pH冲击对降解五氯酚(PCP)微氧颗粒污泥产气及代谢能力的影响

分别在pH为6.0和9.0的冲击条件下,对降解五氯酚(PCP)微氧颗粒污泥系统的产气及代谢能力进行了研究.结果发现,在pH=6.0的条件下冲击8d,污泥系统的产气量降至400mL·d-1以下,甲烷含量为0.而后将pH调至7.0并经过6d的恢复实验,产气情况基本恢复正常.而在pH=9.0的冲击下,污泥系统的产气量及甲烷含量急剧下降至0,经过6d的恢复过程仍然没有达到正常水平.在不同pH冲击的第8d,对PCP和COD去除率及脱氯中间产物进行了研究,结果表明,PCP及COD降解率均在较低的水平,且发生了PCP及其脱氯中间产物的严重积累.与pH=9.0相比,pH=6.0的冲击对系统代谢的影响要小得多.     

提升我国城市化水平的重要意义和政策调整

我国的城市化水平落后于工业化水平,已成为制约我国经济与社会发展的重要因素。提升我国城市化水平,从经济上讲,具有如下重要意义：（1）有利于化解有效需求不足矛盾。（2）有利于带动相关产业增长和主人口增加。（3）有利于促进我国产业结构优化,提高经济运行质量。（4）有利于资源的综合利用和耕地保护。（5）有利于缩小城乡差距。提升我国城市化水平是我国新世纪的战略任务,必须进行相关的政策调整与选择。     

pH对SBR处理效果及活性污泥微生物群落结构的影响

采用序批式生物反应器（SBR）对pH值为5.0、6.0、7.0、8.0、9.0和10.0的原水进行处理,发现COD和TN去除率在pH=8.0时达到最大,NH4+-N去除率随pH升高而增大,在pH=10.0时可达91.0%,碱性条件下污水处理效果更佳;利用聚合酶链式反应-变性梯度凝胶电泳（PCR-DGGE）技术分析不同pH值下的活性污泥总细菌群落结构,其结果显示,碱性条件下的优势菌为β-proteobacterium,承担脱氮功能的细菌中可培养的是Rhodanobacter sp.,pH=8.0时总细菌多样性指数最高。     

硫酸盐还原菌SRB除砷的影响因素

环境中砷的存在往往对人类健康产生不利影响,从而一直受到人们的广泛关注。在厌氧条件下硫酸盐还原菌(SRB)利用有机物还原硫酸根生成硫化物,进一步通过硫化物与溶液中砷反应产生沉淀从而实现砷的最终去除。为了探讨不同因素对SRB除砷的影响,该实验研究了在不同初始pH值、碳源和初始砷浓度条件下的SRB活性及其对砷的去除效果。提取在UASB反应器中长期驯化的富含SRB的厌氧污泥进行批次实验。研究表明,在选取乳酸、乙酸、葡萄糖作为不同外加碳源的对比实验中,微生物利用乳酸作为基质反应相对缓慢(COD分解速率低),SRB具有较高的反应活性(对硫酸根去除率最高),同时保持较好的砷去除率(大约60%);SRB利用不同有机物反应过程中产生碱度导致系统内pH逐渐升高,其中以乳酸作为碳源时系统内pH升高到8.5左右;随着初始pH的升高,砷的去除效果降低,硫化砷沉淀在弱酸性条件下更易稳定存在;随着初始砷浓度的增加,SRB的活性受到抑制,当初始砷浓度达到40 mg·L-1时,SRB基本失去反应活性;利用驯化污泥除砷过程中,部分砷价态发生了变化。     

硫酸钛混凝去除无机砷(III)的效能

使用硫酸钛作为混凝剂,研究了混凝去除As(III)过程中溶液pH值、混凝剂投加量、砷的初始浓度以及阴离子对除砷效果的影响.硫酸钛的水解沉淀物颗粒等电点为pH=5;当pH=6时,水解沉淀物的粒径最大.在pH=5~8范围内,As(III)的去除率高且基本稳定;而沉淀物颗粒Zeta电位降低较大.说明水解沉淀物Zeta电位对As(III)的去除影响不大.混凝剂投加量为2.5~10 mg/L时,As(III)的去除率随投加量的增加而显著增加;混凝剂投加量大于15 mg/L时,As(III)去除率随混凝剂投加量的增加变化趋于平缓.水中阴离子(硅酸根和磷酸根离子)的存在会降低混凝对As(III)的去除效率.     

高pH条件下UASB反应器处理含硫酸盐废水的性能

利用升流式厌氧活性污泥床(UASB)反应器处理高含硫有机废水,考察了其在pH=8.5条件下的运行性能、MPA(产甲烷菌)与SRB(硫酸盐还原菌)的竞争规律及微生物群落结构特征.结果表明:在pH=8.5的厌氧生物处理系统中,COD的去除率达到70％以上和硫酸盐去除量达到1 600 mg?L-1,在整个运行期间均保持较好的...     

南方酸性土壤中汞污染状况调查

通过测量南方酸性土壤中pH值、有机质、硝态氮及汞的含量变化,分析物质间变化关系,了解南方酸性土壤中重金属汞的污染状况,并针对南方酸性土壤的特性提出了污染防治措施及建议.     

九龙江北溪pH值异常变化与生化因子相关性的研究

监测结果表明,九龙江北溪部分断面CODMn浓度介于中富营养～富营养之间,总氮、总磷和叶绿素a浓度均达到极富营养水平。经统计分析,pH值与甲藻显著相关(r=0.327,P=0.025),与溶解氧(r=0.762,P=0.000)、高锰酸盐指数(r=0.456,P=0.001)、总氮(r=0.482,P=0.001)、总磷(r=0.507,P=0.000)和叶绿素a(r=0.649,P=0.000)等非常显著相关。研究表明,虽然各项化学因子与pH值密切相关,但不是pH值变化的直接原因,而是由于水体富营养程度严重且已形成了藻类生境,甲藻的异常增殖才导致pH值异常升高。     

Distribution of Alkalinity, Ph, Salinity and Carbon Dioxide Components in the Coastal Waters of Alexandria

The ara studied is located between El-Dikheila Harbour in Elmex Bay and Mandara, at longitude 29° 47' and 30° East and latitude 31° 17' North. the aim of the work is to look at carbon dioxide components in this areA and the effect of waste water discharged on their concentrations. Surface and bottom water samples were collected from 12 stations during January, April, August and November, 1995. Total alkalinity, salinity, temperature and pH were measured. Carbonate alkalinity, total alkalinity, partial pressure and dissolved carbon dioxide, carbonate and bicarbonate ions were calculated, since the studied area includes two differetn sources of pollution. It wAs found conventient to refer El-Mex Bay as region “A” which contains stations from I to VI and the area located between Kayet Bey outfall and Mandara which contains stations from VII to XII as region “B”. When specific alkalinity is used As A tracer for El-Umum drain water it is observed that the drain water could reach Sidi Bishr area especially in August and November, while in January and April drain water did not reach this area.     

Effects of pore size and dissolved organic matters on diffusion of arsenate in aqueous solution

Presented here is the influence of membrane pore size and dissolved organic matters on the diffusion coefficient(D) of aqueous arsenate, investigated by the diffusion cell method for the first time. The p H-dependent diffusion coefficient of arsenate was determined and compared with values from previous studies; the coefficient was found to decrease with increasing p H, showing the validity of our novel diffusion cell method. The D value increased dramatically as a function of membrane pore size at small pore sizes, and then increased slowly at pore sizes larger than 2.0 μm. Using the Exp Assoc model, the maximum D value was determined to be 11.2565 × 10~-6cm~2/sec. The presence of dissolved organic matters led to a dramatic increase of the D of arsenate, which could be attributed to electrostatic effects and ionic effects of salts. These results improve the understanding of the diffusion behavior of arsenate, especially the important role of various environmental parameters in the study and prediction of the migration of arsenate in aquatic water systems.