[Investigation on Oxygen Gas-liquid Mass Transfer in Sewage Pipelines Under Enhanced Ventilation].

The anaerobic environment of sewers is the main cause of the production of toxic and harmful gases such as hydrogen sulfide and methane. The installation of septic-tanks between the drainage standpipes and municipal sewage pipes has aggravated the current situation of poor ventilation in sewage pipes. A system of enhanced ventilation has been formed. By connecting the drainage standpipes and sewage pipes, the system of enhanced ventilation can ameliorate the ventilation of sewage pipes and improve the gas-phase space environment. The experimental and computational fluid dynamics (CFD) simulation methods were established to explore the law of oxygen gas-liquid mass transfer under the different sewage flow rates or wind speeds. This study aimed to seek a method to enhance the oxygen mass transfer, suppress the anaerobic environment, and achieve the purpose of long-term control of harmful gases. The results showed that increasing the gas-liquid flow rates can accelerate the oxygen mass transfer, and the volumetric mass transfer coefficient increased by 3.5×10-4 min-1 for every increase of 0.1 m·s-1. However, the faster sewage reduced hydraulic retention time. The mass transfer time of oxygen was also shortened, and the promotion effect was not as good as that by enhancing the gas velocity in the pipelines. At the same time, when the average gas velocity increased by 0.1 m·s-1, the lengths of pipes where dissolved oxygen could effectively inhibit H2S increased by 25 m.

Effect of minocycline on the changes in the sewage chemical index and microbial communities in sewage pipes.

With the increasing use of drugs in cities, the sewer is becoming the most suitable place for antibiotic accumulation and transfer. In order to reveal the occurrence and fate of antibiotic sewage during pipeline migration, we used an anaerobic reactor device to simulate the concentration change of minocycline in the sewer and its impact on the sewage quality. The results showed that 90.8 % of minocycline was removed during sewer transportation. In the presence of minocycline, although the consumption of Chemical Oxygen Demand and total nitrogen in the sewage did not change significantly, the consumption rate of total phosphorus, nitrate nitrogen and the growth rate of ammonia nitrogen at the front end of the pipeline were decreased from 29.4 %, 86.3 %, 60.3 % to 3.7 %, 81.5 %, 18.3 % respectively. Minocycline inhibited the reduction of SO42-, while also reducing the production of H2S gas and increasing the release of CH4 gas. Moreover, the decline in the abundance of functional bacteria such as phosphorus accumulating organisms was consistent with the consumption of sewage nutrients. This experiment provides data support for the risk of wastewater leakage of medical and pharmaceutical wastewater into domestic sewage, and will helps to maintain the safe operation of actual sewage pipes.

Simultaneous removal of Cd2+, NO3-N and hardness by the bacterium Acinetobacter sp. CN86 in aerobic conditions.

This study investigated the factors influencing the simultaneous removal of Cd2+, NO3-N and hardness from water by the bacterial strain CN86. Optimum conditions were determined experimentally by varying the type of organic matter used, initial Cd2+ concentration, and pH. Under the optimum conditions, the maximum removal ratios of Cd2+, NO3-N and hardness were 100.00, 89.85 and 71.63%, respectively. The mechanism of Cd2+ removal is a combination of co-precipitation with calcium carbonate and pH. Further confirmation that Cd2+ can be removed by strain CN86 was provided by XRD and XPS analyses. Meteorological chromatography analysis showed that N2 was produced as an end product. These results demonstrate that the bacterial strain CN86 is a suitable candidate for simultaneously removing Cd2+, NO3-N, and hardness during in wastewater treatment.

[Seasonal Succession Characteristics of the Morphologically-based Functional Groups (MBFG) in Deep-water Reservoir].

Morphologically-based functional groups (MBFG) is the basis for a simple way of distinguishing the phytoplankon to cluster species according to their similar morphological traits observed by optical microscope.In order to understand the application of morphologically-based functional groups (MBFG) in the research on phytoplankton community structure and variation of deep-water reservoir,as well as the succession characteristics of algae,the Jinpen Reservoir was studied from August 2011 to July 2013.Using morphologically-based functional groups (MBFG),the phytoplankton communities found in the reservoir were classified to functional groups,and the relations between the morphologically-based functional groups succession and environment cases were explored with redundancy analysis (RDA) method.The results suggested that five morphologically-based functional groups were found in the reservoir,namely Ⅱ,Ⅳ,Ⅴ,Ⅵ,Ⅶ;The succession of reservoir algal functional groups had seasonal characteristics,a variety of Morphologically-based functional groups coexisted in spring and summer,while reservoir algal functional groups were relatively simple in autumn and winter;meanwhile,the density of each morphologically-based functional group decreased with the increase of water depth among the environmental factors,morphologically-based functional groups Ⅳ and Ⅵ were respectively affected by temperature;the other water layers of the reservoir morphologically-based functional groups Ⅵ was significantly affected by TN content.

[Redox Transformation of Arsenic and Antimony in Soils Mediated by Pantoea sp. IMH].

Soil contamination with co-existing arsenic (As) and antimony (Sb) has become a serious environmental problem worldwide. Microorganisms play a dominant role in the redox transformation and mobilization of As and Sb. As and Sb belong to the same family; they are alike in nature and have related microbial oxidation-reduction mechanisms. However, limited knowledge is available about the impact of As-reducing bacteria on the fate of As and Sb in their co-existing soils. The purpose of this study was to explore the redox transformation and release of As and Sb in the presence of an arsC carrier, Pantoea sp. IMH, which has high As(Ⅴ)-reducing capability. In addition to the IMH incubation system, the dead cell system and abiotic control experiments were conducted. The results showed that the IMH incubation reduced all soluble As(Ⅴ) (72.7 µg·L-1) to As(Ⅲ) form, whereas soluble Sb(Ⅴ) (364.8 µg·L-1) was not reduced, indicating that the As (V)-reducing pathway mediated by arsC genesis was not able to reduce Sb(Ⅴ). The amounts of total As (506.8 µg·L-1) and total Sb (821.1 µg·L-1) in the dead cell system were approximately four times higher than in the living cell system (As=155.2 µg·L-1; Sb=364.8 µg·L-1) and the abiotic control (As=57.6 µg·L-1; Sb=271.1 µg·L-1) because of the biomolecules released from the dead cells which enhanced the release of As and Sb. The correlation analysis of dissolved As and Sb showed that the release of total As and Sb was correlated (P<0.05) in three systems. Our study shed new light on the impact of bacteria on the fate of As and Sb in soils.

Effect of nitrate concentration, pH, and hydraulic retention time on autotrophic denitrification efficiency with Fe(II) and Mn(II) as electron donors.

The role of electron donors (Fe(2+) and Mn(2+)) in the autotrophic denitrification of contaminated groundwater by bacterial strain SY6 was characterized based on empirical laboratory-scale analysis. Strain SY6 can utilize Fe(2+) more efficiently than Mn(2+) as an electron donor. This study has shown that the highest nitrate removal ratio, observed with Fe(2+) as the electron donor, was approximately 88.89%. An immobilized biological filter reactor was tested by using three levels of influent nitrate (10, 30, and 50 mg/L), three pH levels (6, 7, and 8), and three levels of hydraulic retention time (HRT; 6, 8, and 12 h), respectively. An optimal nitrate removal ratio of about 95% was achieved at pH 6.0 using a nitrate concentration of 50 mg/L and HRT of 12 h with Fe(2+) as an electron donor. The study showed that 90% of Fe(2+) and 75.52% removal of Mn(2+) were achieved at pH 8.0 with a nitrate concentration of 50 mg/L and a HRT of 12 h. Removal ratio of Fe(2+) and Mn(2+) is higher with higher influent nitrate and HRT. A weakly alkaline environment assisted the removal of Fe(2+) and Mn(2+).

Algicidal and denitrification characterization of Acinetobacter sp. J25 against Microcystis aeruginosa and microbial community in eutrophic landscape water.

Acinetobacter sp. J25 exhibited good denitrification and high algicidal activity against toxic Microcystis aeruginosa. Response surface methodology (RSM) experiments showed that the maximum algicidal ratio occurred under the following conditions: temperature, 30.46°C; M. aeruginosa density, 960,000cellsmL(-1); and inoculum, 23.75% (v/v). Of these, inoculum produced the maximum effect. In the eutrophic landscape water experiment, 10% bacterial culture was infected with M. aeruginosa cells in the landscape water. After 24days, the removal ratios of nitrate and chlorophyll-a were high, 100% and 87.86%, respectively. The denitrification rate was approximately 0.118mgNO3(-)-N·L(-1)·h(-1). Moreover, the high-throughput sequencing result showed that Acinetobacter sp. J25 was obviously beneficial for chlorophyll-a and nitrate removal performance in the eutrophic landscape water treatment. Therefore, strain J25 is promising for the simultaneous removal of chlorophyll-a and nitrate in the eutrophic landscape water treatment.

[Spatiotemporal succession of algae functional groups and the influence of environment change in a deep-water reservoir].

Algae functional group has become an important theory and method of algae research in recent years. In order to explore the spatiotemporal succession of algae functional groups and the influence of environment change, water samples were collected in August, 2011 from a deep-water reservoir in Northwest China. The research combined the methods of on-line monitoring and laboratory analysis. The results showed that there were 10 functional groups of algae in the reservoir. They were designated as B, D, P, X1, X3, F, G, J, L(M) and MP. Wherein, the groups B, P, F, X1, MP, D and J were comparatively common functional groups, and the groups X3, G and L(M) were less common. The populations of groups B, D, P, X1 and X3 were larger than those of the others. Besides, the analysis of changes in the environment factors suggested that temperature was the most important factor influencing the spatiotemporal succession of algae functional groups. The strategy of algal growth followed the law: R/CR in spring --> CR/C in late spring and early summer C/CR/R/CS/S in late summer and early autumn --> CR/R in late autumn and winter. The purpose of this article is to provide theoretical support for water withdrawal safety in deep-water reservoirs.