Conventional wastewater analysis based on on-site sampling holds a limitation of accuracy because of fluctuation of influent composition in time and its corruptible nature in organics. To cope with the problem, this study aimed at developing an alternative method using on-site lab-scale activated sludge reactors, where a set of mean influent material concentrations was calculated from the analysis of activated sludge constituents of which fluctuation was damped due to long sludge retention time. Focusing on the activated sludge collected from the reactor having a primary settling tank, the soluble biodegradable material concentrations in the influent were calculated using IWA Activated Sludge Model. Similarly the concentrations of inert and biodegradable particulates in the influent were obtained from the increment of activated sludge constituents between the reactor without a primary settling tank and that with a primary settling tank. The specific decay rate of the activated sludge, which was an influential kinetic parameter on the mathematical calculation, was also regularly monitored. According to the statistical analysis, 6 collection frequencies seemed to be enough to grab the parameter. This new method required noticeably low manpower to estimate particulate BOD, soluble BOD, SS and VSS in the wastewater compared to the conventional techniques.

The study was aimed at developing an alternative method to catch biodegradable concentrations in municipal wastewater, especially for designing wastewater treatment plants receiving storm water where the influent concentrations significantly changed in time. As conventional water analytical methods required lots of samples and numerous analysis, which was practically infeasible, a lab-scale nitrifying activated sludge reactor having on-line DO meter and quick-test nitrate kit was installed at the experimental site in Hue, Vietnam. By fixing the hydraulic retention time with 2.0 hours and aeration intensity, the biodegradable concentrations in the influent including carbonaceous and nitrogenous compounds were back-calculated from the dynamic response of dissolved oxygen concentration in the aeration tank and the nitrate concentration in the effluent using IWA Activated Sludge model. During the data collection event for 24 hours, the influent was also sampled at 1-hr interval and its concentrations were compared with those calculated. The field experiment successfully demonstrated that the back-calculation method could reasonably estimate the influent biological concentration on the basis of biological oxygen demand where the concentration was highly fluctuated in time. Based on the experiment, the feasibility to measure sudden elevation and decrease of pollutant load in the first flush was discussed in the paper.

Objectives: The coronavirus disease 2019 (COVID-19) pandemic has increased the workload of healthcare workers (HCWs), impacting their health. This study aimed to assess sleep quality using the Pittsburgh Sleep Quality Index (PSQI) and identify factors associated with poor sleep among HCWs in Vietnam during the COVID-19 pandemic.Methods: In this cross-sectional study, 1000 frontline HCWs were recruited from various healthcare facilities in Vietnam between October 2021 and November 2021. Data were collected using a 3-part self-administered questionnaire, which covered demographics, sleep quality, and factors related to poor sleep. Poor sleep quality was defined as a total PSQI score of 5 or higher.Results: Participants’ mean age was 33.20±6.81 years (range, 20.0-61.0), and 63.0% were women. The median work experience was 8.54±6.30 years. Approximately 6.3% had chronic comorbidities, such as hypertension and diabetes mellitus. About 59.5% were directly responsible for patient care and treatment, while 7.1% worked in tracing and sampling. A total of 73.8% reported poor sleep quality. Multivariate logistic regression revealed significant associations between poor sleep quality and the presence of chronic comorbidities (odds ratio [OR], 2.34; 95% confidence interval [CI], 1.17 to 5.24), being a frontline HCW directly involved in patient care and treatment (OR, 1.59; 95% CI, 1.16 to 2.16), increased working hours (OR, 1.84; 95% CI,1.37 to 2.48), and a higher frequency of encountering critically ill and dying patients (OR, 1.42; 95% CI, 1.03 to 1.95).Conclusions: The high prevalence of poor sleep among HCWs in Vietnam during the COVID-19 pandemic was similar to that in other countries. Working conditions should be adjusted to improve sleep quality among this population.

Aims: To determinate the correlation between IVC diameter and CVP in patients with shock. Patients and Method: A study of 64 patients with low blood pressure, admitted to Quang Nam general hospital. The CVP catheter was placed, the IVC diameter at the end of expiration and at the end of inspiration was measured with the ultrasound at bed, determine the maximum diameter at the end of expiration, the smallest diameter at the end of inspiration. Results: There was a good correlation between the IVC diameter and the central venous pressure: (r = 0.74; p <0.01). There was a correlation between the IVC index and and central venous pressure (r = -0.862; p <0.01). IVC index ≥ 38.19% had a central venous pressure predicton value of < 8 cm H20 (sensitvity 97.3%, specifcity 85.2%). Conclusion: IVC diameter may be used to predict the CVP Key words: IVC, echocardiography

Ascertaining peak oxygen demand is crucial for plant designers to determine blower capacities of wastewater treatment plants in planning phase. To obtain this technical information without cumbersome influent sampling and analysis, a set of field-test activated sludge reactors equipped with DO and nitrate-N sensors was installed at 3 sites and continuously operated for a couple of months in each field. Under the controlled aeration and hydraulics of the reactors, the hourly influent oxygen demands were back-calculated as biodegradable constituents using the IWA-Activated Sludge Model #1. The daily maximum concentrations (rounded to last for 1-hour) of biodegradable organics and nitrogen were ranged between 45~258 mg-COD/L and 10.4~32.3 mg-N/L in Site #1; 119~244 mg-COD/L and 28.3~38.7 mg-N/L in Site #2; 194~552 mg-COD/L and 30.2~51.7 mg-N/L in Site #3 respectively. The marginal blower capacities to maintain at least 1.0 mg-O 2 /L of DO in the daily maximum oxygen demand were estimated based on the datasets using the statistical method, Extreme Value Distribution analysis. To maintain the DO concentration for 99 days out of 100 days of the plant operations, the blower capacity was supposed to be designed as high as 1.4~2.2 times than those of the blower calculated from the daily average concentration.