Phytodegradation of extra heavy oil-based drill cuttings using mature reed wetland: an in situ pilot study

Environmental contamination caused by extra heavy oil-based drill cuttings (DCs) is a major problem in the Liaohe Oilfield, northeastern China. To study the potential effectiveness of the mature reed wetland in removing extra heavy oil contained in drill cuttings, biodegradation of extra heavy oils and study of the effects on soil property and ecophysiological and quality indices of reeds were carried out in a 2-year in situ pilot experiment. In the wetland, four reed beds were used to treat drill cuttings in various loadings: 0 (control), 5, 20, and 40 kg/m(2), corresponding to 150, 600, and 1200 g/m(2) extra heavy oil hydrocarbons (HCs). The obtained results demonstrate that the mature reed wetland was effective at degrading extra heavy oils without extra fertilization. Removal efficiencies of reed bed 2 in the 0- to 80-cm soil profile increased with time, from 90.1% (first harvest season) to 95.8% (second harvest season). After 2 years, only 4.2% of the initial hydrocarbons residual was retained in the surface soil. There was no apparent adverse effects on the surface soil property during degradation of extra heavy oils and, actually, the deeper soil property and reed quality indices were improved at the end of the experiment. Phytotoxicity, resulting in reduction of reed yield, was observed in the most heavily treated beds in the first year. However, long-term reed yield recovered robustly. During the 2-year period, reed height and leaf number were slightly inhibited.     

Mechanical Property and Biodegradability of Cast Films Prepared from Blends of Oppositely Charged Biopolymers

Biodegradable cast films of about 50 m thickness were fabricated by blending oppositely charged biopolymers such as anionic starch–chitosan, and cationic starch–pectin. The tensile strength and elongation at break (%) of films were evaluated as well as their capacity to degrade in compost. Films recovered from soil every 48 h showed consistent degradation (weight loss), diminution of the polymers characteristic peak absorbance in the carbohydrate fingerprint region of the FTIR, and changes in the surface morphology via scanning electron microscopy (SEM). Anionic starch–chitosan films had much superior tensile strength and elongation compared to cationic starch–pectin, suggesting that the ionic bonds formed between anionic-starch and positively charged groups in chitosan polymer were much more stable and stronger. Initially, both films lost about 36% weight within 96 h, which also correlated well with the loss in the characteristic absorption peaks in the region of the infrared spectrum typical of biopolymers. The total mineralization of films by microorganisms in compost soil was also measured using respirometric techniques. Though the rate of mineralization differed for two formulations, total mineralization (extent) for both films were achieved within 45 days.     

Total waste-load control and allocation based on input-output analysis for Shenzhen, south China

The general objective for this paper is to reveal the dynamic relationships between the rapid economic development, water pollution and the subsequent waste-load allocation in different economic sectors through a case-study in Shenzhen City, South China. Two-objective analysis model was employed based on the input-output table for Shenzhen with the full consideration of various constraints in local area. The improved Tchebycheff procedure was used for obtaining the solutions. The predictions were made on economic development and pollutants from wastewater in different sectors and different planning years. The present study allows for the consideration of the economic structural adjustment. It is found that the current situation of economic structure is generally good and is subject to further adjustment in Shenzhen, although it has undergone the rapid development in the past 18 years. When the maximum Gross Domestic Production and the minimum Chemical Oxygen Demand are chosen as the two objectives subject to other constraints, the harmonized results indicated a scheme that claims substantial reduction of polluting effluences in Shenzhen while closely keeping the economic growth rate as planned.     

天然气净化清洁生产工艺的应用

针对天然气净化生产过程中的主要产污环节,重庆天然气净化总厂成功推广应用了PALL高效过滤器、胺液复活装置等先进设备及超级或改良克劳斯硫磺回收、升流式厌氧污泥床层反应器(UASB)等清洁生产工艺。通过加强生产全过程管理,实施污染源头控制,显著削减污染物的产生量,取得了较好的环境效益和经济效益。     

沼泽红假单胞菌去除铅的实验研究

采用沼泽红假单胞菌(Rhodopseudomonas palustris)N菌株进行了去除铅的研究。考查pH、温度、接种量、供氧光照条件等因素对其生长及去除铅的影响。结果表明:菌株生长及去除Pb2+的最优条件是pH为7、厌氧光照、温度为30℃,接种量为0.6g·L-1,Pb2+的去除率可达95%以上;模拟了N菌株去除不同浓度Pb2+的动力学方程。进一步研究不同浓度Pb2+对N菌株细胞中半胱氨酸脱巯基酶比活力的影响,结果显示:Pb2+浓度分别为50,100,150mg·L-1时,可提高半胱氨酸脱巯基酶的活力,而当Pb2+浓度提高到200mg·L-1时则抑制其活力。     

重庆市城区地质灾害分级评价研究

我国是世界上地质灾害最严重的国家之一。本文以重庆市为例,对九大城区各种地质灾害进行分级评价,根据本地区实际情况,得到灾害发生的频率和严重度,从而计算出灾害指数。利用这种方法,可以简单直观地对各种地质灾害进行危害程度的评价。     

低分子量有机酸对红壤中硫丹释放动力学的影响

采用自行设计的动力学试验装置及平衡振荡试验,系统研究了3种低分子量有机酸(草酸、酒石酸和柠檬酸)和水对红壤中α-硫丹(-αendosulfan,αES)的动力学释放行为.结果表明,10 mmol/L的酒石酸和柠檬酸可使αES的释放百分率相对于水和草酸提高7~18个百分点,其中尤以酒石酸的效果最为明显,但水和草酸对αES的释放能力却不存在显著差异(p>0.05),αES的释放存在明显的快速和慢速释放期,特别在前200 mL释放较快;水和草酸对αES的释放动力学数据可由双常数方程和抛物线扩散方程较好描述,并不是代表简单表面扩散的表观一级动力学方程,而酒石酸和柠檬酸则更倾向于Elovich方程(R2>0.99,p<0.000 1),说明对这类立体结构较复杂的有机氯农药来说,影响其在水相中释放的主导因素已不是简单的颗粒表面扩散机制,还可能涉及到土壤颗粒内部的向外扩散机制、颗粒表面的活化与去活化作用、土壤颗粒表面的溶解及对包被在土壤矿物表面的固有有机质结构干扰造成的表面点位能量分布的不均匀等多种机制,使释放动力学的机制更进一步复杂化.     

好氧/厌氧多级串联潜流人工湿地脱氮效果

为了调整传统潜流湿地内部溶解氧分布状态,提高其对生活污水水质净化的效率,对传统潜流湿地进行了不同区段的划分及功能强化,设计了不同结构的好氧/厌氧多级串联潜流人工湿地,研究了好氧/厌氧段比例、位置及人工曝气等因素对脱氮效率的影响,并与传统潜流湿地进行净化效果的比较.结果表明,传统潜流湿地对NH4+-N和TN的去除率分别为...     

Non-carcinogenic risks induced by metals in drinking source water of Jiangsu Province, China

In this study, we investigated the levels of eight metallic elements in source water of 40 tap water treatment plants (TWTPs) located along Yangtze River, Taihu Lake and Huaihe River in the section of Jiangsu Province, China during 2007?C2009 and assessed the non-carcinogenic risks induced by the metals. Among the metals, Fe had the highest concentration (121.5 ??g L^???1) and Pb contributed most (32.4%) to the average hazard index (HI) of 40 TWTPs, followed by Cd (24.7%) and Cr (21.6%). The average concentration of each metal was below the permissible limit of China and USA except for Pb. Both hazard quotients of individual metals and HI of total non-carcinogenic risk in each TWTP were lower than 1.0, suggesting that these pollutants posed negligible hazards to public health of local residents. Temporal and spatial comparisons showed that high HIs occurred more frequently in low water seasons, and the three TWTPs located along Huaihe River (Dongtai, Jinhu and Yishuichang) had relatively higher HIs.     

Occurrence of chlorinated and brominated polycyclic aromatic hydrocarbons in surface sediments in Shenzhen, South China and its relationship to urbanization

One hundred and fourteen surface sediments were collected from the Maozhou River Watershed in Shenzhen, China from December 2009 to January 2010. Three individual chlorinated polycyclic aromatic hydrocarbons (ClPAHs), six individual brominated polycyclic aromatic hydrocarbons (BrPAHs), and five corresponding parent polycyclic aromatic hydrocarbons (PAHs) were determined. The concentration of 9-chlorophenanthrene was the highest ranging from 0.51-289 ng g(-1) (average, 16.5 ng g(-1)). For BrPAHs, the concentration of 2-bromofluorene was the highest ranging from 0.31-266 ng g(-1) (average, 35.3 ng g(-1)). No correlation was observed between the concentrations of ClPAHs and parent PAHs in surface sediments. In addition, there was no correlation between 1-bromopyrene, 7-bromobenz(a)anthracene and 9,10-dibromoanthracene, and corresponding parent PAHs. However, a significant correlation was found between 9-bromophenanthrene and phenanthrene (p < 0.01), between 9-bromoanthracene and anthracene (p < 0.05), and between 2-bromofluorene and fluorene (p < 0.05). Six fly ash samples collected from one of the municipal domestic waste incineration plants in Shenzhen were also analyzed for source identification. The concentration of 7-bromobenz(a)anthracene was the highest, ranging from 3.21-4.08 ng g(-1). In addition, 2-bromofluorene was not detected in all the fly ash samples. No correlation was found between the concentrations of Cl-/BrPAHs and corresponding parent PAHs in fly ashes. We also examined the relationship between the levels of Cl-/BrPAHs in surface sediments and the urbanization process. Our results suggested the levels of individual Cl-/BrPAHs congeners presented a similar increasing trend with the increasing urbanization level.