3种微藻在龟鳖养殖废水中的生长与脱氮除磷特性

选取小球藻(Chlorella sp.)、栅藻(Scenedesmus sp.)和螺旋藻(Spirulina sp.)为试验藻种,分别接种于经沉淀池初步处理后排放的龟鳖养殖废水(取自无为县某养殖场,简称WW废水)和无任何处理直接排放的龟鳖养殖废水(取自大杨镇某养殖场,简称DY废水),考察3种微藻生长特性和对废水中氮磷的去除效果,比较其对龟鳖养殖废水的净化能力。结果表明:所选的3种微藻在两种废水中生长特性不同,DY废水中3种微藻细胞密度与生物量均大于其在WW废水中的相应指标,DY废水中小球藻、栅藻和螺旋藻的最大生物量分别为0.26 g/L、0.28 g/L和0.20 g/L。不同微藻对废水中氮磷去除效果各不相同,栅藻去除TN效果最好,最大去除率为93.65%,小球藻去除TP效果最好,最大去除率为99.46%,螺旋藻去除NH+4-N效果最好,最大去除率为98.79%。     

不同价态铁对四尾栅藻生长的影响及机理探讨

采用实验室模拟培养的方法,分别培养初始Fe2+和Fe3+为0.2 mg/L、0.4 mg/L、0.5mg/L、0.7mg/L时的四尾栅藻。结果表明:四尾栅藻对于铁的吸收利用主要包括蛋白转运和铁置换两个过程,对于Fe2+的吸收利用以蛋白转运为主,通过修正Shaked铁吸收模型,蛋白转运进一步分为Fe3+还原和Fe2+转运两个步骤。铁的不同价态对四尾栅藻的生长影响差异明显,Fe2+较之Fe3+表现出更强的藻利用时效,同样的游离态浓度下,藻增殖速度快,藻峰值更高。四尾栅藻倾向于优先吸收Fe2+。四尾栅藻的生长环境存在一个最佳的Fe2+浓度范围,在初始Fe2+为0.4mg/L条件下,四尾栅藻生长速率最快,藻峰值最大,分别达到0.136 7个/(L·d)和2.9×108个/L。当Fe2+大于0.4mg/L时,抑制作用不明显,但增殖速率有所减缓。营养充足条件下,四尾栅藻生长曲线满足y=Aln(x)+B,A、B系数随着初始Fe2+浓度的不同而不同。     

Fenton氧化预处理磷酸酯阻燃剂生产废水

针对磷酸酯阻燃剂生产废水中COD质量浓度高,含有微生物难降解的成分,是一种难处理的有机废水的现实,利用Fenton氧化工艺对磷酸酯阻燃剂生产废水进行预处理,测定水中COD质量浓度的变化情况,以评价Fenton氧化工艺的处理效果,并考察Fe SO4·7H2O投加量、H2O2投加量及不同酸调节p H值对处理效果的影响。结果表明,最佳工艺条件为:Fe SO4·7H2O加入量为5 g/L,H2O2加入量为5.55 g/L;用硫酸调整p H值优于用盐酸调整p H值。     

某磷矿尾矿废水作磷酸铵镁沉淀利研究

磷酸铵镁(MAP)沉淀技术能够应用于废水处理实践的关键之一是探索高效、低廉的沉淀剂。采用某磷矿尾矿废水为磷源与MgCl2·6H2O作沉淀剂,与某化肥厂氨氮废水进行反应生成MAP,并与MgCl2·6H2O+Na2HPO4·12H2O和Mg(OH)2+85%H3PO4两组沉淀剂进行比较,研究各组沉淀剂在不同pH和沉淀离子配比时氨氮的沉淀效果。结果表明,以磷矿尾矿废水作为磷源的沉淀剂可以获得较好的沉淀效果,沉淀产物主要成分为MAP,该沉淀剂成本低,可实现以废治废。     

Fenton试剂处理选矿废水的试验研究

研究用Fenton试剂处理含苯胺黑药(二苯胺基二硫代磷酸)模拟废水和实际选矿废水,分别考查了反应初始pH值、Fe2+浓度及H2O2用量对COD去除率的影响。结果表明:氧化时间为10 min,反应初始pH值为4,ρ(Fe2+)=1.83 g/L,ρ(H2O2)=5.55 g/L,模拟废水苯胺黑药的质量浓度为300 mg/L时,COD去除率达到83.6%;对于实际废水,当ρ(Fe2+)=50mg/L,pH值=3.5,ρ(H2O2)=1800mg/L时,出水ρ(COD)从1000mg/L降到32 mg/L,COD去除率为96.8%,达到废水排放标准,药剂成本估计为每处理1 m3废水需要费用18元。     

北京城市化进程中地下水水化学特征识别

以北京市永定河冲洪积扇中部、紧邻老城区的两眼水源井为研究对象,采用1960—2008年近50 a的地下水水质资料,揭示了地下水的水化学演化特征:地下水先后受生活污水、工业废水、强阳离子交换作用的影响,水化学类型演化的一般序列为HCO3-Mg·Ca→HCO3·Cl-Mg·Ca→HCO3·Cl·SO4-Mg·Ca→HCO3·Cl·SO4-Ca·Na·Mg→HCO3·Cl-Ca·Na·Mg→HCO3·Cl-Na·Ca·Mg;地下水从天然状态到污染状态,HCO-3相对含量降低,而Cl-与SO2-4相对含量升高;后期受到强阳离子交换作用的影响,Na+相对含量升高,Ca2+与Mg2+相对含量降低;天然状态下,反映碳酸岩矿物溶解作用的Ca2++Mg2+与HCO-3的毫克当量比值为1.1~1.3,污染状态下该值超过2.0。     

北京市朝阳区地下水化学特征及其变化规律

为了揭示北京市朝阳区水化学特征的形成机制,采集2007—2009年不同季节中共计144个地下水样品进行监测,应用相关分析法、水化学方法和离子比例法分析地下水水化学特征、影响因素和变化规律。结果表明:丰水期和枯水期地下水水化学组分差别较小。地下水阴离子中HCO3-占绝对主导地位且含量相对稳定,质量浓度均值在290～302 mg/L,而Cl-受环境影响质量浓度变化较大,变异系数在95.7%～132%,阳离子则以Na+、Ca2+为主,质量浓度均值分别为53～72 mg/L和49～62 mg/L,且Na+质量浓度变化稍大。总体上朝阳区地下水TDS中等,均值为449.4 mg/L,与Cl-、SO24-、HCO3-、Ca2+和Mg2+的质量浓度呈显著正相关关系。地下水化学类型以HCO3-NaCa为主,少数地段出现HCO3Cl-CaMg和HCO3SO4-NaCa。     

基于碳纳米材料修饰电极快速测定水中亚硝酸盐

利用碳纳米材料石墨烯、碳纳米管分别对玻碳电极进行修饰,根据亚硝酸根(NO2-)在修饰电极上的电化学行为,快速定量测定水中NO2-的含量。实验发现石墨烯修饰玻碳电极对NO2-的检测效果更好。在最佳检测条件下(石墨烯碳纳米材料用量4μl(1 mg/ml)、溶液p H值4.0、富集时间1 min和富集电压0.7 V),石墨烯修饰玻碳电极的氧化峰电流与NO2-的浓度呈良好的线性关系,线性范围为5.0×10-6~1.0×10-3 mol/L,相关系数为0.999 0,检测限为1.0×10-6mol/L(以3倍信噪比计)。在高浓度的K+,Ca2+,Mg2+,Zn2+,Al3+,Na+,SO42-,COOH-,Cl-,Cl O-,PO43-,CO32-等离子存在条件下,对NO2-的测定没有影响。利用该修饰电极对自来水中的NO2-进行测定,结果令人满意。     

实验室自配HACH-COD替代试剂研究

通过调节COD测定系统的酸度、重铬酸钾浓度以及用量的方法来研究HACH COD自配替代试剂 ,结果发现以 0 0 3gHgSO4 + 0 5 0mL 4 9 0 3mg/mLK2 Cr2 O7+ 2 5mL 1%浓H2 SO4 Ag2 SO4 (低浓度COD时 :0 0 3gHgSO4 + 0 5 0mL 4 90 3mg/mLK2 Cr2 O7+ 2 0mL 1%浓H2 SO4 Ag2 SO4 )方式组成的替代试剂测试结果和国家标准方法GB1114 - 89测定值之间具有良好的可比性。使用本研究开发的替代试剂测定城市污水、化工废水、屠宰废水等水样时具有良好的准确性和精密性     

Fenton试剂在微波条件下处理稻壳热解发电含酚废水的试验

采取试验手段,研究在微波条件下用Fenton试剂处理含酚废水的效果,探讨H2O2质量浓度、FeSO4质量浓度、pH值、反应时间和微波功率等因素对稻壳热解发电废水中COD、挥发酚及色度去除率的影响,并进行不同条件下Fenton反应的对比试验。结果表明,在微波条件下,Fenton试剂能快速降解含酚废水,处理后水样的COD去除率超过73%,挥发酚去除率超过99%,色度去除率接近50%。该含酚废水的最佳处理条件是:H2O2质量浓度为1500 mg/L,FeSO4质量浓度为100 mg/L,pH值为3,反应时间为10 min,微波功率为400 W。     

改性生物炭的光谱表征及砷的吸附效果研究

为了研究棉花秸秆生物炭的基本性质及其对砷的吸附效果,采用FeCl₃·6H₂O改性棉花秸秆生物炭,通过XRD、FT-IR和SEM等技术表征其光谱性能,并探究其对砷的吸附效果。结果表明：采用FeCl₃·6H₂O改性棉花秸秆生物炭后,生物炭的pH值、比表面积以及C、N、H元素的含量和C/N的比值随Fe含量的提高显著降低,灰分和O元素的含量以及H/C、O/C和(N+O)/C的比值随Fe含量的提高显著增加,生物炭表层Fe₂O₃和Fe₃O₄的含量增加。生物炭改性后缩短了吸附砷的平衡时间,吸附率高达73.4%,远高于未改性生物炭的吸附率（44.7%）,吸附量高达7.63 mg/g,远高于未改性生物炭的吸附量（4.33 mg/g）,且随Fe含量的提高,吸附率和吸附量均显著增加。其作用机制主要是通过改性生物炭静电吸附能力、离子交换和Fe3+的还原作用降低水溶液中的As的含量,进而达到去除水溶液中As的目的。     

Restoring native vegetation in a Eurasian water-milfoil dominated plant community using the herbicide triclopyr

In an effort to evaluate the selective control of the exotic weed Eurasian water milfoil (Myriophyllum spicatum L.) and to assess the recovery and restoration of the native submersed plant community, a 6-ha river and 4-ha cove plot were treated with the herbicide triclopyr at application rates of 2·5 and 1·75 mg/l, respectively, in the Pend Oreille River, WA, in August 1991. Water exchange half-lives within the plots were measured using rhodamine WT dye (river, t_1/2=20 h; cove, t_1/2=52 h), and triclopyr dissipation rates were also calculated (river, t_1/2=19 h); cove, t_1/2=53 h). Triclopyr concentrations were below the proposed potable water tolerance level (0·5 mg/l) within the river treatment plot by 3 days after treatment (<0·01 to 0·41 mg/l), and 675 m downstream of that plot by 1 day after treatment (<0·01 to 0·47 mg/l). Following the cove treatment, triclopyr residues ranged from 0·12 to 0·29 mg/l by 7 days after treatment, and from<0·01 to 0·06 mg/l as close as 150 m downstream from the plot. Eurasian water milfoil biomass was reduced by 99% in the treated plots at 4 weeks post-treatment, remained low one year later (river treatment, 28% of pretreat levels; cove treatment 1% of pre-treat levels) and was still at acceptable levels of control at two years post-treatment (river treatment, 47% of pre-treat levels; cove treatment, 24% of pre-treat levels). The four-week post-treatment efficacy results verified triclopyr concentration/exposure time relationships for controlling Eurasian water milfoil developed under laboratory conditions. Non-target native plant biomass increased 500–1000% by one year post-treatment, and remained significantly higher in the cove plot at two years after treatment. Native species diversity doubled following herbicide treatment, and the restoration of this robust community delayed the re-establishment and dominance of Eurasian water milfoil for three growing seasons. ©1997 John Wiley & Sons, Ltd.     

改良型人工快渗系统脱氮除磷效果研究

人工快渗(CRI)系统是一种广为人知的无动力生态处理技术措施,但传统CRI系统存在对氮、磷去除率普遍较低的问题。本研究采用海绵铁、沸石、火山岩、红壤土和杂沙作为填料,构建了一个改良型CRI系统,在水力负荷为1 m~3/(m~3·d)的条件下,以实际生活污水为试验进水,进行为期20天的试验。实验结果表明,该系统在运行16天后出水TP、TN和NH_3-N浓度均趋于稳定,稳定后出水平均浓度分别为0.21 mg/L、8.38 mg/L和2.34 mg/L,能分别满足《城镇污水处理厂污染物排放标准》(GB18918-2002)一级A排放标准的0.5 mg/L、15 mg/L和5 mg/L的限值。TP、TN和NH3-N三项指标的总平均去除率为84.44%,远高于传统CRI系统的44.06%总平均去除率。该研究成果为治理农村生活污水提供了一项行之有效的生态治理技术措施。     

Experiences of nitrogen and phosphorus removal in deep-bed filters at Henriksdal sewage works in Stockholm

Deep-bed down-flow two-media filters were used in pilot plant studies with filtration of secondary settled wastewater. FeSO₄ or FeCl₃ was applied as a precipitation agent, and NaAc·3H₂O was chosen as a carbon source when denitrification was desired. The concentration of PO₄-P in the filtrate from the pilot plant study never exceeded 0.05 mg PO₄-P/l when iron salts were dosed. The curves showing the concentration of P-tot and PO₄-P in the filtrate as a function of the quotient between the dosage of iron and the concentration of PO₄-P in the influent to the filter followed approximately an exponential relationship. The total nitrogen reduction over the filter bed increased from an average of 2.3 mg (NO₃+NO₂-N/l at the beginning of each experiment to an average of 4.3 mg (NO₃+NO₂)-N/l towards the end of the lest. When only secondary settled wastewater, suspended solids, primary settled wastewater, iron salts, or sodium acetate was added, at a hydraulic load of 10 m/h, the time before clogging became 100 h, 10 h, 10 – 15 h, 20 – 40 h, and 20 – 40 h, respectively. Almost the entire pressure drop was located on the surface of the filter bed and 0.25 metre down in the expanded clay layer.     

Precise Radiotracer Measurement of the Rate of Sediment Reworking by Stylodrilus Heringianus and the Effects of Variable Dissolved Oxygen Concentrations

A radiotracer method is used to determine the rate of sediment reworking by the worm, Stylodrilus heringianus, an organism common in profundal sediments of the Great Lakes. A submillimeter layer of sediment labeled with gamma-emitting cesium-137 is added to the surface of worm-inoculated sediments contained in cells of rectangular cross-section placed in an insulated aquarium (10° C). This layer, progressively buried by the conveyor belt feeding action of the worms, is located by scanning the cell with a well-collimated detector mounted on a hydraulically actuated elevator. Precision in locating the marked layer is greatly enhanced by Gaussian profile analysis developed in this study. Relative uncertainties in location of less than 0.01 cm allow reworking rates as low as 10^?3cm/hr to be determined in 1 to 2 days. The effect of variable dissolved oxygen (D.O.) concentrations on sediment reworking rates was determined by adjusting the relative proportions of N₂ and O₂ introduced into the aquarium through a continuous bubbler system. In a cell subject to gradual reductions in D.O. (about 1 mg/L every 50 hours) from saturation concentration (10.6 mg/L), sediment reworking rates remained virtually constant down to 1 mg/L. Below this value, the rate decreased, approaching zero at 0.2 mg/L. On increasing D. O. values above about 4 mg/L, reworking returned to the initial rate. Gradual decreases in D.O. induced a reversible dormant mode in these organisms. In cells subject to coarse D.O. changes (3.7 to 8.8 mg/L per step), reworking stopped at around 4 to 5 mg/L and did not resume following reinstatement of saturation values for up to 18 days. In all cases more than 70% of worms were alive at the end of the experiment. This study illustrates the potential of the gamma scan system for quantitative behavioral bioassay of the interactions of zoobenthos with altered sedimentary environments.     

Physico-chemical and bacteriological characterization of wastewater from Mexico city

This study was designed to characterize the behavior of the wastewater produced by Mexico City after being subjected to a physicochemical treatment of Al₂(SO₄) and FeCl₃ in a jar test simulation of an Advanced Primary Treatment (APT). Special attention was paid to the evaluation of the removal efficiency of suspended solids and of helminth eggs. The effluent thus obtained was first subjected to a simulated filtration process (through a fiberglass filter paper with an opening of 11 μm) and then it was disinfected with the use of two chemicals: sodium hypochlorite (NaOCl) and copper sulphate (CUSO₄).The use of both the Al₂(SO₄)₃ (dose ranging from 25 to 40 mg/L) and the FeCl₃ (varying from 20 to 40 mg/L) in combination with the filtration process proved to be quite effective in what refers to the removal mechanisms of helminth eggs. The concentrations recorded in each of the effluents fell always below the international regulations for irrigation reuse (<1 org/L as helminth eggs). The removal rates achieved for both coagulants were close to 99%.In what refers to the disinfection accomplished with the use of NaOCl (from 4 to 17 mg/L as Cl₂) and CUSO₄ (from 3 to S mg/L as Cu), it was found to be an excellent supplementary process because less than 1000 CFU/100 mL were recorded and this value satisfies the international recommendations. The treatment as a whole showed removal efficiencies of 45% as COD, 73% SST, 99% helminth eggs, 99.99% faecal coliforms and from 7 to 87% in heavy metals.     

FeS矿活化H2O2降解水中对氯苯胺的实验研究

以对氯苯胺(PCA)为目标污染物,研究了常温下Fe S矿活化H2O2非均相类Fenton体系对难降解有机物的去除效果。分析了初始p H值、催化剂和H2O2投加量等重要因素对PCA降解率的影响。当PCA浓度为0.2×10-3mol/L,溶液初始p H值为3.0,H2O2投加量为3.2×10-3mol/L,Fe S矿用量为0.4 g/L,反应20 min时,PCA去除率可达100%,且反应进行到40 min后,已达到完全脱氯效果。在此基础上,通过对Cl-、SO42-、Fe3+等中间产物离子和总有机碳(TOC)变化规律的测定,探讨了有机物降解机理。研究结果表明:Fe S矿对催化H2O2氧化具有很强的催化活性,能提高H2O2的利用效率,相比于单一含铁矿物具有更好的催化性能,并且催化剂易于沉淀分离,回收利用。     

Impact of an urban centre on the nitrogen cycle processes of epilithic biofilms during a summer low‐water period *

Nitrogen transformations in epilithic biofilms of a large gravel bed river, the Garonne, France, has been studied upstream (one site) and downstream (four sites) of a large urban centre (Toulouse, 740 000 inhabitants). High biomass, up to 49 g AFDM m^?2 (ashes free dry matter) and 300 mg chlorophyll a m^?2 (Chl. a), were recorded at 6 and 12 km downstream from the main wastewater treatment plant outlet. The lowest records upstream and larger downstream (less than 16 g AFDM m^?2 or 120 mg Chl. a m^?2) could be explained by recent water fall (early summer low‐water period). Measurements of nitrogen exchange at the biofilm–overlying water interface were performed in incubation chambers under light and dark conditions. The addition of acetylene at the mid‐incubation time allowed evaluation of both nitrification (variation in NH₄⁺ flux after the ammonium monooxygenase inhibition) and denitrification (N₂O accumulation related to the inhibition of N₂O reduction). Denitrification (D_w) and nitrification rates were maximum at sites close to the city discharges in dark conditions (up to 9.1 and 5.6 mg N m^?2 h^?1, respectively). Unexpected denitrification activities in light conditions (up to 1.4 mg N m^?2 h^?1) at these sites provided evidence for enhanced nitrogen self‐purification downstream. As confirmed by most probable number (MPN) counts, high nitrification rates in biofilm close downstream were related to enhanced (more than almost 3 log) nitrifying bacteria densities (up to 7.6×10⁹ MPN m^?2). Downstream of an urban centre, nitrogen transformations in the biofilm appeared to be influenced by the occurrence of an adapted microflora which is inoculated or stimulated by anthropic pollution. Copyright © 2002 John Wiley & Sons, Ltd.     

Effect of selenium on the growth of some selected green and blue-green algae

An algal assay procedure using microplate technique was carried out to assess the effect of selenium on the growth of some green and blue-green algae. Sodium selenite pentahydrate (Na₂SeO₃.5H₂O) and selendioxide (Se₂O₄) were tested as selenium. The test algae were Selenastrum capricornutum, Scenedesmus obliquus, Chlorella sp., Monoraphidium convolutum, Monoraphidium contortum, Monoraphidium griffithii, Anabaena flos-aquae, Micro-cystis aeruginosa, and Oscillatoria agardhii. The blue-green algae are toxin-producing strains. Cell number and in vivo chlorophyll fluorescence were the growth parameters of green and blue-green algae respectively. Dose-response curves quantify the selenium toxicity in terms of EC₅₀. The lowest selenium concentrations giving no detectable growth (EC₁₀₀) were visually inspected. The test algae showed distinctly different responses to various selenium treatments. Selenium at concentrations < 0.1 mg L⁻¹ stimulates, to varying degrees, the growth of all the green algae with one exception: S. capricornutum was dramatically inhibited at all treatments. O. agardhii, A. flos-aquae and M. aeruginosa showed marginal growth stimulation up to 0.1 mg Se L⁻¹, 1.0 mg Se L⁻¹ and 3.2 mg Se L⁻¹ respectively. In terms of EC₅₀, the compound selendioxide was more toxic to greens than sodium selenite. The reverse was indicated for the blue-greens. In general, the EC₅₀ presented a wide range (0.08–7.2 mg Se L⁻¹), with the lowest values reported for S. obliquus and the highest for M. aeruginosa. All the test algae, except S. obliquus, maintained observable growths at higher selenium levels (EC₁₀₀>1.0<100mg Se L⁻¹).