Limitations to Natural Bioremediation of Perchlorate in a Contaminated Site

Perchlorate (ClO₄ ^?) has been detected in many drinking water supplies in the United States, including the Las Vegas Wash and Lake Mead, Nevada. These locations are highly contaminated and contribute perchlorate to Lake Mead and the Colorado River system. Essential elements for perchlorate bioremediation at these locations were examined, including the presence of perchlorate-reducing bacteria (PRB), sufficient electron donors, occurrence of competing electron acceptors, and ability of PRB to utilize a variety of electron donors. Enumeration of PRB was performed anoxically using most probable number (MPN). Values ranged from ≤20 to 230 PRB/100 ml or ≤20 to ≥ 1.6× 10⁵ PRB/g for Lake Mead water samples and Las Vegas Wash sediments, respectively. 16S rRNA sequences revealed that isolates were γ -proteobacteria, Aeromonas, Dechlorosoma, Rahnella and Shewanella. A screening of potential electron donors using BIOLOG^TM demonstrated that all isolates were capable of metabolic versatility. Measurements of total organic carbon (TOC), nitrate and dissolved oxygen (DO) indicated limited presence of electron donor at all sites, whereas the electron acceptors varied throughout the Wash and Lake Mead. The persistence of perchlorate in the sites is attributed to lack of available electron donor and/or the presence of competing electron acceptors. A location has been identified where perchlorate biodegradation could be implemented thereby halting the transport of perchlorate to Lake Mead and the Colorado River.     

Limitations to Natural Bioremediation of Perchlorate in a Contaminated Site

Perchlorate (ClO₄^-) has been detected in many drinking water supplies in the United States, including the Las Vegas Wash and Lake Mead, Nevada. These locations are highly contaminated and contribute perchlorate to Lake Mead and the Colorado River system. Essential elements for perchlorate bioremediation at these locations were examined, including the presence of perchlorate-reducing bacteria (PRB), sufficient electron donors, occurrence of competing electron acceptors, and ability of PRB to utilize a variety of electron donors. Enumeration of PRB was performed anoxically using most probable number (MPN). Values ranged from ≤20 to 230 PRB/100 ml or ≤20 to ≥ 1.6× 10⁵ PRB/g for Lake Mead water samples and Las Vegas Wash sediments, respectively. 16S rRNA sequences revealed that isolates were γ -proteobacteria, Aeromonas, Dechlorosoma, Rahnella and Shewanella. A screening of potential electron donors using BIOLOG^TM demonstrated that all isolates were capable of metabolic versatility. Measurements of total organic carbon (TOC), nitrate and dissolved oxygen (DO) indicated limited presence of electron donor at all sites, whereas the electron acceptors varied throughout the Wash and Lake Mead. The persistence of perchlorate in the sites is attributed to lack of available electron donor and/or the presence of competing electron acceptors. A location has been identified where perchlorate biodegradation could be implemented thereby halting the transport of perchlorate to Lake Mead and the Colorado River.     

石油污染土壤生物修复过程中微生物生态研究

石油是重要的工业原料 ,同时又是燃料与能源。随着工业的发展 ,需求量大幅度增加 ,使得开采面积不断扩大 ,在开采、运输、贮藏、加工过程中 ,由于意外事故或管理不当 ,排放到农田、地下水、海洋 ,使环境遭受石油污染 ,直接危害人类生产与生活[10 ] 。石油主要成份有烷烃、苯、甲苯、二甲苯等多种复杂芳香烃 ,这些物质毒性大 ,有的有致癌、致突变等作用 ,因此被列为重要污染物[11] 。石油对土壤的污染主要是破坏土壤结构 ,影响土壤通透性。损害植物根部 ,阻碍根的呼吸与吸收 ,最终导致植物死亡。其次 ,污染物进入食物链造成人体损伤。鉴于以…     

Bioremediation of Vegetable Oil and Grease from Polluted Wastewater Using a Sand Biofilm System

Pseudomonas sp. (L1), P. diminuta(L2) were among eight bacterial strains isolated from vegetable grease and oil-contaminated industrial wastewater, four of which only were found to have the ability to degrade oil and grease. They were identified and investigated for oil and grease degradation either individually or in combinations in previous unpublished work by the authors. Since the combination M1 (Pseudomonas sp. andP. diminuta) produced the highest degradative activity, it was used in the present study in a biofilm sand filter system for vegetable oil and grease removal. This system was tested either as one unit or two units in sequence where different flow rates (30, 50, 100 ml/h) were applied compared to a control unit(s). Results showed that both biofilm systems reduced oily wastewater, even in cases of high degree of pollution (fat, oil & grease (FOG), 7535 ppm; biochemical oxygen demand (BOD₅), 525 ppm; chemical oxygen demand (COD), 1660 ppm). Results also showed a removal of FOG with efficiency at 100%; BOD₅ at 95.9% and COD at 96%, at 50 ml/h flow rate using one unit of biofilm system. On using two units in sequence, a complete removal of FOG, BOD₅ and COD with efficiency 100%, at flow rate 100 ml/h was achieved. In conclusion, the previous biofilm results indicated the efficiency of such a system in treating oily polluted wastewater (vegetable oil origin) on the basis of bacterial isolates being used, the optimum flow rate, and the number of biofilm units used in sequence to obtain the highest removal capacity of such a system. This revised version was published online in July 2006 with corrections to the Cover Date.     

生物反应器法处理油泥污染土壤的研究

采油过程产生的油泥是整个石油烃污染源的重点。在陆地生态环境中 ,烃类的大量存在往往对植物的生物学质量产生不利影响 ,更重要的是石油中的一些多环芳烃是致癌和致突变物质 ,这些致癌和致突变的有机污染物进入农田生态系统后 ,在动植物体内逐渐富集 ,进而威胁人类的生存和健康[1 ,1 1 ] 。大量的废弃油泥 ,不仅污染农田 ,同时也给石油行业带来巨大的经济损失。污染土壤的治理主要有物理、化学和生物 (生物修复 )方法 ,生物修复方法被认为最有生命力。污染土壤生物修复技术主要有 3种 ,即原位处理、挖掘堆置处理和反应器处理。反应器处理是…     

中国水青冈分布,生长和更新特点

中国水青冈分布、生长和更新特点吴刚（中国科学院生态环境研究中心,北京１０００８５）Ｄｉｓｔｒｉｂｕｔｉｏｎ,ＧｒｏｗｔｈａｎｄＲｅｖｅｇｅｔａｔｉｏｎａｌＣｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆＦａｇｕｓｉｎＣｈｉｎａ．ＷｕＧａｎｇ（ＲｅｓｅａｒｃｈＣｅｎ...     

Bioremediation of Soils Contaminated with Nigerian Petroleum Products Using Composted Municipal Wastes

The efficiency of ready-to-use, source-separated, composted municipal organic wastes of Nigerian origin on degradation of soil total petroleum hydrocarbons (TPHs) in soils polluted with petroleum products (crude oil, diesel, and spent engine oil) was assessed in screen house experiments. The effect of compost:soil ratios and combined effect of compost-phytoremediation technique were also studied. TPH was determined spectrophotometrically, after extraction with 1:1 acetone-dichloromethane mixture at 425 nm. Soil pH, electrical conductivity, and phytotoxicity to seed germination and growth of maize (Zea mays L.) served as risk assessments on soil quality and evidence of recovery for the oil-impacted soil. Results showed that the treatments increased soil pH and electrical conductivity but reduced TPH. Reductions in TPH by compost technology ranged from 40% to 75.87%. Toxicity to seed germination reduced from 100% to 16.12%. Positive correlations were obtained for plant agronomical parameters and growth period, for all treatments, with coefficients in the range of .905 to .996, p < .05. This study revealed that ready-to-use composted waste has the potential for bioremediation of soils polluted with petroleum and petroleum products. This study is a contribution to the data bank of relatively simple bioremediation methods, suitable for workers in the developing countries, where there is no easy access to high-technology facilities. However, further development of this technique to achieve zero residual TPH is recommended.     

In-Situ Bioremediation of DDTs and PAH Contaminated Aging Farmland Soil Using Blood Meal

The use of blood meal was studied for in-site bioremediation of contaminated farmland soil. The combination of blood meal and indigenous microorganisms helped to in-site remediate the combined contaminated aging farmland soil of DDTs and PAH in Shenyang, China. The concentration of DDTs and PAHs was 47.94 ± 0.63 μg/kg and 690.10 ± 5.16 μg/kg, respectively. Biostimulation using blood meal or glucose promoted the bioremediation rate of DDTs and PAHs. Compared to glucose, blood meal was a longer term repair additive of DDTs and PAHs, and the remediation result was more efficient and durable. In the blood meal treatment, plowing the soil once every 7 days could increase the soil enzyme activities and bacterial populations, and it could significantly promote the remediation rates of DDTs (P < 0.05) and more evidently promote the remediation rates of PAHs. The DDTs and PAHs remediation rates increased from 32.18% and 20.17% to 43.41% and 26.09%, respectively, in soil treated with blood meal and plowed weekly after the five month remediation. This study provides an highly efficient in-site farmland soil bioremediation technology that could have practical utility.     

Disinfection of Contaminated Water by Using Solar Irradiation

Contaminated water causes an estimated 6 to 60 billion cases of gastrointestinal illness annually. The majority of these cases occur in rural areas of developing nations where the water supply remains polluted and adequate sanitation is unavailable. A portable, low-cost, and low-maintenance solar unit to disinfect unpotable water has been designed and tested. The solar disinfection unit was tested with both river water and partially processed water from two wastewater treatment plants. In less than 30 min in midday sunlight, the unit eradicated more than 4 log₁₀ U (99.99%) of bacteria contained in highly contaminated water samples. The solar disinfection unit has been field tested by Centro Panamericano de Ingenieria Sanitaria y Ciencias del Ambiente in Lima, Peru. At moderate light intensity, the solar disinfection unit was capable of reducing the bacterial load in a controlled contaminated water sample by 4 log₁₀ U and disinfected approximately 1 liter of water in 30 min.     

Plant Biotests for Soil and Water Contaminated with Oil and Oil Products

Reactions of higher plants (mustard, oat, rye, lettuce, dill and barley) and microalgae (Euglena gracilis) to the contamination of soil and water with oil and oil products was studied. The germination of seeds was analyzed. The length of sprouts, dry biomass and length of plant roots, as well as the optical density of microalgal broth culture were determined. Negative effects of soil and water contamination with oil and oil products on plant and microalgal parameters examined was shown. After biological destruction of contaminants by an association of destructor strains (Acinetobactersp., Mycobacterium flavescens andRhodoccocussp.), the toxicity of contaminated mediums decreased. The data suggest that the integral toxicity of soil and water contaminated with oil and oil products and toxicity changes during biodestruction of these pollutants can be analyzed by using plant test organisms.     

石油污染土壤生物降解生态条件研究

生物治理是石油污染土壤主要的有效的治理方法。微生物、污染物及环境等方面的因素都影响着生物降解效率。通过最佳生物降解条件的研究,提出了提高生物降解效率的措施。     

石油污染土壤的生物修复技术

1　前　言在石油生产、贮运、炼制加工及使用过程中 ,由于事故 ,不正常操作及检修等原因 ,都会有石油烃类的溢出和排放。例如 ,油田开发过程中的井喷事故 ;输油管线和贮油罐的泄漏事故 ;油槽车和油轮的泄漏事故 ;油井清蜡和油田地面设备检修 ;炼油和石油化工生产装置检修等。石油烃类大量溢出 ,应当尽可能予以回收 ,但有的情况下回收很困难 ,即使尽力回收 ,仍会残留一部分 ,对环境 (土壤、地面和地下水 )造成污染。其进入土壤后 ,会破坏土壤结构 ,分散土粒 ,使土壤的透水性降低。其富含的反应基能与无机氮、磷结合并限制硝化作用和脱磷酸作…     

酞酸酯污染农田土壤生物修复研究进展

酞酸酯是目前世界上产量最大、应用面积最广的人工合成有机物,作为塑化剂被广泛应用于塑料制品中。近年来发现酞酸酯是一类典型的环境内分泌干扰物。随着生活中塑料制品日益增多,尤其是农用薄膜和有机肥的大量使用,农田土壤中酞酸酯污染日益加剧,酞酸酯污染土壤的修复逐渐引起国内外学者的广泛关注。生物修复具有价格低廉、效果良好和环境友好等特点,尤其适合于大面积污染农田土壤修复。从植物修复、微生物修复、植物微生物联合修复和动物修复等方面综述了国内外酞酸酯污染土壤生物修复的研究现状,并从高效修复植物筛选及机理探讨、实际污染土壤的降解菌修复研究、高效降解菌群的构建和作用机制等方面对该领域的研究进行了展望,以期为酞酸酯污染土壤的修复研究提供借鉴并拓展新的思路。     

Bioremediation Assessment of a BTEX‐Contaminated Soil

The elimination of BTEX (benzene, toluene, ethylbenzene, o‐xylene) compounds from soil was studied. After 18 days at 20 °C, 21% of the initial total BTEX contamination (400 mg/kg soil) was lost due to sorption onto soil. Biodegradation decreased in the order ethylbenzene > toluene > benzene > o‐xylene. NPK fertilisation stimulated biodegradation, particularly that of benzene and toluene, significantly, and oleophilic fertilisation inhibited biodegradation. After 18 days, the residual contamination in the NPK‐fertilised, unfertilised and with oleophilic nutrients amended soil was 96, 166 and 196 mg total BTEX/kg soil, respectively. The presence of BTEX initially inhibited the biological activity of the soil (fluorescein diacetate hydrolysis) considerably. This short‐term, reversible inhibition was significantly higher in the unfertilised soil than in the fertilised soil.     

有机污染土壤生物修复的生物反应器技术研究进展

人类广泛的工农业生产活动常常导致土壤污染。常见的土壤污染有重金属污染和有机污染。近年来 ,世界各国开始重视污染土壤的治理。处理方式主要包括热处理 (焚烧法 )、物理及物理化学处理(洗涤 )和生物处理 (生物修复技术 )。其中生物修复技术被认为最有生命力[1,7] 。目前 ,国外采用的土壤生物修复技术有原位处理、场上处理和生物反应器。生物反应器技术能够有效地发挥生物法的特长 ,是污染土壤生物修复技术中最有效的处理工艺 ,但该技术尚处于实验室研究阶段 ,未广泛应用于现场处理。本文就国外使用生物反应器治理有机污染土壤的研究进展…     

Kinetic Modelling and Half-Life Study on Bioremediation of Soil Co-Contaminated with Lubricating Motor Oil and Lead Using Different Bioremediation Strategies

The focus of this study was to investigate the effect of nutrient supplement (urea fertilizer) and microbial species augmentation (mixed culture of Aeromonas, Micrococcus, and Serratia sp.) on biodegradation of lubricating motor oil (LMO) and lead uptake by the autochthonous microorganism in LMO and lead-impacted soil were investigated. The potential inhibitory effects of lead on hydrocarbon utilization were investigated over a wide range of lead concentrations (25–200 mg/kg) owing to the complex co-contamination problem frequently encountered in most sites. Under aerobic conditions, total petroleum hydrocarbons (TPH) removal was 45.3% in the natural attenuation microcosm while a maximum of 72% and 68.2% TPH removal was obtained in biostimulation and bioaugmentation microcosms, respectively. Lead addition, as lead nitrate, to soil samples reduced the number of hydrocarbon degraders in all samples by a wide range (11–52%) depending on concentration and similarly, the metabolic activities were affected as observed in mineralization of LMO (3–60%) in soils amended with various lead concentrations. Moreover, the uptake of lead by the autochthonous microorganisms in the soil reduced with increase in the initial lead concentration. First-order kinetics described the biodegradation of LMO very well. The biodegradation rate constants were 0.015, 0.033, and 0.030 day^?1 for LMO degradation in natural attenuation, biostimulation and bioaugmentation treatment microcosms, respectively. The presence of varying initial lead concentration reduced the biodegradation rate constant of LMO degradation in the biostimulation treatment microcosm. Half-life times were 46.2, 21, and 23 days for LMO degradation in natural attenuation, biostimulation and bioaugmentation treatment microcosms, respectively. The half-life time in the biostimulation treatment microcosm was increased with a range between 10.7 and 39.2 days by the presence of different initial lead concentration. The results have promising potential for effective remediation of soils co-contaminated with hydrocarbons and heavy metals.     

生物技术在放射性污染土壤修复中的研究进展

综述了植物提取和植物稳定等植物修复技术和微生物修复技术等生物技术在放射性重金属污染土壤修复中的研究进展,并对其研究中存在的问题及今后的应用前景进行了讨论。     

Kinetic Study of Carbon Dioxide (CO2) Respiration Rate in Bioremediation of Soil Contaminated with Spent Motor Oil

This study was carried out to investigate the kinetics of CO₂ generation from the bioremediation of soil contaminated with spent motor oil (SCSMO) in an aerobic fixed-bed bioreactor designed and fabricated using indigenous technology. Six contaminated soil samples with different compositions at the same contaminant strength were investigated under a controlled air flow rate of 10 L/h. Results obtained revealed that treatment option “6” (i.e., the biostimulation option) gave the best result, with 75% reduction in the initial oil and grease content (O&G) and CO₂ generation of 6,242 mg/kg contaminated soil (CS). Therefore, the biostimulation option was chosen as the treatment technology and kinetic investigation was based on the treatment technology. Results of kinetic investigation of the treatment technology showed that the growth rate can be represented by the popular Monod equation and the kinetic parameters are μ_max = 1.115 × 10^?16 h^?1; K _O&G = 37,490.9 mg/kg; yield of CO₂ = 42.59%; and yield of biomass = 57.41%. The rate equation and kinetic parameters can be used to design a bioreactor and monitor biodegradation reaction during bioremediation process.