巢湖蓝藻的机械清除工艺以及藻水分离实验研究简

对巢湖蓝藻进行机械清除以及藻水分离实验研究，实验采用的浮式围栏引导-机械清除-投加剥离液辅助机械清除工艺处理量大，除藻效率高，筛网过滤-浓缩-卧螺离心机脱水成藻泥的藻水分离工艺较为理想，藻泥含水率仅为89%。2011年5—10月在巢湖运用上述方法清除湖面水华蓝藻，共处理富藻水1.6万m³，得到藻泥970 t，累计清除蓝藻106.7 t（干重）。按照所清除蓝藻的总氮、总磷的平均含量计算，相当于从湖中移除了氮6.25 t，磷2.1 t。表明在富营养湖泊中水华蓝藻大量暴发时，采用上述方法除藻，对控制蓝藻水华污染，有效降低内源氮、磷等污染物负荷具有十分重要的作用。     

生物合成聚合硫酸铁混凝-厢式压滤组合工艺对富藻水脱水效果的影响研究

针对湖泊蓝藻爆发期间经物理作业产生的富藻水含水率高、不易脱水、难于后续处置的问题,尝试采用生物合成聚合硫酸铁（BPFS）混凝-厢式压滤机组合工艺对富藻水进行脱水处理,并探讨了投加BPFS、BPFS与石灰复合药剂及采用不同滤布对富藻水压滤后滤液水质及蓝藻脱水性能的影响。结果表明,富藻水中加入3.30 g/L石灰与0.17...     

浓缩湖泊蓝藻液的加压混凝沉淀处理

为了提高蓝藻液浓缩效率,降低能耗,采用外加压力压破蓝藻气囊,使蓝藻失去气囊浮力易于混凝沉淀分离。采用中试实验研究了加压混凝浓缩蓝藻液的技术方法,优化了工艺参数,并进行了经济分析。结果表明,在原藻液含水率99.4%~99%时,最佳的混凝剂(PAC)投加量与干藻质量比为1/20,最佳的助凝剂(PAM)投加量与干藻质量比为1/1 500。浓缩后出水浊度在1~5 NTU之间,出水叶绿素a在10 mg·m~(-3)以内,浓缩藻泥含水率都小于97%,原藻液浓缩了3.52~5.51倍。加压破蓝藻气囊能耗0.008 k W·h·m~(-3),比现有高速旋转法破蓝藻气囊工艺节省能耗0.6 k W·h·m~(-3)。     

四步盐析提取巢湖新鲜蓝藻中藻蓝蛋白及其稳定性

实验采用四步盐析法提取巢湖水华蓝藻中的藻蓝蛋白并对其稳定性进行研究。以藻蓝蛋白纯度和得率为指标,采用3次冻融破壁后蓝藻,运用黄金分割法在饱和度为0%~70%的范围内选取合适的硫酸铵用量。并考察了光照、时间、环境温度、p H、乙醇及常见食品添加剂对藻蓝蛋白稳定性的影响。结果表明,常温下四步盐析法采用硫酸铵的饱和度分别为21%、30.4%、26.28%和47.76%,藻蓝蛋白纯度和得率分别为3.157和1.664%。藻蓝蛋白在避光和常温中性条件下保持稳定,超出此范围稳定性下降。添加乙醇和柠檬酸将导致藻蓝蛋白稳定性下降,氯化钠和苯甲酸钠对藻蓝蛋白稳定性影响较小。     

改进的硫酸盐-聚乙烯醇法包埋藻菌脱氮除磷研究

采用改进的硫酸盐-PVA固定化法将藻与菌混合固定。在三种不同藻菌比的情况下，固定化系统对氮去除均可达100％，但是去除速度与固定的细菌量有关，细菌量越大，对氮的去除速度越快；对磷的去除随实验进行，最大去除率逐步下降，其下降速度与固定藻的量有关，藻量越大，下降速度越慢。由此说明脱氮的主要贡献者是细菌，而藻对除磷起了主要作用。为达到有效的脱氮除磷，应适当提高固定化藻的浓度，藻菌比应大于2：1。透射电镜照片显示，在聚乙烯醇载体上，藻类的生长没有受到限制。     

改良型A2／O-MBR工艺的反硝化除磷性能研究

重点考察了-种改良型膜生物反应器（A2／O—MBR）的脱氮除磷性能。该工艺主要特点在于对膜池硝化回流液进行了固液分离，并将上清液和浓缩污泥分别回流至缺氧池和厌氧池，这种改进提高了系统对氮、磷的同步去除效率。实验结果表明，在水力停留时间（HRT）为12h，污泥龄（SRT）为30d，混合液回流比为200％的运行条件下，进水COD、NH4＋-N、TN和TP平均浓度分别为（225±38）、（24．8±3．9）、（26．7±2．9）和（2．90±0．53）mg／L时，增加膜池硝化回流液固液分离装置前后，系统对COD和NH4＋-N的去除都维持在较高水平，而系统对TN和TP的去除效果显著提高，出水TN和TP平均浓度分别由（14．9±3．3）mg／L和（1．95±0．72）mg／L下降到（9．4±1．9）mg／L和（0．91±0．38）mg／L，表明增加膜池硝化回流液固液分离装置显著改善了A2／O-MBR系统的脱氮除磷效果。反硝化除磷活性实验结果进一步表明，改进后系统中反硝化除磷活性占总除磷活性的比例由51．5％上升至61．7％，说明增加膜池硝化回流液固液分离装置强化了系统的反硝化除磷性能。     

水解酸化-A2O污泥减量工艺的运行性能研究

生物处理单元采用水解酸化、多级串联接触曝气、连续流的除磷脱氮A2／O工艺，并辅以外排厌氧富磷污水侧流除磷，开发了一个新型的具有强化除磷脱氮功能的污泥减量HA—A／A—MCO工艺。用该工艺处理校园生活污水发现，在SRT60d、进水COD316～407mg／L、NH4＋-N30～40mg／L、TN35～53mg／L、TP8—12mg／L的条件下，出水COD≤18mg／L、NH4＋-N≤2．1mg／L、TN≤10．3mg／L、TP≤0．44mg／L。研究还发现，水解酸化池处理产生的VFA能有效促进生物除磷脱氮，导致厌氧释磷量达57mg／L，进入化学除磷池的侧流液量仅相当于进水量的13％；系统最主要的脱氮形式是SND和缺氧反硝化，SND脱氮占脱氮总量的50％，缺氧反硝化占26％；HA-A／A—MCO系统有效实现了生物相分离，并利用生物捕食作用获得较低的污泥产率，0．1gMLSS／gCOD。     

海河干流天津段氮磷对藻类生长的影响及动力学分析

本实验以海河干流天津段水体为对象,对其中四种典型共存藻类(即铜绿微囊藻、小球藻、卵囊藻和席藻)在不同氮磷营养盐环境条件下的响应生长规律进行了过程表征及动力学研究。实验结果表明,N/P在10~40范围适宜藻类生长,N/P为10时藻类比增长率最大;氮浓度水平在2.0~15 mg·L~(-1)、磷浓度水平在0.2~1.5 mg·L~(-1)内,藻类比增长率随着氮磷浓度的升高而增大,当氮浓度为15 mg·L~(-1),磷浓度为1.5 mg·L~(-1)时达到最大,优势藻为卵囊藻;通过Monod藻类生长动力学分析得出,藻类最大比增长率为0.050 8,半饱和常数为0.157,表明目标河段水华暴发风险相对较低,且磷是藻生长限制性因子。     

改进型双泥反硝化除磷脱氮工艺 --一种可望从根本上解决脱氮除磷矛盾的新工艺

在对单污泥系统同时脱氮除磷内在矛盾分析的基础上,探讨了目前国内外双泥系统优化脱氮除磷的可行性,提出了强化解决氮磷矛盾的新工艺——改进型双泥反硝化除磷脱氮工艺。本研究利用SBR反应器对改进型工艺进行了实验室模拟,并为该系统的进一步完善提出了建议。     

壳聚糖-纳米金属絮凝剂絮凝沉降水华蓝藻研究

研究了壳聚糖与纳米钛、纳米铁或妫水湖沉积物絮凝剂絮凝沉降水华蓝藻的效果。结果表明:在壳聚糖浓度为3 mg/L情况下,与妫水湖沉积物和纳米钛相比,纳米铁絮凝沉降蓝藻细胞的效果最好,在10 min内可以絮凝沉降79.5%以上的水华蓝藻细胞。进一步研究显示,在pH值为5~9的范围内,随着pH值的降低,絮凝沉降藻细胞的效率逐渐提高,pH值为5时10 min内可以絮凝去除89.6%以上的水华蓝藻细胞,具有重要的研究价值与应用价值。     

Internal ecosystem feedbacks enhance nitrogen-fixing cyanobacteria blooms and complicate management in the Baltic Sea

Eutrophication of the Baltic Sea has potentially increased the frequency and magnitude of cyanobacteria blooms. Eutrophication leads to increased sedimentation of organic material, increasing the extent of anoxic bottoms and subsequently increasing the internal phosphorus loading. In addition, the hypoxic water volume displays a negative relationship with the total dissolved inorganic nitrogen pool, suggesting greater overall nitrogen removal with increased hypoxia. Enhanced internal loading of phosphorus and the removal of dissolved inorganic nitrogen leads to lower nitrogen to phosphorus ratios, which are one of the main factors promoting nitrogenfixing cyanobacteria blooms. Because cyanobacteria blooms in the open waters of the Baltic Sea seem to be strongly regulated by internal processes, the effects of external nutrient reductions are scale-dependent. During longer time scales, reductions in external phosphorus load may reduce cyanobacteria blooms; however, on shorter time scales the internal phosphorus loading can counteract external phosphorus reductions. The coupled processes inducing internal loading, nitrogen removal, and the prevalence of nitrogen-fixing cyanobacteria can qualitatively be described as a potentially self-sustaining "vicious circle." To effectively reduce cyanobacteria blooms and overall signs of eutrophication, reductions in both nitrogen and phosphorus external loads appear essential.     

Secondary nitrogen limitation in a subtropical lake impacted by non-point source agricultural pollution

A 20-year history of nutrient limitation was quantified for Lake Okeechobee, a nutrient-impacted lake in Florida, USA. Limiting status (nitrogen versus phosphorus) was estimated from deviations between trophic state index (TSI) parameters, calculated from routine monitoring data. The lake is presently nitrogen-limited. However, historical trends in the TSI deviations indicate that contemporary nitrogen limitation is a secondary, unnatural condition that has arisen due to excessive phosphorus loading. Prior to 1980, there was evidence of lake-wide limitation by phosphorus, rather than nitrogen. The finding of secondary nitrogen limitation in Lake Okeechobee has important management implications. Phosphorus loads are presently being reduced in order to reduce in-lake concentrations and create phosphorus-limited conditions (nitrogen limitation is undersirable because it has favored bloom-forming cyanobacteria). The present results indicate that this long-term management goal is ecologically sound; it is consistent with the concept of restoration of the lake.     

新型人工快速渗滤系统处理村镇污水工艺参数优化

在巢湖双桥河建立了中试规模的人工快速渗滤系统(CRI),系统经过一个月左右启动期后挂膜成功。通过考察不同湿干比条件下CODMn、TP、TN和NH3-N的去除效果,确定系统湿干比为1 d∶2 d,水力负荷周期为3 d。TP、TN和NH3-N在1.0 m/d的水力负荷条件下能够达到最佳的处理效果,特别是TN;而CODMn在1.3 m/d取得最佳的去除效果。综合考虑脱氮除磷和有机污染物的去除,选取水力负荷为1.0 m/d可得到最佳的出水水质。综合4种污染物的去除特点,特别考虑到对TN去除的需要,同时兼顾工程成本,填料厚度确定为1.2～1.5 m之间为最佳。选取生物陶粒、钢渣、活性炭和天然沸石为渗滤介质,研究结果表明,从去除有机污染物和TP角度考虑,选取活性炭和钢渣可达到较好的去除效果,其中钢渣对TP去除效果更佳;而活性炭具有其他4种填料不可替代的脱氮效果。以上工艺组合形式的确定将为巢湖流域CRI系统的推广提供科学依据和数据支持。     

巢湖合肥地区洗衣粉排磷占入湖磷贡献率的研究

合肥地区人均洗衣粉用量为3．12kg/a,洗衣粉总用量为8345t/a,洗衣粉带入水体的总磷量为256．08t/a,占入湖总磷负荷量的13．62％。因此,实行“禁磷”措施后,可削减该地区入湖总磷负荷量的13．62％,对改善巢湖水质将会起到一定的积极作用。     

N:P ratios,light limitation,and cyanobacterial dominance in a subtropical lake impacted by non-point source nutrient pollution

A long-term (28-year) data set was used to investigate historical changes in concentrations of phosphorus (P), nitrogen (N), N:P ratios, and Secchi disk transparency in a shallow subtropical lake (Lake Okeechobee, Florida, USA). The aim was to evaluate changes in the risk of N2-fixing cyanobacterial blooms, which have infrequently occurred in the lake's pelagic zone. Predictions regarding bloom risk were based on previously published N:P ratio models. Temporal trends in the biomass of cyanobacteria were evaluated using phytoplankton data collected in 1974, 1989-1992, and 1997-2000. Concentrations of pelagic total P increased from near 50 microg l-1 in the mid-1970s to over 100 microg l-1 in the late 1990s. Coincidentally, the total N:P (mass) ratio decreased from 30:1 to below 15:1, and soluble N:P ratio decreased from 15:1 to near 6:1, in the lake water. Published empirical models predict that current conditions favor cyanobacteria. The observations confirm this prediction: cyanobacteria presently account for 50-80% of total phytoplankton biovolume. The historical decrease in TN:TP ratio in the lake can be attributed to a decreased TN:TP ratio in the inflow water and to a decline in the lake's assimilation of P, relative to N. Coincident with these declines in total and soluble N:P ratios, Secchi disk transparency declined from 0.6 m to near 0.3 m, possibly due to increased mineral turbidity in the lake water. Empirical models predict that under the turbid, low irradiance conditions that prevail in this lake, non-heterocystous cyanobacteria should dominate the phytoplankton. Our observations confirmed this prediction: non-N2-fixing taxa (primarily Oscillatoria and Lyngbya spp.) typically dominated the cyanobacteria community during the last decade. The only exception was a year with very low water levels, when heterocystous N2-fixing Anabaena became dominant. In the near-shore regions of this shallow lake, low N:P ratios potentially favor blooms of N2-fixing cyanobacteria, but their occurrence in the pelagic zone is restricted by low irradiance and lack of stable stratification.     

Determination of atmospheric nitrogen input to Lake Greenwood, South Carolina: part 2--Gaseous measurements and modeling

The Reedy River branch of Lake Greenwood, SC, has repeatedly experienced summertime algal blooms, upsetting the natural system. A series of experiments were carried out to investigate atmospheric nitrogen (N) input into the lake. N was examined because of the insignificant phosphorus dry atmospheric flux and the unique nutrient demands of the dominant algae (Pithophora oedogonia) contributing to the blooms. Episodic atmospheric measurements during January and March 2001 have shown that the dry N flux onto the lake ranged from 0.9 to 17.4 kg N/ha-yr, and on average is caused by nitric acid (HNO3; 31%), followed by nitrogen dioxide (NO2; 23%), fine ammonium (NH4+; 20%), coarse nitrate (NO3-; 16%), fine NO3 (5%), and coarse NH4+ (5%). Similar measurements in Greenville, SC (the upper watershed of the Reedy River), showed that the dry N deposition flux there ranged from 1.4 to 9.7 kg N/ha-yr and was mostly caused by gaseous deposition (40% NO2 and 40% HNO3). The magnitude of this dry N deposition flux is comparable to wet N flux as well as other point sources in the area. Thermodynamic modeling showed low concentrations of ammonia, relative to the particulate NH4+ concentrations.     

改进的TLI指数法及其在巢湖营养状态评价中的应用

对巢湖2000—2008年的监测数据运用SPSS做统计分析,得出叶绿素a与总氮、总磷和透明度的相关系数。通过得出的权重结果,分析出与26个湖泊的差异性,构建了改进的综合营养状态指数(TLI)评价方法,并提出评价的4个步骤。以巢湖为例,运用该方法对湖泊的营养状态进行评价,且对巢湖的富营养化程度做了年际和年内变化的综合评价,评价结果显示各营养物指标的相关关系在近30年有了较大变化,巢湖的富营养化现象已日益严重,已从轻度富营养化状态转变为中度富营养化状态。     

模糊物元识别模型在巢湖水体富营养化评价中的应用研究

选取TN、TP、Chl-a、COD、BOD5、DO和SD等7项指标,应用模糊物元识别模型对2000~2007年巢湖的12个水质监测点的富营养化等级进行了模糊识别。通过与巢湖同期水质浓度变化及其分布区域进行对比分析,验证了模糊物元识别模型在巢湖水体富营养化评价中的适用性。巢湖富营养化评价结果表明,2000~2007年富营养化呈逐年加重的趋势,据采样点模糊物元计算结果得知西巢湖(1#~6#)的富营养化状况比东巢湖(7#~12#)更严重,西巢湖贴近度最高值为0.9974,接近极富营养状态,而东巢湖的最高值仅为0.5866。从年际变化上看,2000~2007年东巢湖富营养化状况变化不大,营养状态级处在较低的水平,而西巢湖的富营养状况变化则较大,营养状态级则处在较高水平。     

Determination of Atmospheric Nitrogen Input to Lake Greenwood,South Carolina—I. PM Measurements

Abstract

The Reedy River branch of Lake Greenwood, SC, has repeatedly experienced summertime algal blooms, upsetting the natural system. This lake’s shallow depth makes it susceptible to atmospheric influence. A series of experiments were carried out in order to investigate the effect of atmospheric nitrogen deposition into the lake. Nitrogen was examined because of the insignificant phosphorus dry atmospheric flux and the unique nutrient demands of the dominant algae (Pithophora oedogonia) contributing to the blooms.

In this paper, results are presented of the experimental measurement of coarse and fine atmospheric concentrations of atmospheric particulate nitrogen adjacent to and in the watershed of the Reedy River (downtown Greenville) and Lake Greenwood. Experiments were carried out during four 24-hr periods in January 2001 and again during four 24-hr periods in March 2001. Results are presented here for atmospheric particulate nitrogen as well as other constituents of the airborne aerosol. Mass concentrations of PM_2.5 averaged 14.0 and 21 µg/m³ for Lake Greenwood and downtown Greenville, respectively. Mass concentrations of total suspended particulates (TSP) averaged 22.6 and 38.5 μg/m³ for Lake Greenwood and downtown Greenville, respectively. This ambient aerosol concentration was apportioned to its chemical constituents, and the greatest contributors to PM_2.5 mass were organics (45 and 42% for downtown Greenville and the lake, respectively) and sulfate (14.1 and 19.7% for downtown Greenville and the lake, respectively).

The information gathered here, despite its episodic nature, is important not only in determining atmospheric nitrogen but also in documenting the composition of aerosol in South Carolina, which so far has not been studied. In a companion paper, results for gaseous pollutants as well as thermodynamic modeling of the aerosol and nitrogen flux determinations are presented.