Ren Nanqi

The effect of decreasing alkalinity on microbial community dynamics in a sulfate-reducing bioreactor as analyzed by PCR-SSCP

PCR-single-strand conformation polymorphism (SSCP) and Southern blotting techniques were adopted to investigate microbial community dynamics in a sulfate-reducing bioreactor caused by decreasing influent alkalinity. Experimental results indicated that the sulfate-removal rate approached 87% in 25 d under the conditions of influent alkalinity of 4000 mg/L (as CaCO3) and sulfate-loading rate of 4.8 g/(L·d), which indicated that the bioreactor started up successfully. The analysis of microbial community structure in this stage showed that Lactococcus sp., Anaerofilum sp. and Kluyvera sp. were dominant populations. It was found that when influent alkalinity reduced to 1000 mg/L, sulfate-removal rate decreased rapidly to 35% in 3 d. Then influent alkalinity was increased to 3000 mg/L, the sulfate-removal rate rose to 55%. Under these conditions, the populations of Dysgonomonas sp., Sporobacte sp., Obesumbacterium sp. and Clostridium sp. got to rich, which predominated in the community together with Lactococcus sp., Anaerofilum sp. and Kluyvera sp. However, when the alkalinity was decreased to 1500 mg/L, the sulfate-removal rate rose to and kept stable at 70% and populations of Dysgonomonas sp., Sporobacter sp. and Obesumbacterium sp. died out, while some strains of Desulfovibrio sp. and Clostridium sp. increased in concentration. In order to determine the minimum alkalinity value that the system could tolerate, the influent alkalinity was decreased from 1500 to 400 mg/L secondly. This resulted in the sulfate-removal rate, pH value and effluent alkalinity dropping quickly. The amount of Petrotoga sp., Prevotella sp., Kluyvera sp. and Neisseria sp. reduced obviously. The result data from Southern blotting indicated that the amount of sulfate-reducing bacteria (SRBs) decreased with influent alkalinity dropping. Analysis of the microbial community structure and diversity showed that the SRBs populations were very abundant in the inoculated activated sludge and the alkalinity decrease caused the reduction of the populations noted. Most of resident populations in the bioreactor were fermentative acidogenic bacteria (FABs), among which the phylum Firmicute was in the majority, but SRBs were very few. This community structure demonstrates the cooperation between SRBs and FABs, which sustains the system’s high sulfate-removal and operation stability.

Harbin city wetland safety analysis and countermeasures

Urban wetland ecosystems play in the city to maintain ecosystem equilibrium, wetland ecosystems in maintaining the safety of the ecological functions of wetlands play a huge role. Articles by SPSS statistical software, using factor analysis method and clustering analysis method to select a number of indicators before and after the Songhua River pollution incident on the North Pine wetlands were studied. The results show that: the highest level of ecological security in the eastern region, the worst safety in the western region. Songhua River pollution incident, the best scores of the Eastern biological factors; Eastern stability of the strongest water pollution incident; loose the safety of northern wetlands in water pollution after a downward trend. That pollution directly affects the safety of urban wetland.

Notice of Retraction City of Harbin Songbei wetland ecosystem functions and protection measures Prospects

Pine is located in the Songhua River in the north section of the wetland north beach terrace area of Harbin City, the largest piece of the existing urban natural wetland. In recent decades, due to the strong interference of human activities and natural conditions, the impact of ecosystem functions by the interference and damage. Article Songbei wetland resources in the investigation, based on the wetland ecosystem services a comprehensive and systematic research, analysis of the human city of wetland impact and affect the service functional stability of the factors of urban wetland sustainable conservation Using the theory and technical methods, the corresponding measures in order to achieve sustainable urban development of natural wetlands and conservation purposes.

Molecular characterization and fermentative hydrogen production of a wild anaerobe in clostridium genus

Anaerobic process of biohydrogen production is developed in this paper. The isolation and identification of high efficient biohydrogen production anaerobic bacteria are the important foundations for the fermented biohydrogen production process by anaerobic digesting organic wastewater. Taking the physiological and biochemical traits, the morphological characteristics and 16S rDNA sequence into consideration, the isolate Rennanqilyf33 is a new species.