硫酸盐还原菌处理高浓硫酸盐废水

采用硫酸盐还原菌(SRB)在厌氧序批式反应器(ASBR)中处理高浓度硫酸盐废水。对钛白粉生产废水的试验显示，SO4^2-的去除率可达到83．5％，达到了国家排放标准(250mg／L)。COD／SO4^2-值对SO4^2-的去除率有较大影响，比值为2～3时去除效果最佳。在试验装置的设计中采用了气循环与水循环并用的方法，以防止H2S气体对SRB的毒害并起到搅拌作用。     

几种含铬钙矾石的合成试验研究

通过室内人工合成的几种含铬钙矾石的试验发现,Cr(Ⅲ)、Cr2O7^2-、CrO4^2-等均可进入钙矾石晶格而被固化。Cr2O7^2-是以CrO4^2-的形式进入钙矾石晶格的。试验表明,在缺乏SO4^2-供应充分时,CrO4^2-很容易替代SO4^2-进入钙矾石晶格,形成铬酸钙矾石;但在SO4^2-供应充分时,CrO4^2-基本上不能进入钙矾石晶格。因此为了有效地固化CrO4^2-,必须选择无石膏的水泥类型。在无铝离子时。Cr(Ⅲ)在高浓度的NaOH溶液中可替代Al与SO4^2-或与CrO4^2-结合分别形成Cr(Ⅲ)-硫酸钙矾石或双铬钙矾石。但在Ca(OH)2中等碱性溶液中,Cr(Ⅲ)主要以Cr(OH)3的形式存在,其溶解度很小,Cr(Ⅲ)基本上不能替代Al与SO4^2-或与CrO4^2-结合形成钙矾石。尽管如此,双铬钙矾石的成功合成对同时含有Cr(Ⅲ)和CrO4^2-的废水进行S／S处理提供了新的思路。     

臭氧系统在净水厂深度处理中的应用

介绍了某水厂臭氧生物活性炭（O3／BAC）深度处理工艺中臭氧系统的组成、工作条件、设备技术参数。生产运行结果表明，采用预O3可节省矾耗20％，O3／BAC深度处理技术对浊度、色度、CODMn、NH4^＋-N、NO2^--N的去除效果好，出水平均浊度为0．121～0．161NTU，去除率〉99．25％；出水CODMn值为0．48～1．57mg／L，去除率为57％～77％；出水NH4^＋-N平均值为0．02～0．237mg／L，去除率为61％～99．7％；出水NO2^--N值为0．001～0．053mg／L，去除率最高达99．74％．     

新型A/O/A直流脱氮工艺处理焦化废水的研究

采用新型A／O／A直流脱氮工艺处理焦化废水,考察了对COD和NH4^＋ -N的去除效果。四个月的连续流试验表明,在进水COD平均为2470mg／L、NH4^＋ -N为102mg／L的条件下,系统出水COD和NH4^＋ -N平均浓度分别为120、10mg／L,达到了《污水综合排放标准》的二级标准。由于无回流,因而与工程上常用的A^2O^2工艺相比,动力消耗节省了约50％,而占地面积却仅为其1／3。前置厌氧池减轻了好氧段的负荷,改善了对COD的去除效果;出水分流则为缺氧池内的反硝化提供了较充足的碳源,避免了投加甲醇的额外花费。     

铝盐一级强化处理城市污水的正交试验

为研究一级强化处理城市污水的最佳工艺条件和各种因素对处理效果的影响,采用Al2(SO4)3和PAC分别与非离子、阴离子、弱阳离子的高分子助凝剂配合,进行了6种药剂组合的正交试验。结果表明,混凝剂投量是出水水质最主要的影响因素,在优化条件下,一级强化工艺对COD的去除率达到60%,出水COD为150mg/L左右;对TP的去除率由铝盐混凝剂的投量决定,出水TP<1mg/L,并可随混凝剂投量的继续增加而降低。高分子助凝剂能有效提高Al2(SO4)3的除磷效果,是影响出水TP的第二重要因素,但PAC系列是影响出水TP最小的因素。总之,Al2(SO4)3 高分子助凝剂与PAC 高分子助凝剂两个系列对COD的去除效果差别不大;但是,Al2(SO4)3 高分子助凝剂系列除磷效果更好。     

Fenton氧化/混凝法后续处理垃圾渗滤液研究

六里屯垃圾填埋场的垃圾渗滤液经UASB＋A／O系统处理后,COD和氨氮含量分别在1350～1500和280～420mg／L,还需要进一步处理。因此采用Fenton氧化／混凝法作为后续处理工艺,考察了不同条件下对污染物的去除效果。结果表明,当pH=7、[Fe^2＋]=0．0167mol／L、[H2O2]=0．05mol／L、[FeCl3]=600mg／L、[AP410C]=4mg／L时,该工艺对浊度、COD和氨氮的去除率分别为82％、80．7％、55．9％,去除效果较好。     

铝酸钙粉对水中硫酸根的去除研究

采用铝酸钙粉去除水中SO2-4,考察了铝酸钙粉投加量、温度、pH等因素对去除效果的影响.结果表明,当原水中SO2-44为300～1 000mg/L、温度为30℃时,投加7.5g/L铝酸钙粉,调节pH值为9.0,反应30 min后,水中残余SO2-4稳定在250 mg/L以下.反应后生成的沉淀物粒径及过水比阻特征测定表明...     

化学辅助除磷在改良A2O工艺中的应用

深圳坂雪岗污水处理厂的改良A^2O工艺在运行中，当原水BOD／TP在11左右、TP平均约8mg／L（最高TP〈11mg／L）时，很难使出水TP≤1mg／L，为此开展了化学辅助除磷研究。结果表明，当采用Al2（SO4）3或FeCl3作除磷剂时，控制Al^3＋、Fe^3＋浓度分别为0．2、0．17mmol／L可使出水TP达标。     

石灰软化法处理高硬度含氟地下水的研究

采用石灰软化法处理高硬度含氟地下水，考察了药剂投量、反应时间对处理效果的影响。结果表明，在CaO和Na2CO3的投量分别为187和106mg／L并反应25min的条件下，再投加10mg／L的聚合氯化铝铁和0．25mg／L的PAM可将出水浊度降至1NUT以下；若要将出水总硬度分别降至400、300、200mg／L，在略高于理论投药量的条件下，需控制搅拌反应时间分别为25、35、50min；水中氟化物可通过与软化过程中生成的Mg（OH）2形成共沉淀而得到有效去除，但由于出水pH值过高，需进行调节。     

微生物增效技术在制药废水处理中的应用

以某制药公司废水为处理对象,通过在A/O池内投加外源微生物进行生物强化,考察微生物增效技术对COD和氨氮的去除效果。结果表明,采用微生物增效技术能有效去除制药废水中的COD和氨氮,当进水COD、NH3-N、SO2-4分别为(8 000~13 500)、(400~750)、(4 000~5 500)mg/L时,出水COD为150~300 mg/L、氨氮5 mg/L。采用静态Fenton工艺对试验出水进一步处理,COD可降至100 mg/L以下,出水水质可达到《污水综合排放标准》(GB 8978—1996)的一级标准。     

Effects of adding organic materials to an acid sulfate soil on the growth of cocoa (Theobroma cacao L.) seedlings

Acid sulfate soils having a pH of less than 3.5 are widespread in Malaysia. Some of these soils are planted to cocoa, but the yield is reported to be low due to soil infertility related to Al toxicity. Cocoa growth is sensitive to the presence of Al in the soil. To a certain extent, Al toxicity in soils can be reduced by organic matter application and to a greater extent in iron-poor acid sulfate soil. A study was conducted to determine the efficacy of various types of organic materials easily available in the country to ameliorate acid sulfate soil infertility for growing cocoa seedlings. The treatments were control (nil), lime (3 t/ha), peat (10% w/w), peat plus green manure (10% w/w), peat plus rice straw (10% w/w), peat plus chicken dung (10% w/w) and peat plus POMS (Palm oil mill sludge) (10% w/w). The growth of cocoa seedlings was affected significantly by the presence of Al in the cocoa tissues. As the amount of Al in the leaves increased, the relative top dry weight of cocoa seedlings decreased. Likewise, the relative plant height was negatively correlated with Al in the leaves. Peat as well as peat in combination with green manure, rice straw, chicken dung or palm oil mill sludge was able to reduce Al toxicity in acid sulfate soil; the highest top dry weight of cocoa seedlings were obtained in the peat plus green manure treatment. The best cocoa seedlings root growth was found for the peat treatment alone. The relative top dry weight of cocoa seedlings was negatively correlated with Al(3+) as well as Al(3+)+Al(OH)(2+)+Al(OH)(2)(+) activity in the soil solution. The critical values for Al(3+) and the combination of Al(3+)+Al(OH)(2+)+Al(OH)(2)(+) activity in the soil solution were 10 microM and 15 microM, respectively.     

Laboratory investigation of aluminum solubility and solid-phase properties following alum treatment of lake waters

Water samples from two southern California lakes adversely affected by internal nutrient loading were treated with a 20 mg/L dose of Al3+ in laboratory studies to examine Al solubility and solid-phase speciation over time. Alum [Al2(SO4)3 . 18 H2O] applications to water samples from Big Bear Lake and Lake Elsinore resulted in a rapid initial decrease in pH and alkalinity followed by a gradual recovery in pH over several weeks. Dissolved Al concentrations increased following treatment, reaching a maximum of 2.54 mg/L after 17 days in Lake Elsinore water and 0.91 mg/L after 48 days in Big Bear Lake water; concentrations in both waters then decreased to <0.25 mg/L after 150 days. The solid phase was periodically collected and analyzed using X-ray diffraction (XRD), differential scanning calorimetry-thermogravimetric analysis (DSC-TGA), scanning electron microscopy (SEM), and surface area analyses to investigate the nature of the reaction products and crystallinity development over time. Poorly ordered, X-ray amorphous solid phases transformed over time to relatively well-ordered gibbsite, with strong diffraction peaks at 4.8 and 4.3 A. XRD also indicated the formation of a second (possibly aluminosilicate) crystalline phase after 150 days in Lake Elsinore water. Surface areas also decreased over time as crystals reordered to form gibbsite/microcrystalline gibbsite species. DSC-TGA results suggested that the initially formed amorphous Al(OH)3 underwent transformation to >45% gibbsite. These results were supported by geochemical modeling using Visual MINTEQ, with Al solubility putatively controlled by amorphous Al(OH)3 shortly after treatment and approaching that of microcrystalline gibbsite after about 150 days. These findings indicate that Al(OH)3 formed after alum treatment undergoes significant chemical and mineralogical changes that may alter its effectiveness as a reactive barrier to phosphorus release from lake sediments.     

Sulfate and metal removal in bioreactors treating acid mine drainage dominated with iron and aluminum

Bioreactors represent an emerging technology for removing metals and sulfate commonly found in acid mine drainage (AMD). Six continuously fed anaerobic bioreactors employing organic and alkaline waste materials were operated to investigate relationships between metal and sulfate removal from AMD. Median AMD influent chemistry was 65.8 mg/L Fe (49.7-113 mg/L), 46.5 mg/L Al (33.5-72.4 mg/L) and 608 mg/L sulfate (493-1007 mg/L). Bioreactors containing mussel shells as an alkaline substrate amendment were more effective at removing metals and sulfate than those containing limestone. Experimental results indicated bioreactor design and operation should be dependent on treatment goals. These include 0.3 mol sulfate loading/m³/day for sulfate removal (mean of 94.1% (87.6-98.0%), 0.4 mol metals/m³/day for metal (mean of 99.0% (98.5-99.9%)) and partial sulfate (mean of 46.0% (39.6-57.8%)) removal and 0.8 mol metals/m³/day for metal (mean of 98.4% (98.2-98.6%) and minimal sulfate (mean of 16.6% (11.9-19.2%)) removal. Aluminum removal efficiency was on average 1.72% (0.04-3.42%) greater than Fe during stable operating conditions.     

低温A2/O工艺投加耐冷菌剂试验研究

本试验针对北方地区冬季污水厂生物处理效果差的问题,以 A<'2>/O 为研究工艺,考察耐冷菌剂对低温条件下 A<'2>/O 工艺处理效果的影响,将常温(约 23℃)、低温(约 12℃)及低温投加耐冷菌剂后三种条件下的处理效果进行对比分析.得到三种条件下 COD 的平均出水浓度分别为 25.04,45.36 及 28.6...     

Effect of citric acid on aluminum hydrolytic speciation

The mechanisms of the influence of organics on Al transformation were not fully understood. This study investigated the effect of citric acid on Al speciation in partially neutralized aluminum solution. The partially neutralized solution was prepared with 20 mmol L(-1) AlCl3 without citrate (citrate/Al molar ratio of 0, control) or with citrate (citrate to Al molar ratios between 0.1 and 3.0) at pH between 3.0 and 7.0. The nature of aluminum hydrolytic products as influenced by citrate complexation was investigated by turbidity measurement, ferron kinetic color development, peak line width in 27Al nuclear magnetic resonance (NMR) deconvolution demodule quantitative methods, and the MinteqA2 chemical speciation program. Sulfate precipitates from Al solution as influenced by citrate were examined by X-ray diffraction (XRD) analysis and atomic force microscopy (AFM). The turbidity of the Al solution increased with increasing pH values. Increases in citrate/Al molar ratio from 0 to 0.1 decreased dramatically the turbidity due to citrate complexation. The 27Al NMR peak at 6 ppm of the Al solution at a citrate/Al molar ratio of 0.5 shifted to 8 and 10 ppm in the solutions at citrate/Al molar ratio of 1.0 and 3.0, respectively. Comparison of 27Al NMR data and the data obtained from the MinteqA2 chemical speciation program, indicate that the Al-citrate complexes as revealed by 27Al NMR data are largely Al(citrate), AlH(citrate)+, and Al(citrate)(2)3- complexes (99-112%) in the pH range of 4.5-6.5. The non-detected Al fractions by the MinteqA2 program account for 82-99% of the non-detected Al fractions by NMR quantitation in the same pH range. The AFM of sulfate precipitates from solutions with low citrate/Al molar ratios (i.e., 0.01, pH 4.5, aged 40 days) shows that Al13 sulfate precipitates were ellipse-shaped. These ellipse-shaped precipitates were aggregated when solution pH increased from 4.5 to 7.0 (aged 40 days), indicating the fast hydrolytic rate of Al at high pH. The sulfate precipitates from solution with a high citrate/Al molar ratio (i.e., 0.05, pH 4.5, aged 40 days) also shows aggregate of particles, and XRD non-crystallized precipitates the hampering effect of citrate on Al precipitates.     

Evaluation of the catalytic reduction of nitrate for the determination of dissolved organic nitrogen in natural waters

The catalytic reduction of nitrate ions into nitrogen gas was tested to partly remove dissolved inorganic nitrogen (DIN) before the determination of dissolved organic nitrogen (DON). Experiments were conducted on nitrate solutions enriched with natural organic matter (NOM) isolates previously extracted from surface waters. Three catalysts Pd-In/Al2O3, Pd-Sn/Al2O3 and Pd/SnO2 were tested. Their noble metal (palladium) and promoter metal (indium or tin) contents are 5 and 1.75 wt%, respectively. Preliminary experiments performed on a solution containing 17 amino acids showed that most compounds were removed by less than 15%, probably due to sorption onto the catalysts. Reduction of nitrate in absence of NOM was complete after 20 min of reaction time and the removal of DIN was about 80% (about 19% formation of ammonium). In the presence of NOM (DOC 20 mgC/L, DON 0.67 mg N/L), the kinetic of nitrate reduction was slower and the reduction in DIN content was limited to 15% i.e. selectivity toward ammonium reached 85%. Adsorption tests showed a similar removal of both DOC and DON of about 70% and 30% onto Pd-Sn/Al2O3 and Pd/SnO2 catalysts, respectively, which confirmed that NOM probably compete with nitrate for active catalytic sites. In conclusion, catalytic reduction of nitrate before DON determination cannot be used because of DON sorption and low DIN removal.     

蒽醌染整废水的混凝沉淀-Fenton催化氧化处理

采用混凝沉淀-Fenton催化氧化组合工艺对蒽醌染整废水进行处理，研究了混凝剂和Fenton试剂投加量以及各种反应条件对处理效果的影响。试验结果表明，当pH值为6．2、A12（SO4）3投量为300mg／L、PAM投量为3mg／L、沉淀时间为30min时，混凝沉淀出水的COD为233～260mg／L，色度为15～20倍；后续处理采用Fenton试剂催化氧化，当FeSO4投量为200mg／L、H2O2投量为100mg／L、pH值为5．0、反应时间为30min时，出水色度≤10倍，BOD5≤10mg／L，COD≤50mg／L。     

Treatment of MTBE by air stripping, carbon adsorption, and advanced oxidation: technical and economic comparison for five groundwaters

An investigation was made of the treatability of methyl tert-butyl ether (MTBE) in five groundwaters with highly varied water quality characteristics. Air stripping, granular activated carbon (GAC) adsorption, and the O(3)/H(2)O(2) and UV/H(2)O(2) advanced oxidation processes were compared in a mobile water treatment pilot plant under a variety of process conditions. Air stripping was shown to have the lower unit treatment costs for higher flowrates (i.e., 3800L/min), although relatively tall towers were required for greater treatment requirements. At low flowrates (i.e., 38L/min), advanced oxidation provided the lowest treatment costs for four of five waters (but was ineffective for a high chemical oxygen demand water). Both the O(3)/H(2)O(2) and UV/H(2)O(2) processes were more efficient at pH 7 versus 9 due in part to increased scavenging at higher pH. GAC was examined using rapid small-scale column tests (RSSCT). GAC was effective at most conditions, although it was also the most costly alternative for most waters. The results of this study can help to provide specific guidance into process selection for treating MTBE in contaminated groundwaters.     

Evaluating mercury transformation mechanisms in a laboratory--scale combustion system

Mercury speciation measurements during injections of 10 microg/m3 Hg0(g) into a 42-MJ/h combustion system containing gaseous O2-Ar- and O2-N2-rich mixtures indicate that 43 and 55% of the Hg (g) spike was transformed rapidly (< 0.1 s) to Hg2+X(g) within a refractory-lined heat exchanger where gas temperatures decrease from approximately 620 to 200 degrees C. O2(g) is the probable Hg0(g) oxidant (i.e. X = O2-). The apparent formation of HgO(g) involves a heterogeneous reaction with adsorbed Hg0 or O2 on refractory surfaces or a Hg0(g)-O2(g) reaction catalyzed by corundum (Al2O3) and/or rutile (TiO2) components of the refractory. The potential catalytic effects of Al2O3 and TiO2 on Hg0(g) oxidation were investigated by injecting Al2O3 and TiO2 powders into approximately 650 degrees C subbituminous coal (Powder River Basin, Montana, USA) combustion flue gas. On-line Hg0(g) and total mercury measurements indicate, however, that Al2O3 and TiO2 injections were ineffective in promoting the formation of additional Hg2+X(g). Apparently, either the chemically complex flue gas hindered the catalytic effects of Al2O3 and TiO2, or these compounds are simply not Hg0(g) oxidation catalysts.