Efficient municipal wastewater treatment by oxidation ditch process at low temperature: Bacterial community structure in activated sludge.

Temperature is a key element affecting the activity of microorganisms in activated sludge. Low water temperature generally leads to decreasing wastewater treatment efficiency and destroying sludge settleability. In this study, activated sludge samples from a municipal wastewater treatment plant (WWTP) implementing oxidation ditch process was used to investigate the bacterial community characteristics of a system that operates well in a cold region (Xinjiang, China) by high-throughput 16S rRNA gene sequencing. The results showed that the influent temperature was 7-12 °C in winter and 13-17 °C in summer, while the sludge volume index (SVI) of samples was between 51 and 74 mL/g. The average removal efficiencies for chemical oxygen demand (COD), biochemical oxygen demand (BOD5), suspended solid (SS), ammonia nitrogen (NH4+-N), total nitrogen (TN), and total phosphorus (TP) were 94%, 95%, 95%, 91%, 73% and 89%, respectively. The bacteria were distributed in 32 phyla and 559 genera. The dominant phyla were Proteobacteria (28.85-48.45%), Bacteroidetes (20.00-31.22%), Chloroflexi (3.59-12.23%), Actinobacteria (1.58-15.54%) and Firmicutes (1.38-10.49%). The dominant genera were Saprospiraceae_norank (4.41-12.23%), Comamonadaceae_unclassified (3.82-8.83%), Anaerolineaceae_norank (1.39-9.35%), Dokdonella (1.13-11.26%), Candidatus_Microthrix (0.26-7.50%), Flavobacterium (0.32-8.14%), Ferribacterium (0.36-5.19%) and Nitrospira (0.084-5.37%), which were different from those found in warm-region WWTPs. Contrary to previous studies, the relative abundance of ammonia-oxidizing bacteria (AOB; Nitrosomonas and Nitrosomonadaceae) and nitrite-oxidizing bacteria (NOB; Nitrospira) increased when the temperature decreased. The successful operation of this WWTP suggests that cold-region WWTPs can achieve good pollutants removal efficiency by simultaneously maintaining an ultra-low sludge load and high dissolved oxygen concentration in the oxidation ditch. The findings of this study provide fundamental knowledge required for an efficient and stable operation of WWTPs in cold regions.

Anatomy of Mine Rescue Teams' Casualty Incidents: A Basis for Medical Emergency Preparedness and Injury Prevention.

OBJECTIVE: Mine rescue teams bear a high risk of injury. To improve medical emergency preparedness and injury prevention, this work analyzed the causes and severity of mine rescue teams' casualty incidents, the primary injuries, and the link between the causes and the occurrences of the casualty incidents. METHODS: A total of 81 cases from 1953 to 2013 were used to analyze the casualty incidents of mine rescue teams based on the frequency of accidents. A panel with 4 rescue experts was set up to ensure the accuracy of the analysis. RESULTS: The 81 casualty incidents occurred in 7 types of rescue work and were due to 6 causes. Organizational and personal factors were the leading cause, followed by rescue skill and equipment factors. Problems with decision-making and command have gradually become the primary inducement of casualty incidents in recent years, with an average death toll reaching up to 6 to 7 people. The main injuries causing death to team members were blast injury, burns, poisoning, suffocation, blunt trauma, and overwork injury. Some of the injured died because of medical emergency response failure. CONCLUSION: The construction of emergency medical teams and the preparedness of disaster medicine need to be improved to reduce the mortality of the injured team members. Actions according to the causes of casualty incidents should be adopted for injury prevention. (Disaster Med Public Health Preparedness. 2019;13:695-699).

[Preparation and evaluation of a new type of amino-bonded silica chromatographic stationary phase for the determination of lactose].

A method for the separation and determination of lactose and sucrose using high performance liquid chromatography-refractive index (HPLC-RI) detection base on the prepared amino-bonded silica gel chromatographic stationary phase was established. The method was accorded to the content determination method in Pharmacopoeia of the People's Republic of China (2015). Then, a series of chromatographic behaviors of lactose and sucrose such as the retention times, resolutions and peak area stabilities were investigated on three different types of amino-bonded silica columns (300 mm×4.6 mm, 5 µm). The mobile phase was acetonitrile-water (70:30, v/v) with isocratic elution, the flow rate was 1.0 mL/min and the injection volume was 10 µL. The resolution of lactose and sucrose was 3.03 by isopropyl side chain protected amino column, and the peak shape of each target compound was good. The relative standard deviation (RSD) of peak area of lactose was 1.14%, less than 2.0% prescribed in the Pharmacopoeia of the People's Republic of China (2015). Therefore, this method meets the requirements of lactose content determination, and is suitable as the quality control method in the above mentioned Pharmacopoeia.