亚硫酸钙脱硫法及其机理

针对石灰乳直接脱硫存在的结垢问题,提出了亚硫酸钙脱硫法,并研究了该法的反应机理及主要因素对脱硫率的影响,确立了适宜的操作条件.即在空塔气速2.75m/s、L/G=3.0 L/m³、固含量6.7%、气温31℃、进口SO₂初始体积分数1500×10^-6、进塔液pH=8.0并维持不变的条件下,连续运转中的脱硫率可达87%.该法从理论上解释、实践上解决了石灰湿法脱硫过程中设备的结垢问题,其实质是以全钙基物质为脱硫剂的新型间接石灰法.     

连续流系统中好氧段及沉淀段对污泥及其缺氧段脱氮能力的影响

在好氧段3种溶解氧(DO)[3. 0～3. 5 mg·L~(-1)(Ⅰ阶段)、2. 0～2. 5 mg·L~(-1)(Ⅱ阶段)和1. 5～2. 0 mg·L~(-1)(Ⅲ阶段)]的A~2/O实验系统,考察了本段及后续沉淀阶段污泥的变化,以及对系统缺氧段反硝化的影响,并与DO为1. 5～2. 0 mg·L~(-1)的缺氧-好氧(A/O)系统进行了对比.结果表明,沉淀阶段污泥开始发生反硝化作用,脱氮碳源由内、外碳源同时提供;沉淀污泥优先利用外碳源进行反硝化;好氧段DO为1. 5～2. 0 mg·L~(-1)时,沉淀阶段污泥的硝酸盐还原酶活力及反硝化活性最强,此时A~2/O系统缺氧段的反硝化效果也最佳;在与A~2/O系统相同污泥负荷下的A/O系统中,好氧段后污泥中细菌胞内残留的PHB含量要高于A~2/O系统; A~2/O系统沉淀段污泥的反硝化活性高于A/O系统,其硝酸盐还原酶活力是A/O系统的1. 08倍;该污泥回流后,尽管硝态氮充分但A/O系统缺氧段反硝化效果却较A~2/O系统差;沉淀阶段污泥的脱氮性能直接关系到缺氧段反硝化效果.因此,本研究认为在保证沉淀污泥反硝化不严重影响泥水分离的前提下,污水生物脱氮工程中应适当控制好氧段运行、维持沉淀池污泥适当反硝化来提升系统的脱氮效能,而不能仅仅是考虑控制缺氧段.     

异化Mn(IV)还原耦合降解卡马西平及双氯芬酸

本文以卡马西平（CBZ）和双氯芬酸（DCF）2种代表性有机药物作为目标污染物,嘉陵江沉积物中提取的微生物作为菌源,利用锰矿物为填料的厌氧生物滤柱探究了异化锰还原过程对CBZ和DCF的处理效果.同时研究了外加有机碳源（乙酸钠）和MnO₂对异化锰还原去除CBZ和DCF过程的影响.结果表明,在无外加乙酸钠和MnO₂时,厌氧生物滤柱对10μg/L的CBZ和DCF能分别实现25.23%和32.44%的去除.其中异化锰还原贡献的去除率分别为2.81%和14.87%,而外加0.5g/L乙酸钠和25g MnO₂均能提高异化锰还原过程中对CBZ的处理效果（分别提高6.35%和4.63%）,但对DCF的去除无显著影响.本试验可为难降解有机药物的降解提供新的思路.     

AQS对Shewanella oneidensis MR-1还原含Cd聚合硫酸铁絮体的影响

考察了一种典型的溶解性腐殖质蒽醌-2-磺酸钠(disodium anthraquinone-2-sulfonate,AQS)存在时,典型异化铁还原菌Shewanella oneidensis MR-1在厌氧条件下还原含镉聚铁絮体的过程。结果表明:AQS的存在促进了含Cd絮体中Fe(Ⅲ)的还原,也促进了Cd~(2+)的释放。相比无AQS体系,存在AQS的体系中,Fe~(2+)和Cd~(2+)达到最高浓度的时间均有所缩短,最高浓度也更高;且低浓度AQS的促进效果明显高于高浓度AQS;AQS的存在没有改变二次矿物的种类,仍是针铁矿和磁铁矿,但降低了矿物的结晶度,且AQS浓度越高,改变越明显。存在AQS的体系中,菌体结合的Cd~(2+)更多,且镉的直接释放和间接释放风险均增大,低浓度AQS体系中镉的直接释放风险更大。     

紫外/亚硫酸钠还原降解三氯乙酰胺的效能

卤乙酰胺(HAc Ams)是一类具有高细胞毒性和高遗传毒性的饮用水含氮消毒副产物(N-DBPs),并在饮用水中被广泛检出,其中三氯乙酰胺(TCAc Am)的毒性显著高于传统DBPs.本实验以配置的TCAc Am溶液作为目标污染物,采用紫外(UV)活化亚硫酸钠(Na_2SO_3)体系降解水中的TCAc Am,并探究在该体系下光强、还原剂投加剂量(Na_2SO_3)和p H对还原降解TCAc Am效果的影响.结果表明,采用UV/Na_2SO_3体系可快速降解TCAc Am,其降解效果与光强、Na_2SO_3投加剂量和p H均呈正相关,且p H值对反应速率与降解率有显著影响,当p H值从6提高至9,TCAc Am的降解率在反应120 min时从12. 8%提高至99. 6%.在光强为450μW·cm~(-2),p H为9,Na_2SO_3投加剂量为1. 00 mmol·L~(-1),连续30 min光照条件下,TCAc Am降解率达到99. 4%.实验证明UV/Na_2SO_3体系是一种有效消减TCAc Am的高级还原技术,并且具备还原降解其他卤代DBPs的潜力,可用于饮用水中卤代DBPs的降解.     

脱硫脱硫弧菌去除SO2的工艺条件研究

从太原污水处理厂分离到1株硫酸盐还原菌,对其进行形态学观察及生理生化特征测定,鉴定为脱硫脱硫弧菌(Desulfovibriodesulfuricans).该菌株在pH=7、温度30℃、搅拌速度270r/min时生长最好,处理SO2的能力最强.当二氧化硫进口浓度小于10334mg/m3,SO2-3累积浓度小于87.31mg/L时,菌体生长良好,碱液流加速率较小,但当二氧化硫进口浓度达到11582mg/m3,SO2-累积至124.06mg/L时,菌体生长受到抑制,系统被破坏.图6参11     

Evaluation of a fetus at risk for dihydropteridine reductase deficiency by direct mutation analysis using denaturing gradient gel electrophoresis

Dihydropteridine reductase (DHPR) is an enzyme involved in the recycling of tetrahydrobiopterin (BH₄), which is an obligate co-factor of the aromatic amino acid hydroxylases. DHPR deficiency is a rare, autosomal recessive disorder caused by mutations in the QDPR gene. DHPR-deficient patients are diagnosed by a lack of response to a low phenylalanine diet and by severe neurological symptoms. Final diagnosis is made by measurements of neurotransmitters and pterin metabolites in cerebrospinal fluid (CSF) and urine, in addition to DHPR enzyme activity, which can be assessed in whole red blood cells. Treatment of DHPR deficiency can be difficult and the outcome is not always satisfying, even if all treatment strategies are followed. Therefore prenatal diagnosis is of great importance in affected families. Prenatal diagnosis is possible by measuring DHPR activity in different cell types but this is time consuming. More than 25 different mutations have to date been identified in the QDPR gene and direct identification of a mutation in a fetus would be easy and rapid. We have developed a method based on denaturing gradient gel electrophoresis (DGGE) for the analysis of the QDPR gene. The method is useful for rapid and simultaneous scanning of all exons and flanking intronic sequences of the QDPR gene. We describe the first prenatal diagnosis conducted using this method. Copyright © 2001 John Wiley & Sons, Ltd.     

不同氮源对利玛原甲藻(Prorocentrum lima)生长和产毒的影响

采用单因子实验,设置4个浓度梯度:12μmol·L-1、25μmol·L-1、50μmol·L-1和lOOp.mol·L-1,研究了NaNO3、NH4Cl和尿素对利玛原甲藻(Prorocentrum lima)的生长、硝酸还原酶(nitrate reductase,NR)活性以及腹泻性贝毒(diarrhetic shellfish poisoning,DSP)产生的影响.对比分析了利玛原甲藻对3种不同氮源的利用特征.结果发现,以NaNO3、NH4Cl和尿素分别作为氮源时,利玛原甲藻最大生长速率(μmax)相差不大;NaNO3组和尿素组之间最大生物量(X)和硝酸还原酶活性也相近;NH4Cl组最大生物量(X)和硝酸还原酶活性明显低于NaNO3组和尿素组.平台期NaNO3组单位藻细胞OA含量明显高于NH4Cl组和尿素组,NH4Cl组和尿素组之间无显著性差异.这些结果表明,利玛原甲藻可以利用无机氮(NaNO3、NH4Cl)和有机氮盐尿素,利玛原甲藻中可能存在尿素酶;NaNO3和尿素比NH4Cl可能更有利于维持利玛原甲藻的生长;利玛原甲藻毒素的合成与营养盐的形态有关,其中NaNO3最有利于毒素的合成.     

Dssimilatory Fe(Ⅲ) reduction characteristics of paddy soil extract cultures treated with glucose or fatty acids

Dissimilatory Fe(Ⅲ) reduction is a universal process with irreplaceable biological and environmental importance in anoxic environments. Our knowledge about Fe(Ⅲ) reduction predominantly comes from pure cultures of dissimilatory Fe(Ⅲ) reducing bacteria (DFRB). The objective of this study was to compare the effects of glucose and a selection of short organic acids (citrate, succinate, pyruvate, propionate, acetate, and formate) on Fe(Ⅲ) reduction via the anaerobic culture of three paddy soil solutions with Fe(OH)3 as the sole electron acceptor. The results showed significant differences in Fe(Ⅲ) reduction among the three paddy soil solutions and suhstrate types. Bacteria from the Sichuan paddy soil responded quickly to substrate supply and showed higher Fe(Ⅲ) reducing activity than the other two soil types. Bacteria in the Jiangxi paddy soil culture solution could not use propionate as a source of electrons for Fe(Ⅲ) reduction. Similarly, bacteria in the Jilin paddy soil culture could not use succinate effectively. Pyruvate was readily used by cultures from all three paddy soil solutions, thus indicating that there were some similarities in substrate utilization by bacteria for Fe(Ⅲ) reduction. The use of glucose and citrate as substrate for dissimilatory Fe(Ⅲ) reduction indicates important ecological implications for this type of anoxic respiration.     

淹水厌氧条件下腐殖酸对红壤中铁异化还原过程的影响

采用室内培养实验,观测淹水厌氧条件下分别添加及共同添加葡萄糖和不同制备来源的腐殖酸,对红壤中铁的异化还原作用的影响.结果表明,红壤单独培养条件下,Fe(Ⅱ)浓度培养前后没有发生变化.添加葡萄糖促进了铁的异化还原,培养至12 d其Fe(Ⅱ)浓度为培养前的25倍.腐殖酸不能作为电子供体促进铁的异化还原,单独添加时红壤中Fe(Ⅱ)浓度没有发生变化,而同时添加葡萄糖情况下,培养前期促进而后期减弱铁的异化还原,其Fe(Ⅱ)浓度增幅仅为单独添加葡萄糖处理的35%.腐殖酸的浓度对红壤中铁的异化还原作用有影响,浓度为2.00 g/kg时培养前期促进而后期减弱铁的异化还原,低浓度时（0.20和0.02 g/kg）影响很小.不同制备来源的腐殖酸对红壤中铁异化还原过程的影响不同.培养前期,从山西大同风化煤(HAs)、河南巩县褐煤(HAh)和云南昆明滇池底泥(HAk)中提取的腐殖酸都促进了红壤中铁的异化还原;培养后期,HAk依然发挥促进作用,其Fe(Ⅱ)浓度始终高于G处理,而添加HAs和HAh的处理培养至7 d Fe(Ⅱ)仅为单独添加葡萄糖处理的14%和25%,减弱了铁的异化还原.