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Cellular foams are widely applied as protective and energy absorption materials in both civil and military fields. A facile and simple one-step heating method to fabricate polymeric foams is measured by adopting thermally expandable microspheres (TEMs). The ideal foaming parameters for various density foams were determined. Moreover, a mechanical testing machine and split Hopkinson bar (SHPB) were utilized to explore the quasi-static and dynamic compressive properties. Results showed that the cell sizes of the as-prepared TEMs foams were in the micrometer range of 11 μm to 20 μm with a uniform cell size distribution. All the foams exhibited good compressive behavior under both quasi-static and high strain rate conditions, and were related to both foam densities and strain rates. The compressive strength of the TEMs foams at 8400 s−1 was up to 4 times higher than that at 10−4 s−1. The effects exerted by the strain rate and sample density were evaluated by a power law equation. With increasing density, the strain rate effect was more prominent. At quasistatic strain rates below 3000 s−1 regime, initial cell wall buckling and subsequent cellular structure flattening were the main failure mechanisms. However, in the high strain rate (HSR) regime (above 5000 s−1), the foams were split into pieces by the following transverse inertia force. [ABSTRACT FROM AUTHOR]

The concentration of suspended solids of effluent often varies in a wide range, therefore the dose of ultraviolet light (UV) in disinfection process needs to be adjusted to meet the disinfection criterion at a high frequency, and the desired disinfection effect is difficult to be ensured. The particles size and particle-associated fecal coliform (F.C.) contribution, and their influence on UV disinfection were investigated when ClO_2 and UV combined disinfection process was used. The results showed that suspended solids content had a major impact on UV disinfection efficiency, especially the large particle size fraction. Particles (D>10μm) associated F.C. were difficult to be disinfected and were the main part of the tailings of F.C. inactivation curve. Pre-ClO_2 oxidation could reduce the number of particles in effluent, and make large particles decrease to small ones. Therefore, the influence of particles on UV disinfection could be reduced after pre-ClO_2 oxidation, and the resistance ability to particle loadings of combined process was enhanced. Moreover, the combined process has a lot of advantages, such as low toxicity, low operational/maintenance costs; it is also convenient to be established in the existing wastewater plant or the new planned one. [ABSTRACT FROM AUTHOR]

Simultaneous biological phosphorus and nitrogen removal with enhanced anoxic phosphate uptake via nitrite was investigated in an anaerobic-aerobic-anoxic-aerobic sequencing batch reactor ((AO)^2 SBR). The system showed stable phosphorus and nitrogen removal performance, and average removals for COD, TN and TP were 90%, 91% and 96%, respectively. The conditions of pH 7.5–8.0 and temperature 32°C were found detrimental to nitrite oxidation bacteria but favorable to ammonia oxidizers, and the corresponding specific oxygen uptake rates (SOUR) for phase 1 and 2 of nitrification process were 0.7 and 15 mgO_2/(gVSS·h) in respect, which led to the nitrite accumulation in aerobic phase of (AO)^2 SBR. Respiratory tests showed that 40 mgNO_2-N/L did not deteriorate the sludge activity drastically, and it implied that exposure of sludge to nitrite periodically enabled the biomass to have more tolerance capacity to resist the restraining effects from nitrite. In addition, batch tests were carried out and verified that denitrifying phosphorus accumulation organisms (DPAOs) could be enriched in a single sludge system coexisting with nitrifiers by introducing an anoxic phase in an anaerobic-aerobic SBR, and the ratio of the anoxic phosphate uptake capacity to aerobic phosphate uptake capacity was 45%. It was also found that nitrite (up to 20 mgNO_2-N/L) was not inhibitory to anoxic phosphate uptake and could serve as an electron acceptor like nitrate, but presented poorer efficiency compared with nitrate. [ABSTRACT FROM AUTHOR]

The operational performance of a full-scale subsurface-flow constructed wetland, which treated the mixed industrial and domestic wastewater with BOD5/COD mean ratio of 0.33 at Shatian, Shenzhen City was studied. The constructed wetland system consists of screens, sump, pumping station, and primary settling basin, facultative pond, first stage wetland and secondary stage wetland. The designed treatment capacity is 5000 m³/d, and the actual influent flow is in the range of <2000 to > 10000 m³/d. Under normal operational conditions, the final effluent quality well met the National Integrated Wastewater Discharge Standard (GB 8978--1996), with the following parameters(mean values): COD 33.90 mg/L, BOD5 7.65 mg/L, TSS 7.92 mg/L, iN 9.11 mg/L and TP 0.56 mg/L. [ABSTRACT FROM AUTHOR]

Domestic wastewater was treated by combined anaerobic biofilm-aerobic membrane bioreactor(MBR) process, and part biomass in MBR was withdraws to treat with ozone, than the ozonated sludge was returned to anaerobic inlet. In aerobic MBR, MLSS and DO were controlled at 3000--3500 mg/L and 0.8 mg/L respectively. Comparing the experimental results of two stages, it was noticed that ozonation did not affect the removal efficiency for organics but had a significant on the removals of NH[sub3] -N and TN. During the ozonation period of two months, no excess sludge was wasted, and a zero sludge yield was obtained. [ABSTRACT FROM AUTHOR]

Abstract: The oxidation ditch has been used for many years all over the world as an economic and efficient wastewater treatment technology. It can remove COD, nitrogen and a part of phosphorus efficiently. In the experiment described, a pilot scale Pasveer oxidation ditch system has been tested to investigate the removal of phosphorus from wastewater. The experimental results showed that influent total phosphorus(TP) was removed for 35% - 50%. After this, two anaerobic tanks with total volume of 11 m³ were added to the system to release phosphorus. As a result, the TP removal efficiency increased by about 20%. At an anaerobic HRT of about 6 hours, a TP removal efficiency of 71% was achieved. [ABSTRACT FROM AUTHOR]

In 30 patients with Lyme disease, the lesions of erythema chronicum migrans were absent or atypical. Thirty biopsy specimens were obtained from cutaneous lesions of these patients. The predominant histological finding was a superficial dermal and deep perivascular and interstitial infiltrate composed mostly of lymphocytes but containing a few eosinophils and plasma cells. In serial sections with a silver stain, a few Borrelia burgdorferi were found in the biopsy specimens from cutaneous lesions in five patients. Thus, there is evidence that the typical lesions of erythema chronicum migrans of the classical Lyme disease do not develop while Borrelia burgdorferi survive and persist in cutaneous lesions. [ABSTRACT FROM AUTHOR]

Abstract: A bench-scale anaerobic/anoxic/aerobic process-biological aerated filter (A2/O-BAF) combined system was carried out to treat wastewater with lower C/N and C/P ratios. The A2/O process was operated in a short aerobic sludge retention time (SRT) for organic pollutants and phosphorus removal, and denitrification. The subsequent BAF process was mainly used for nitrification. The BAF effluent was partially returned to anoxic zone of the A2/O process to provide electron acceptors for denitrification and anoxic P uptake. This unique system formed an environment for reproducing the denitrifying phosphate-accumulating organisms (DPAOs). The ratio of DPAOs to phosphorus accumulating organisms (PAOs) could be maintained at 28% by optimizing the organic loads in the anaerobic zone and the nitrate loads into the anoxic zone in the A2/O process. The aerobic phosphorus over-uptake and discharge of excess activated sludge was the main mechanism of phosphorus removal in the combined system. The aerobic SRT of the A2/O process should meet the demands for the development of aerobic PAOs and the restraint on the nitrifiers growth, and the contact time in the aerobic zone of the A2/O process should be longer than 30 min, which ensured efficient phosphorus removal in the combined system. The adequate BAF effluent return rates should be controlled with 1–4 mg/L nitrate nitrogen in the anoxic zone effluent of A2/O process to achieve the optimal nitrogen and phosphorus removal efficiencies. [Copyright &y& Elsevier]

The water quality of a small watershed will directly affect the water quality safety of the entire watershed. The Lidu small watershed of the Fulin District in Chongqing was selected for this study. The characteristics of runoff and the microbial community in the receiving water body were analyzed by high-throughput sequencing technology. The effects of the physical and chemical factors of the water body on the microbial diversity in the water body were also investigated. The results showed that the small watershed of Lidu was an important source of nitrite and dissolved organic carbon for the receiving water. There was no significant difference in the microbial richness and diversity of the water flowing through different pollution sources in the small watershed, and the microbial diversity index was negatively correlated with the total phosphorus ( r -0.79--0.84, P ≤ 0.01) and phosphate ( r -0.71--0.80, P ≤ 0.01) of the water. At the phylum level, Actinobacteria (37.33% ±14.69%) accounted for the largest proportion of runoff flowing through the agricultural area, followed by Proteobacteria (32.53% ±7.18%), Cyanobacteria (14.65% ±22.64%), Bacteroidetes (8.50% ±3.67%), and others. Proteobacteria (43.67% ±10.80%) accounted for the largest proportion of runoff flowing through the industrial area, followed by Bacteroidetes (25.33% ±11.97%), Actinobacteria (24.17% ±14.66%), Firmicutes (2.53% ±0.72%), and others. At the genus level, hgcI&#95;clade (19.08% ±13.46%) accounted for the largest proportion of runoff flowing through the agricultural area, followed by CL 500-29 &#95;marine&#95;group (7.40% ±4.44%), Limnohabitans (7.05% ±3.14%), and others. Flavobacterium (20.40% ±12.37%) accounted for the largest proportion of runoff flowing through the industrial area, followed by hgcI&#95;clade (15.30% ±11.11%), Acinetobacter (9.33% ±11.50%), and others. The Flavobacterium in the runoff water may be related to the input of industrial sources in the watershed. Nitrous nitrogen, total phosphorus, phosphate, pH, and Zn 2+ were the main environmental factors that affected the microbial community in the small watershed. They can explain the variance of microbial community 0.26, 0.21, 0.20, 0.15, and 0.14, respectively. DOC, nitrate nitrogen, and heavy metal ions such as Cu 2+ , Zn 2+ , Mn 2+ , and As 3+ were also related to the proportion of some microorganisms in the water.

By parallel operation of three phosphorus removal systems (SBR) using different electron acceptors of O2, NO3(-) and NO2(-), process characteristics and inherent competition mechanism of microorganisms were discussed. Although NO2(-) had no direct inhibition on anoxic phosphorus uptake after the DPAO cultivation, system performance was still much lower than that with NO3(-) as electron acceptor. And it ultimately resulted from the washout of the group of DPAO (DPAO5) that lacked the ability to denitrify NO2(-) and the enhanced GAO growth in the system. Being the efficient electron acceptor, NO3(-) or O2 supplying SBRs removed phosphorus smoothly and comparatively, in viewpoint of stiochoimetry and constitution of functional bacteria. In all three test systems, mass of GAO was present to exhaust limited organics with PAO population. Moreover, total PAO could be divided into 6 distinct groups, i.e., PO, PN, Pn, PNn, PON and PONn, based on the abilities of utilizing different electron acceptors. And facultative PAO of PON and PONn were found as the main contributors for the phosphorus removal. The higher ratio they accounted in sludge, the more capacity the system possessed to remove phosphorus, i.e., SBR0 > SBRn5 > SBRn3.

In order to investigate shortcut nitrification, an intermittent-aeration SBR was employed to treat the domestic wastewater containing low concentration of NH4+ . The results shows that under the SRTs of 10, 5, 2.5 and 1.25 d, NO2- produced in effluent were built up to 18, 19, 14 and 5 mg/L, respectively, with accumulation ratio of 73%, 85%, 91% and 78% respectively. As to the continuous-aeration SBR, however, the NO2- accumulation ratios were only 14%, 21%, 31% and 34%. In addition, the corresponding removals of NH4- in the intermittent-aeration SBR were maintained at a comparable level in contrast to those for the continuous-aeration SBR, i.e., 97%, 95%, 76% and 39% vs. 92%, 97%, 71% and 47%. By exploring the growth kinetics of nitrifiers, ammonia-oxidizing bacteria (AOB) in the intermittent-aeration system was capable of increasing its biomass in the reactor by an elevation in growth yield (Y(AOB)), which as a result compensated the decreased specific substrate utilization rate at low DO level and further led to the unchanged microm value and NH4+ oxidation rate. On the contrary, nitrite-oxidizin bacteria (NOB) was lack of the function of compensability, and it hence lowered the microm value and NO2-oxidation rate, and therefore resulted in an accumulation of NO2- in the effluent.

Based on theoretical analysis, a mathematic model was primarily set up to describe the relationship between the ozone mass transfer efficiency (U) and the systematic factors, including sludge concentration, input gas concentration, mixed liquor height h, observed gas velocity u(obs) and the bubble diameter d. By different experimental design, furthermore, the contribution of these factors for transfer efficiency was investigated respectively. The results show that the mixed liquor height h and bubble diameter d impacted the mass transfer efficiency of ozone more significantly, as compared to the other factors of sludge concentration, input gas concentration and observed gas velocity u(obs). When mixed liquor height h was 0.2 m, the ozone gas utilization U was only 0.45; when h was 0.8 m, U increased to 0.883; when h was 1.4, U was almost up to 1. The U and h show strong index relationship. For mixed liquor with h 0.8 m, when bubble diameter d decreased from 0.007 5 to 0.005, U increased from 0.89 to 0.96, and, for mixed liquor with h 0.6 m, similar increase from 0.8 to 0.93 was observed. According to the acquired experimental data, a quantitative expression among mass transfer efficiency U, mixed liquor height h and mean bubble diameter d, with R2 equal to 0.861 6, was finally obtained, as a reference tool for project design.

Based on the simulated results from N cycling and transformation model of duckweed pond, the influences of different major transfer pathways on various nitrogen removal performances are investigated. The effects of seasonal variations of water conditions on nitrogen transformations are determined. The simulated results show that nitrification and denitrification were the major removal pathways for nitrogen in duckweed pond, and the removal contributions of organic nitrogen sedimentation and ammonia volatilization for total nitrogen removal were less than 2.1%. Furthermore, in duckweed pond, nitrification and denitrification decided the removal efficiencies of ammonia and NOx., respectively; both algae decaying and organic nitrogen ammonification controlled primarily the organic nitrogen removal performances; both organic nitrogen sedimentation and mineralization of sedimentary nitrogen determined the variations of sedimentary nitrogen. Duckweed pond with duckweed growing largely can increase sharply algae mortality and keep the low content of algae in effluent. Besides, through accelerating the nitrification and denitrification rate, duckweed can evidently improve the removal efficiencies of total nitrogen.

The aim of this work is operational optimization of an A/O process in the lab plant with synthetic wastewater for improving nitrogen removal efficiency. Ammonia control aims at maintaining the required concentration of ammonia in the effluent by manipulating the dissolved oxygen (DO) set point and aeration volumes. Nitrate control aims at the optimal use of the denitrification potential at any moment by continuously adjusting the internal recirculation flow or (and) external carbon addition flow in order to maintain a desired nitrate set point in the anoxic zone. The control strategies have been based on a hierarchical structure where a high level or supervisory control selects the set point of the low level or conventional controllers. Results indicated that it was possible to increase nitrogen removal efficiency, improve the effluent water quality, save energy, and reduce operating costs.

Objective: To investigate effects of Chinese herb compound on myocardial SDH, ATP-ase and energy reserves in tail-suspended rats., Method: Male SD rats were randomly divided into three groups (n=10 each): (A) normal control group; (B) tail-suspended group; (C) tail-suspended + Chinese Medical herb compound group. Rats in group B and C were tail-suspended (-30 degrees) for 5 d to simulate weightlessness. All rats B were decapitated after the experiment. Myocardial SDH (method of Anderson N-BT), ATP-ase (method of Wachstein and Meisel) and energy reserves (method of HPLC) were examined., Result: Compared with rats in groups A and C, SDH activity increased, SDH staining deepened, value of OD SDH enhanced, ATP-ase activity and OD value increased and enhanced significantly (P<0.01) but value of myocardial energy reserves decreased in group B rats., Conclusion: Tail-suspension strengthens compensatory oxidation metabolism of cardiac muscle and activates SDH and ATP-ase, at the same time decrease, myocardial energy reserves. Normal are maintained the low level of metabolism by the medical herb compound used which shows a protecting effects through mitigation, tranguilization and replenishment of Qi.

Simultaneous biological phosphorus and nitrogen removal with enhanced anoxic phosphate uptake via nitrite was investigated in an anaerobic-aerobic-anoxic-aerobic sequencing batch reactor ((AO)2 SBR). The system showed stable phosphorus and nitrogen removal performance, and average removals for COD, TN and TP were 90%, 91% and 96%, respectively. The conditions of pH 7.5-8.0 and temperature 32 degrees C were found detrimental to nitrite oxidation bacteria but favorable to ammonia oxidizers, and the corresponding specific oxygen uptake rates(SOUR) for phase 1 and 2 of nitrification process were 0.7 and 15 mgO2/(gVSS x h) in respect, which led to the nitrite accumulation in aerobic phase of (AO)2 SBR. Respiratory tests showed that 40 mgNO2-N/L did not deteriorate the sludge activity drastically, and it implied that exposure of sludge to nitrite periodically enabled the biomass to have more tolerance capacity to resist the restraining effects from nitrite. In addition, batch tests were carried out and verified that denitrifying phosphorus accumulation organisms (DPAOs) could be enriched in a single sludge system coexisting with nitrifiers by introducing an anoxic phase in an anaerobic-aerobic SBR, and the ratio of the anoxic phosphate uptake capacity to aerobic phosphate uptake capacity was 45%. It was also found that nitrite (up to 20 mgNO2-N/L) was not inhibitory to anoxic phosphate uptake and could serve as an electron acceptor like nitrate, but presented poorer efficiency compared with nitrate.

Two runs of experiments were carried out to obtain an understanding of phosphorus release and uptake under the anaerobic condition and then the aerobic condition respectively. Under anaerobic condition, it was found that the extent of phosphorus release appeared to increase with the increase of the initial organic loading rate when the initial organic loading rate was up to 0.1 gSCOD/gMLSS. When the initial organic loading rate was higher than 0.1 gSCOD/gMLSS, the amount of phosphorus release per unit mass of MLSS reached nearly a same stationary value, and it seemed this is not affected by organic loading rate when there is external available substrate remained. In addition, the effect of NOx-N on the phosphorus release and uptake was also investigated, it was proved that the denitrifiers has an advantage over polyphosphate accumulating bacteria in competition for organic substrate under anoxic condition. Therefore, the existence of NOx-N is disadvantageous to the phosphorus release. Based upon the above investigations, the process configuration of membrane bioreactor(MBR) in combination with anaerobic phase was proposed to enhance the removal of phosphorus in treating domestic wastewater. During the experimental period of four months, average removals of 92.50%, 84.25%, 100%, 94.09% and 85.33% were achieved for COD, TP, SS, NH3-N and TN respectively.

The innovative process consists of biological unit for wastewater treatment and ozonation unit for excess sludge treatment. An aerobic membrane bioreactor (MBR) was used to remove organics and nitrogen, and an anaerobic reactor was added to the biological unit for the release of phosphorus contained at aerobic sludge to enhance the removal of phosphorus. For the excess sludge produced in the MBR, which was fed to ozone contact column and reacted with ozone, then the ozonated sludge was returned to the MBR for further biological treatment. Experimental results showed that this process could remove organics, nitrogen and phosphorus efficiently, and the removals for COD, NH3-N, TN and TP were 93.17%, 97.57%, 82.77% and 79.5%, respectively. Batch test indicated that the specific nitrification rate and specific denitrification rate of the MBR were 1.03 mg NH3-N/(gMLSS x h) and 0.56 mg NOx-N/(gMLSS x h), and denitrification seems to be the rate-limiting step. Under the test conditions, the sludge concentration in the MBR was kept at 5000-6000 mg/L, and the wasted sludge was ozonated at an ozone dosage of 0.10 kgO3/kgSS. During the experimental period of two months, no excess sludge was wasted, and a zero withdrawal of excess sludge was implemented. Through economic analysis, it was found that an additional ozonation operating cost for treatment of both wastewater and excess sludge was only 0.045 RMB Yuan (USD 0.0054)/m3 wastewater.