油污土壤的生物处理技术及其影响因素分析

生物处理技术可以用于转化和去除土壤中的石油类污染物,微生物对油污土壤产生降解作用,其降解的最终产物是CO2和水,不产生二次污染。重点分析了影响微生物降解的主要因素,包括pH值、温度、湿度、供氧情况、营养素、表面活性剂加入量、油污染强度,论述了各种影响因素的调整和控制方法。     

微生物对石油污染物的降解作用

针对油井附近落地油污染地表土壤的问题,利用热蒸发色谱技术,对油污土壤中加入微生物对原油的降解特征进行了实验研究。实验结果表明,在油污土壤中加入微生物,对落地油有明显的降解作用,可以减轻石油生产过程中油污对土壤的破坏和对环境的污染。随着微生物降解作用的不断进行,土壤中污油的相对降解速度逐渐加快,相对降解率逐渐增加。生物处理法的过程较简单,处理费用低,处理效果好,一般不会产生二次污染。     

土壤石油类污染物强化生物修复技术研究进展

通过对石油类污染土壤的危害进行分析,指出生物修复技术是土壤石油类污染去除的重要手段。由于石油类污染物组成的复杂性及难降解性,高效降解微生物的富集、驯化,特别是基于多种生物协同共生的高效降解菌群的构建,是实现强化生物修复的重要途径。降解过程中污染物种类及理化性质、温度和pH值、电子受体、营养元素等都对污染物的降解产生较大的影响。     

石油类污染物在土壤中的环境行为

土壤中石油类污染物的环境行为一直是环保界研究的重点。为此,简述了土壤中石油类污染物的来源、危害及存在状态,介绍了其在土壤中的迁移、吸附和降解行为,以及其行为特征和影响因素。全面了解土壤中石油类污染物的环境行为,对保护生态环境、推动石油工业的持续发展具有重要意义。     

油污土壤微生物生态研究

利用微生物降解土壤中的油等有机污染物的就地生物治理技术受土壤及环境的诸多条件影响,在使用该技术之前,首先要进行油污土壤微生物生态研究,弄清影响微生物处理效果的各种因素。通过对胜利油田油污土壤微生物研究得知：胜利油田油污土壤的ｐＨ值、含水量等指标利于微生物降解原油。土壤优势菌种多为原油降解菌,并且与含油量呈正相关。油污土壤中氮、磷等营养物质含量不足时,向其添加一定数量的营养物质和降解菌,能够提高微生物处理地面溢油的处理效率。     

土壤中石油烃微生物降解动力学

以长安大学渭水校区未被污染的粉质壤土为研究对象,通过土壤灭菌、添加由石油污染土壤红三叶草(Trifolium Repens Linn)根际修复区分离筛选得到的4株以原油作为惟一碳源和能源的高效石油烃降解菌(动性杆菌、藤黄微球菌、蜡状芽孢杆菌和短小芽孢杆菌),调控反应温度与石油烃初始浓度,研究在土壤中添加优势石油烃降解菌后石油烃降解动力学及其影响因子。结果表明:优势石油烃降解菌对土壤中石油烃降解起主导作用,在40d内,在2 000mg/kg石油烃浓度下添加石油烃降解菌其石油烃降解率是灭菌条件下的2倍左右,土壤中石油烃降解菌降解量为36~271mg/kg,非灭菌处理半衰期时间短于灭菌处理;在设定的实验温度范围内,石油烃降解速率随着温度增加逐渐加快,在(38±1)℃时残留量最小为1 662mg/kg,半衰期最短;土壤中的石油烃在浓度为2 000mg/kg时降解最快,随着初始浓度的增加,石油烃降解速率呈递减趋势,半衰期逐渐增长。     

用生物法治理大庆油田地表油污土壤

多年来采油作业中常发生各种漏油事件,导致油井周围土壤污染严重,如何在发展生产的同时有效地保护环境是目前迫切需要解决的一个重要课题。大庆油田将微生物处理和植物处理等生物方法用于土壤原油污染的治理。微生物处理法利用存在能够降解污染物的有效微生物等条件,处理原油污染物。植物处理法利用植物的生长发育将土壤中的石油污染物吸收、转化,达到净化土壤的目的。大庆油田比较适宜采用生物处理技术进行地表土壤石油污染的治理。利用生物技术进行油污土壤治理具有广阔的应用前景。     

海洋沉积物中石油类污染物动态释放的实验研究

以海洋沉积物为研究对象,通过动态模拟实验研究了海洋沉积物中石油类污染物释放的影响因素及各条件下上覆水体中污染物浓度随时间的变化规律。实验结果表明,海洋沉积物中石油类污染物释放强度与沉积物土壤颗粒是否悬起有关,当土壤颗粒大量悬起时污染物释放强度得到显著提高;上覆水体盐度的增加抑制了石油类污染物的释放;海洋沉积物在一定的受污染范围内,随着受污染程度的增加,石油类污染物的释放强度会随之增加;上覆水体中石油类污染物的浓度与反应物的固液比成正相关。     

NAPL态石油类污染物在黄土中迁移的稳态数学模型

根据NAPL态石油类污染物迁移的特点，建立了NAPL态石油类污染物在土壤中迁移的稳态数学模型，提出了综合污染系数的概念；根据延安黄土高原地区土壤和石油类污染物的特性测定了NAPL态石油类污染物对黄土的综合污染系数S＝6－8。最后在实验室条件下对模型进行了验证，结果表明模型计算值与实验值能够较好吻合。     

石油降解菌的分离筛选及混合菌群的构建与优化

以河南濮阳油田超重质原油为研究对象,从污染井场土壤中分离并筛选出几株高效降解细菌、酵母菌和霉菌。由于不同类型微生物对碳源的利用目标和方式有所不同,而将3类不同类型菌种进行排列组合进行降解实验,最终优选出一组石油降解优势菌群。该文还利用正交优化法对降解菌的最佳添加量进行计算,结果显示,最佳接种量为X25：1．5％,Z3：1％,X18：1％,Z28：2％。利用该优化结果进行降解实验,石油的降解率在一定程度上提高了。在对濮阳、南阳和延长油田不同原油进行为期8d的降解实验中,显示了较高的降解效率,降解率分别为56．93％、65．66％、82．69％。实验证明,该降解菌群能不仅能有效够降解超重油,而且对重质原油和轻质原油表现出更好的降解能力。因此,该研究为石油污染物的降解提供了有效的菌种资源。     

Influence of rhizosphere microbial ecophysiological parameters from different plant species on butachlor degradation in a riparian soil

Biogeochemical processes in riparian zones regulate contaminant movement to receiving waters and often mitigate the impact of upland sources of contaminants on water quality. However, little research has been reported on the microbial process and degradation potential of herbicide in a riparian soil. Field sampling and incubation experiments were conducted to investigate differences in microbial parameters and butachlor degradation in the riparian soil from four plant communities in Chongming Island, China. The results suggested that the rhizosphere soil had significantly higher total organic C and water-soluble organic C relative to the nonrhizosphere soil. Differences in rhizosphere microbial community size and physiological parameters among vegetation types were significant. The rhizosphere soil from the mixed community of Phragmites australis and Acorus calamus had the highest microbial biomass and biochemical activity, followed by A. calamus, P. australis and Zizania aquatica. Microbial ATP, dehydrogenase activity (DHA), and basal soil respiration (BSR) in the rhizosphere of the mixed community of P. australis and A. calamus were 58, 72, and 62% higher, respectively, than in the pure P. australis community. Compared with the rhizosphere soil of the pure plant communities, the mixed community of P. australis and A. calamus displayed a significantly greater degradation rate of butachlor in the rhizosphere soil. Residual butachlor concentrations in rhizosphere soil of the mixed community of P. australis and A. calamus and were 48, 63, and 68% lower than three pure plant communities, respectively. Butachlor degradation rates were positively correlated to microbial ATP, DHA, and BSR, indicating that these microbial parameters may be useful in assessing butachlor degradation potential in the riparian soil.     

Phytoremediation of aged petroleum sludge: effect of irrigation techniques and scheduling

The use of higher plants to accelerate the remediation of petroleum contaminants in soil is limited by, among other factors, rooting depth and the delivery of nutrients to the microsites at which remediation occurs. The objective of this study was to test methods of enhancing root growth and remediation in the subsurface of a contaminated petroleum sludge. The phytoremediation of highly contaminated petroleum sludge (total petroleum hydrocarbons >35 g kg(-1) was tested in the greenhouse as a function of the frequency and the depth of irrigation and fertilization. Water and dissolved plant nutrients were added to the soil surface or at a depth of 30 cm, either daily or weekly. Equivalent quantities of water and nutrients were added in all cases. Daily irrigation at a depth of 30 cm invoked greater root growth and enhanced contaminant degradation relative to all other treatments. In the absence of plants, residual concentrations of petroleum hydrocarbons after 7 mo were higher than with plants. The presence of plant roots clearly improved the physical structure of the soil and increased microbial populations. Thus, the plant roots in conjunction with daily additions of soluble N and P appeared to enhance oxygen transport to greater depths in the soil, stimulate petroleum-degrading microorganisms, and provide microbial access to soil micropores. Subsurface irrigation with frequent, small amounts of water and nutrients could significantly accelerate phytoremediation of field soils contaminated with petroleum hydrocarbons.     

Efficiency of cassava steep liquor for bioremediation of diesel oil-contaminated tropical agricultural soil

Soil artificially contaminated with diesel oil, treated with cassava steep liquor (CSL) and designated EXPS. Similar polluted soil without CSL amendment (CSS1) and uncontaminated soil (CSS2) served as controls. There were dramatic changes in the physico-chemistry of systems EXPS and CSS1 with utilization of the inorganic nutrients to near-depletion in the former than the latter. In contrast, the properties of CSS2 remained relatively stable throughout the investigated period. Similarly, the population densities of microflora in the polluted soils showed an initial decrease between days 0 and 5 before assuming an increasing trend with percent hydrocarbon-utilizers ranging significantly (P < 0.05) from 0.56 to 6.6, 0.1 to 2.46 and 0.56 to 0.26, respectively for EXPS, CSS1, and CSS2. In EXPS, the residual oil decreased from 98,045 to 1,102.3 mg/kg soil at day 35 representing about 98.88% degradation. The corresponding value for CSS1 was 98,106.1 to 52,110 mg/kg soil, amounting to 46.88% oil disappearance. The GC fingerprints of alkane fractions of the recovered oil reduced significantly by day 15 for EXPS with near-similar results of CSS1. However, by day 35, there was complete disappearance of all peaks including the pristane and phytane molecules in the former whereas in CSS1, there were no observable changes. The germination and growth profiles of maize seed plants as evidence of recovery of oil-impacted soils were poor in CSS1 (10%) with pronounced abnormal morphology when compared with the data obtained for EXPS (74%) and CSS2 (80%). These results suggest that CSL could be an indispensable tool in bioremediation of environments contaminated with hydrocarbons. The technology of application is simple, rapid and cost-effective and may be appropriate for use in developing countries to ameliorate the problems of petroleum pollution.     

Utilization of biosolids during the phytoremediation of hydrocarbon-contaminated soil

Addition of anaerobically digested sewage sludge (biosolids) to soil may improve conditions for phytoremediation of petroleum hydrocarbons (PHCs) through improved soil chemical, biological, and physical properties. A 32-wk greenhouse study investigated three rates of biosolids addition (0, 13.34, and 26.68 g oven-dry biosolids kg(-1) oven-dry soil) and the presence or absence of smooth brome (Bromus inermis Leyss. cv. Carlton) plants on the removal of diesel (3.5 g kg(-1) oven-dry soil) in an industrial, sandy loam soil. Diesel PHCs were divided into two fractions based on equivalent normal straight-chain boiling point ranges (F2: nC10-nC16; F3: nC16-nC34). The addition of biosolids did not increase the extent of PHC degradation but did result in significantly greater first-order decay constants compared to unamended controls. Overall, the presence of plants did not increase the rate or extent of PHC degradation, relative to that observed in unamended, non-vegetated soils. Vegetation was, however, an important factor within the biosolids-amended soils as was observed by a greater extent of PHC degradation. Some of this decrease was attributed to plant-induced removal of biosolids components that were contributing to the F3 fraction. Overall, the low-amendment rate (13.34 g oven-dry biosolids kg(-1) oven-dry soil) was considered to be the most effective treatment because it produced the greatest overall PHC degradation rate (0.226 wk(-1) for total PHCs) and resulted in the greatest recovery of biosolids-derived N by smooth brome (26.6%).     

高盐废水人工湿地处理中耐盐植物的筛选

天津塘沽作为滨海新区核心区,是目前天津发展最快的地区之一。由于本区盐碱土壤等自然条件,污水中盐分含量较高,制约了废水的回用。本文通过模拟人工湿地实验,比较了芦苇（Phragmites australis）、盐地碱篷（Suaeda salsa）、碱蒿（Artemisia anethifo原lia）、黄花鸢尾（Iris wilsonii）、盐角草（Salicornia europaea）和大米草（Spartina anglica）等耐盐植物对轻污染水体中高浓度氯离子的去除能力,筛选出去除能力较强的植物,并确定植物对盐分去除率达到最大时的生态系统条件。结果表明,适合人工湿地的耐盐碱植物对氯离子的去除效果依次为：芦苇＆gt;盐地碱篷＆gt;碱蒿＆gt;黄花鸢尾＆gt;盐角草＆gt;大米草,停留时间一般在第4d时可达到平衡。该研究为利用人工湿地处理高盐废水提供了科学依据。     

石油降解菌的降解特性研究

以0#柴油为唯一碳源,对石油降解菌DSP菌的生长、疏水性、产表面活性剂、脱氢酶活性及降解能力进行研究。结果表明:DSP菌在生长过程中可产生糖脂类生物表面活性剂,对石油烃的降解有很好的促进作用,其脱氢酶活性与降解率有较好的相关性。当土壤中柴油含量为10%时,利用DSP菌经过40d的处理(30℃,pH值为6),油含量下降到1.82%,降解率最高可达65.4%。     

Effects of plants on the removal of hexavalent chromium in wetland sediments

The effect of two wetland plants, Typha latifolia L. (cattail) and Phragmites australis (Cav.) Trin. ex Steud (common reed), on the fate of Cr(VI) in wetland sediments was investigated using greenhouse bench-scale microcosm experiments. The removal of Cr(VI) was monitored based on the vertical profiles of aqueous Cr(VI) in the sediments. The Cr(VI) removal rates were estimated taking into account plant transpiration, which was found to significantly concentrate dissolved species in the sediments. After correcting for evapotranspiration, the actual Cr(VI) removal rates were significantly higher than would be inferred from uncorrected profiles. On average, the Cr(VI) removal rates were 0.005 to 0.017 mg L(-1) d(-1), 0.0003 to 0.08 mg L(-1) d(-1), and 0.004 to 0.13 mg L(-1) d(-1) for the control, T. latifolia, and P. australis microcosms, respectively. The fate of the removed Cr(VI) was examined by determining the quantity and chemical speciation of the Cr in the sediment and plant materials. Chromium(III) was the dominant form of Cr in both the sediment and plants, and precipitation of Cr(III) in the sediment was the major pathway responsible for the disappearance of aqueous Cr(VI) from the pore water. Incubation results showed that abiotic reduction was the primary mechanism underlying Cr(VI) removal in the microcosm sediments. Organic compounds produced by plants, including root exudates and mineralization products of dead roots, are thought to be the factor that is either directly or indirectly responsible for the gap between Cr(VI) removal efficiencies in the sediments of the vegetated and unvegetated microcosms.     

Zinc accumulation in plant species indigenous to a Portuguese polluted site: relation with soil contamination

The levels of zinc accumulated by roots, stems, and leaves of two plant species, Rubus ulmifolius and Phragmites australis, indigenous to the banks of a stream in a Portuguese contaminated site were investigated in field conditions. R. ulmifolius, a plant for which studies on phytoremediation potential are scarce, dominated on the right side of the stream, while P. australis proliferated on the other bank. Heterogeneous Zn concentrations were found along the banks of the stream. Zn accumulation in both species occurred mainly in the roots, with poor translocation to the aboveground sections. R. ulmifolius presented Zn levels in the roots ranging from 142 to 563 mg kg(-1), in the stems from 35 to 110 mg kg(-1), and in the leaves from 45 to 91 mg kg(-1), vs. average soil total Zn concentrations varying from 526 to 957 mg kg(-1). P. australis showed Zn concentrations in the roots from 39 to 130 mg kg(-1), in the stems from 31 to 63 mg kg(-1), and in the leaves from 37 to 83 mg kg(-1), for the lower average soil total Zn levels of 138 to 452 mg kg(-1) found on the banks where they proliferated. Positive correlations were found between the soil total, available and extractable Zn fractions, and metal accumulation in the roots and leaves of R. ulmifolius and in the roots and stems of P. australis. The use of R. ulmifolius and P. australis for phytoextraction purposes does not appear as an effective method of metal removing, but these native metal tolerant plant species may be used to reduce the effects of soil contamination, avoiding further Zn transfer to other environmental compartments.