Effects of river sediment addition to the beach microbial communities

During the processes of claiming land from the sea, river sediments are used to fill and transform the sea area along the margin of islands and lands into new lands. These activities would probably affect microbial ecosystems of the beach sediment. However, little is known about these effects. In this study, a simulation test was conducted to evaluate these effects. Pyrosequencing technique was employed to assess the effects of river sediment addition to the beach bacterial communities. The used river sediments were collected from different rivers. The results indicated that river sediment addition greatly impacted microbial ecosystems of the beach and caused a clear shift in the beach bacterial community composition. These processes remarkably increased toxic metals and decreased the bacterial diversity in the beach sediment, mainly including the phyla of Bacteroidetes, Cyanobacteria, Proteobacteria, and Spirochaetes. River sediment addition caused an increase in potentially pathogenic bacterial genera of the beach sediment. Bacterial phylotype richness in the beach without river sediment addition was higher than that in the beach with river sediment input. There were significant differences in bacterial communities between beach sediments with and without river sediment addition, and the most dominant classes were Gammaproteobacteria and Flavobacteria.     

Development of pretreatment protocol for DNA extraction from biofilm attached to biologic activated carbon (BAC) granules

The biologic activated carbon (BAC) process is widely used in drinking water treatments. A comprehensive molecular analysis of the microbial community structure provides very helpful data to improve the reactor performance. However, the bottleneck of deoxyribonucleic acid (DNA) extraction from BAC attached biofilm has to be solved since the conventional procedure was unsuccessful due to firm biomass attachment and adsorption capacity of the BAC granules. In this study, five pretreatments were compared, and adding skim milk followed by ultrasonic vibration was proven to be the optimal choice. This protocol was further tested using the vertical BAC samples from the full-scale biofilter of Pinghu Water Plant. The results showed the DNA yielded a range of 40 μg·g^-1 BAC (dry weight) to over 100 μg·g^-1 BAC (dry weight), which were consistent with the biomass distribution. All results suggested that the final protocol could produce qualified genomic DNA as a template from the BAC filter for downstream molecular biology researches.     

一种经济、简单的微生物基因组DNA的提取方法

获得一定浓度和纯度的DNA是进行分子生物学研究的基础。破解细胞壁与细胞膜是获得基因组DNA的前提，而蛋白质和核酸物质的分离是获得高质量DNA产物的关键。目前，主要采用的破壁方法有：冷冻研磨法、溶菌酶法、EDTA测等，这些方法一般采用复杂的裂解液体系，并借助蛋白酶K和RNA酶的帮助来获得高质量的抽提产物。由于细胞裂解体系不仅配制十分麻烦，而日部分药品有毒操作危险性大，此外部分药品及相关酶试剂价格昂贵。本文充分利用DNA在不同温度下自身可变性与复性的特性和在高盐与高温条件下蛋白质能够变性并沉淀。以无菌的SDS（c／c=20％）和NaCl（c/c=8％）的混合液作裂解体系，在沸水浴中破壁膜并使得部分的蛋白质变性和DNA变性并得到初步分离；随后在60℃和72℃水浴中使变性的DNA复性和重新凝聚，同时让RNA、蛋白质和细胞壁碎片等杂质降解或沉淀，从而获得高质量的DNA产物。     

Mobilization kinetics of heavy metals from contaminated river sediment of northern Taiwan by complexing agents

A laboratory experiment was used to investigate the mobilization kinetics of heavy metals from the sediment of a contaminated river located in northern Taiwan with varied concentrations of NTA and EDTA. We found that there were two stages of desorption in the mobilization of heavy metals from the sediment. As the concentrations of NTA and EDTA ranged 0–3.9 x 10^‐4M (0–100mg/l) and 0–2.7 x 10^‐4M (0–100mg/l) respectively, the mobilization percentages of heavy metals were proportional to the logarithm values of the concentrations of NTA and EDTA. The physical meaning of the multiple first‐order reaction was significant for the actual condition, but occasionally, it had more errors for Cu and Zn in the initial phase. The two‐constant model was most appropriate for describing the rates of mobilization of Pb, Cu, Zn, and Cr. The agreement between the diffusion model and the experimental data was satisfactory for Pb, Cu, Zn, and Cr only in the initial 5 h.     

活性污泥总DNA不同提取方法的比较

为了快速、简便和经济地获得活性污泥的总DNA,以用于分子生物学研究,采用5种不同的DNA提取方法提取活性污泥的总DNA,并通过提取的核酸总量、纯度、是否含有聚合酶链反应抑制剂等指标综合分析不同的提取方法对活性污泥总DNA提取效果的影响.结果表明:蛋白酶K-SDS-酚氯仿法和柱提取DNA试剂盒法提取活性污泥总DNA效果最好,提取DNA总量多,纯度高,可不经纯化直接进行PCR扩增反应。     

An integrated method for the rapid dewatering and solidification/stabilization of dredged contaminated sediment with a high water content

• An integrated method, called PHDVPSS, was proposed for treating DCS. • The PHDVPSS method showed superior performance compared to conventional method. • Using the method, water content (%) of DCS decreased from 300 to<150 in 3 days. • The 56-day UCS from this method is 12‒17 times higher than conventional method. • Relative to PC, GGBS-MgO binder yielded greater reduction in the leachability. To more efficiently treat the dredged contaminated sediment (DCS) with a high water content, this study proposes an integrated method (called PHDVPSS) that uses the solidifying/stabilizing (S/S) agents and prefabricated horizontal drain (PHD) assisted by vacuum pressure (VP). Using this method, dewatering and solidification/stabilization can be carried out simultaneously such that the treatment time can be significantly shortened and the treatment efficacy can be significantly improved. A series of model tests was conducted to investigate the effectiveness of the proposed method. Experimental results indicated that the proposed PHDVPSS method showed superior performance compared to the conventional S/S method that uses Portland cement (PC) directly without prior dewatering. The 56-day unconfined compressive strength of DCS treated by the proposed method with GGBS-MgO as the binder is 12‒17 times higher than that by the conventional S/S method. DCS treated by the PHDVPSS method exhibited continuous decrease in leaching concentration of Zn with increasing curing age. The reduction of Zn leachability is more obvious when using GGBS-MgO as the binder than when using PC, because GGBS-MgO increased the residual fraction and decreased the acid soluble fraction of Zn. The microstructure analysis reveals the formation of hydrotalcite in GGBS-MgO binder, which resulted in higher mechanical strength and higher Zn stabilization efficiency.