水体pH和曝气方式对藻类生长的影响

利用水族箱微宇宙研究了藻类在不同pH和曝气条件下的生长和种类变化.使用天然湖水,一组试验每天调节pH,使其分别保持在8.0、8.5、9.0和9.5;另一组试验是设定不同的曝气方式,分别为不曝气、完全曝气、昼间曝气和夜间曝气,定期测定水体叶绿素a和藻类组成.pH试验结果显示,在pH 8.0～9.5范围内,pH 8.5下藻类生长状况最好,pH 9.5下生长最差,人为改变pH使其远离8.5能够抑制藻类生长.曝气试验结果显示,曝气不能抑制水体中藻类的生长,昼间曝气甚至还有明显的促进作用.     

扬水曝气技术对周村水库藻类的控制

扬水曝气作为湖泊、水库水体修复技术之一,在国内多个水源水库水质改善工程中得到应用。为进一步研究扬水曝气技术对湖库藻类的控制效果及其机理,在对北方温带季节性分层水库-周村水库垂向水体的理化指标及藻类参数进行常年监测的基础上,于2015年8月—9月扬水曝气运行前后对垂向水体理化指标及浮游植物生物量、群落结构及丰度进行了连续监测和对比分析。结果表明,扬水曝气破坏了水体分层,藻类生物量锐减,多样性水平提高,藻类密度垂向差异消失,优势种群由威胁性较大的蓝藻、绿藻变为威胁性较小的硅藻,水体生态状况良好。扬水曝气系统对氮营养盐含量、热分层结构和光照条件的影响是促进了藻类群落结构改变的主要原因。     

蜘蛛兰去除不同程度富营养水体中氮磷及抑藻效应简

研究了蜘蛛兰在不同程度富营养化水体中对氮、磷的去除和对藻类的抑制效应。结果表明,蜘蛛兰在3种不同程度富营养化水体中均能正常生长,且对富营养水体中的氮、磷和叶绿素a浓度均表现出良好的净化去除效果。在45 d的实验中,3种不同程度富营养水体的TN、NO₃^--N、NH₄⁺-N和TP浓度分别由初始的3.69~25.65、2.79~21.14、0.75~3.57和0.14~1.23mg/L降至1.25~18.99、1.08~16.03、0.18~1.39和0.06~0.77mg/L,在3种不同程度富营养水体中植物的平均生物量累积增长率分别为40.98% 、64.41% 和95.08%。实验各处理组富营养化水体中的叶绿素a浓度及荧光参数短期内都显著下降,而各对照组中则较稳定或略有下降。蜘蛛兰不仅可以净化富营养水体中营养元素,且对水体中藻类的生长有明显的抑制作用,其在水体生态修复工程中具有良好的应用前景。     

纳滤膜对不同水源水中有机物处理效果

为探究纳滤(NF)在实际水体中去除有机物的特性,以水质常规指标、三卤甲烷生成势(THMFP)、亲水性有机碳及三维荧光为主要指标,综合研究了两种NF膜(NF1和NF2)对不同水体中有机污染的处理效果,并探索了膜污染机制。结果表明,NF1、NF2均能有效改善饮用水水质,对总有机碳的去除率分别可达到94%、72%以上;对高锰酸盐指数的去除率分别可达到80%、66%以上。NF1对进水THMFP的去除率均在90%左右。无机和有机污染的协同作用是造成NF膜污染的主要原因。     

水体富营养化及其治理研究进展

随着水体污染和富营养化程度的加剧 ,藻类爆发的频率和强度日趋严重 ,已成为一种生态灾害。文章就水体中藻类爆发的成因和危害作了简要的概括 ,并对国内外水体富营养化的治理和控制方法进行了总结和分析 ,主要有物理法、化学法、生物法 3种方法。在此基础上 ,提出了水体富营养化治理的研究内容和方向。     

采用热解技术将湖泊浮游藻类用于燃料生产

湖泊的富营养化问题已成为中国湖泊环境保护中最严重的问题之一.回收利用富营养化湖泊中的浮游藻类是减轻水体中氮、磷等营养负荷,治理湖泊环境污染的一项重要措施.通过热解技术可将藻类转化成焦炭、生物油和合成气等多种燃料形式,因而是回收利用湖泊浮游藻类的一个理想途径.同木质-纤维素类生物质相比,藻类作热解原料具有易预处理、易热解、易获得高产等优点,可以为社会提供大量优质的燃料.     

利用生物制剂处理北京动物园富营养型地表水的初步研究

北京市的地表水水质日益恶化,富营养化表现突出。目前改善水质、抑制藻类生长是解决富营养化水体的关键。试验采用从美国引进的新型生物制剂Eclean应用于北京动物园富营养化水体,试验结果表明,水体中的CODMn、总氮(TN)、总磷(TP)、浊度、叶绿素a、藻类浓度各项指标均有明显下降,水质明显改善,藻类生长基本得到控制。     

最大光能转化效率F_V/F_M用于城市人工水体藻华的监控预警

结合2012年5—10月对上海市区2个典型城市人工水体藻华过程叶绿素、最大光能转化效率FV/FM变化,及其与水质指标的关系,研究FV/FM用作城市人工水体藻华监控预警指标的可行性。结果表明,曲阳公园、黄兴公园的FV/FM分别在0.57~0.71和0.58~0.63之间;人工模拟昼夜日照和温度变化培养曲阳公园藻华的水藻得到,藻类生长适应期FV/FM<0.60,对数期FV/FM>0.60,FV/FM与藻类生物量无显著相关性,仅反映藻类所处生长阶段。分析FV/FM和叶绿素a与浊度、COD、TN、TP的相关性得到,FV/FM能兼顾藻类在富营养化水体中的生理环境和生长特性,综合反映了藻华在城市人工水体形成相关的物理、化学、生长特性等因素,对研究水体FV/FM=0.63可作为预警水体藻华发生的阈值。研究成果为城市人工水体藻华暴发的监控、预警提供新的途径和方法。     

藻类光合作用对运河(杭州段)水质影响的初步研究

在河流水体自净规律的研究中,浮游藻类的生长状况是一个不可忽视的因素。通过藻类的生命活动,影响和改变水的理化性、透明度、颜色等。藻类通过光合作用,吸收水体中的 CO_2,同时释放出氧气,增加水体的溶解氧含量。反之,当藻类大量繁殖时,水体处于富营养化阶段,藻类的呼吸及残骸的分解,大量耗氧,又减少水体的溶解氧。这种对水体的充氧和耗氧明显影响水体的自净过程。另一方面,水体严重污染的环境,会影响藻类正常生长,因此研究运河藻类光合作用对水质的影响和改变浮游藻类的生长环境的可能,对研究运河水     

蜘蛛兰去除不同程度富营养水体中氮磷及抑藻效应

研究了蜘蛛兰在不同程度富营养化水体中对氮、磷的去除和对藻类的抑制效应。结果表明,蜘蛛兰在3种不同程度富营养化水体中均能正常生长,且对富营养水体中的氮、磷和叶绿素a浓度均表现出良好的净化去除效果。在45d的实验中,3种不同程度富营养水体的TN、N03-N、NH4-N和TP浓度分别由初始的3．69～25．65、2．79～21．14、0．75～3．57和0．14—1．23mg／L降至1．25～18．99、1．08～16．03、0．18～1．39和0．06～0．77mg／L,在3种不同程度富营养水体中植物的平均生物量累积增长率分别为40．98％、64．41％和95．08％。实验各处理组富营养化水体中的叶绿素a浓度及荧光参数短期内都显著下降,而各对照组中则较稳定或略有下降。蜘蛛兰不仅可以净化富营养水体中营养元素,且对水体中藻类的生长有明显的抑制作用,其在水体生态修复工程中具有良好的应用前景。     

Historical record of nutrients inputs into the Xin’an Reservoir and its potential environmental implication

The Xin’an Reservoir is an important water supply source and water conservation area for the Qiantang River. However, after the occurrence of the two algae blooms in 1998 and 1999, the safety of water quality has been put into question. In order to study the historical deposition of nutrients, sediment cores were collected in different regions from the Xin’an Reservoir. The stable isotopes δ¹³C and δ¹⁵N, nutrients, total organic carbon (TOC), and inorganic carbon (IC) in the sediment cores were determined. Radiometric methods (²¹⁰Pb and ¹³⁷Cs) were used to obtain sediment chronologies. Spatially, it was found that the average total nitrogen (TN) content in the upper 5 cm of sediments increased from 0.21% in the riverine zone, to 0.33%, and then to 0.57% in the lacustrine zone. The average TP content in the upper 5 cm increased from 0.67 g kg^?1 in the riverine zone, to 1.03 g kg^?1 in the estuary region, and then to 1.65 g kg^?1 in the lacustrine zone. In addition, TOC levels showed a distinct increase from 1.42% in the bottom to 5.97% in the surface of the lacustrine zone. These results demonstrated that although primary productivity and the input of nutrients constantly increased in recent years, algae blooms rarely occurred in the Xin’an Reservoir, due to “depth effect” and an aquatic environment protection-oriented fishery policy. However, high TOC flux and high bio-available phosphorus and nitrogen in surface sediment demonstrated that the reservoir is still confronted with the potential risk of algae blooms.     

Determination of nitrate and other water quality parameters in groundwater from UV/Vis spectra employing partial least squares regression

The use of UV/Vis spectroscopy in combination with partial least squares (PLS) regression for the simultaneous prediction of nitrate and non-purgeable organic carbon (NPOC) in groundwaters was evaluated. A model of high quality was obtained using first order derivative spectra in the range 200-300 nm. Inclusion of non-UV-absorbing constituents in the modeling procedure, i.e., chloride, sulfate, fluoride, total carbon (TC), inorganic carbon (IC), alkalinity, pH and conductivity was also evaluated. This model seemed to be useful for prediction of chloride, TC, IC, alkalinity and conductivity, while its ability to predict sulfate, fluoride and pH was poor. In conclusion, application of PLS regression, which requires neither filtration of samples nor addition of chemicals, is a promising alternative for fast interpretation of geochemical patterns of groundwater quality.     

微滤膜与活性炭联用工艺去除富营养化水源水中藻类

湖泊及水库含藻水问题带有一定的普遍性,处理技术复杂,难度较大。因此,除藻技术的提高和发展显得越来越紧迫。膜处理技术在给水中的应用是水处理技术的重大突破,正逐渐成为21世纪水处理技术中最有发展前途的技术。本文以继承和吸收成熟技术,并将其工程化,以便及时解决具体问题为原则,根据国内外最新水质标准要求,提出了微滤膜与活性炭联用的除藻新上艺,并对除藻工艺方案确定原则、研究内容和目标,以及除藻工艺方案设计进行了说细分析说明。本文认为微滤膜技术在我国供水行业推广已经具备了较好的条件,在不断积累经验的基础上可以达到大规模工程应用。应用微滤膜与活性炭联用工艺解决富营养化水源水中藻类问题在技术上是成熟的,在经济上是可行的。     

Long-term trends in water chemistry of acid-sensitive Swedish lakes show slow recovery from historic acidification

Long-term (1987–2012) water quality monitoring in 36 acid-sensitive Swedish lakes shows slow recovery from historic acidification. Overall, strong acid anion concentrations declined, primarily as a result of declines in sulfate. Chloride is now the dominant anion in many acid-sensitive lakes. Base cation concentrations have declined less rapidly than strong acid anion concentrations, leading to an increase in charge balance acid neutralizing capacity. In many lakes, modeled organic acidity is now approximately equal to inorganic acidity. The observed trends in water chemistry suggest lakes may not return to reference conditions. Despite declines in acid deposition, many of these lakes are still acidified. Base cation concentrations continue to decline and alkalinity shows only small increases. A changing climate may further delay recovery by increasing dissolved organic carbon concentrations and sea-salt episodes. More intensive forest harvesting may also hamper recovery by reducing the supply of soil base cations.     

Petroleum Pollutant Degradation by Surface Water Microorganisms (8 pp)

Background, Aims and Scope It is well known that the composition of petroleum or some of its processing products changes in the environment mostly under the influence of microorganisms. A series of experiments was conducted in order to define the optimum conditions for an efficient biodegradation of petroleum pollutant, or bioremediation of different segments of the environment. The aim of these investigations was to show to what extent the hydrocarbons of a petroleum pollutant are degraded by microbial cultures which were isolated as dominant microorganisms from a surface water of a wastewater canal of an oil refinery and a nitrogen plant. Biodegradation experiments were conducted on one paraffinic, and one naphthenic type of petroleum during a three month period under aerobic conditions, varying the following parameters: Inorganic (Kp) or an organic medium (Bh) with or without exposition to light. Methods Microorganisms were analyzed in a surface water sample from a canal (Pančevo, Serbia), into which wastewater from an oil refinery and a nitrogen plant is released. The consortia of microorganisms were isolated from the water sample (most abundant species: Phormidium foveolarum - filamentous Cyanobacteria, blue-green algae and Achanthes minutissima, diatoms, algae). The simulation experiments of biodegradation were conducted with the biomass suspension and crude oils Sirakovo (Sir, paraffinic type) and Velebit (Ve, naphthenic type). After a three month period, organic substance was extracted by means of chloroform. In the extracts, the content of saturated hydrocarbons, aromatic hydrocarbons, alcohols and fatty acids was determined (the group composition). n-Alkanes and isoprenoid aliphatic alkanes, pristane and phytane, in the aliphatic fractions, were analyzed using gas chromatography (GC). Total isoprenoid aliphatic alkanes and polycyclic alkanes of sterane and triterpane types were analyzed by GC-MS. Results and discussion. Paraffinic type petroleums have a significant loss of saturated hydrocarbons. For naphthenic type petroleum, such a trend has not been observed. The most intensive degradation of n-alkanes and isoprenoid aliphatic alkanes (in paraffinic oil) and isoprenoids (in naphthenic oil) was observed using the inorganic medium Kp in the light; the microbial conversion is somewhat lower with Kp in the dark; with organic medium Bh in the light the degradation is of low intensity; with the same medium in the dark the degradation is hardly to be seen. Steranes and triterpanes were not affected by microbial degradation under the conditions used in our experiments. Obviously, the petroleum biodegradation was restricted to the acyclic aliphatics (n-alkanes and isoprenoids). Conclusion Phormidium foveolarum (filamentous Cyanobacteria - blue-green algae) and Achanthes minutissima (diatoms, algae), microbial cultures isolated as dominant algae from a surface water in a wastewater canal of an oil refinery and a nitrogen plant, have degradable effects dominantly involving petroleum hydocarbons. Petroleum microbiological degradation is more intensive when inorganic medium (in the light) is applied. Having in mind that the inorganic pollutants have been released into the canal as well, this medium reflects more the natural environmental conditions. Polycyclic alkanes of sterane and triterpane type, in spite of the fact that these compounds could be degraded, have remained unchanged regarding abundance and distribution. Since this is the case even for naphthenic type petroleum (which is depleted in n-alkanes), it can be concluded that the biodegradation of petroleum type pollutants, under natural conditions, will be restrained to the n-alkane and isoprenoid degradation. Recommendation and Outlook Performed experiments and simulations of petroleum microbiological degradation may serve for the prediction of the fate of petroleum type pollutants, as well as for definition of conditions for bioremediation of some environmental segments.     

Enhanced coagulation with polyaluminum chlorides: role of pH/alkalinity and speciation

Enhanced coagulation is considered to be among the best available techniques (BAT) for disinfection by-product (DBP) precursor removal in water treatment. Improving existing understanding requires further consideration of nuances of chemical speciation relative to source water chemistry. In this paper, the effect of alkalinity/pH and speciation on inorganic polymer flocculants, polyaluminum chlorides (PACls) for enhanced particle and natural organic matter (NOM) removal was investigated. Three kinds of well-characterized typical source waters in China with low, moderate, and high alkalinity were selected. Performance of coagulants is controlled not only by preformed species but also by those formed in situ. At neutral and basic pH values, PACls with higher basicity (ratio of OH(-)/Al), which have more stable preformed Alb (the rapid reacted species as in ferron assay), are more efficient for turbidity and NOM removal. At slightly acidic pH, PACls with lower basicity are more efficient since more Alb can be formed in situ. Optimal NOM removal was achieved at pH 5.5-6.5 for all PACls. Basicity, speciation, and dosage of coagulant should be optimized based on raw water alkalinity to enhance the removal efficiency of NOM.     

Determining the effectiveness of conventional and alternative coagulants through effective characterization schemes

Polymeric forms of metal coagulants in water treatment have become increasingly used due to their wider availability and reduction in cost. These specialized coagulant forms and products are claimed by manufacturers to be superior to conventional coagulants in particulate and/or organic removal with inherent advantages of lower alkalinity consumption and lesser sludge production. However, due to their proprietary nature, little is known about their chemical composition. To determine and understand the effectiveness of these alternative coagulants, a comprehensive study was undertaken to characterize metal coagulants, and to comparatively evaluate them on a well-characterized source water. The objective of this study was to provide a scheme for utilities that could be employed as a screening process and a method of selecting an appropriate coagulant based on raw water characteristics and insight into the coagulatability of the source water. Characterizations of coagulants included: (i) active metal content, (ii) anion content, (iii) acidity, (iv) alkalinity consumption, (v) charge reversal by colloidal titration, and (vi) molecular weight determination. A total of five poly-aluminum chlorides (PACl), along with a conventional coagulant (aluminum sulfate or alum) were evaluated. Results show that through the characterization scheme, an effective coagulant (conventional versus alternative) and coagulant type (among various PACl) can be chosen before undertaking time-consuming bench or pilot-scale evaluation.     

Engineered in situ bioremediation of a petroleum hydrocarbon-contaminated aquifer: assessment of mineralization based on alkalinity, inorganic carbon and stable carbon isotope balances

A concept is proposed to assess in situ petroleum hydrocarbon mineralization by combining data on oxidant consumption, production of reduced species, CH₄, alkalinity and dissolved inorganic carbon (DIC) with measurements of stable isotope ratios. The concept was applied to a diesel fuel contaminated aquifer in Menziken, Switzerland, which was treated by engineered in situ bioremediation. In the contaminated aquifer, added oxidants (O₂ and NO₃⁻) were consumed, elevated concentrations of Fe(II), Mn(II), CH₄, alkalinity and DIC were detected and the DIC was generally depleted in ¹³C compared to the background. The DIC production was larger than expected based on the consumption of dissolved oxidants and the production of reduced species. Stable carbon isotope balances revealed that the DIC production in the aquifer originated mainly from microbial petroleum hydrocarbon mineralization, and that geochemical reactions such as carbonate dissolution produced little DIC. This suggests that petroleum hydrocarbon mineralization can be underestimated if it is determined based on concentrations of dissolved oxidants and reduced species.     

Biological treatment of wastewater by selected aquatic plants

Pollutant-removal efficiency of certain macrophytes and algae, such as Eichhornia crassipes, Microcystis aeruginosa, Scenedesmus falcatus, Chlorella vulgaris and Chlamydomonas mirabilis, has been tested in laboratory conditions to evaluate their potential role in wastewater treatment. Sewage of Varanasi city, mixed with the effluents of about 1200 small-scale industries, was used for the tests. The investigation was performed in three stages i.e. a water hyacinth culture followed by an algal culture, and finally a second water hyacinth culture. For the first water hyacinth culture, 10 water hyacinth plants were grown in a tank of wastewater with 15 days' retention time. In the second stage, algal species were cultured in the treated wastewater for 5 days, whilst in the third stage, water hyacinth plants were again grown for further treatment of the wastewater for 9 days. This three-stage aquaculture resulted in very high reductions of BOD (96.9%), suspended solids (78.1%), total alkalinity (74.6%), PO(4)-P (89.2%), NO(3)-N (81.7%), acidity (73.3%), NH(4)-N (95.1%), COD (77.9%), hardness (68.6%) and coliform bacteria (99.2%). An increase in the concentration of dissolved oxygen (70%) was also observed.     

Arsenosugars and other arsenic compounds in littoral zone algae from the Adriatic Sea

In 10 different marine algae from the littoral zone (found between the highest and lowest tide marks on the seashore) arsenic compounds were determined by means of a high-performance liquid chromatography (anion and cation exchange)-UV photochemical digestion-hydride generation-atomic fluorescence spectrometry (HPLC-UV-HGAFS) system. Samples (Ceramium sp., Cystoseira barbata, Enteromorpha sp., Fucus virsoides, two different species of Gelidium, Padina pavonica, Polisyphonia sp. and Ulva rigida) were collected along the Adriatic Sea coast of Slovenia. The total arsenic content of the algal samples, as determined by ICP-MS, ranged from 1.35 to 28.1 microg g(-1) (fresh weight). In all algae but two, the most abundant arsenic species found were arsenosugars with minor amounts of other arsenic compounds. Cystoseira barbata and Ceramium sp. contained high amounts of mainly inorganic arsenic. A small quantity of arsenobetaine was detected in most of the investigated Adriatic algae, which probably originates from mesofauna attached to the algae in their natural habitat.