Effect of biological activated carbon filter depth and backwashing process on transformation of biofilm community

We studied BAC biofilm during the process of initial operation and backwash. Microbial diversity decreased gradually with the increase of BAC filter depth. Proteobacteria dominated at the phylum level among the BAC biofilm samples. α-proteobacteria increased about 10% in all carbon filter depth after backwash. The biological activated carbon (BAC) is a popular advanced water treatment to the provision of safe water supply. A bench-scale device was designed to gain a better insight into microbial diversity and community structure of BAC biofilm by using high-throughput sequencing method. Both samples of BAC biofilm (the first, third and fifth month) and water (inlet water and outlet water of carbon filter, outlet water of backwashing) were analyzed to evaluate the impact of carbon filter depth, running time and backwash process. The results showed that the microbial diversity of biofilm decreased generally with the increase of carbon filter depth and biofilm reached a steady-state at the top layer of BAC after three months’ running. Proteobacteria (71.02%–95.61%) was found to be dominant bacteria both in biofilms and water samples. As one of opportunistic pathogen, the Pseudomonas aeruginosa in the outlet water of device (1.20%) was about eight times higher than that in the inlet water of device (0.16%) at the genus level after five-month operation. To maintain the safety of drinking water, the backwash used in this test could significantly remove Sphingobacteria (from 8.69% to 5.09%, p<0.05) of carbon biofilm. After backwashing, the operational taxonomic units (OTUs) number and the Shannon index decreased significantly (p<0.05) at the bottom of carbon column and we found the Proteobacteria increased by about 10% in all biofilm samples from different filter depth. This study reveals the transformation of BAC biofilm with the impact of running time and backwashing.     

大沽排污河底泥释放总氮的影响

在实验室模拟条件下,考察了上覆水的溶解氧DO、pH值、温度、含盐量及扰动速率等环境因子对大沽排污河底泥释放总氮的影响.结果表明:厌氧条件下底泥释放总氮的强度高于好氧条件和自然条件下的释放强度;上覆水的pH呈中性时底泥释放总氮的强度最大,酸性条件下底泥释放总氮的强度高于碱性条件;升高温度可促进底泥释放总氮;扰动可提高底泥释放总氮的强度,但当扰动速率增加到一定程度时,反而会抑制总氮的释放,因此,至最后实验结束时,扰动速率为60r.min-1的体系中底泥释放总氮的能力最强;当实验达到平衡时,含盐量为0mg.L-1的体系中底泥释放总氮的能力最强.     

薄板超塑胀形材料参数m、K值的测定

此文提出了一种测定薄板超塑胀形材料参数的新方法:等高胀形法,并在文中进行了有关公式的推导,通过实例计算证明了该方法操作简单,精度高。     

氧化铈/活性炭催化臭氧氧化技术去除水中邻苯二甲酸二甲酯

用浸渍法在活性炭(AC)上负载氧化铈(CeO2)制备催化刺CeO2/AC催化臭氧氧化去除邻苯二甲酸二甲酯(DMP),考察了臭氧投加量,DMP初始浓度和溶液初始pH的影响.结果表明,CeO2/AC催化臭氧氧化去除DMP的最佳臭氧投加量为50mg/h,DMP初始浓度和溶液初始pH对CeO2/AC催化臭氧氧化DMP过程都有一定的影响.在DMP初始质量浓度为30 mg/L、溶液初始pH为5、臭氧投加量为50 mg/h、反应60 min时,CeO2/AC的加入(1.5g/L)有利于催化臭氧氧化DMP过程中总有机碳(TOC)的去除,TOC去除率由AC催化臭氧氧化的48%提高到68%.而单独臭氧氧化过程中的TOC去除率仅22%;且单独臭氧氧化与AC、CeO2/AC催化臭氧氧化DMP的矿化过程均符合二级反应动力学方程,CeO2/AC催化臭氧氧化DMP时TOC降解的二级反应动力学常数为0.0015L/(mg·min),分别是AC催化臭氧氧化的2.5倍和单独臭氧氧化的7.5倍.     

Effect of Tween 80 and beta-cyclodextrin on degradation of decabromodiphenyl ether (BDE-209) by White rot fungi

The environmental safety of decabromodiphenyl ether (BDE-209), a widely used flame retardant, has been the topic of controversial discussions during the past several years. Degradation of BDE-209 into lower brominated diphenyl ether congeners, exhibiting a higher bioaccumulation potential, has been a critical issue. White rot fungi are known to degrade a wide variety of recalcitrant pollutants. In this work, white rot fungi were used to degrade BDE-209 in liquid culture medium, and the effects of Tween 80 and beta-cyclodextrin on BDE-209 degradation by white rot fungi were evaluated. On the basis of these results, it appears that BDE-209 could be degraded by white rot fungi, and Tween 80 and beta-cyclodextrin can both increase the biodegradation. The best result in Tween 80 experiments was obtained at a Tween 80 concentration of 500mgl(-1) within 10d, which showed 96.5% (w/w) BDE-209 transformed. Tween 80 at a high concentration will restrain the fungal growth and the degradation of BDE-209. However, beta-cyclodextrin had positive effects both on the BDE-209 degradation and the fungal growth.     

Specific biotests to assess eco-toxicity of biodegradable polymer materials in soil

Eco-toxicity investigation of polymer materials was considered extremely necessary for their potential menace, which was widely use as mulching materials in agricultural. In this study, polyethylene (PE), polystyrene (PS) and synthetic biomaterials-Ecoflex and cellulose were applying into soil cultivated with two potential indicator plants species: oat (Avena sativa) and red radish (Raphanus sativum). Variety of chemical, biochemical parameters and enzyme activity in soil were proved as effective approach to evaluate polymers phytotoxicity in plant-soil mesocosm. The F-value of biomass, pH, heavy metal and electoral conductivity of Raphanus behaved significant different from T0. Significant analysis results indicated biodegradation was fast in PE than PS, besides, heavy metals were dramatically decrease in the end implied the plant absorption may help decrease heavy metal toxicity. The increase value at T2 of Dehydrogenase activity (0.84 higher than average value for Avena & 0.91 higher for Raphanus), Metabolic Index (3.12 higher than average value for Avena & 3.81 higher for Raphanus) means during soil enzyme activity was promoted by biodegradation for its heterotrophic organisms’ energy transportation was stimulated. Statistics analysis was carried on Biplot PC1 (24.2% of the total variance), PC2 (23.2% of the total variance), versus PC3 (22.8% of the total variance), which indicated phosphatase activity and metabolic index was significant correlated, and high correlation of ammonium and protease activity. Furthermore, the effects were more evident in Raphanus treatments than in Avena, suggesting the higher sensitivity of Raphanus to polymers treatment, which indicate biodegradation of polymers in Raphanus treatment has produced intermediate phytotoxic compounds.     

The role of extracellular organic matter on the cyanobacteria ultrafiltration process

The membrane fouling caused by extracellular organic matter (EOM) and algal cells and organic matter removal of two typical cyanobacteria (M. aeruginosa and Pseudoanabaena sp.) during ultrafiltration (UF) process were studied in this work. The results showed that EOM had a broad molecular weight (Mw) distribution and the irreversible membrane fouling was basically caused by EOM. Moreover, humic acid and microbial metabolites were major components of EOM of two typical cyanobacteria. Since EOM could fill the voids of cake layers formed by the algal cells, EOM and algal cells played synergistic roles in membrane fouling. Fourier transform infrared spectroscopy analysis indicated that the CH₂ and CH₃ chemical bonds may play an important role in membrane fouling caused by EOM. Interestingly, the cake layer formed by the algal cells could trap the organic matter produced by algae and alleviate some irreversible membrane fouling. The results also showed that although the cake layer formed by the algal cells cause severe permeate flux decline, it could play a double interception role with UF membrane and increase organic matter removal efficiency. Therefore, when using UF to treat algae-laden water, the balance of membrane fouling and organic matter removal should be considered to meet the needs of practical applications.     

Formation and Evolution of Ancient Lakes on South Coast Plain of Laizhou Bay

Abstract

Based on the data of historical geography, the analysis of the stratigraphic section, and the textual research of place names and satellite photographic interpretations, the authors study the formation and evolution of ancient lakes on the south coast plain of Laizhou Bay where there were once three lakes: Judian Lake, Qingshuibo Lake and Biehua Lake. All the lakes formed 6000 years ago evolved from the lagoons near the estuary and went through two periods, the golden age in the Middle Holocene and the shrinking age in the Late Holocene. The disappearance of the lakes resulted from the drying climate, the migration of the river courses and the activities of human beings. Among the three reasons, the migration of the river courses is the main one.     

珠江口及邻近海域环境动态与基础生物结构初探

本文着重讨论珠江口及其邻近海域水环境状况与基础生物结构特点，初步分析结果表明，珠江口宫养盐丰富，无机Ｎ、Ｐ和石油类超二类海水标准，其它理化因子、有机质、基础生物量及其种群结构随季节而变化；年平均叶绿ａ含量和初级生产力分别为４．０２ｍｇ／ｍ＾３和３０９ｍｇ／ｍ＾２·ｄ（以Ｃ计，下同）；浮游生物以咸淡水种类为主，多样性指数和均匀度值在丰水期和枯水期有较大差别。崖门口水域除无机Ｎ明显超标外，其余要素尚未