College reopening and community spread of COVID-19 in the United States.

OBJECTIVE: After months of lockdown due to the COVID-19 outbreak, the US postsecondary institutions implemented different instruction approaches to bring their students back for the Fall 2020 semester. Given public health concerns with reopening campuses, the study evaluated the impact of Fall 2020 college reopenings on COVID-19 transmission within the 632 US university counties. STUDY DESIGN: This was a retrospective and observational study. METHODS: Bayesian Structural Time Series (BSTS) models were conducted to investigate the county-level COVID-19 case increases during the first 21 days of Fall 2020. The case increase for each county was estimated by comparing the observed time series (actual daily cases after school reopening) to the BSTS counterfactual time series (predictive daily cases if not reopening during the same time frame). We then used multilevel models to examine the associations between opening approaches (in-person, online, and hybrid) and county-level COVID-19 case increases within 21 and 42 days after classes began. The multigroup comparison between mask and non-mask-required states for these associations were also performed, given that the statewide guidelines might moderate the effects of college opening approaches. RESULTS: More than 80% of our university county sample did not experience a significant case increase in Fall 2020. There were no significant relationships between opening approaches and community transmission in both mask-required and non-mask-required states. Only small metropolitan counties and counties with a non-community college or a higher percentage of student population showed significantly positive associations with the case number increase within the first 21-day period of Fall 2020. For the longer 42-day period, the counties with a higher percentage of the student population showed a significant case increase. CONCLUSION: The overall findings underscored the outcomes of US higher education reopening efforts when the vaccines were still under development in Fall 2020. For individual county results, we invite the college- and county-level decision-makers to interpret their results using our web application.

Evaluation of biological stability and corrosion potential in drinking water distribution systems: a case study.

The appearance of assimilable organic carbon (AOC), microbial regrowth, disinfection by-products (DBPs), and pipe corrosion in drinking water distribution systems are among those major safe drinking water issues in many countries. The water distribution system of Cheng-Ching Lake Water Treatment Plant (CCLWTP) was selected in this study to evaluate the: (1) fate and transport of AOC, DBPs [e.g., trihalomethanes (THMs), haloacetic acids (HAAs)], and other organic carbon indicators in the selected distribution system, (2) correlations between AOC (or DBPs) and major water quality parameters [e.g. dissolved oxygen (DO), free residual chlorine, and bacteria, and (3) causes and significance of corrosion problems of the water pipes in this system. In this study, seasonal water samples were collected from 13 representative locations in the distribution system for analyses of AOC, DBPs, and other water quality indicators. Results indicate that residual free chlorine concentrations in the distribution system met the drinking water standards (0.2 to 1 mg l(-1)) established by Taiwan Environmental Protection Administration (TEPA). Results show that AOC measurements correlated positively with total organic carbon (TOC) and UV-254 (an organic indicator) values in this system. Moreover, AOC concentrations at some locations were higher than the 50 microg acetate-C l(-1) standard established by Taiwan Water Company. This indicates that the microbial regrowth might be a potential water quality problem in this system. Higher DO measurements (>5.7 mg l(-1)) might cause the aerobic biodegradation of THMs and HAAs in the system, and thus, low THMs (<0.035 mg l(-1)) and HAAs (<0.019 mg l(-1)) concentrations were observed at all sampling locations. Results from the observed negative Langelier Saturation Index (LSI) values, higher Ryznar Stability Index (RSI) values, and high Fe3+ concentrations at some pipe-end locations indicate that highly oxidative and corrosive conditions occurred. This reveals that pipe replacement should be considered at these locations. These findings would be helpful in managing the water distribution system for maintaining a safe drinking water quality.

Application of surfactant enhanced permanganate oxidation and bidegradation of trichloroethylene in groundwater.

The industrial solvent trichloroethylene (TCE) is among the most ubiquitous chlorinated solvents found in groundwater contamination. The main objectives of this study were to evaluate the feasibility of using non-ionic surfactant Simple Green (SG) to enhance the oxidative dechlorination of TCE by potassium permanganate (KMnO4) employing a continuous stir batch reactor system (CSBR) and column experiments. The effect of using surfactant SG to enhance the biodegradation of TCE via aerobic cometabolism was also examined. Results from CSBR experiments revealed that combination of KMnO4 with surfactant SG significantly enhanced contaminant removal, particularly when the surfactant SG concentrated at its CMC. TCE degradation rates ranged from 74.1% to 85.7% without addition of surfactant SG while TCE degradation rates increased to ranging from 83.8% to 96.3% with presence of 0.1wt% SG. Furthermore, results from column experiments showed that TCE was degraded from 38.1microM to 6.2microM in equivalent to 83.7% of TCE oxidation during first 560min reaction. This study has also demonstrated that the addition of surfactant SG is a feasible method to enhance bioremediation efficiency for TCE contaminated groundwater. The complete TCE degradation was detected after 75 days of incubation with both 0.01 and 0.1wt% of surfactant SG addition. Results revealed that surfactant enhanced chemical oxidation and bioremediation technology is one of feasible approaches to clean up TCE contaminated groundwater.

Application of in situ biosparging to remediate a petroleum-hydrocarbon spill site: field and microbial evaluation.

In this study, a full-scale biosparging investigation was conducted at a petroleum-hydrocarbon spill site. Field results reveal that natural attenuation was the main cause of the decrease in major contaminants [benzene, toluene, ethylbenzene, and xylenes (BTEX)] concentrations in groundwater before the operation of biosparging system. Evidence of the occurrence of natural attenuation within the BTEX plume includes: (1) decrease of DO, nitrate, sulfate, and redox potential, (2) production of dissolved ferrous iron, sulfide, methane, and CO(2), (3) decreased BTEX concentrations along the transport path, (4) increased microbial populations, and (5) limited spreading of the BTEX plume. Field results also reveal that the operation of biosparging caused the shifting of anaerobic conditions inside the plume to aerobic conditions. This variation can be confirmed by the following field observations inside the plume due to the biosparging process: (1) increase in DO, redox potential, nitrate, and sulfate, (2) decrease dissolved ferrous iron, sulfide, and methane, (3) increased total cultivable heterotrophs, and (4) decreased total cultivable anaerobes as well as methanogens. Results of polymerase chain reaction, denaturing gradient gel electrophoresis, and nucleotide sequence analysis reveal that three BTEX biodegraders (Candidauts magnetobacterium, Flavobacteriales bacterium, and Bacteroidetes bacterium) might exist at this site. Results show that more than 70% of BTEX has been removed through the biosparging system within a 10-month remedial period at an averaged groundwater temperature of 18 degrees C. This indicates that biosparging is a promising technology to remediate BTEX contaminated groundwater.

Application of potassium permanganate as an oxidant for in situ oxidation of trichloroethylene-contaminated groundwater: a laboratory and kinetics study.

The objectives of this bench-scale study were to (1) determine the optimal operational parameters and kinetics when potassium permanganate (KMnO4) was applied to in situ oxidize and remediate trichloroethylene (TCE)-contaminated groundwater and (2) evaluate the effects of manganese dioxide (MnO2) on the efficiency of TCE oxidation. The major controlling factors in the TCE oxidation experiments included molar ratios of KMnO4 to TCE (P value) and molar ratios of Na2HPO4 to Mn2+ (D value). Results show that the second-order decay model can be used to describe the oxidation when P value was less than 20, and the observed TCE decay rate was 0.8M(-1)s(-1). Results also reveal that (1) higher P value corresponded with higher TCE oxidation rate under the same initial TCE concentration condition and (2) higher TCE concentration corresponded with higher TCE oxidation rate under the same P value condition. Results reveal that significant MnO2 production and inhibition of TCE oxidation were not observed under acidic (pH 2.1) or slightly acidic conditions (pH 6.3). However, significant reduction of KMnO(4) to MnO2 would occur under alkaline condition (pH 12.5), and this caused the decrease in TCE oxidation rate. Results from the MnO2 production experiments show that MnO2 was produced from three major routes: (1) oxidation of TCE by KMnO4, (2) further oxidation of Mn2+, which was produced during the oxidation of TCE by KMnO4, and (3) reduction of MnO4(-1) to MnO2 under alkaline conditions. Up to 81.5% of MnO2 production can be effectively inhibited with the addition of Na2HPO4. Moreover, the addition of Na2HPO4 would not decrease the TCE oxidation rate.

Application of immobilized cells to the treatment of cyanide wastewater.

Cyanide is highly toxic to living organisms, particularly in inactivating the respiration system by tightly binding to terminal oxidase. To protect the environment and water bodies, wastewater containing cyanide must be treated before discharging into the environment. Biological treatment is a cost-effective and environmentally acceptable method for cyanide removal compared with the other techniques currently in use. Klebsiella oxytoca (K. oxytoca), isolated from cyanide-containing industrial wastewater, has been shown to be able to biodegrade cyanide to non-toxic end products. The technology of immobilized cells can be applied in biological treatment to enhance the efficiency and effectiveness of biodegradation. In this study, potassium cyanide (KCN) was used as the target compound and both alginate (AL) and cellulose triacetate (CTA) techniques were applied for the preparation of immobilized cells. Results from this study show that KCN can be utilized as the sole nitrogen source by K. oxytoca. The free suspension systems reveal that the cell viability was highly affected by initial KCN concentration, pH, and temperature. Results show that immobilized cell systems could tolerate a higher level of KCN concentration and wider ranges of pH and temperature, especially in the system with CTA gel beads. Results show that a longer incubation period was required for KCN degradation using immobilized cells compared to the free suspended systems. This might be due to internal mass transfer limitations. Results also indicate that immobilized systems can support a higher biomass concentration. Complete KCN degradation was observed after the operation of four consecutive degradation experiments with the same batch of immobilized cells. This suggests that the activity of the immobilized cells can be maintained and KCN can be used as the nitrogen source throughout KCN degradation experiments. Results reveal that the application of immobilized cells of K. oxytoca is advantageous to the maintenance of KCN degradation efficiency. Thus, it is conceivable that the immobilized cells of K. oxytoca would be applicable to the treatment of cyanide-containing wastewaters.

Application of monitored natural attenuation to remediate a petroleum-hydrocarbon spill site.

Contamination of groundwater by petroleum-hydrocarbons is a serious environmental problem. The Monitored Natural Attenuation (MNA) approach is a passive remediation to degrade and dissipate groundwater contaminants in situ. In this study, a full-scale natural bioremediation investigation was conducted at a gasoline spill site. Results show that concentrations of major contaminants (benzene, toluene, ethylbenzene, and xylenes) dropped to below detection limit before they reached the downgradient monitor well located 280 m from the spill location. The results also reveal that natural biodegradation was the major cause of the observed contaminant reduction. The calculated natural first-order attenuation rates for BTEX and 1,2,4-trimethylbenzene (1,2,4-TMB) ranged from 0.051 (benzene) to 0.189 1/day (1,2,4-TMB). Evidence for the occurrence of natural attenuation includes the following: (1) depletion of dissolved oxygen, nitrate, and sulfate; (2) production of dissolved ferrous iron, sulfide, and CO2; (3) decreased BTEX concentrations and BTEX as carbon to TOC ratio along the transport path; (4) increased alkalinity and microbial populations; (5) limited spreading of the BTEX plume; and (6) preferential removal of certain BTEX components along the transport path. Additionally, the biodegradation capacity (44.73 mg/L) for BTEX and 1,2,4-TMB was much higher than other detected contaminants within the plume. Hence, natural attenuation can effectively contain the plume, and biodegradation processes played an important role in contaminant removal.

Application of a constructed wetland for industrial wastewater treatment: a pilot-scale study.

The main objective of this study was to examine the efficacy and capacity of using constructed wetlands on industrial pollutant removal. Four parallel pilot-scale modified free water surface (FWS) constructed wetland systems [dimension for each system: 4-m (L)x1-m (W)x1-m (D)] were installed inside an industrial park for conducting the proposed treatability study. The averaged influent contains approximately 170 mg l(-1) chemical oxygen demand (COD), 80 mg l(-1) biochemical oxygen demand (BOD), 90 mg l(-1) suspend solid (SS), and 32 mg l(-1) NH(3)-N. In the plant-selection study, four different wetland plant species including floating plants [Pistia stratiotes L. (P. stratiotes) and Ipomoea aquatica (I. aquatica)] and emergent plants [Phragmites communis L. (P. communis) and Typha orientalis Presl. (T. orientalis)] were evaluated. Results show that only the emergent plant (P. communis) could survive and reproduce with a continuous feed of 0.4m(3)d(-1) of the raw wastewater. Thus, P. communis was used in the subsequent treatment study. Two different control parameters including hydraulic retention time (HRT) (3, 5, and 7d) and media [vesicles ceramic bioballs and small gravels, 1cm in diameter] were examined in the treatment study. Results indicate that the system with a 5-d HRT (feed rate of 0.4m(3)d(-1)) and vesicles ceramic bioballs as the media had the acceptable and optimal pollutant removal efficiency. If operated under conditions of the above parameters, the pilot-plant wetland system can achieve removal of 61% COD, 89% BOD, 81% SS, 35% TP, and 56% NH(3)-N. The treated wastewater meets the current industrial wastewater discharge standards in Taiwan.

Characteristics of neonatal bacterial meningitis in a teaching hospital in Taiwan from 1984-1997.

During the period from 1984 to 1997, 85 bacterial meningitis neonates with positive cerebrospinal fluid cultures were treated. The ages of these patients ranged from 1 to 28 days. The male to female ratio was 1.7 to 1. The most common causative agent was group B beta-hemolytic streptococci (GBS, 31.8%), followed by Escherichia coli (20%), Proteus mirabilis (7.1%), Enterobacter cloacae (5.9%), other streptococci excluding Streptococcus pneumoniae (5.9%), Chryseobacterium meningosepticum (5.9%), enterococci (4.7%), and Klebsiella pneumoniae (3.5%). Among the 85 patients treated, 51 (60%) were younger than 7 days old. Among them, dyspnea was the most common clinical manifestation. In contrast, fever and diarrhea were seen more frequently in neonates with late onset of disease (after seven days of age). Ampicillin and cefotaxime were the most commonly used antibiotics. The most frequently encountered complications were hydrocephalus and seizures. Since 1991, GBS has overtaken E. coli as the leading cause of neonatal bacterial meningitis. This was accompanied by a fall in the mortality rate, but a sustained high incidence of complications and sequelae. The results of this study highlight the importance of developing strategies to prevent group B streptococcal infection.

Aneurysm of the ascending aorta in a neonate.

Aneurysms of the thoracic aorta rarely occur in children. We present a female neonate who was referred to our hospital due to a heart murmur associated with cough and fever at 22 days of age. Both the echocardiography and aortography displayed an aneurysm of the ascending aorta at the aortic root. A patent ductus arteriosus (PDA) flow was detected on admission but it was not detectable when she was 3 months old. Neither physical characteristics of Marfan nor Turner syndrome were found, but she has had a huge cutaneous hemangioma over the right trunk since birth. The aneurysm did not progress during one year of follow-up. The etiology might be idiopathic or medial agenesis. Surgery will be warranted only if the aneurysm enlarges.