[Bacterial Community Shifts and Nitrogen Removal Characteristics for a SNAD Process Treating Anaerobic Digester Liquor of Swine Wastewater (ADLSW) in a Continuous-Flow Biofilm Reactor (CFBR)].

To realize a simultaneous partial nitrification, ANAMMOX (anaerobic ammonium oxidation), and denitrification (SNAD) process treating anaerobic digester liquor of swine wastewater (ADLSW) in a continuous-flow biofilm reactor (CFBR), we first gradually increased the influent ammonium (NH4+-N) concentration, and then enhanced the ADLSW ratio in the influent during operation; dissolved oxygen (DO) was controlled at (0.4±0.1) mg·L-1 by adjusting the air flow rate, and the temperature was kept at (30±1)℃. Meanwhile, high-throughput sequencing and quantitative PCR (polymerase chain reaction) techniques were used to analyze the bacterial community shifts and the amount of dominant nitrogen removal bacteria. The results demonstrated that a successful start-up of the SNAD process was accomplished in 150 d, and replacement of the actual biogas slurry was completed in 298 d. The effluent (NO3--N+NO2--N)/ΔNH4+-N value was less than 0.11, and the average removal rates of NH4+-N and TN (total nitrogen) increased to 63.26% and 55.71%, respectively. Moreover, high-throughput sequencing results demonstrated that the dominant microbial populations at phylum level were Chloroflexi (with a relative abundance of 50.78%), Proteobacteria (13.34%), and Planctomycetes (9.26%). The relative abundance of Nitrosomonas increased from 1.55% to 1.98%. In addition, the relative abundance of Candidatus_Brocadia and Candidatus_Kuenenia increased from 0.01% and (<0.01%) to 4.66% and 4.18%, respectively, and the relative abundance of Denitratisoma increased from (<0.01%) to 2.06%. Meanwhile, qPCR analysis showed that the amounts of ammonia-oxidizing bacteria, ANAMMOX, and denitrifying bacteria increased significantly compared with the inoculated sludge. An efficient and stable nitrogen removal rate can be achieved, and the follow-up processing cost can be reduced, by application of the SNAD treatment process for ADLSW.

Effects of Uric Acid on Expression of Lysyl Oxidase and Matrix Metalloproteinase-2 in Rat Smooth Muscle Cells / 中国循环杂志

Objectives: To explore the effects of uric acid on expression of lysyl oxidase (LOX) and matrix metalloproteinase-2 (MMP-2) in rat vascular smooth muscle cells. Methods: Rat vascular smooth muscle cell was cultured, and divided into following groups: control group, uric acid group (cells were treated with 20, 40, 60 mg/L uric acid for 48 hours, cells were treated with 40 mg/L uric acid for 24, 48, 72 h) and β-aminopropionitrile group (cells were treated with 10 mg/ml β-aminopropionitrile for 24 hours). The reactive oxygen species was detected by confocal microscopy. mRNAs and protein expression levels of LOX and MMP-2 in rat vascular smooth muscle cells were measured by RT-PCR and Western blot, respectively. Results: The number of increased cell proliferation, reactive oxygen species burst, mRNAs and protein expression levels of LOX and MMP-2 were significantly increased in uric acid group than in control group (P<0.01). The mRNAs and protein expression levels of LOX and MMP-2 were significantly downregulated in β-aminopropionitrile group than in uric acid group (P<0.01). Conclusions: Uric acid can enhance the expression of LOX and MMP-2 in rat vascular smooth muscle cells.

[Effects of Magnetic Activated Carbon with Different Particle Sizes on Sludge Granulation in a SBR System].

In this paper, 1.5 g·L-1 of magnetic activated carbon with different particle sizes being 80, 140, 200, and 300 mesh (numbered 2, 3, 4, 5) were inoculated into the same sequencing batch reactor (SBR). The sludge volume index (SVI), particle size distribution characteristics, changes of extracellular proteins (PN), polysaccharide (PS), and polymeric substances (EPS) and their decontamination capability were studied and compared with a control group without addition (numbered 1). The results show that different particle diameters of magnetic activated carbon have certain influences on the granulation process. For example, it is easier for activated sludge to form aerobic granular sludge (AGS) when particle size are 140 mesh and 200 mesh acting as an inner core. Under these conditions, the AGS has a close structure and good sedimentation characteristics. Gaussian distribution was adopted to analyze the characteristics of Tparticle size distribution and standard deviations. The average diameter of the sludge in 3# and 4# all reached 780 µm within 50 days, which was higher than other reactors, with the same standard deviations being 318.9 µm and 362.3 µm respectively, which is lower than 2# and 3#. Besides, the granular sludge formed in both reactors was uniform in size and stable in operation. Different particle sizes of magnetic activated carbon were beneficial for the enhancement of proteins (PN), especially those with appropriate diameters (140 and 200 mesh), but had little effects on polysaccharides (PS). The formation of aerobic granular sludge based-magnetic activated carbon was in accordance with the inert kernel model. Meanwhile, the PN/PS in 3# and 4# were obviously higher than other SBRs with the same removal rate of TN and TP reaching 50% and 60% respectively.

[Preparation of HDTMA-modified Zeolite and Its Performance in Nitro-phenol Adsorption from Wastewaters].

In this study, natural zeolite was modified by HDTMA. Effects of the modified conditions, HDTMA-modified zeolite doses, solution pH values, and reaction time on nitro-phenol removal were investigated, and the adsorption kinetics and isotherms were discussed. Compared with natural zeolite, HDTMA-modified zeolite showed better performance in nitro-phenol removal. An adsorption capacity of 2.53 mg · g⁻¹ was achieved when the concentration of HDTMA solution (pH = 10) was 1.2% in preparation of modified zeolite. This adsorption capacity was higher than that obtained by natural zeolite (0.54 mg · g⁻¹). In adsorption tests, when HDTMA- modified zeolite dose was adjusted to 8 g · L⁻¹, the removal efficiency of nitro-phenol reached 93.9% after 90 min reaction, with wastewater pH of 6. Furthermore, the nitro-phenol adsorption process could be well fitted to the pseudo-first-order kinetics model (R² > 0.90), whereas the adsorption isotherm results indicated that Langmuir model provided the best fitting for the equilibrium data at different temperatures, with R² of higher than 0.90.

[Long-term Performance and Bacterial Community Composition Analysis of AGS-SBR Treating the Low COD/N Sewage at Low DO Concentration Condition].

This study utilized the sequencing batch activated sludge reactor (SBR) inoculated aerobic granular sludge (AGS) to treat the low COD/N ratio (<4.0) domestic wastewater under low DO (0.5-1.0 mg·L-1) concentration condition. Long-term performance of simultaneous nitrogen and phosphorus removal and bacterial community composition of AGS-SBR were studied. The results showed that the AGS-SBR system had good and stable decontamination abilities in its 180-day operation. The average removal rates of COD, NH4+-N, TN and TP were 87.17%, 95.21%, 77.05%, and 91.11%, respectively. At the same time, the AGS showed good settling performance, and always kept its integrated and compact structure. No obvious granular sludge disintegration phenomenon occurred in 180 days. Meanwhile, by using Illumina 16S rRNA gene MiSeq sequencing, we investigated the bacterial abundance in AGS-SBR reactor. Proteobacteria, Firmicutes, Chlorobi, Chloroflex, and Bacteroidetes were the dominant microbial communities in the simultaneous nitrogen and phosphorus removal reactor. Denitratisoma, Planctomycetaceae, Thauera, Comamonas, Nitrosomonas and Nitrospira were suggested to be the primary organisms responsible for the nitrogen removal. Clostridium and Anaerolinea were the main bacterial communities of phosphorus removal.

[Rapid Start-up of Simultaneous Nitrification and Denitrification Coupled Phosphorus Removal Process and Its Performing Characteristics].

In this study, simultaneous nitrification and denitrification (SND) coupled Phosphorus removal process through gradually decreasing DO concentration was investigated by treating wastewater with a low COD/TN ratio (C/N = 3 : 1-4: 1) in a sequencing batch reactor (SBR) inoculated with aerobic granular sludge (AGS). Successful SND coupled Phosphorus phenomenon occurred after 20d at the DO concentration of 0.50-1.0 mg x L(-1). In the following 40 days, the average removal rates of COD, NH4(+) -N, TN and TP were 84.84% , 93.51%, 77.06% and 85.69%, and the NO3(-) -N and NO2(-) -N average accumulations in the effluent were only 4.01 mg x L(-1) and 3.17 mg x L(-1), respectively. The AGS had complete forms and good settling performances, and the sludge volume index (SVI) was about 55.22 mL x g(-1) at the end of starting-up stage. The results of different nitrogen sources showed that the removal rate of TN was in the order of NH4(+) -N > NO2(-) -N > NO3(-) -N, and the removal rate of TP was in the order of NO3(-) -N > NO2(-) -N > NH4(+) -N. The nitrogen and phosphorus removal of wastewater were mainly realized by simultaneous nitrification and denitrification and denitrifying phosphorus removal, respectively.

[Identification of a high ammonia nitrogen tolerant and heterotrophic nitrification-aerobic denitrification bacterial strain TN-14 and its nitrogen removal capabilities].

A new strain of high ammonia nitrogen tolerant and heterotrophic nitrification-aerobic denitrification bacterium TN-14 was isolated from the environment. Its physiological and biochemical characteristics and molecular identification, performences of heterotrophic nitrification-aerobic, the abilities of resistance to ammonia nitrogen as well as the decontamination abilities were studied, respectively. It was preliminary identified as Acinetobacter sp. according to its physiological and biochemical characteristics and molecular identification results. In heterotrophic nitrification system, the ammonia nitrogen and total nitrogen removal rate of the bacterial strain TN-14 could reach 97.13% and 93.53% within 24 h. In nitrates denitrification system, the nitrate concentration could decline from 94.24 mg · L(-1) to 39.32 mg · L(-1) within 24 h, where the removal rate was 58.28% and the denitrification rate was 2.28 mg · (L · h)(-1); In nitrite denitrification systems, the initial concentration of nitrite could be declined from 97.78 mg · L(-1) to 21.30 mg x L(-1), with a nitrite nitrogen removal rate of 78.22%, and a denitrification rate of 2.55 mg · (L· h)(-1). Meanwhile, strain TN-14 had the capability of flocculant production, and the flocculating rate could reach 94.74% when its fermentation liquid was used to treat 0.4% kaolin suspension. Strain TN-14 could grow at an ammonia nitrogen concentration as high as 1200 mg · L(-1). In the aspect of actual piggery wastewater treatment by strain TN-14, the removal rate of COD, ammonia nitrogen, TN and TP cloud reached 85.30%, 65.72%, 64.86% and 79.41%, respectively. Strain TN-14 has a good application prospect in biological treatment of real high- ammonia wastewater.

[Biological phosphorus removal in intermittent aerated biological filter].

Under intermittent aerated and continuous fed operation where the biofilm system was subjected to alternated anaerobic/aerobic condition, the effect of influent volatile fatty acids (VFAs) concentrations, operation cycle and backwash on the biological phosphorus removal performance of the biofilter was studied. In the experiment, synthetic domestic wastewater was used, and the influent velocity was 5 L x h(-1) with gas versus liquid ratio of 8:1 and hydraulic retention time (HRT) of 1.3 h, resulting in average COD, ammonium and phosphorus load of 4.7, 0.41 and 0.095 g x (L x d) (-1) respectively. Results show that, (1) effective release and uptake of phosphorus was achieved in a operation cycle; (2) when influent VFAs was 100 mg x L(-1) (calculated by COD value) and operation cycle was 6 h the filter performed best in phosphorus removal, the phosphorus loading removal rate can be as much as 0.059 g x (L x d)(-1) at the aerated phase with those of COD and ammonium being 3.8 g x (L x d)(-1) and 0.28 g x (L x d)(-1) respectively, and with average effluent phosphorus, COD and ammonium concentrations being 1.8, 43.6 and 8.7 mg x L(-1), which shows nitrogen loss also happened; (3) the pause of backwash decreased the phosphorus removal performance rapidly with the removal efficiency lower than 40% in two days, but the consequent daily backwash operation gave a short improvement on the phosphorus removal, which disappeared in another two days. Thus, it is shown that biological phosphorus removal achieved with better phosphorus loading removal performance in the biofilter under intermittent aerated and continuous fed operation, and that sufficient and stable influent VFAs concentration, proper operation cycle, and more frequent backwash favored the performance.