Simultaneous removal of cyanobacterial blooms and production of clean water by coupling flocculation with a rotary drum filter

Environmental Science and Pollution Research - A mechanical harvesting technology based on coupling flocculation with a rotary drum filter (RDF, 35-μm) was applied to remove cyanobacterial...     

不同填料载体生物膜对微囊藻毒素的去除效果

利用自行设计的生物膜培养装置,通过对4种不同填料载体进行连续曝气循环培养生物膜,对湖水中的溶解态微囊藻毒素(MCs)的去除作用进行了研究。结果表明,填料载体上生物膜从形成到稳定大约需要3周;生物膜形成后对MCs的去除效率由高到低的顺序是:颗粒活性炭柱>多密孔球型滤料柱>塑料悬浮填料柱>陶瓷滤球柱。在实验水质条件下,当水力停留时间(HRT)=5 h,进水MCs浓度为21.5～47.25μg/L时,颗粒活性炭、多密孔球型滤料柱对MCs的去除率最高可达100%,塑料悬浮填料柱对MC-LR和MC-RR的去除率分别为70%和88%。当HRT=2.5 h时,塑料悬浮填料柱对MC-RR的去除率为MC-LR的2倍。生物膜对MCs的降解效果随温度(5～20℃)和溶解氧的升高而增加。塑料悬浮填料作为合适的生物膜挂膜填料载体对水源水的生物预处理具有良好的应用前景。     

Spatiotemporal dynamics of cell abundance, colony size and intracellular toxin concentrations of pelagic and benthic Microcystis in Lake Caohai, China

Lake Caohai has experienced extensive Microcystis blooms in recent years,and to improve its water quality,the local government carried out a series of water control measures.To better understand the dynamics of both pelagic and benthic Microcystis and their characteristics in Lake Caohai,we conducted a 1-year investigation from December 2015to December 2016 to gain a seasonal outlook on the distribution and dynamics of cell abundance,colony size and intracellular microcystins(MCs)of Microcystis.The results indicated that the Microcystis bloom occupied primarily the northeastern region and then moved gradually from lakeshore to lake center.The perennial southwesterly winds and the water inflow from northeast to southwest in Lake Caohai determined the spatiotemporal distribution of pelagic Microcystis.Benthic Microcystis was mainly distributed in the northeastern region in summer,occupied the lake center in autumn and then occupied the southeastern region in winter,determined by the sedimentation of pelagic Microcystis and the death of benthic Microcystis.Small colonies(20-60μm)overwintered more easily in both water column and sediment.The concentrations of intracellular toxin of benthic Microcystis were observed to be significantly higher than those of pelagic Microcystis.This might be because Microcystis synthesized large amount of MCs to acclimate to an unfavorable benthic environment.This knowledge on the dynamics of Microcystis expands our understanding of mechanisms underpinning the formation of Microcystis blooms.     

铅在模拟预处理稳定塘中的归宿

本文较全面地研究了城市污水中的铅在模拟预处理稳定塘中的归宿。不论在哪种预处理稳定塘中,悬浮颗粒态锅的沉降作用是去除污水中铅的主要作用。进入城市污水中的铅,大部分和污水中的悬浮物结合转变成悬浮颗粒态铅,它们输入到模拟预处理预处理稳定塘,这些悬浮颗粒态铅即可在很短的时间内（１ｄ）通过沉降作用得以有效地去除。停留时间分别为１,２,３,５和１０ｄ的实验表明,模拟预处理稳定塘对城市污水中铅的去除率可达５２－     

河湖沉积物中酸挥发性硫化物对重金属吸附及释放的影响

通过吸附、释放实验研究了河流及湖泊沉积物酸挥发性硫化物对上覆水中重金属元素的影响，采用兼具Langmuir及Freundlish等温线方程两种方程特征的Sips表达工及无机离子分级交换理论，较好地对重金属元素在沉积物或颗粒物上的吸附及释放特征进行了描述。结果表明，存在于水溶液中的重金属可以不断地与沉积物结合，从而使水溶液中的重金属浓度维持在一很低的水平上；并且，一旦与沉积物结合，重金属就很难再释放出来。酸挥发性硫化物的存在增加了沉积物的吸附容量，但酸挥发性硫化物经过酸化除去后，沉积物中的与之结合重金属元素就会释放出来，从而对水环境造成危害。     

黑藻根际对沉积物中氨氧化细菌和古菌的影响

氨氧化反应对水生态系统氮循环和氮的去除有重要作用,沉水植物通过根系泌氧促进沉积物中硝化反应并对氨氧化细菌和古菌的分布产生影响。本研究以轮叶黑藻为实验对象,利用微电极研究沉积物-水界面的溶解氧变化,研究了黑藻根系对沉积物中氨氧化细菌和古菌数量的影响。结果表明,黑藻通过根系泌氧增加沉积物-水界面的溶解氧量和表层沉积物有氧层厚度,有氧层厚度增加了3 mm以上;种植黑藻后,根际沉积物中氨氧化细菌数量逐渐增加,氨氧化古菌数量前30天增加随后减少,氨氧化细菌与氨氧化古菌amoA基因拷贝数的比值由0.51增加到6.75,说明黑藻根际沉积物更适宜氨氧化细菌的生存。     

淡水水体麻痹性贝毒污染的现状

麻痹性贝毒是一类水溶性的神经毒素,造成神经细胞电压敏感性钠离子通道(VSSC)高亲和力障碍,与细胞膜离子结合后引起细胞膜内外正常离子的流动失衡,造成膜电位反常,使人瘫痪.麻痹性贝毒的污染及其产毒藻已成为一个受人关注的公共健康问题.综述麻痹性贝毒的理化性质和毒性特点、淡水水体麻痹性贝毒污染及其5种淡水产毒蓝藻,并对淡水中PSP防治工作提出建议.     

A laboratory study on risk assessment of microcystin-RR in cropland

The persistence time and risk of microcystin-RR (MC-RR) in cropland via irrigation were investigated under laboratory conditions. In order to evaluate the efficiency of the potential adsorption and biodegradation of MC-RR in cropland and the persistence time of MC-RR for crop irrigation, high performance liquid chromatography (HPLC) was used to quantify the amount of MC-RR in solutions. Our study indicated that MC-RR could be adsorbed and biodegraded in cropland soils. MC-RR at 6.5mg/L could be completely degraded within 6 days with a lag phase of 1-2 days. In the presence of humic acid, the same amount of MC-RR could be degraded within 4 days without a lag phase. Accordingly, the persistence time of MC-RR in cropland soils should be about 6 days. This result also suggested the beneficial effects of the organic fertilizer utilization for the biodegradation of MC-RR in cropland soils. Our studies also demonstrated that MC-RR at low concentration (<10microg/L) could accelerate the growth of plants, while high concentration of MC-RR (>100microg/L) significantly inhibited the growth of plants. High sensitivity of the sprouting stage plants to MC-RR treatments as well as the strong inhibitory effects resulting from prolonged irrigation further indicated that this MC-RR growth-inhibition may vary with the duration of irrigation and life stage of the plants.     

曝气-混凝一体法去除碱性废水中砷的研究

采用曝气－混凝一体法处理碱性含砷废水。氧化方式研究表明,以曝气替代混凝机械搅拌过程,既起到氧化作用,又完成了混合作用,同时具有较好的处理效果;采用该法结合二次混凝工艺处理高浓度碱性含砷废水（砷浓度达414.94mg/L）,聚合铁为絮凝剂,总Fe/As＝3.0,砷去除率99.92％,出水中砷浓度0.33mg/L;在所选用的三种混凝剂中,聚合铁处理效果最佳。     

Co-regulatory role of Microcystis colony cell volume and compactness in buoyancy during the growth stage

The buoyancy of Microcystis colonies determines the occurrence and dominance of bloom on the water surface. Besides the cell density regulation and the formation of larger size aggregates, increases in cell volume per colony (V_cell) and the colony’s compactness (i.e., volume ratio of cells to the colony, VR) may promote Microcystis colony buoyancy. Yet only a few studies have studied the relationship between the internal structure variation of colonies and their buoyancy, and the co-regulatory role of V_cell and VR of Microcystis colonies in the floating velocity (FV) remains largely unexplored. In the present study, we optimized a method for measuring the compactness of Microcystis colonies based on the linear relationship between total V_cell and chlorophyll a. Different relationships between the VRs and FVs were observed with different colony size and V_cell range groups. Both field and laboratory experiments showed that FV/(D₅₀, median diameter)² had a significant linear relationship with VR, indicating that the cell density and extracellular polysaccharides were unchanged over a short time period and could be estimated via the slope and intercept of a fitted line. We also constructed a functional relationship between FV, VR, and V_cell and found that high VR and V_cell can promote Microcystis buoyancy. This means that increasing cell compactness or V_cell may be an active regulation strategy for Microcystis colonies to promote buoyancy. Therefore, quantifying the internal structure of Microcystis colonies is strongly recommended for the assessment of Microcystis bloom development and their management.

Graphical abstract