Effects of advanced oxidation pretreatment on residual aluminum control in high humic acid water purification

Due to the formation of disinfection by-products and high concentrations of Al residue in drinking water purification, humic substances are a major component of organic matter in natural waters and have therefore received a great deal of attention in recent years. We investigated the effects of advanced oxidation pretreatment methods usually applied for removing dissolved organic matters on residual Al control. Results showed that the presence of humic acid increased residual Al concentration notably. With 15 mg/L of humic acid in raw water, the concentrations of soluble aluminum and total aluminum in the treated water were close to the quantity of Al addition. After increasing coagulant dosage from 12 to 120 mg/L, the total-Al in the treated water was controlled to below 0.2 mg/L. Purification systems with ozonation, chlorination, or potassium permanganate oxidation pretreatment units had little effects on residual Al control; while UV radiation decreased Al concentration notably. Combined with ozonation, the effects of UV radiation were enhanced. Optimal dosages were 0.5 mg O3/mg C and 3 hr for raw water with 15 mg/L of humic acid. Under UV light radiation, the combined forces or bonds that existed among humic acid molecules were destroyed; adsorption sites increased positively with radiation time, which promoted adsorption of humic acid onto polymeric aluminum and Al(OH)3(s). This work provides a new solution for humic acid coagulation and residual Al control for raw water with humic acid purification.     

Speciation and bioaccessibility of lead and cadmium in soil treated with metal-enriched Indian mustard leaves

Indian mustard (Brassica juncea (L.) Czern.) has shown good potential for the phytoremediation of soil contaminated with heavy metals. However, there is little information about the speciation and bioaccessibility of heavy metals in soil during the decomposition of metal-rich Indian mustard leaves. Incubation experiments (1-, 3-, and 6-month) were carried out in Beijing and Hunan soil with metal-rich Indian mustard leaves addition (1% and 3%) and the e ects of mustard leaves addition on the speciation and bioaccessibility of heavy metals were studied. The results showed that the addition of mustard leaves led to significant increases in pH and DOC in the Hunan soil. Both 1% and 3% of mustard leaf amendment caused the percentage of the exchangeable (F1), precipitated with carbonates (F2), bound to Fe/Mn oxides (F3) and bound to organic matter (F4) fractions of Pb and Cd to increase dramatically, while the percentage of the residual fraction (F5) of Cd and Pb significantly dropped in both Beijing and Hunan soils. Mustard leaf addition caused the bioaccessibility of Pb to decrease in the gastric phase, whereas the values increased in the small intestinal phase. The Cd bioaccessibility increased with mustard leaf addition in both the gastric and small intestinal phases. In conclusion, the metal-enriched mustard leaves addition induces Pb and Cd concentrations and their mobility increasing in the Beijing and Hunan soils. Therefore, heavy metal risk in metal-enriched plant leaves should be considered in phytoremediation system in which heavy metal might be brought back to soil and changed over time.     

新疆色日克牙依拉克蛇绿岩特征及成矿远景

论文讨论了色日克牙依拉克蛇绿岩的岩石类型组合及岩石地球化学特征,结合区域地质情况分析认为:该蛇绿岩形成于裂谷—小洋盆环境,代表了塔里木板块和伊犁中天山微板块的最后缝合线位置。蛇绿岩出露地带,二辉橄榄岩和纯橄榄岩内均见有铬铁矿、磁铁矿等,局部地表见有镍华。因此,该地对于寻找铬、镍等矿床,有较大的潜力。     

东北老工业基地不同土地利用类型土壤重金属污染特点

以东北老工业基地北部城市群为例,对其重点区域及周边的不同土地利用类型中Hg,Pb,Cr,Zn4种元素进行测定分析,利用单因子污染评价和多因子污染评价方法进行评价。结果表明,4种元素在不同利用类型土壤中,汞和铅在土壤中的迁移能力较弱,且汞元素在土壤中积累程度不高,只是在个别区域其含量有所波动;铅在农田和工业用地土壤中都有一定的积累,但向其他利用类型土壤的迁移效果不明显;铬在个别区域的旱田,蔬菜地中的积累略高,并迁移威胁到了其周围的林地土壤;锌在某些地区的工业用地,旱田,蔬菜地的污染程度相比其他几种元素污染更为严重。     

原子荧光光谱法测定环境水样中的锡

AFS-9700双道原子荧光光度计测定环境水样中的锡,选择最佳的仪器条件:负高压300V,原子化器高度8mm,灯电流80mA,载气流量400ml/min,屏蔽气流量900ml/min。在最佳酸碱比例-体积分数为4.0%的硝酸介质与20g/L硼氢化钾中,锡荧光强度与其质量浓度在1.00~10.0ug/L成线性关系,方法检出限为0.010ug/L,加标回收率为94.4%~105%,RSD(n=7)<2.3%。此方法更为简便,快速,灵敏度高,适用于环境水样中锡的测定。     

Preliminary study of groundwater denitrification using a composite membrane bioreactor

A composite membrane bioreactor (CMBR) integrating the immobilized cell technique and the membrane separation technology was developed for groundwater denitrification. The CMBR had two well mixed compartments with one filled with the nitrate-containing influent and the other with a dilute ethanol solution; the compartments were separated by the composite membrane consisting of a microporous membrane facing the influent and an immobilized cell membrane facing the ethanol solution. Nitrate and ethanol molecules diffused from the respective compartments into the immobilized cell membrane where nitrate was reduced to gaseous nitrogen by the denitrifying bacteria present there with ethanol as the carbon source. The microporous membrane was attached to one side of the immobilized cell membrane for retention of the disaggregated bacteria. Relative to the single dose of external ethanol, the two-dose supplementation produced better treatment results as evidenced by the lower concentrations of NO₃⁻-N and ethanol (as measured by total organic carbon) of the effluent. The batch treatment in CMBR removed most of the nitrate in the influent and attained a stable denitrification rate of 0.1 g·m⁻²·h⁻¹ for most of the 96-h cycles during the 30-cycle study. The effluent was essentially free of ethanol and nitrite nitrogen.     

Influence of influent on anaerobic ammonium oxidation in an Expanded Granular Sludge Bed-Biological Aerated Filter integrated system

Shortcut nitrification-denitrification, anaerobic ammonium oxidation (ANAMMOX), and methanogenesis have been successfully coupled in an Expanded Granular Sludge Bed-Biological Aerated Filter (EGSB-BAF) integrated system. As fed different synthetic wastewater with chemical oxygen demand (COD) of 300–1200 mg·L⁻¹ and NH₄⁺-N of 30–120 mg·L⁻¹ at the outer recycle ratio of 200%, the influence of influent on ANAMMOX in the integrated system was investigated in this paper. The experimental results showed that higher COD concentration caused an increase in denitrification and methanogenesis but a decrease in ANAMMOX; however, when an influent with the low concentration of COD was used, the opposite changes could be observed. Higher influent NH₄⁺-N concentration favored ANAMMOX when the COD concentration of influent was fixed. Therefore, low COD =NH₄⁺-N ratio would decrease competition for nitrite between ANAMMOX and denitrification, which was favorable for reducing the negative effect of organic COD on ANAMMOX. The good performance of the integrated system indicated that the bacterial community of denitrification, ANAMMOX, and methanogenesis could be dynamically maintained in the sludge of EGSB reactor for a certain range of influent.     

结构抗震的"形而上""形而下"之思辨及工程意义

"形而上"、"形而下"是中国古代哲学中的基本范畴之一.古人借此推演出很多指导人们生产和生活实践的重要思想,并取得一系列的成功.中国古代科学的发展曾遥遥领先世界数千年之久--在结构抗震性能上也是如此,这些都与华夏先贤的哲学思维不无关系.本文通过一些实例的对比,重点分析了古今建筑结构抗震哲学思想的一些异同,这些异同可以从"...     

黑化集团有限公司水解解吸装置改造

总结了黑龙江黑化集团有限公司尿素系统水解解吸装置改造的实践,表明利用立体传质塔板技术改造水解解吸装置可有效地提高装置氨回收能力,解决氨氮超标排放问题.     

污泥堆肥含水率监测方法的选择与探讨

城市污泥的堆肥过程中,快速、准确的含水率测定方法有助于掌握堆体腐熟程度和水分脱除进程,并据此进行工艺的优化和反馈调控.本文介绍了污泥堆肥的含水率监测方法及其优缺点.由于堆肥物料性质与堆肥环境的特殊性和复杂性,缺乏可直接应用的测定仪器,应根据物料性质、工况条件等选择合适的含水率测定技术,并对相关仪器进行改进.对于污泥堆肥的工程化应用而言,实时在线监测的原位含水率测定方法更适合指导工艺的调控和优化、提高堆肥效率.