巢湖蓝藻的机械清除工艺以及藻水分离实验研究

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一机械清除．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970t，累计清除蓝藻106．7t（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6．25t，磷2．1t。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)。     

改良型A2/O-MBR工艺的反硝化除磷性能研究简

重点考察了一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12 h，污泥龄（SRT）为30 d，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。     

A-A2/O工艺脱氮实践运行效果及优化

A-A²/O工艺是预缺氧/厌氧/缺氧/好氧组成的生物脱氮除磷工艺，广州市某污水处理厂采用该工艺处理城市污水，具有同时去除有机物、脱氮除磷能力，但是TN去除率较低。分析了其TN去除率低的原因，并提出相应措施。该水厂针对本厂水质特征以及影响工艺脱氮性能的主要因素，优化了工艺控制参数，提高了TN去除率和TN达标保证率。     

倒置A2/O污水处理工艺的特点及应用实例

传统A²/O工艺在保证脱氮效果的同时除磷效果往往不佳。在充分分析传统A²/O工艺的基础上，提出了将缺氧池置于厌氧池前面，厌氧池后设置好氧池的分点进水倒置A²/O工艺。某污水厂的现场试验表明，在COD去除能力与常规A²/O工艺相当的情况下，倒置A²/O工艺的脱氮除磷功能明显优于常规A²/O工艺。     

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。     

MB(A2/O)处理城市污水富磷上清液的化学除磷研究

为开发新型除磷脱氮工艺，研制了将MBR和A²/O工艺相结合的新型MB(A²/O)反应器。研究了MB(A²/O)反应器处理城市污水厌氧富磷上清液的化学除磷，并分析了过程机理及特性。结果表明：对于TP在30～45 mg/L的富磷上清液，采用含20% Ca(OH)₂的工业石灰与P的最佳投加质量比为22.5；纯Ca(OH)₂与P的最佳投加质量比为5.6（摩尔比为2.5）；FeSO₄·7H₂O与P的最佳投加质量比为10.7（Fe^2＋与P的摩尔比为1.3）；Al₂(SO₄)₃·12H₂O与P的最佳投加质量比为12（Al^3＋与P的摩尔比为1.3）时，均可使出水TP稳定在0.3 mg/L以下；以石灰、NaOH的联合投加方式可大幅减少石灰投加量。     

4种营养元素对水华鱼腥藻和四尾栅藻增殖的影响

以水华鱼腥藻和四尾栅藻分别作为蓝藻,绿藻代表藻种,采用均匀设计实验方法(uniform design experimentation,UDE)设计藻类AGP实验。采用通径分析法(Path Analysis,PA)对氮、磷、铁和锰在不同藻种增殖过程中的影响程度进行分析。结果表明,4种营养元素对水华鱼腥藻增殖影响的决策排序为FeTNTPMn,微量金属元素铁是影响水华鱼腥藻(蓝藻)增殖的主要因素;对四尾栅藻增殖影响的决策排序为TNTPFeMn,常量元素是影响四尾栅藻(绿藻)增殖的主要因素。联合通径分析法和逐步二次方回归分析法(QRA)建立的数学模型,可用于预判藻增殖。     

双泥膜法SBR脱氮除磷效果研究

通过实验室小试，以人工模拟生活污水为研究对象，考察了基于反硝化除磷理论开发的双泥膜法SBR工艺的脱氮除磷效果。长期试验结果表明：双泥膜法SBR工艺能使硝化菌和除磷菌各自在最佳的环境中生长，解决了传统工艺中脱氮和除磷的矛盾，节省了碳源和能源，并取得了稳定高效的脱氮除磷效果。在进水C∶N∶P为25∶5∶1，换液比为75%的情况下，系统对COD，TP和NH⁺₄-N的平均去除率分别为89.13%、96.12%和86.78%。     

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.