Tribulus terrestris L. protects glomerular endothelial cells via the miR155-H2AC6 interaction network in hypertensive renal injury.

BACKGROUND: Hypertensive renal injury is one of the most lethal complications of hypertension. At present, renin-angiotensin-aldosterone system (RAAS) blockers are considered the best drugs for the treatment of renal injury in hypertension because of their nephroprotective effect of reducing proteinuria, but there are no specific drugs for this purpose, however, clinical trials proved that Chinese medicine has a protective effect on target organs in the treatment of hypertension. Tribulus terrestris L. (TrT), a traditional Chinese medicine (TCM), has potential applications due to its reno-protective and immunomodulatory effects. METHODS: We investigated the underlying reno-protective mechanism of TrT on Angiotensin II (AngII)-induced hypertensive renal injury in glomerular endothelial cells by integrating the differential expression profiles of micro RNA (miRNA) and messenger RNA (mRNA) to construct a miRNA-mRNA interaction network associated with hypertensive kidney injury, followed by quantitative real-time polymerase chain reaction (qRT-PCR) for validation. RESULTS: Seventy-six differentially expressed mRNAs (DEmRNAs) and 1 differentially expressed miRNAs (DEmiRNAs) were identified in the control group and the AngII-induced hypertensive renal injury group, respectively. 110 DEmRNAs and 27 DEmiRNAs were identified in the TrT treatment group and the AngII-induced group, respectively. The core component of the miRNA-mRNA network was miR-155-5p. Our study showed that miR-155-5p expression levels were more decreased in the AngII-induced hypertensive renal injury group than the control group. TrT treatment also significantly upregulated miR-155-5p. Additionally, we found that miR-155-5p expression levels were negatively correlated with H2A clustered histone 6 (H2AC6). CONCLUSIONS: The results of this study indicate that TrT has a reno-protective effect on AngII-induced hypertensive renal injury by miR-155-5p, which negatively regulates the expression of H2AC6. Our findings offer a new therapeutic strategy and have identified an effective candidate target for the treatment of hypertensive renal injury in clinical settings.

[Partial Nitritation and Anaerobic Ammonia Oxidation Synergistic Denitrification to Remove Nitrogen and Carbon from Domestic Sewage].

A sequencing batch reactor-anaerobic sequencing batch reactor(SBR-ASBR) process was used to treat domestic sewage. In the SBR, the effects of the anoxic/aerobic time ratio and temperature on the realization of partial nitritation(PN) were investigated. In the ASBR, the effects of different COD/NO2--N(C/N) ratios on the removal of nitrogen and carbon using anaerobic ammonia oxidation(ANAMMOX) and denitrification were studied. The results illustrated that:① After three single cycles and on the 22nd day, the NO2--N accumulation rate(NiAR) was 98.06%, and the nitrate nitrogen generation rate(SNiPR, calculated as N/VSS) was 0.28g·(g·d)-1, and simultaneous nitrification and denitrification removal the TN and COD were 12.29 and 110.36mg·L-1, respectively(temperature=25℃, anoxic/aerobic time ratio=30 min:30 min). ② At an anoxic/aerobic time ratio of 30 min:30 min, the filamentous sludge bulked, the sludge activity decreased, and sludge settleability was poor at 15℃. Furthermore, the conversion rate of NH4+-N to NO2--N was 86.83%, indicating that the effluent NH4+-N concentration was too low to provide suitable matrix concentrations for ANAMMOX at 30℃. The effluent concentrations of NH4+-N and NO2--N were 31.58 mg·L-1 and 35.04mg·L-1, respectively, matching the ratio of the ANAMMOX substrate at 25℃. ③ The SBR-ASBR combined process showed good denitrification performance; the effluent TN, NH4+-N, and COD concentrations were stable at 13.13, 4.83, and 69.96mg·L-1, respectively, and the removal rates were 83.10%, 93.64%, and 75.11%, respectively. When the influent C/N of the ASBR was 2.5, 2.0, and 1.5, respectively, anaerobic ammonia oxidation and denitrification showed the best performance with respect to nitrogen and carbon removal with a C/N of 2.0. The effluent NH4+-N, NO2--N, NO3--N, and COD were 0.09, 0.25, 1.04, and 32.73 mg·L-1, respectively.

[Application of Iron and Sulfate-Modified Biochar in Phosphorus Removal from Water].

The excessive discharge of phosphate into natural water has caused serious environmental problems. Adsorption is an efficient technology for phosphorus removal from water. In this study, a novel biochar modified by chitosan, ferrous sulfate, and sodium sulfide was synthesized and performed well in phosphorus adsorption. The results of batch experiments showed that the optimum synthesized composite could adsorb 49.32 mg·g-1 of phosphate at 298 K. Meanwhile, the simulation results showed better fitting with the pseudo-second-order model and Langmuir model. The adsorption rate was dominated by three-dimensional diffusion within the inner pores. The adsorption process was defined as physic/chemisorption, while the adsorption mechanism was concluded to be electrostatic adsorption, porous filling, surface chemical precipitation, hydrogen binding, and the ligand effect. This study showed that the composite is effective in phosphorus removal from water, and we anticipate that our research will offer guidelines for adsorbent design and reveal the adsorption mechanism.

[Synthesis of Magnetic Iron Modifying Biochar for Ammonia Nitrogen Removal from Water].

A significant factor for eutrophication is the excessive discharge of ammonia nitrogen. Unfortunately, traditional methods to remove ammonia nitrogen are ineffective when facing gradually strict rules. Recently, adsorption has gained interest from scholars due to its efficiency and safety in ammonia nitrogen treatment. In this study, a novel biochar, modified with magnetic iron, was synthesized through co-precipitation, which performed well in ammonia nitrogen removal. The maximum adsorption amount at 293 K of the composite that was synthesized at 80℃(MB80) was 17.52 mg·g-1. Meanwhile, the simulation results displayed a good fitting with the pseudo second order model and Langmuir model. Additionally, the adsorption mechanism could be attributed to electrostatic adsorption, porous filling, ion exchange, and hydrogen bonding. Noticeably, MB80 maintained a good performance after 5 cycles, with desirable adsorption amount of 3.18 mg·g-1. This study aimed to provide an efficient method to treat ammonia nitrogen as well as a new way to dispose of municipal sludge.

[Effect of HRT on Denitrifying Phosphorus and Nitrogen Removal in Modified A2/O-BAF].

The effect of hydraulic retention time (HRT) on denitrifying phosphorus and nitrogen removal in a modified two sludge A2/O-BAF system was studied. The influent COD, NH4+-N, and TP were 189.6, 60.4, and 5.1 mg·L-1, respectively. When HRT was 9, 8, 7, and 6 h, the average effluent COD was less than 42 mg·L-1. The average effluent NH4+-N levels were 2.4, 2.8, 3.3, and 6.5 mg·L-1, respectively. The average effluent TP values were 0.3, 0.4, 0.7, and 0.8 mg·L-1, respectively. The ratio of the denitrifying phosphorus accumulation organisms (DPAOs/PAOs) in the system of anoxic zone was reduced from 76.8% to 48.8%. When HRT was 8 h, the ratio of denitrifying phosphorus to nitrogen (ΔPO43-/ΔNO3--N) was increased by 37.5% by a mathematical statistics method. The ΔPO43-/ΔNO3--N in the anoxic zone was 1.24 (the theoretical value is 1.41). At this time, the effect of denitrifying phosphorus to nitrogen was the best. The SVI value was lower than 100 mL·g-1 throughout the experiment, and the MLVSS/MLSS gradually decreased from 0.74 to 0.63, indicating that the sludge activity was reduced.

Tuning Magnetic Anisotropy in a Class of Co(II) Bis(hexafluoroacetylacetonate) Complexes.

Tuning the magnetic anisotropy of metal ions remains highly interesting in the design of improved single-molecule magnets (SMMs). We herein report synthetic, structural, magnetic, and computational studies of four mononuclear CoII complexes, namely [Co(hfac)2 (MeCN)2 ] (1), [Co(hfac)2 (Spy)2 ] (2), [Co(hfac)2 (MBIm)2 ] (3), and [Co(hfac)2 (DMF)2 ] (4) (MeCN=acetonitrile, hfac=hexafluoroacetylacetone, Spy=4-styrylpyridine, MbIm=5,6-dimethylbenzimidazole, DMF=N,N-dimethylformamide), with distorted octahedral geometry constructed from hexafluoroacetylacetone (hfac) and various axial ligands. By a building block approach, complexes 2-4 were synthesized by recrystallization of the starting material of 1 from various ligands containing solution. Magnetic and theoretical studies reveal that 1-4 possess large positive D values and relative small E parameters, indicating easy-plane magnetic anisotropy with significant rhombic anisotropy in 1-4. Dynamic alternative current (ac) magnetic susceptibility measurements indicate that these complexes exhibit slow magnetic relaxation under external fields, suggesting field-induced single-ion magnets (SIMs) of 1-4. These results provide a promising platform to achieve fine tuning of magnetic anisotropy through varying the axial ligands based on Co(II) bis(hexafluoroacetylacetonate) complexes.

Two Four-Coordinate and Seven-Coordinate CoII Complexes Based on the Bidentate Ligand 1, 8-Naphthyridine Showing Slow Magnetic Relaxation Behavior.

For a long time, the cobalt(II) complex ([Co(napy)4 ](ClO4 )2 ) (napy=1, 8-naphthyridine) has been considered as an eight-coordinate complex without any structural proof. After careful considerations, two complexes [Co(napy)2 Cl2 ] (1) and [Co(napy)4 ](ClO4 )2 (2) based on the bidentate ligand napy were synthesized and structurally characterized. X-ray single-crystal structural determination showed that the cobalt(II) center in [Co(napy)2 Cl2 ] (1) is four-coordinate with a tetrahedral geometry (Td ), while [Co(napy)4 ](ClO4 )2 (2) is seven-coordinate rather than eight-coordinate with a capped trigonal prism geometry (C2v ). Direct-current (dc) magnetic data revealed that complexes 1 and 2 possess positive zero-field splitting (ZFS) parameters of 11.08 and 25.30 cm-1 , respectively, with easy-plane magnetic anisotropy. Alternating current(ac) susceptibility measurements revealed that both complexes showed slow magnetic relaxation behaviour. Theoretical calculations demonstrated that the presence of easy-plane magnetic anisotropy (D>0) for complexes 1 and 2 is in agreement with the experimental data. Furthermore, these results pave the way to obtain four-coordinate and seven-coordinate cobalt(II) single-ion magnets (SIMs) by using a bidentate ligand.

[Short-cut Nitrification Start-up and Optimization of Operating Conditions Under Different Control Strategies].

Low C/N domestic sewage was treated in a SBR. With an operating temperature of (25±0.5)℃, NO2--N accumulation rates reached 96.79%, 98.80%, and 98.78% after 69, 63, and 58 cycles, respectively. In each case, alternating modes of hypoxia/aerobic (four times), aerobic/anoxic (five times), and aerobic/anoxic (four times) were applied, respectively, with an alternating time of 30 min. At the same temperature, when the aerobic/anoxic time ratios were 30 min:30 min, 40 min:20 min, and 30 min:60 min, and the single-cycle alternating times were 5, 3, and 5, respectively, stable NO2--N accumulation rates reached 98.81%, 97.71%, and 94.64% after 63, 73, and 78 cycles, respectively. The activity of AOB was 96.30, 99.27, and 102.26, respectively. Simultaneous nitrification and denitrification occurred under the three aerobic/anoxic time ratios. The total amounts of nitrogen removed by synchronous nitrification and denitrification were 29.89, 28.77, and 29.78 mg·L-1. When temperatures were adjusted to 18, 25, and 30℃, and when the aerobic/anoxic time ratio was 30 min:30 min, the NO2--N accumulation rates were 99.58%, 99.21%, and 95.93% after 90, 64, and 61 cycles, respectively. The activity of the sludge (f) peaked when after 64, 40, and 48 cycles, while the sludge-settling performance was good.

[Start-up Performance of Low-substrate Anaerobic Ammonium Oxidation Under Different COD Concentrations].

An anaerobic sequencing batch reactor(ASBR)was used to treat low-substrate simulated wastewater with NH4+-N and NO2--N concentrations of (25.00±0.40) mg·L-1 and (33.00±0.60) mg·L-1, respectively. The COD concentrations were controlled at 5.00, 15.00, 30.00, and 50.00 mg·L-1 by adding sodium acetate, and its effects on start-up of anaerobic ammonia oxidation (ANAMMOX) were investigated under the temperature of 30℃. The results showed that ① The start-up of ANAMMOX could be achieved successfully after 74, 94, 106, and 129 days. The nitrogen removal efficiency was optimum when the COD concentration was between 15.00 and 30.00 mg·L-1. In the steady phase, the average effluent concentrations of NH4+-N were 1.98 and 1.89 mg·L-1, the average effluent concentrations of NO2--N were below 0.62 mg·L-1, and the average effluent concentrations of TN were 2.37 and 2.28 mg·L-1. ② The average contribution of heterotrophic denitrification to nitrogen removal decreased to 4.78%, 9.59%, 10.21%, and 36.50%, respectively, during start-up process. The average contribution of ANAMMOX to nitrogen removal gradually increased to 95.22%, 90.41%, 89.79%, and 63.50%, respectively. ③ The activities of ANAMMOX exceeded denitrification activities at 44, 76, 86, and 114 days, respectively, which finally reached 0.700, 0.690, 0.670, and 0.510 mg·(g·h)-1, and the denitrification activities were 0.110, 0.130, 0.240 and 0.410 mg·(g·h)-1, respectively. Thus, the research results have provided references for the application of ANAMMOX to engineering.

[Realization of Short-cut Nitrification in a CAST Process at High Temperature and Its Phosphorus Removal Performance].

A synthetic wastewater was employed to investigate the realization of short-cut nitrification and its phosphorus removal performance in a CAST reactor operated at 22℃, 25℃, and 28℃. The results showed that TN removal of the system was stable and higher than 80% at different temperatures, and NH4+-N removal performed well. When the temperature was at 22℃ and 25℃, nitrite accumulation was not observed in the system and the phosphorus removal rate were 94.3% and 86.9%, respectively. When the temperature was increased to 28℃, nitrite accumulation efficiency in the reactor reached 87.2%, implying the system achieved a stable short-cut nitrification. In addition, in the short-cut nitrification stage at high temperature (28℃), the phosphorus release and uptake capacity of the system decreased. The anaerobic phosphorus release/COD consumption (P/C) ratio was much lower compared those at 22℃ and 25℃. However, the phosphorus removal performance of the reactor did not deteriorate at this stage. The phosphorus removal rate was 68.9%, indicating that a sufficient carbon source in the influent could not only guarantee the removal of TN, but also detoxify NO2- to reduce its inhibitory effect on the phosphate accumulating organisms (PAOs). The batch tests of phosphorus uptake by the sludge under different temperature conditions revealed that O2, NO3-, and NO2- could all be used as electron acceptors for phosphorus uptake. The aerobic phosphorus uptake rate was higher than that with NO3- and NO2- as electron acceptors. The phosphorus uptake rates of O2 and NO3- as electron acceptors were also found to be negatively correlated with temperature.

[Simultaneous Nitrification and Denitrifying Phosphorus Removal in Continuous Flow Reactor with Intermittent Aeration].

A continuous flow reactor (TCFR) with 10 compartments was used to treat domestic sewage. The anaerobic compartments of TCFR were kept at 3. The anoxic compartments of TCFR were reduced from 2 to 0. Therefore, the aerobic compartments of TCFR were increased gradually from 5 to 7. The aerobic compartments were set to continual aeration in Run1 and intermittent aeration from Run2 to Run4. The aeration/non-aeration ratios were 40 min/20 min,40 min/30 min, and 40 min/40 min, respectively. The nitrification liquid reflux ratios were reduced gradually from 150% to 0%. When the average influent concentrations of COD, NH4+-N, TN, and PO43--P were 259.34, 60.26, 64.42, and 6.10 mg·L-1, respectively, the corresponding effluent concentrations were 26.40, 1.03, 5.84, and 0.3 mg·L-1, respectively in Run4. The nitrogen removal amounts increased gradually from 192.30 mg·h-1 in Run1 to 244.00 mg·h-1 in Run4, and the corresponding removal rates increased from 65.40% to 95.30%. The activity of denitrifying phosphorus accumulating organisms (DPAOs) and phosphorus accumulating organisms (PAOs) increased from 36.05% and 38.20% in Run1 to 140.50% and 133.40% in Run4, respectively. Simultaneous nitrification and denitrifying phosphorus removal was achieved in TCFR by adopting intermittent aeration, which provided a reference for the reformation of sewage treatment plants.

Fine structure, crystalline and physicochemical properties of waxy corn starch treated by ultrasound irradiation.

As a simple and effective physical method, ultrasound irradiation has been used to modify starch. Native waxy corn starch was treated by ultrasound irradiation at 100 and 400 W in this study. Compared with native waxy corn starch, lower proportion of B1, B2, and B3, higher proportion of A chain were observed in ultrasonicated waxy corn starch. 1H NMR combined with HPSEC-MALLS-RI data showed that lower degree of branching was observed in ultrasonicated waxy corn starch, and α-1,4 glycosidic linkages were more stable than α-1,6 glycosidic linkages in waxy corn starches. 13C NMR data indicated that the content of double helices was decreased, and single helix and amorphous components were increased after ultrasound irradiation. The A-type crystal structure was scarcely affected according to X-ray diffraction (XRD) analysis. The granule surface of ultrasonicated waxy corn starch became notch and rough fragment, and lower particle diameter was observed in ultrasonicated waxy corn starch. These results demonstrated that ultrasound irradiation affected chain length distribution, double helices, single helices and amorphous state, especially α-1,4 glycosidic linkages and α-1,6 glycosidic linkages, of waxy corn starch.

[Characteristics of Denitrifying Phosphorus Removal by A2/O-BAF at Low Temperatures].

Low C/N domestic sewage was treated by an A2/O-biological aerated filter (BAF) system at low temperatures (11-14℃). The characteristics of pollutant removal, the ratio of denitrifying phosphorus to nitrogen (ΔPO43-/ΔNO3-N) and effects of aeration flow and effective packing height on nitrification in BAF were studied. The results showed that when the average influent concentrations of COD, NH4+-N, TN and PO43- were 193.1, 58.6, 60.3 and 5.1 mg·L-1 respectively, their effluent concentrations were 46.3, 2.5, 13.4 and 0.3 mg·L-1 respectively, which met the first level A criteria specified in the discharge standard of pollutants for municipal wastewater treatment plant (GB 18918-2002). The linear fitting of ΔPO43-/ΔNO3--N was between 0.47 and 1.75. The normal distribution of mathematical statistics was applied-and the average standard deviation for ΔPO43-/ΔNO3--N were 1.20 and 0.29 respectively. When the aeration flows were 60 L·h-1 and 100 L·h-1, the effluent concentration of NH4+-N was less than 5.0 mg·L-1, corresponding to the effective packing heights in the BAF of 1.8 m and 1.0 m respectively. However, when the aeration flow was increased to 120 L·h-1, the air-water flow led to biofilm detachment, which caused the effluent concentration of NH4+-N to increase beyond 5.0 mg·L-1.

[Effect of HRT on Nitrogen Removal Using ANAMMOX and Heterotrophic Denitrification].

Real domestic sewage was first treated in SBR and partial nitrification was achieved. When average concentrations of NH4+-N, NO2--N, and COD were 37.27, 39.97, and 120 mg·L-1, respectively, the effluent was delivered as influent of an anaerobic ammonia oxidation reactor (ASBR). The effect of different HRTs (36 h, 33 h, 30 h, 27 h) on nitrogen removal of ANAMMOX and heterotrophic denitrification were investigated under conditions of temperature of 24℃ and pH of 7.2±0.2. Results showed that 1 nitrogen removal efficiency was optimum with HRT of 33 h. The average total nitrogen load rate(TNLR)and total nitrogen removal rate(TNRR)were 0.056 kg·(m3·d)-1and 0.050 kg·(m3·d)-1, respectively. The average effluent concentrations of NH4+-N, NO2--N, and COD were 1.36, 0.47, and 49.79 mg·L-1, and removal rates were 96.30%, 98.83%, and 56.17%, respectively. △NO2--N/△NH4+-N and △NO3--N/△NH4+-N were 1.17 and 0.15, 0.15 and 0.11 less than theoretical ANAMMOX values (1.32, 0.26) due to heterotrophic denitrification. 2 The contribution of ANAMMOX to nitrogen removal decreased; however, the contribution of heterotrophic denitrification to nitrogen removal gradually increased with decreasing HRT. This provides a point of reference for ANAMMOX in engineering applications.

[Effect of Aeration Rate on Shortcut Nitrification Recovery in Intermittent Aeration Mode].

Shortcut nitrification sludge, which was set aside for two months, was recovered using Reactors Ⅰ, Ⅱ, Ⅲ, and Ⅳ. The aeration rates of Reactors Ⅰ, Ⅱ, Ⅲ, and Ⅳ were 120, 100, 80, and 60 L·h-1, respectively, while treating real domestic sewage, and the ratio of aerobic/anoxic was 30 min/30 min at the temperature of 25℃. The influent of ammonia was 50-80 mg·L-1, and the concentration of effluent ammonia was stable, at below 5 mg·L-1, after the 12th, 18th, 21st, and 21st cycles. The removal ratio of ammonia nitrogen was about 95%. The highest concentrations of nitrite for Reactors Ⅰ, Ⅱ, Ⅲ, and Ⅳ were 20.83, 22.81, 21.50, and 20.73 mg·L-1, respectively, which occurred in the 30th, 35th, 38th, and 42nd cycles, respectively. The concentrations of effluent nitrate were lower than 0.5 mg·L-1, and the nitrite accumulation rates were higher than 99%. The activity of ammonia-oxidizing bacteria (AOB) increased gradually and finally stabilized at 100.00%; however, the activity of nitrite-oxidizing bacteria (NOB) was gradually inhibited. The recovery of shortcut nitrification was achieved successfully in the different aeration modes.

[Effect of Step Feed on Denitrifying Phosphorus and Nitrate Removal in a Modification of the Two Sludge A2/O-BAF System].

A modification of the two sludge A2/O-BAF system was used to treat low C/N real domestic sewage. In order to improve the utilization of the carbon source, the effects of two step feeds (pre-anoxic zone and anoxic zone) on denitrifying phosphorus and nitrate removal were studied. According to the formula of material balance for COD, the utilization of carbon source was analyzed and evaluated under different ratios of step feed, simultaneously. The results showed that when the ratio of step feed was 7:3 and the influent concentrations of COD, NH4+-N, TN, and TP were 174.99, 58.19, 59.10, and 5.15 mg·L-1, respectively, their effluent concentrations were 29.48, 4.07, 14.10, and 0.40 mg·L-1, and the removal rates were 82.12%, 92.76%, 75.45%, and 91.20%, respectively. It was found that when the ratio of the denitrifying phosphorus accumulation organisms to the phosphorus accumulation organisms(DPAOs/PAOs) was 98.81%, the efficiencies of denitrifying phosphorus and nitrate removal were optimum. By optimizing step feed, the carbon source was utilized effectively, and the efficiencies of nitrogen and phosphorus removal were improved simultaneously. The theoretical basis has thus been provided for the modification of the two sludge A2/O-BAF system to treat low C/N waste water.

[Performance of the Removal of Nitrogen During Anaerobic Ammonia Oxidation Using Different Operational Strategies].

The effects of low substrate ratio, cooling methods, and pH on nitrogen removal performance were studied in a laboratory-scale anaerobic ammonium oxidation reactor (ASBR) while treating simulated domestic waste water. The results illustrated that the average removal efficiencies of NH4+-N and NO2--N increased from 54.4% and 65.3% to 95.8% and 92.5%, respectively, at a temperature of 30℃ and an influent concentration of NO2--N of (30±0.2)mg·L-1. The substrate ratio (NO2--N/NH4+-N) increased from 0.9 to 1.4.However, the removal efficiency of NH4+-N was affected negligibly, and the average removal efficiency of NO2--N decreased to 54.6% when the substrate ratio was increased to 1.6, suggesting that the nitrogen removal performance of anaerobic ammonium oxidation was best when the substrate ratio was close to the theoretical value of 1.32.The average removal efficiencies of NH4+-N and NO2--N decreased from 97.5% and 98.5% to 35.2% and 40.1%, respectively, when the temperature of the reactor dropped from 30℃ to 15℃ at one time. The average removal efficiencies of NH4+-N and NO2--N dropped from 97.7% and 98.6% to 52.7% and 62.4%, respectively, when the ladder cooling method(30℃→25℃→20℃→15℃) was used. The average removal efficiencies of NH4+-N and NO2--N increased initially and then decreased when the pH was increased gradually from 7.7 to 8.5.The highest nitrogen removal efficiency was achieved when the pH was controlled at 8.3 with a substrate ratio of NO2--N/NH4+-N equal to 1.4.

[Effect of Substrate Ratio on Removal of Nitrogen and Carbon Using Anaerobic Ammonium Oxidation and Denitrification].

Real domestic sewage was treated in a sequencing batch reactor (SBR). When the partial nitrification of SBR was achieved, the effluent was fed with quantitative NaNO2, which served as the influent of the anaerobic ammonium oxidation (ANAMMOX) process of the anaerobic SBR (ASBR). The effect of different substrate ratios on the removal of nitrogen and carbon using anaerobic ammonium oxidation and denitrification was investigated under conditions with a temperature of 24℃ and pH of 7.2±0.2. The results showed that ① the nitrogen removal efficiency was optimum when the influent NO2--N/NH4+-N was 1.4-1.6. The average effluent concentrations of NH4+-N, NO2--N, and chemical oxygen demand (COD) were 2.14, 1.07, and 30.50 mg·L-1, and their removal rates were 93.62%, 97.79%, and 74.75%, respectively. The △NO2--N/△NH4+-N and △NO3--N/△NH4+-N ratios were 1.60 and 0.17, respectively. Total nitrogen was removed by the joint action of denitrifying and ANAMMOX bacteria. ② When the influent ratio of NO2--N/NH4+-N increased, the contribution of ANAMMOX to nitrogen removal decreased, but the contribution of heterotrophic denitrification to nitrogen removal increased gradually. ③ The NH4+-N and NO2--N degradation processes corresponded with zero-order reactions and fitted the linear relationship in the typical cycle. Their specific degradation rates were 0.404 and 0.599 mg·(g·h)-1, respectively. Their ratio was 1.48, and the specific degradation rate of COD gradually increased.

[Effects of Temperature on Shortcut Nitrification and Nitrification Activity of Nitrification in an Intermittent Aeration Sequencing Batch Reactor].

Real domestic sewage was treated with sequencing batch reactors (SBR). The aerobic/anoxic modes were alternated 4 times at 30℃ and 7 times at 18℃ in a single-cycle, respectively, and the ratio of aerobic/anoxic cycles was 30 min/30 min. The influent concentration of ammonia and nitrite was 61.44 mg·L-1 and 0.77 mg·L-1, respectively. After the experiments were run for 61 and 90 cycles, the effluent of the ammonia was 0.68 mg·L-1 and 1.28 mg·L-1 and the removal rate for ammonia was 98.94% and 99.57%, respectively. The nitrite concentrations were 20.57 mg·L-1 and 20.18 mg·L-1, and the nitrite accumulation rate reached 95.92% and 99.58%, respectively. During shortcut nitrification, the activity of the ammonia oxidizing bacteria (AOB) increased gradually before finally stabilizing at 100.00%, however the activity of nitrite oxidizing bacteria (NOB) increased first and then decreased gradually, the activity of AOB exceeded NOB at 32 and 74 cycles respectively, where the AOB became the dominant bacteria and the activity of NOB was completely inhibited at 61 and 90 cycles.