fmol·cell−1·d−1 increase in ϕ. This finding reconciles other recent experiments that have identified growth stage and oxygen availability as variables affecting TEX86. Depth profiles from the marine water column show minimum TEX86 values at the depth of maximum nitrification rates, consistent with our chemostat results. Our findings suggest that the TEX86 signal exported from the water column is influenced by the dynamics of ammonia oxidation. Thus, the global TEX86–SST calibration potentially represents a composite of regional correlations based on nutrient dynamics and global correlations based on archaeal community composition and temperature.

Kinetic study of compost liquor nitrification

This study is a first kinetic approach about the compost liquor treatment by activated sludge. This industrial wastewater is highly loaded in organic and nitrogen compounds (COD≈12,000 mg L−1 and NH4+-N≈4,000 mg L−1). The possibility of its treatment in an urban WWTP is studied measuring ammonia oxidation rate with non-acclimated sludge to the industrial effluent. Compost liquor appears as an inhibitor substrate. The ammonia oxidation rate can be modelled by the Haldane model: UMAX=0.180 d−1, KS=12.0 mgN.L−1 and KI=26.0 mgN.L−1. The ammonia oxidation rate also follows for a synthetic substrate which has the same pollutant load as the real substrate. In this case, the ammonia oxidation rate can be modelled by the Monod model: UMAX=0.073 d−1 and KS=4.3 mgN.L−1. This result confirms that the ammonia oxidising bacteria are inhibited by the real wastewater. The following-up of nitrate production shows also the inhibition of nitrite oxidising bacteria. The compost liquor treatment seems not possible in an urban WWTP (<50,000 p.e.). That’s why a specific WWTP is recommended and an acclimation step of activated sludge is essential.

Phylogenetic and Microbial Community Analysis Based on amoA Gene and 16SrDNA in Nitrosification Biofilm Reactor

In order to analyze microbial community and phylogenesis in nitrosification biofilm reactor, a partial stretch of the gene encoding the active-site polypeptide of ammonia monooxygenase (amoA) was amplified and the gene libraries were constructed. The result of gene sequences and phylogenetic analysis showed that Nitrosomonas eutropha was the predominant species in the reactor. Besides, there were also some kinds of ammonia-oxidizing microbe uncultured in the system. PCR-SSCP analysis of 16SrDNA of archaebacteria and eubacterium indicated that with the rising of ammonia oxidation rate, the structure and distribution of microbial community was influenced and the diversity of microbial communities decreased, and the decreasing of specificity in the reactor might be the key factor for the rising of ammonia oxidation rate.