纳米TiO2水悬浮液对大肠杆菌生长的影响

为了考察纳米TiO2(<100nm)水悬浮液对典型环境微生物--革兰氏阴性菌大肠杆菌生长的影响,制备并表征了水中分散的平均粒径和含量分别为74.3nm、1.5 mg·L-1(样品1)和82.2nm、3.1 mg·L-1(样品2)的2种纳米TiO2水悬浮液,并在有、无紫外光照条件下进行细菌培养实验.实验结果显示,在无紫外光照条件下,2个样品对大肠杆菌的生长均有抑制作用,在大肠杆菌生长稳定期,样品1和样品2分别使OD600值平均下降0.03和0.11;单独紫外光照可对大肠杆菌生长产生抑制作用,使OD600值平均下降0.04,而同样紫外光照剂量下样品2可使OD600值平均下降0.18,显示出纳米TiO2对大肠杆菌生长的协同抑制作用.     

Effect of microbial mediated iron plaque reduction on arsenic mobility in paddy soil

The potential of microbial mediated iron plaque reduction, and associated arsenic (As) mobility were examined by iron reducing bacteria enriched from As contaminated paddy soil. To our knowledge, this is the first time to report the impact of microbial iron plaque reduction on As mobility. Iron reduction occurred during the inoculation of iron reducing enrichment culture in the treatments with iron plaque and ferrihydrite as the electron acceptors, respectively. The Fe(II) concentration with the treatment of anthraquinone-2, 6-disulfonic acid (AQDS) and iron reducing bacteria increased much faster than the control. Arsenic released from iron plaque with the iron reduction, and a significant correlation between Fe(II) and total As in culture was observed. However, compared with control, the increasing rate of As was inhibited by iron reducing bacteria especially in the presence of AQDS. In addition, the concentrations of As(III) and As(V) in abiotic treatments were higher than those in the biotic treatments at day 30. These results indicated that both microbial and chemical reductions of iron plaque caused As release from iron plaque to aqueous phase, however, microbial iron reduction induced the formation of more crystalline iron minerals, leading to As sequestration. In addition, the presence of AQDS in solution can accelerate the iron reduction, the As release from iron plaque and subsequently the As retention in the crystalline iron mineral. Thus, our results suggested that it is possible to remediate As contaminated soils by utilizing iron reducing bacteria and AQDS.     

钢铁企业二次能源综合利用

钢铁企业二次能源种类多、数量大,按特征分为可燃气体、余热、余能三类。介绍了钢铁企业二次能源产生环节及主要利用途径,通过案例对二次能源利用效益进行分析。     

冶金钢铁行业废水中CODcr与TOC相关性研究

CODcr和TOC均是表征水体有机污染程度的指标,对于一般有机废水,理论上两者线性相关。采用线性回归法对冶金钢铁行业废水中TOC和CODcr两项指标的监测数据进行统计分析,建立CODcr对TOC的转换方程,并用相关系数法进行显著性检验。结果表明冶金钢铁行业废水中CODcr值和TOC值的线性关系显著,建立的一元线性回归方程的准确度可以满足水质监测的需要,在一定条件下可以使用TOC监测值间接换算CODcr值。     

高磷铁矿湿法脱磷废水除磷工艺及其循环利用

以氧化钙为除磷剂,采用化学法对高磷铁矿脱磷废水除磷工艺进行探讨。研究了溶液pH值、反应温度、反应时间及搅拌速度对脱磷的影响。实验结果表明:在酸性含磷废水的pH为10、温度为70℃、反应时间为30 min以及搅拌速度为200 r/min的优化条件下,除磷效果最佳,脱磷率可达99.99%以上,废水的含磷量由3020μg/mL下降到0.5μg/mL以下,完全符合国家第二类污染物综合排放标准的一级标准磷含量要求。采用除磷后废水对高磷铁矿除磷,精矿中的磷含量均在0.1%以下,完全满足高炉冶炼配料要求,达废水减排效果。     

钢铁联合企业固体废物综合利用分析

阐述了钢铁联合企业固体废物的分类和来源,以柳钢生产实践为例,分析高炉煤气除尘灰、转炉除尘污泥等固体废物的化学成分,探讨冶金固体废物处理方式和综合利用途径,对钢铁企业固体废物综合利用发展方向提出建议。     

Humic acid and metal ions accelerating the dechlorination of 4-chlorobiphenyl by nanoscale zero-valent iron

Transformation of polychlorinated biphenyls (PCBs) by zero-valent iron represents one of the latest innovative technologies for environmental remediation. The dechlorination of 4-chlorobiphenyl (4-ClBP) by nanoscale zero-valent iron (NZVI) in the presence of humic acid or metal ions was investigated. The results showed that the dechlorination of 4-ClBP by NZVI increased with decreased solution pH. When the initial pH value was 4.0, 5.5, 6.8, and 9.0, the dechlorination efficiencies of 4-ClBP after 48 hr were 53.8%, 47.8%, 35.7%, and 35.6%, respectively. The presence of humic acid inhibited the reduction of 4-ClBP in the first 4 hr, and then significantly accelerated the dechlorination by reaching 86.3% in 48 hr. Divalent metal ions, Co2+, Cu2+, and Ni2+, were reduced and formed bimetals with NZVI, thereby enhanced the dechlorination of 4-ClBP. The dechlorination percentages of 4-ClBP in the presence of 0.1 mmol/L Co2+, Cu2+ and Ni2+ were 66.1%, 66.0% and 64.6% in 48 hr, and then increased to 67.9%, 71.3% and 73.5%, after 96 hr respectively. The dechlorination kinetics of 4-ClBP by the NZVI in all cases followed pseudo-first order model. The results provide a basis for better understanding of the dechlorination mechanisms of PCBs in real environment.     

生物除铁除锰滤层营养条件的研究

采用模拟生物除铁除锰滤柱,通过测定整个生物滤层对铁、锰的去除效果考察了营养物质对生物滤层综合生化能力的影响,从而探求了生物滤层对铁、碳、氮等营养元素的需求.结果表明,成熟滤层内的铁、锰氧化细菌对进水铁的营养需求极低(0.04 mg/L).成熟滤层对有机物具有一定的去除能力,而无机碳减少量相对较大,大约有3～4 mg/L,溶解在水中的二氧化碳即可保证滤层对碳的需求.成熟滤层将氨氮转化为硝酸盐和亚硝酸盐,但这种转化实际上并没有使水中氮的总量减少,只是氮的形态发生了转化;而滤柱内氮的减少是被生物体利用的结果.极低的氮素含量即可保证成熟生物滤层对氮素的需求.这表明极低的营养条件即可满足铁、锰氧化细菌的正常生理代谢,铁、锰氧化细菌可以在贫营养环境下生存.结合全国大部分地区的地下水水质状况,进而得出地下水生物除铁除锰技术在全国大部分地区可以推广使用.     

Fe0对饮用水中砷的去除效率及影响因素

研究零价铁(Fe0)的除砷效果,试验考察了Fe0投加量、接触时间、pH值、DO浓度、温度、腐殖质、竞争性阴离子(SO2-4,NO-3,SiO2-3,H2PO-3,HCO-3)对Fe0除砷效率的影响.结果表明,Fe0(80目)投加量为2 g/L,接触时间180 min,pH值为6.5,DO值6.5 mg/L的条件下,对质量浓度为1 mg/L的含砷水样,Fe0对As(Ⅴ)的去除率高达96.5%,而对As(Ⅲ)的去除率只有75.8%.降低水样pH值或提高DO可显著提高Fe0的除砷效率,温度对Fe0除砷影响不大,水体中的腐殖质、磷酸盐、硅酸盐的存在会由于竞争性吸附而导致Fe0除砷效率下降.采用Fe0颗粒去除饮用水中的砷高效、经济,具有良好的应用前景.实际应用中,对于DO值较低的地下含As水,可通过充氧提高Fe0除As效率.当水体中腐殖质、磷酸盐或硅酸盐浓度较高时,应考虑采取相应的预处理措施.     

纳米FeO作用下4-氯酚的脱氯特性及机理

采用化学还原法制备了纳米Fe^O, ESEM测定结果表明其颗粒在1～100 nm内. 实验表明这些纳米Fe^O能在20 h内将初始浓度为20 mg/L的4-氯酚完全降解, Fe^O对4-CP的还原脱氯是主要去除途径. 苯酚是脱氯反应的主要产物. 当4-CP的初始浓度由20　mg/L增大到50, 100, 150　mg/L时, 其相对去除率明显降低, 但绝对降解量有较大提高. 温度不仅影响脱氯速率, 而且影响4-CP去除的途径. 30℃时, 脱氯反应为主要反应; １０℃时, 较易产生氧化产物. Fe原子的迁移过程在4-CP的降解中也是一个重要的限速步骤. 此外, 纳米Fe^O具有很好的稳定性, 在受试的379　h内, 纳米Fe^O能够应对不同浓度冲击及反复投加的4-氯酚冲击的能力.