Heavy metal (Cu,Cd, Pb,Cr) washing from river sediment using biosurfactant rhamnolipid

Heavy metal-contaminated sediments posed a serious threat to both human beings and environment. A biosurfactant, rhamnolipid, was employed as the washing agent to remove heavy metals in river sediment. Batch experiments were conducted to test the removal capability. The effects of rhamnolipid concentration, washing time, solution pH, and liquid/solid ratio were investigated. The speciation of heavy metals before and after washing in sediment was also analyzed. Heavy metal washing was favored at high concentration, long washing time, and high pH. In addition, the efficiency of washing was closely related to the original speciation of heavy metals in sediment. Rhamnolipid mainly targeted metals in exchangeable, carbonate-bound or Fe-Mn oxide-bound fractions. Overall, rhamnolipid biosurfactant as a washing agent could effectively remove heavy metals from sediment.

     

Role of goethite dissolution in the oxidation of 2-chlorophenol with hydrogen peroxide.

It is well known that the dissolution of goethite plays an important role in catalyzing the oxidation of organic chemicals. Therefore, this study investigates how surface dissolution of goethite affects 2-chlorophenol oxidation in the goethite/H2O2 process. Experimental results indicate that ligand and reductant can enhance the dissolution rate of goethite, which is surface-controlled. Our results further indicate 2-chlorophenol degradation depends on goethite concentration. In addition, the oxidation rate of 2-CP is correlated with reductive dissolution rate at various dosages of goethite. Moreover, the oxidation mechanism of 2-CP is also a surface-controlled reaction. A mechanism proposed herein indicates that, in addition to the contaminant, its intermediate species affect the oxidation rate as well.     

Hexabromocyclododecanes in soils and plants from a plastic waste treatment area in North China: occurrence,diastereomer- and enantiomer-specific profiles,and metabolization

Plastic waste is a source of organic contaminants such as hexabromocyclododecanes (HBCDs). HBCDs have been found to cause developmental and reproductive toxicity; it is important to investigate the occurrence and metabolization of HBCDs in the soil environments with plastic waste contamination. This work analyzed HBCDs and their metabolites in soil and plant samples collected from Xinle and Dingzhou—the major plastic waste recycling centers in North China. Results showed that total HBCD concentrations in soils followed the order: plastic waste treatment site (11.0–624 ng/g) > roadside (2.96–85.4 ng/g) ≥ farmland (8.69–55.5 ng/g). HBCDs were detected in all the plant samples with total concentrations ranging from 3.47 to 23.4 ng/g. γ-HBCD was the dominant congener in soils, while α-HBCD was preferentially accumulated in plants. Compositions of HBCD isomers in soils and plants were significantly different (P < 0.05) among sampling sites and among plant species. HBCDs in farmland soil and all plant samples exhibited high enantio-selectivity based on the enantiomeric fractions (EFs). Furthermore, metabolites of pentabromocyclododecenes (PBCDEs) were frequently identified in soils, and mono-OH-HBCDs were the most common ones in plants. This study for the first time provides evidences of HBCD contamination in the soil-plant system caused by plastic waste, their stereo-selectivity, and metabolization behavior, improving our understanding of the environmental behavior and fate of HBCDs.     

白腐菌应用于堆肥处理含木质素废物的研究

白腐菌对木质素具有较强的降解能力。通过在含大量木质素的模拟垃圾堆肥中采取添加白腐菌菌剂与不添加该菌剂2组实验对比,在相同堆肥处理条件下,接种菌剂的堆肥中木质素总量由274988mg降至15438mg,降解率达4386%,远高于未接种菌剂的堆肥中木质素的降解率,表明白腐菌可有效用于含木质素废弃物的堆肥处理,并有望于加速堆肥腐熟,提高堆肥效率。     

新型膜-生物反应器在不同通量下的膜污染特性研究

选择适当的膜通量是膜-生物反应器控制膜污染的有效手段之一.本文根据膜通量与临界通量的关系选取了5个不同的膜通量,考察在这些通量条件下新型膜-生物反应器膜污染发展特性的变化.试验结果表明,膜通量的变化会影响膜污染的发展特性.当膜通量小于临界通量区时,膜污染发展具有"2阶段"趋势,并且膜通量越小"第1阶段"和"第2阶段"的膜污染发展速率对比越显著.当膜通量在临界通量区通量内时,首先出现短暂的膜污染快速增长期,随后膜污染发展仍呈现"2阶段"现象.当膜通量大于临界通量区通量时,膜操作压力(TMP)从开始运行即迅速上涨直至试验结束.     

中国南方某城市自来水厂处理工艺对多环芳烃的去除效果研究

讨论了中国南方某城市自来水厂饮用水中的多环芳烃残留规律以及现有净水工艺对多环芳烃的去除效果。研究结果表明,该自来水厂饮用水中检出多环芳烃以2~4环芳烃为主,强致癌性高环数多环芳烃均在检出限以下,且多环芳烃总量未超出中国供水行业标准(2000年)的相关限值。各处理工艺段中,砂滤过程对多环芳烃的去除效果最好,相较于原水对多环芳烃总量的去除率可达64%。     

多隔室厌氧折流板反应器(ABR) 的水力特性试验研究

对ABR反应器的水力流态进行了示踪剂试验,分析了特征截面面积对ABR水力特性的影响,采用停留时间分布(RTD)法研究了不同进水COD浓度和HRT条件下ABR反应器的水力特性,结果表明不同进水COD浓度时ABR反应器的RTD曲线相似,表明进水COD浓度不是影响ABR水力特性的主要因素;不同HRT条件下RTD曲线差异很大,表明HRT对ABR的水力特性影响较大,随着水力停留时间的延长,N值增大,1/Pe减小,ABR的流态趋于推流流态,随着HRT的缩短,N值减小,1/Pe数增大,ABR反应器趋于完全混合流态.     

TiO2/H2O2/UV和TiO2/O3/UV降解对氯苯甲酸和喹啉的试验研究

主要叙述TiO2/H2O2/UV和TiO2/O3/UV体系降解对氯苯甲酸（4-CBA）和喹啉的试验研究.研究表明,（1）在TiO2/H2O2/UV体系里目标物降解速度先随过氧化氢投加量的增加而提高,但超过一定浓度之后便开始下降;（2）在TiO2/O3/UV体系中,目标降解物的反应速度都非常快,且臭氧浓度高的时候降解速度更快;（3）二氧化钛催化剂在TiO2/O3/UV体系中作为积极因素有助于提高反应速率,而在TiO2/H2O2/UV体系是消极因素,会降低反应速率.     

生化法处理煤气废水

采用Ａ／Ｏ工艺处理煤气废水的研究结果表明,该工艺能同时去除煤气废水中的有机物和氨氮,在试验确定的条件下,该工艺对煤气废水中的ＣＯＤｃｒ去除率达９１．０％,ＢＯＤ５去除率达９９．１％,ＮＨ３－Ｎ去除率达９９．２％,ＴＮ去除率达９４．７％。     

改进的硫酸盐-聚乙烯醇法包埋藻菌脱氮除磷研究

采用改进的硫酸盐-PVA固定化法将藻与菌混合固定。在三种不同藻菌比的情况下，固定化系统对氮去除均可达100％，但是去除速度与固定的细菌量有关，细菌量越大，对氮的去除速度越快；对磷的去除随实验进行，最大去除率逐步下降，其下降速度与固定藻的量有关，藻量越大，下降速度越慢。由此说明脱氮的主要贡献者是细菌，而藻对除磷起了主要作用。为达到有效的脱氮除磷，应适当提高固定化藻的浓度，藻菌比应大于2：1。透射电镜照片显示，在聚乙烯醇载体上，藻类的生长没有受到限制。