Composting of Wood Containing Polycyclic Aromatic Hydrocarbons (PAHs)

The addition of various nitrogen sources, such as liquid hog manure and mineral medium, to pine wood accelerated the composting process in Dewar vessels, which was obvious from the increased decomposition temperature and the more intensive oxygen consumption and carbon dioxide production. During composting in Dewar vessels of artificially PAH-contaminated pine wood soaked with liquid manure, the PAH degradation was influenced by the inoculum used. The fastest PAH degradation was achieved by compost addition, but the most intensive carbon dioxide evolution was measured with hydrocarbon-polluted soil as an additive. After 61 days, the PAH content of the wood was reduced from each 1000 mg/kg to 26 mg/kg of phenanthrene and 83 mg/kg of pyrene. The relation between the microbial wood decay and PAH degradation shows that the detoxification at least of artificially PAH-polluted wood demands only a partial wood decay.

A pilot scale percolator was applied to composting of artificially contaminated pine wood and really polluted waste wood. After 27 days of remediation, the portion of residual PAHs was higher in the case of the really polluted material. The slower degradation in the real waste wood may be explained by the lower bioavailability of pollutants in comparison with the artificially contaminated wood. In really polluted wood, the degradation rate of PAHs depended on their degree of condensation (the higher the number of aromatic rings the smaller the degradation rate was).     

多环芳烃污染土壤的生物修复

综述了土壤环境中多环芳烃的来源、归宿、生物转化机理、影响因素及生物修复技术研究进展,提出了利用生物技术治理土壤环境中多环芳烃的思路及方法。     

Harnessing the Hydrocarbon-Degrading Potential of Contaminated Soils for the Bioremediation of Waste Engine Oil

Waste engine oil pollution is an endemic problem in African countries as waste oil is often discharged into the environment without adequate treatment because waste oil recycling facilities are not readily available. In this study, laboratory-based microcosms (natural attenuation, biostimulation, bioaugmentation and combined treatment of biostimulation?Cbioaugmentation) were set up with soils (from old hydrocarbon biopiles) spiked with waste engine oil and monitored for 3 months. Total petroleum hydrocarbon analysis showed that biostimulation and biostimulation?Cbioaugmentation accelerated hydrocarbon degradation with over 84% reduction (<10,000 mg?kg^?1) by week 8. It took another 2 weeks for other microcosms to get below this classification of low-level contaminated waste and landfill disposal level. The highest degradation rate of 92% was obtained in biostimulated?Cbioaugmented microcosms (week 10). However, by week 12, there were no significant differences in hydrocarbon levels in naturally attenuated and treated microcosms. 16S rRNA and ITS-based denaturing gradient gel electrophoresis profiling showed diverse bacterial and fungal communities with some dominant members belonging to hydrocarbon-degrading Proteobacteria, Ascomycetes and Basidiomycetes. This research has therefore shown that hydrocarbon-polluted soils possess substantial microbial hydrocarbon-degrading capacity which was successfully harnessed for degrading engine oil. In developing countries without recycling facilities but readily available hydrocarbon-contaminated soils, using such soils for ex situ monitored natural attenuation could be an effective, low-cost and environment-friendly option for treating waste engine oil.     

土壤环境中多环芳烃的微生物降解及联合生物修复

研究土壤环境中持久性有机污染物的生物降解及其生物修复技术是当今国际环境修复科学技术前沿领域的重要课题。本文重点论述了土壤环境中持久性有机污染物多环芳烃的微生物降解机理及其在生物修复中的应用等,并结合当前研究进展,展望了基于多种修复措施相结合的多环芳烃污染土壤联合生物修复工程技术的开发与应用前景。     

高分子量多环芳烃污染土壤的菌群修复研究

多环芳烃(Polycyclic aromatic hydrocarbons,PAHs)是环境中普遍存在的一类有机污染物,由于其在土壤中的半衰期较长和致癌、致畸形、致突变的性质而受到人们的重视。微生物是生态系统中最重要的分解者,对PAHs具有较强的分解代谢能力和较高的代谢速率。通常认为,PAHs的环数越高,越难被微生物降解利用[1]。高分子量PAHs(三环以上的PAHs)具有更高的毒性和亲脂性,更难被微生物降解。环境中PAHs通常以多种组分同时存在,呈现其复合污染现象,增加了微生物降解的难度。因此,筛选能够同时降解多种高分子量PAHs的微生物,具有重要的现实意义。目前,越来越多的国内外学者采用微     

Potential of Spent Mushroom Substrate for Bioremediation Purposes

? Several approaches involving the use of spent mushroom substrate (SMS) for bioremediation purposes warrant further investigation. SMS has important potential for the biological treatment of contaminated soils in situ and offers an attractive technology for the decontamination of land sites used for the disposal of hazardous wastes. Development of the bioremediation potential of SMS, coupled with the well-documented environmental benefits of SMS (e.g. provision of plant nutrients, neutralization of soil acidity, improvement of water quality), should serve to enhance the value of SMS as an additional source of revenue to the mushroom grower. large scale bioremediation system involves the seeding of contaminated sites with microbial inoculants. Apart from cost considerations (i.e. they must be cheap to produce to have any practical value), bioremediation inoculants should be selected for their degradative capacity (ability to totally mineralise the contaminant, broad substrate specifity). The stability of that capacity and their survival properties under the conditions that prevail at the contaminated site also are important, and they should not possess any undesirable characteristics such as pathogenicity and allergenicity.     

Isolation and Optimization of PAH-Degradative Bacteria from Contaminated Soil for PAHs Bioremediation

The aim of the present study was to determine the amount ofcoal fly ash required to stabilize sewage sludge, without causing an adverse effect on the growth of Zea mays L. seedlings (corn) in a loamy soil receiving the ash-sludge mixtures amendment. Sludge was stabilized by mixing with fly ash at an amendment rate of 0, 5, 10, 35 and 50% (w/w) beforeundergoing a short fermentation period to produce a range of ash-sludge fertilizer product. Each mixture was then mixed with a loamy soil at either 1:1 or 1:5 ash-sludge mixture:soil(v/v). Soil pH, electrical conductivity (EC), and solubleCa, Mg and B contents increased while soluble NH₄-N,PO₄-P, K, Cd, and Ni contents decreased with anincrease in ash amendment rate. Dry weight yields of potsreceiving 1:5 ash-sludge:soil mixture (v/v) weresignificantly higher than their counterparts with asoil-mixing ratio of 1:1 (v/v). The highest yields were obtainedat 5 and 10% ash-sludge mixture amended soil at 1:5 soilmixing ratio. Nevertheless, the yield at 35% ash-sludgeamended loamy soil at 1:1 v/v was still higher than that ofthe control soil with fertilizer treatment. The nutrientcontent of corn seedlings was higher at 35% and 10% ash-sludge mixture amended soil at 1:1 v/v, and 5% and 10% at1:5 v/v than other treatments. Zinc concentrations of cornseedlings increased while B decreased with the decreasingamounts of fly ash added. Hence, the present experimentdemonstrates the beneficial effects of the ash-sludgemixture on soil nutrient status and plant root growthenvironment. An ash amendment rate of up to 35% in theash-sludge mixture would not have any adverse effects onplant production even at a high soil-mixing volume of 1:1(v/v), but an addition of 5% to 10% ash-sludge mixture at1:5 (v/v) produced the optimum condition for corn seedlingsgrowth. The results support the use of coal fly ash as astabilizing agent for sewage sludge and the product couldbe used for land application.     

锯末对生物修复荧蒽和芘污染土壤的强化作用及影响因素

通过土壤微宇宙培养试验,研究了锯末尺寸、添加量和种类等因素对荧蒽特效降解菌MC(Mycobacterium flavescens)修复污染土壤(潮土、红壤、黑土、黄棕壤和水稻土)的效果.结果表明:锯末联合降解菌MC修复荧蒽污染的黄棕壤效果较好,优化条件下25 d荧蒽降解率为42.63％ ±1.05％;该联合修复对黑土和...     

石油污染土壤的生物修复研究进展

生物修复技术是解决环境污染、恢复被人类活动破坏的生态系统、实现人类社会可持续发展的重要手段之一,它具有速度快、消耗低、效率高、成本低、反应条件温和以及无二次污染等显著优点.本文主要介绍了生物修复的原理和特点,石油污染土壤的各种生物修复技术:微生物修复技术、植物修复技术和菌根根际生物修复技术的研究和应用进展.     

玉米草（Zea Mexicana）与海藻寡糖联合修复石油烃污染土壤的研究

采用玉米草及海藻寡糖联合修复技术研究了石油污染土壤的修复效果,对修复过程中酶活性变化进行了测定,并采用变性梯度凝胶电泳（DGGE）技术测定了土壤中微生物群落的变化。结果表明,种植玉米草可以有效提高土壤中石油烃的降解,与对照相比石油烃降解率增加了11%;加入不同浓度海藻寡糖进一步增加了石油烃的降解效果,降解率最高达到28.6%。种植植物及加入海藻寡糖可以有效提高多酚氧化酶、脱氢酶及尿酶的活性。PCR-DGGE结果表明植物种植及海藻寡糖的加入增加了土壤中微生物数量,其微生物群落结构与未种植植物及修复前土壤相比发生了较大的变化。     

Potential Compost Benefits for Restoration Of Soils Disturbed by Urban Development

Compost amendment of soils degraded by urban development is seen as a way to improve soil and landscape quality, reduce runoff, and create a high-value market for locally produced compost. This review evaluates literature on organic soil amendments used in agriculture and horticulture, and extends results to disturbed soils in urban landscapes. Research on agricultural use of organic amendments consistently shows soil bulk density and penetration resistance decreasing with increasing amendment rate, and aggregate stability, porosity, and infiltration rate increasing with amendment rate. The effect of organic amendments on plant available water is less clear. Although organic amendments increase soil water holding capacity, much of the increase may not be available to plants. The nutrient benefits of compost amendments are often overlooked. Composts with a C:N ratio of 20:1 or less can provide significant amounts of nitrogen and other nutrients, improving the establishment of turf and landscape plants, and reducing the amount of supplemental nutrients needed. Materials with a high C:N ratio immobilize N, which can retard plant establishment. Results suggest that compost amendment rates of about one-third by volume should be suitable for establishing landscape beds in humid, temperate environments in soils degraded by development. Rates of 15 to 25% by volume are suggested for lawn establishment.     

Windrow Composting of Waste Paint Sludge Containing Melamine Resins

ABSTRACT

Melamine resins (MR), widely used in various industries, are thermosetting plastics that have hard and durable properties. These resins can be introduced into the environment as components of waste products or via industrial effluents. It is important to seek environmentally friendly means to recycle, remove, or degrade melamine resins before they are released to the environment. Waste paint sludge containing MR has been shown to be efficiently composted under bench-scale conditions. In this study, the impacts of C/N ratios on windrow composting of waste paint sludge containing MR were evaluated. As composting proceeded, temperature, concentrations of MR and melamine degradation products (i.e., ammeline, ammelide, and cyanuric acid) were determined. After 98 days of composting, 87.5, 83.3, 80.9, and 70.1% of the initial MR were degraded under the treatments with C/N ratios of 30, 33, 35, and 37, respectively. Degradation of MR was enhanced by relatively low C/N ratios. Significant amounts of plant nutrients were found in the final composts, while heavy metals were well below values considered to be of concern regarding surface water quality or crop production. We conclude that adjusting C/N ratio to approximately 30 in the initial mixtures with oat and hay straws can increase the degradation of MR and its derivatives during windrow composting of waste paint sludge containing MR and produce a good quality compost product.     

Biodegradation of PAHs and PCBs in Soils and Sludges

Results from a multi-year, pilot-scale land treatment project for PAHs and PCBs biodegradation were evaluated. A mathematical model, capable of describing sorption, sequestration, and biodegradation in soil/water systems, is applied to interpret the efficacy of a sequential active–passive biotreatment process of organic chemicals on remediation sites. To account for the recalcitrance of PAHs and PCBs in soils and sludges during long-term biotreatment, this model comprises a kinetic equation for organic chemical intraparticle sequestration process. Model responses were verified by comparison to measurements of biodegradation of PAHs and PCBs in land treatment units; a favorable match was found between them. Model simulations were performed to predict on-going biodegradation behavior of PAHs and PCBs in land treatment units. Simulation results indicate that complete biostabilization will be achieved when the concentration of reversibly sorbed chemical (S _RA) reduces to undetectable levels, with a certain amount of irreversibly sequestrated residual chemical (S _IA) remaining within the soil particle solid phase. The residual fraction (S _IA) tends to lose its original chemical and biological activity, and hence, is much less available, toxic, and mobile than the “free” compounds. Therefore, little or no PAHs and PCBs will leach from the treatment site and constitutes no threat to human health or the environment. Biotreatment of PAHs and PCBs can be terminated accordingly. Results from the pilot-scale testing data and model calculations also suggest that a significant fraction (10–30%) of high-molecular-weight PAHs and PCBs could be sequestrated and become unavailable for biodegradation. Bioavailability (large K _d , i.e., slow desorption rate) is the key factor limiting the PAHs degradation. However, both bioavailability and bioactivity (K in Monod kinetics, i.e., number of microbes, nutrients, and electron acceptor, etc.) regulate PCBs biodegradation. The sequential active–passive biotreatment can be a cost-effective approach for remediation of highly hydrophobic organic contaminants. The mathematical model proposed here would be useful in the design and operation of such organic chemical biodegradation processes on remediation sites.     

蚯蚓在植物修复重金属污染土壤中的应用前景

重金属污染土壤的植物修复技术是绿色生物技术,该技术的应用受制于两个主要因素:超积累植物生物量小和土壤中重金属有效性低。本文在收集大量资料基础上,论述了蚯蚓与重金属的相互关系:重金属对蚯蚓的毒理效应和蚯蚓对重金属的忍耐力。根据在重金属污染土壤中,蚯蚓活动能提高植物生物量和土壤中的重金属的生物有效性,论证了在重金属污染土壤植物修复技术中引入蚯蚓的可行性,并指出引入蚯蚓的植物修复技术当前的研究热点及今后的研究方向。     

Sequential Application of Soil Vapor Extraction and Bioremediation Processes for the Remediation of Ethylbenzene-Contaminated Soils

Soil vapor extraction (SVE) is an efficient, well-known and widely applied soil remediation technology. However, under certain conditions it cannot achieve the defined cleanup goals, requiring further treatment, for example, through bioremediation (BR). The sequential application of these technologies is presented as a valid option but is not yet entirely studied. This work presents the study of the remediation of ethylbenzene (EB)-contaminated soils, with different soil water and natural organic matter (NOMC) contents, using sequential SVE and BR. The obtained results allow the conclusion that: (1) SVE was sufficient to reach the cleanup goals in 63% of the experiments (all the soils with NOMC below 4%), (2) higher NOMCs led to longer SVE remediation times, (3) BR showed to be a possible and cost-effective option when EB concentrations were lower than 335?mg?kg _soil ^?1 , and (4) concentrations of EB above 438?mg?kg _soil ^?1 showed to be inhibitory for microbial activity.     

堆肥对苏打草甸碱土植被重建的影响

为建立一个低成本、易推广的苏打草甸碱土植被的快速重建模式,在试验区内随机选取碱斑,直接在碱斑上堆肥.结果表明:灌水 堆肥与常规堆肥盐分调控的效果最好.堆肥浇水处理的出苗率显著高于未浇水处理,秋季浇水与未浇水处理生物量没有差异.碱斑上经过人工植被建植后,草甸碱土上植物群落己演替到羊草 盐碱植物群落阶段,跨越了盐碱植物群落阶段.碱斑上直接进行常规堆肥是苏打草甸碱土植被重建的快速、经济模式.     

分子标志物参数在识别土壤多环芳烃(PAHs)来源中的应用

土壤中PAHs污染物的成因十分复杂,常见的污染源包括生物质的高温降解产物、石油等化石燃料及其不完全燃烧产物等,其输入方式主要有大气中所含PAHs的干、湿沉降、水体输入、固体废弃物排放等。不同成因的PAHs组成特征有一定差别,并可能具有独特的分子标志物或分子化合物组合特征,由此,可以根据环境介质中PAHs的组成特征判断污染物来源或成因类型。目前,分子标志物特征参数已成为追踪PAHs污染来源的有效手段。介绍了近年来国内外在运用PAHs分子标志物特征参数识别土壤中PAHs污染源方面的主要研究进展、应用潜力及存在的问题。     

Feasibility of Different Bioremediation Strategies for Treatment of Clayey and Silty Soils Recently Polluted with Diesel Hydrocarbons

Bioremediation strategies, including biostimulation, exogenous bioaugmentation and autochthonous bioaugmentation, were evaluated to determine their ability to degrade petroleum hydrocarbons in two recently polluted agricultural soils, one with a clayey texture and a silty loam soil. It was hypothesized in this work that the bioavailability of the pollutant may depend on the soil type, which would determine the biodegradation rate and the correct methodology to be used. The soils were artificially contaminated with diesel fuel, and several soil?Cwater suspension batch microcosm experiments were conducted to observe the bioremediation process. The inocula used in the experiments included an autochthonous soil consortium and an exogenous consortium that had been acclimated to diesel consumption. The clayey soil desorbed diesel quickly, while the silty soil, with a higher organic content, did not. Hydrocarbon availability was limited in the latter case. After 48?h of treatment, the diesel removal efficiency in the clayey soil was clearly higher than that in the silty soil. However, after 11?days, the efficiencies were similar, and more than 95% of the diesel was biodegraded in most experiments. According to the efficiency and bioavailability analyses, the best methodology to bioremediate the silty soil was biostimulation with the native consortium. In contrast, bioaugmentation with a combination of native and exogenous consortia was chosen to treat the clayey soil. The results of this study suggest that when pollutants are easily available, bioaugmentation can successfully remediate the pollution. However, when availability is limited, biostimulation can be more efficient.