Assessing the mechanism for flood control: a case of plain river network cities under extreme rainfalls.

In recent years, frequent floods hit Chinese cities and caused heavy casualties and property losses, making China faced with severe flood problems. In this study, Nanhai Future City in the IX Flood Control Area of Yancheng City, Jiangsu Province, was selected as the research area to simulate water-level changes under different control schemes meeting extreme rainfalls. MIKE model simulated the inundation with the designed storm of different return periods. The results showed that flooding inside the research area was severe. Higher drainage capacity of the pump stations with more engineering and non-engineering measures can reduce the adverse effect of extreme rainfall. The results provide a reference for planning future infrastructure and flood control decisions for Nanhai Future City and the surrounding areas.

[Analysis of PIH1D3 variant in a Chinese pedigree affected with primary ciliary dyskinesia].

OBJECTIVE: To detect variant of PIH1D3 gene in a Chinese pedigree affected with primary ciliary dyskinesia (PCD) and explore its genotype-relationship correlation. METHODS: PCD patients from the pedigree were analyzed. Ultrastructures of the cilia and flagella of the nasal mucosa were analyzed. DNA samples of the patients were sequenced. RESULTS: The proband and all other affected members of his pedigree had a history of various degree of respiratory tract infection. Two patients had visceral heterotopia, and one was infertile. Electronic microscopy revealed abnormal structures of cilia and flagella. The inner and outer dynein arms were missing, and the arrangement of cilia was disordered. DNA sequencing showed that all patients have carried a c.355C>T variant of the PIH1D3 gene. The corresponding nucleotide was located in a key PIH1 domain, and the site is highly conserved among human, macaque, domestic dog, mouse, xenopus and zebrafish. CONCLUSION: Deletion of the PIH1D3 gene can lead to failure of assembly of inner and outer dynein arms in nasal cilia and sperm flagella, and failure of normal swimming of cilia and sperm. The diagnosis rate of PCD can be validated by genetic testing.

Fouling modeling of the mixed liquor in MBR by the individual and combined models.

To predict the membrane fouling phenomena in the membrane filtration operation, the individual models derived from Darcy's law and the corresponding combined models were employed to investigate the kind of models that provided better fits. The filtration of the mixed liquid from membrane bioreactors with different sludge retention time (SRT) at a constant pressure was carried out. The variation of applied pressure had significantly effect on the kind of the individual model provided better fit for the data at longer SRT and less effect for the data at shorter SRT, though it had less effect on the kind of the combined model that provided better fit. The kind of model that provided better fit did not change when the concentration of the diluted mixed liquor was at a certain range, even though the dilution ratio would lead to the variation of the prediction results. The cake-standard model and the complete-standard model provided good fits at different pressure and at different dilution ratio, respectively. The cake-standard and complete-standard models may be applicable to systems where these models are consistent with the experimentally observed fouling mechanisms.

[Phosphorus removal characteristics by aerobic granules in normal molasses wastewater after anaerobic treatment].

COD decreased obviously in normal molasses wastewater after anaerobic treatment, however, concentrations of nitrogen and phosphorus were still higher in the effluent which seriously damaged the ecological balance. In this study, aerobic granules cultivated in sequencing batch airlift reactor (SBAR) were carried out for treating the effluent; phosphorus removal processes and characteristics were discussed as well. The mean diameter of aerobic granules cultivated by multiple carbon sources (acetate, propionate and butyrate) was 1.7 mm. The average phosphorus removal efficiency was 90.9% and the level of phosphorus in effluent was only 1.3 mg x L(-1); TP released per COD consumed was 0.571 and the specific rate of TP released was 5.73 mg x (g x h)(-1). NO3(-) -N usage of phosphorus accumulating organisms (PAOs) improved during denitrifying process because the concentration of propionate and butyrate increased in multiple carbon sources which means the phosphorus uptake efficiency increased when per NO3(-) -N consumed. Phosphorus content represented a stronger correlation with magnesium, calcium and ferrum contents in aerobic granules and their extracellular polymeric substances (EPS), the phosphorus adsorption by EPS could enhance phosphorus removal. 61.9% of phosphorus accumulating organisms were denitrifying phosphorus accumulating organisms in aerobic granules and TP uptake per NO3(-) -N consumed was 1.14 which was higher than that of aerobic granules only cultivated by acetate.

Comparative performance between intermittently cyclic activated sludge-membrane bioreactor and anoxic/aerobic-membrane bioreactor.

A process of intermittently cyclic activated sludge-membrane bioreactor (ICAS-MBR) was developed to enhance the performance of biological phosphorus removal (EBPR), which was constructed under sequencing anoxic/anaerobic/aerobic condition. The performance between ICAS-MBR and conventional anoxic/aerobic-membrane bioreactor (A/O-MBR) in terms of phosphorus removal, nitrification performance and microbial aspects were investigated in this study. The experimental results indicated that the phosphorus removal efficiency in ICAS-MBR process increased from 65% to 83% when compared with A/O-MBR. It was also found that the COD removal efficiencies of the two processes were over 94%, and NH(4)(+)-N and TN average removal efficiencies were 96% and 69% in ICAS-MBR and 96% and 78% in A/O-MBR, respectively. Furthermore, micrographs observation obtained confirmed the succession and diversification of microorganisms in the two systems followed a similar regularity.

Aerobic granules formation and nutrients removal characteristics in sequencing batch airlift reactor (SBAR) at low temperature.

To understand the effect of low temperature on the formation of aerobic granules and their nutrient removal characteristics, an aerobic granular sequencing batch airlift reactor (SBAR) has been operated at 10 degrees C using a mixed carbon source of glucose and sodium acetate. The results showed that aerobic granules were obtained and that the reactor performed in stable manner under the applied conditions. The granules had a compact structure and a clear out-surface. The average parameters of the granules were: diameter 3.4mm, wet density 1.036 g mL(-1), sludge volume index 37 mL g(-1), and settling velocity 18.6-65.1 cm min(-1). Nitrite accumulation was observed, with a nitrite accumulation rate (NO(2)(-)-N/NO(x)(-)-N) between 35% and 43% at the beginning of the start-up stage. During the stable stage, NO(x) was present at a level below the detection limit. However, when the influent COD concentration was halved (resulting in COD/N a reduction of the COD/N from 20:1 to 10:1) nitrite accumulation was observed once more with an effluent nitrite accumulation rate of 94.8%. Phosphorus release was observed in the static feeding phase and also during the initial 20-30 min of the aerobic phase. Neither the low temperature nor adjustment of the COD/P ratio from 100:1 to 25:1 had any influence on the phosphorus removal efficiency under the operating conditions. In the granular reactor with the influent load rates for COD, NH(4)(+)-N, and PO(4)(3-)-P of 1.2-2.4, 0.112 and 0.012-0.024 kg m(-3)d(-1), the respective removal efficiencies at low temperature were 90.6-95.4%, 72.8-82.1% and 95.8-97.9%.