Physical and chemical characteristics of PM2.5 and its toxicity to human bronchial cells BEAS-2B in the winter and summer / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

With the increasing occurrence of haze during the summer, the physicochemical characteristics and toxicity differences in PM2.5 in different seasons are of great concern. Hangzhou is located in an area that has a subtropical monsoon climate where the humidity is very high during both the summer and winter. However, there are limited studies on the seasonal differences in PM2.5 in these weather conditions. In this test, PM2.5 samples were collected in the winter and summer, the morphology and chemical composition of PM2.5 were analyzed, the toxicity of PM2.5 to human bronchial cells BEAS-2B was compared, and the correlation between PM2.5 toxicity and the chemical composition was discussed. The results showed that during both the winter and summer, the main compounds in the PM2.5 samples were water-soluble ions, particularly SO42-, NO3-, and NH4+, followed by organic components, while heavy metals were present at lower levels. The higher the mass concentration of PM2.5, the greater its impact on cell viability and ROS levels. However, when the mass concentration of PM2.5 was similar, the water extraction from the summer samples showed a greater impact on BEAS-2B than that from the winter samples. The cytotoxicity of PM2.5 was closely associated with heavy metals and organic pollutants but less related to water-soluble ions.

Molecular evidence for nitrite-dependent anaerobic methane-oxidising bacteria in the Jiaojiang Estuary of the East Sea (China).

Nitrite-dependent anaerobic methane oxidation (N-DAMO) is a recently discovered process linking the global carbon and nitrogen cycles. This process was reported to be mediated by "Candidatus Methylomirabilis oxyfera". To date, M. oxyfera-like bacteria have been detected in a limited number of freshwater habitats, but whether these bacteria occur in estuarine habitats is currently unknown. In this study, the distribution, diversity and abundance of M. oxyfera-like bacteria were studied in the sediment of the Jiaojiang Estuary of the East Sea (China). Both the 16S ribosomal RNA (rRNA) and pmoA genes confirmed the occurrence of M. oxyfera-like bacteria in the examined estuary. The recovered 16S rRNA gene sequences showed 91.5-97.2 % identity to the 16S rRNA gene of M. oxyfera, and the recovered pmoA gene sequences showed 85.1-95.4 % identity to the pmoA gene of M. oxyfera. Quantitative PCR further confirmed the occurrence of M. oxyfera-like bacteria in this estuary, with the abundance varying from 5.80 ± 0.28 × 10(4) to 8.35 ± 0.52 × 10(7) copies g (dry weight)(-1). Correlation analysis indicated that the sediment organic content was the most important factor affecting the distribution of M. oxyfera-like bacterial communities in the examined sediments among the environmental factors investigated. This study demonstrated for the first time the existence of M. oxyfera-like bacteria in an estuarine environment and showed the correlations between the distribution of these bacteria and the estuarine environmental conditions.

Enrichment of anammox bacteria from three sludge sources for the startup of monosodium glutamate industrial wastewater treatment system.

Three activated sludges from a landfill leachate treatment plant (S1), a municipal sewage treatment plant (S2) and a monosodium glutamate (MSG) wastewater treatment plant (S3) were used as inocula to enrich anaerobic ammonium oxidation (anammox) bacteria for the startup of MSG industrial wastewater treatment system. After 360 days of cultivation using MSG wastewater, obvious anammox activity was observed in all three cultures. The maximum specific anammox activities of cultures S1, S2 and S3 were 0.11 kg N kg(-1) VSS day(-1), 0.09 kg N kg(-1) VSS day(-1) and 0.16 kg N kg(-1) VSS day(-1), respectively. Brownish-red anammox granules having diameters in the range of 0.2-1.0mm were visible in cultures S1 and S2, and large red granules having diameters in the range of 0.5-2.5mm were formed in culture S3 after 420 days of cultivation. Phylogenetic analysis of 16S rRNA genes showed that Kuenenia organisms were the dominant anammox species in all three cultures. The copy numbers of 16S rRNA genes of anammox bacteria in cultures S1, S2 and S3 were 6.8 × 10(7) copies mL(-1), 9.4 × 10(7) copies mL(-1) and 7.5 × 10(8) copies mL(-1), respectively. The results of this study demonstrated that anammox cultivation from conventional activated sludges was highly possible using MSG wastewater. Thus the anammox process has possibility of applying to the nitrogen removal from MSG wastewater.

Operation performance of membrane nitrification bioreactor for ammonia-containing wastewater / 生物工程学报

The operation performance of membrane nitrification bioreactor to treat ammonia-containing wastewater as well as the capabilities of separation and filtration of polypropylene membrane modules were tested. The removal efficiency of ammonia was kept higher than 95% when the hydraulic retention time was set at 1 day, the influent concentration was increased up to 80 mmol (NH4+ -N) x L(-1) and the volume loading rate was increased up to 1.12 kg (NH4+ -N) x m(-3) x d(-1). The biomass in the reactor was accumulated from 5 g x L(-1) to 10 g x L(-1) within 50 days, which indicated that polypropylene membrane modules were efficient in retaining biomass. The biomass attached to the membrane also contributed to the conversion of ammonia and nitrite. When the hydraulic pressure was lower than 80cm, the increase of hydraulic pressure improved the permeation of membrane. However, when the hydraulic pressure was beyond 80cm, the increase of hydraulic pressure did not significantly improve the permeation of membrane. The permeate flux was the highest 2.51 (L x m (-2) x h(-1)) but the resistance was the lowest (2.63 x 10(-5)) m(-1) when the hydraulic pressure was about 20 cm. The results showed that the membrane nitrification bioreactor could be run normally without extra energy input.

Performance of internal-loop air-lift nitrifying bioreactor / 生物工程学报

The performance of internal-loop air-lift nitrifying bioreactor was good with strong tolerance to influent ammonia concentration (78.49 mmol/L), high volume converting rate (163.18 mmol/L.d) and obvious working stability (ammonia removal > 94.42%). During operation of internal-loop air-lift bioreactor, the nitrifying activated sludge was granulated. The nitrifying granular activated sludge began to appear on day 45. Its average diameter was 0.83 mm, settling velocity was 55.53 m/h and specific ammonia removal rate was 0.95 mmol (NH4(+)-N)/g (VS).d. The nitrifying granular activated sludge had the activity for anaerobic ammonia oxidation with ammonia oxidation rate of 0.23 mmol (NH4(+)-N)/g(VS).d and nitrite reduction rate of 0.24 mmol (NO2(-)-N)/g(VS).d.