Compost Practices for Improving Soil Properties and Turfgrass Establishment and Quality on a Disturbed Urban Soil

Urban land disturbance degrades physical, chemical, and biological soil properties by removing topsoil and compacting the remaining subsoil. Such practices create a soil environment that is unfavorable for vegetation establishment. A 3-year field study was conducted to compare the effects of various one-time compost application treatments on soil properties and re-vegetation of a disturbed soil. A disturbed urban soil received the following treatments: (1) inorganic fertilizer; (2) 2.5-cm-depth surface-applied compost; (3) 2.5-cm-depth incorporated compost; (4) 5.0-cm-depth incorporated compost; (5) inorganic fertilizer plus 0.6-cm compost blanket; and (6) inorganic fertilizer plus straw mat cover. The plots were seeded with a mixture of tall fescue Festuca arundinacea Shreb.: ‘Magellan,’ ‘Coronado Gold,’ ‘Regiment,’ and ‘Tomcat,’ perennial ryegrass Lolium perenne L. ‘Linn’, and Kentucky bluegrass Poa pratenis L. ‘Baron.’ Soil chemical and physical attributes and plant growth and quality parameters were measured during 840 days following study establishment. Soil C, N, P, K, Ca, and Mg, and turfgrass growth and quality were increased and soil bulk density was reduced by amending with composts. Incorporation of compost into soil improved soil and plant attributes more than unincorporated surface application, but the differences diminished with time. Compost benefits increased with time. One-time applications of compost can provide immediate and long-term benefits to soil and plant attributes, but there may be no need to incorporate the compost into soil, particularly if the soil has recently been loosened by tillage.     

The Potential for Bioremediation of Soils Containing PAHs by Composting

? Environmental contamination by synthetic polynuclear aromatic hydrocarbons (PAHs) has become a major pollution problem. Plant tissues, lignin, soil humus constituents, some pesticides, and numerous commercial organic chemicals are also based upon aromatic building blocks. Many of these molecules are potentially toxic and carcinogenic. Some PAH compounds occur naturally at a low concentration in soils. Long exposure to naturally occurring hydrocarbons has enabled bacteria to evolve enzymes that degrade them.

Landfarming and incineration are the primary technologies used for removing PAH compounds from soils and groundwater. Recent data suggest that bioremediation by PAH composting can offer significant advantages to other treatment alternatives. Landfarming is a relatively uncontrolled method of reducing PAHs in residues. Composting is quicker, more controlled, and requires less space than landfarming. Although composting is slower and less complete than incineration, it is significantly more cost-effective.

This presentation deals with the feasibility of composting PAH contaminated soils and residues. Included will be methods for process evaluation and control, degradation potential of specific PAHs, and determining the application of composting to specific situations.     

The Use of Compost for the Reclamation of Saline and Alkaline Soils

? The results of a two year field experiment verified hypotheses concerning use of compost to improve saline and alkaline soils. The addition of compost to such soils was expected to release acids which would ultimately lead to the replacement of exchangeable sodium by calcium. The addition of compost would also stabilize soil structure and enhance plant growth. It was shown that the addition of municipal solid waste compost is equivalent, or even superior to the addition of gypsum, the common amendment used to reclaim alkaline soils. The overall effect of treatments on soil fertility was evident from yields of crops. The combined application of compost and gypsum raised yields to levels expected in good commercial fields.     

Growth and Heavy-Metal Uptake by Lettuce Grown in Soils Applied with Sewage Sludge Compost

A pot experiment was conducted to investigate the effect of sewage sludge compost (SSC) alone and applied with chemical fertilizer on growth and heavy-metal accumulations in lettuce grown on two soils, a Xanthi-Udic Ferralosol and a Typic Purpli-Udic Cambosol. The treatments included control; nitrogen–phosphorus–potassium (NPK) fertilizer; sewage sludge compost applied at the rates of 27.54 (SSC), 82.62 (3SSC), 165.24 (6SSC) t hm^–2; and coapplication treatment (1/2 SSC + 1/2 NPK), where the N, P, and K inputs from NPK fertilizer, SSC, and coapplication treatments were normalized to the local recommend rates. The SSC application increased the biomass; copper, zinc, and lead contents in lettuce; and soil total and diethylenetriaminepentaacetic acid (DTPA)–extractable metals. However, SSC alone at the recommended rate caused less plant biomass than NPK fertilizer alone. Coapplication treatment obtained greater or similar biomass to NPK fertilizer alone and did not increase heavy-metal accumulation in soils and plants. The results demonstrated that SSC should be applied to soils with chemical fertilizers.     

DDT Resistance and Transformation by Different Microbial Strains Isolated from DDT-Contaminated Soils and Compost Materials

Bioremediation is a potential option to treat 1, 1, 1-trichloro-2, 2-bis (4-chlorophenyl) ethane (DDT) contaminated sites. In areas where suitable microbes are not present, the use of DDT resistant microbial inoculants may be necessary. It is vital that such inoculants do not produce recalcitrant breakdown products e.g. 1, 1-dichloro-2, 2-bis (4-chlorophenyl) ethylene (DDE). Therefore, this work aimed to screen DDT-contaminated soil and compost materials for the presence of DDT-resistant microbes for use as potential inoculants. Four compost amended soils, contaminated with different concentrations of DDT, were used to isolate DDT-resistant microbes in media containing 150 mg l^?1 DDT at three temperatures (25, 37 and 55°C). In all soils, bacteria were more sensitive to DDT than actinomycetes and fungi. Bacteria isolated at 55°C from any source were the most DDT sensitive. However DDT-resistant bacterial strains showed more promise in degrading DDT than isolated fungal strains, as 1, 1-dichloro 2, 2-bis (4-chlorophenyl) ethane (DDD) was a major bacterial transformation product, while fungi tended to produce more DDE. Further studies on selected bacterial isolates found that the most promising bacterial strain (Bacillus sp. BHD-4) could remove 51% of DDT from liquid culture after 7 days growth. Of the amount transformed, 6% was found as DDD and 3% as DDE suggesting that further transformation of DDT and its metabolites occurred.     

Effect of Water Extract of Compost on the Adsorption of Arsenate by Two Calcareous Soils

The increasing mobility of arsenate will increase its leachingpotential to groundwater and uptake by plants. The mobility ofarsenate in soils is related to the competitive adsorption with other substances. The effect of organic substances on the adsorption of arsenate by soils was evaluated using the water extract of compost (WEC) as a complex anion source in a batch experiment. Two calcareous slate alluvial soils, Chiwulan andShuipientou, with higher arsenic contents of 23.7 and 12.9 mg kg^-1, respectively, were used. The Langmuir equation has been used to describe successfully the As adsorption isotherm for the two soils. The maximum adsorption of As was 6.098 and 4.785 μmol g^-1 for Chiwulan and Shuipientou soils, respectively. There was competitive adsorption for binding siteson the soils between arsenate oxyanions and organic anions derived from the dissolved organic carbon (DOC) of WEC. Differentcritical pH values were for arsenate addition related to arsenateadsorption on both soils in the absence of DOC of WEC but not inthe presence of DOC of WEC. The soil properties related to arsenate adsorption by the two soils may govern the critical pH values.     

The Size of P Pools in Soils is Affected by Soil Properties and Compost Addition

It is well known that compost amendment can improve soil phosphorus (P) availability, but there are few studies comparing the effect of one compost type on soil P pools of soils which differ in properties. The aim of this glasshouse experiment was to determine the effect of compost (derived from garden waste) application on P pools in soils with different properties planted with wheat. Four soils from two sites were used, with a heavier and a lighter textured soil from each site. The compost was applied as a 2.5 cm thick layer on the soil surface and wheat plants were grown for 63 days. The treatments also included soil without compost and plants. All pots were regularly watered. The soils were sampled on day 0 in the unamended soils and on day 63 in soil without compost and with compost, and plants after removal of the compost layer. Without and with compost the concentrations of most P pools were higher in the two heavier textured soils (16% and 35% clay) than in the two lighter textured soils (8% and 13% clay). Principal component analysis (PCA) showed that the concentrations of most P pools were positively correlated with organic matter, clay, and silt content of the soils. Only the concentration of water-soluble P was positively correlated with sand content. Compost addition increased the concentration of microbial P, sodium bicarbonate (NaHCO₃)-Pi, sodium hydroxide (NaOH)-Pi, hydrochloric acid (HCl)-P, and residual P in all soils, whereas the concentration of NaHCO₃-Po was reduced and the concentration of NaOH-Po little affected by compost addition indicating that P was transferred from the compost layer with watering. Compared with the unamended soil on day 0, the concentrations of microbial P, NaHCO₃-Pi, NaOH-Pi, HCl-P, and residual P on day 63 were higher, whereas the concentrations of the two organic pools (NaHCO₃-Po and NaOH-Po) were lower. This suggests mineralization of organic P pools and formation of inorganic P as well as microbial P uptake. These changes occurred in the unamended and compost-amended soils with greater increases over time in the compost-amended soils. It can be concluded that the size of the P pools is predominately affected by soil texture. Compost amendment increases P availability and microbial P uptake but also leads to the formation of less labile P pools such as HCl-P and residual P which could serve as plant P sources in the long term.     

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。     

The Effect of MSW Compost on Metal Uptake and Yield Of Wheat,Barley and Canola in Less Productive Farming Soils of Alberta

Experiments were started in May 1998 at two sites to measure various crop responses to a mixed municipal solid waste-biosolids cocompost (named Nutri Plus) and examine the fate of certain metals associated with Nutri Plus compost. There were six treatments: Check, 50, 100, and 200 T compost/ha, NPKS (75 kg nitrogen (N) /ha, 20 kg phosphorus (P)/ha, 45 kg potassium (K) and 18 kg sulphur (S)/ha), PK (20 kg P, 45 kg K/ha), and three crops: canola (Brassica rapa cv. ‘Hysyn 110’), wheat (Triticum aestivum L. cv. ‘Roblin’) and barley (Hordeum vulgare L. cv. ‘Lacombe’). Each treatment was replicated four times and was in a complete randomized block design. In the compost treatments, 20 kg P and 45 kg K were applied due to low concentration of these two nutrients in the compost. Soil and plant samples were analyzed for nutrient content such as N, P and K. In addition, plant samples and soil samples after the compost application were also analyzed for elemental content of As, B, Cr, Co, Cu, Zn Se, Mo, Cd, Hg and Pb. The research results show that the compost slightly increased heavy metal concentrations in the soil but did not cause any phytoxicity to crops. Yield from 100 and 200 T/ha application was higher with the compost than with NPKS treatment. However, the yield of the 50 T/ha application was similar to that of NPKS treatment. Comparing the two sites, the compost apparently was more beneficial at Site 1 than at Site 2 in the year of application. This is likely due to the lower indigenous soil fertility and poor soil physical properties at Site 1. The N content in cereal grains was similar among the compost treatments but lower than the Check and NPKS treatments due to the diluting effect of higher yield. The oil content in canola seed was similar among all treatments. The results suggest that Nutri Plus compost applications generated positive yield responses in all three crops. Crop yield increased as the application rate increased. Heavy metal loading was not an immediate problem with the compost application, although it will limit total compost application over time to the same soil     

An Analysis of the Horticulture Industry as a Potential Value-Added Market for Compost

A major barrier to adoption of composting by the livestock industry is a lack of information regarding the relative economic advantages and disadvantages for producing and marketing compost. The ten markets evaluated in this research are seen as typical markets for horticultural products or markets that have the greatest potential interest in compost. The focus of the research was to determine and evaluate potential paying markets for compost using Illinois as a model. Approximately 2,275 surveys were mailed to members of various horticultural trade associations in Illinois. Questions included inquiries as to the type of business conducted, the current use of compost and whether it was thought that the company had an organic waste problem. Questions were also asked regarding the respondents' beliefs about the economics of making and using compost, and perceived benefits from utilizing compost. A 33.7% response rate was achieved with 746 surveys returned and analyzed. Substantial numbers of respondents were involved in commercial nursery, golf course and lawn care operations. The operation classifications showing the most interest in composting were commercial tree growers, commercial nurseries and greenhouses, landscape contractors and lawn care operations. A majority of the respondents have either used compost in the past or are currently using compost. Of the respondents who reported using compost, a majority (P<0.05) were satisfied with the results. Most compost users reported purchasing compost in bulk as opposed to in bags. The primary reasons cited for using compost were related to soil tilth, building humus content of the soil and increased plant growth. Replacement of chemical fertilizer use and greater seed germination were not cited as primary reasons for using compost. In addition, respondents to the survey reported that development of quality standards for compost would not encourage use.     

基于生态约束-发展潜力的城镇建设用地开发适宜性分区

[目的]从生态和经济的角度划分城镇建设用地开发适宜性类型区,为江苏省射阳县土地利用空间布局提供参考。[方法]依据最小累积阻力值分析射阳县区域生态约束强度,划分强度等级;运用多因素多因子综合判别模型,从开发强度和空间距离角度构建评价模型,划分区域发展潜力等级;最终在生态约束等级和发展潜力等级的基础上,进行全域城镇建设用地开发适宜性分区。[结果](1)生态约束高区域与生态约束低的区域相差较大,总体上以生态保护为主。从空间分布上,不同等级强度生态约束力表现出了阶梯式的分布,由内向外辐射,强度逐步提高。(2)开发潜力与生态约束分级结果对比,矛盾突出,经济需求旺盛,生态保护用地形势严峻。(3)适宜保护区、较适宜保护区、较适宜建设区、适宜建设区4类,所占比率分别为11.04%,24.78%,34.59%,29.59%。[结论]开发适宜性分区表现出"核心—边缘"的城乡二元结构特征,同时合德镇及周围的适宜建设区较为集聚,外围适宜建设区逐渐减少。     

碱性材料对修复与改良酸性硫酸盐土壤障碍因子的研究

采用盆栽试验研究了不同碱性材料(石灰、自研改良剂、钙镁磷肥)对酸性硫酸盐土壤主要障碍因子的修复及其对水稻生长的影响。结果表明,不同碱性材料对土壤理化特性、土壤养分有效性和水稻生长的影响存在明显差异。与常规施肥(NPK)处理相比,自研改良剂(SAM)和钙镁磷肥(CMP1)处理土壤p H增加了1.25和0.92个单位,土壤速效磷含量分别增加了3.1倍和2.6倍,土壤有效铁、有效锰、交换性H+、Al3+含量均大幅下降。SAM与CMP1处理通过提供足够的有效磷并补充钙、镁等元素,有效改善了根系生长环境,从而有效控制铁、锰、铝等元素向地上部转运,进而对作物的生长起到促进作用。SAM和CMP1处理较NPK处理有效促进了关键生育期水稻根系活力并显著增加了水稻籽粒产量,增幅分别达121.1%和105.1%。石灰效果次之。综上,初步认为碱性材料改良酸性硫酸盐土壤的关键在于保证了充足有效磷的同时,提高了土壤p H,降低了土壤金属的毒害。本试验条件下,钙镁磷肥对修复和改良酸性硫酸盐土壤障碍因子效果非常明显,但其成本是自研改良剂的3倍,因此,基于改良剂的成本与长期适用性考虑,自研改良剂可能是该类土壤改良的最佳选择。     

三种土壤水势传感器在原状与扰动黏壤土上测定精度评价

分别在田间原状黏壤土和室内扰动黏壤土上安装MPS-1、MPS-6、pF水势传感器与TDR315L土壤水分传感器测定土壤水分特征曲线,通过比较测定结果的准确性,提出了三种土壤水势传感器的使用建议。结果表明:MPS-1传感器虽测量范围窄,但无论在原状黏壤土还是扰动黏壤土上均表现良好;MPS-6和pF传感器测量范围宽,但测量的水势值精度不高,且MPS-6传感器对温度敏感,pF传感器在使用期间内表现不稳定。MPS-1传感器应用于原状和扰动黏壤土由其数据拟合出的土壤水分特征曲线与对照曲线重合度较高,而MPS-6和pF传感器应用于原状和扰动黏壤土,当含水量高于0.30 cm~3cm~(-3)时测定结果拟合得到的水分特征曲线与对照曲线重合度较高。比较三个水势传感器的测量表现,可以认为MPS-1传感器用于含水量高于0.30 cm~3cm~(-3)的原状黏壤土和含水量高于0.17 cm~3cm~(-3)的扰动黏壤土,MPS-6传感器用于含水量高于0.30 cm~3cm~(-3)的原状和扰动黏壤土测定土壤水势的效果较好。本研究结果可为使用上述三种传感器测定土壤水分特征曲线提供参考。     

西宁市土地利用效益与新型城镇化耦合协调度研究

基于城市土地利用效率和新型城镇化内涵的分析,建立西宁市土地利用效率和新型城镇化耦合协调指标体系,用熵权法计算了各指标权重,结合耦合度、协调度模型计算了西宁市耦合度和协调度。结果表明:2000—2013年西宁市土地利用效益和新型城镇化综合指数不断升高,土地利用效益相对发展趋势为"超前—滞后"型;土地利用效益和新型城镇化耦合演变过程处于颉颃阶段,由低强度向高强度耦合发展;土地利用效益与新型城镇化协调度总体呈上升趋势,具有逐步优化的趋势。西宁市作为土地资源稀缺的河谷型城市,随着新型城镇化的发展,土地资源紧缺的矛盾将长期存在。今后的发展中应更加注重提高土地资源利用率,合理布局城市结构,从而促进新型城镇化的可持续发展。     

Potential of Fodder Soybean Genotypes for Phosphorus Removal in Poultry Manure-Enriched Soils

Plant-based phosphorus (P) remediation strategies have been suggested to reduce high P accumulation in soil. Eleven fodder soybean genotypes were evaluated to explore their potential for the removal of P from poultry manure-enriched soils. Field experiments were conducted at a site that had a history of heavy poultry manure applications. Green house experiments were conducted using the soils selected for field trials to confirm the results. Harvesting of whole plants, excluding roots of the genotypes, was done at the pod formation stages and plant samples were oven dried at 70°C for three days. The dry samples were ground and analyzed for total P content. Genotype 091734, provided the maximum P removal from amended and unamended soils. Fodder soybean genotypes could play an important role in the extraction of P from poultry manure-enriched soils, which are important from the ecological point of view.     

Effect of Municipal Solid Waste Compost on Mine Soils As Evaluated by Chemical,Biological And Biochemical Properties of Soil

Composts are increasingly used in land rehabilitation because they can improve soil quality and reduce the need for inorganic fertilizers. Their use contributes to an integrated approach to waste management by promoting recycling of nutrients and minimizing final disposal of organic residues that, due to their composition, can pose problems to agricultural soils. We investigated whether compost from mixed municipal solid waste (MSW) could be used to remediate two soils from a mine contaminated with trace elements. One of the soils was less acidic and had a greater content of Cu and Zn while the other had more Pb and a lower pH. The effect of MSW was evaluated by plant growth, trace element leachability, ecotoxicity of soil leachates, and biological and biochemical properties of soils. Growth of perennial ryegrass (Lolium perenne L. cv. Victorian) was stimulated in the MSW compost-amended soils compared with respective controls or with acidic soil when limed. After ryegrass had been growing for 119 days, the amount of water-extractable Zn was lower in MSW compost-amended soils, while the opposite was true for water-extractable Cu. Water-extractable Pb increased following MSW compost application to one soil and decreased in the other. The greatest dehydrogenase activity was obtained in amended limed soil, while the number of culturable bacteria and fungi and the activities of cellulase and β-glucosidase were similar in soil that was limed or following MSW compost application. In contrast, urease activity was repressed in limed or MSW compost-amended soils. Leachates from unamended soils were toxic towards Daphnia magna. Liming the very acidic soil led to a decrease in the toxicity of the leachate, but it was only in MSW compost-amended soils that ecotoxicity was no longer detected.     

福州城市边缘区果园土壤Pb Cu分布特征与潜在生态风险评价

采用现场采样及室内分析方法,从水平和垂直角度研究了福州城市边缘区果园土壤Pb、Cu全量及其HCl、DTPA两种浸提态含量分布特征,利用潜在生态风险指数法评价土壤Pb、Cu潜在生态风险。结果表明,福州城市边缘区果园土壤Pb、Cu存在一定程度的污染,且Pb污染比Cu严重,不同浸提态Pb、Cu含量与其全量呈正相关,与pH呈负相关;Pb、Cu潜在生态风险处于轻微程度。     

长沙市韶山路沿线不同绿地土壤重金属含量及其潜在生态风险

调查和分析了长沙市韶山路沿线4种绿地类型0-20 cm土壤层重金属Mn、Zn、Cu、Pb、Cd、Ni的含量及其来源,并以湖南省土壤背景值和全国土壤平均值为评价标准评价其污染程度和潜在的生态风险。结果表明,公共绿地、居住绿地和道路交通绿地土壤重金属含量普遍较高,而生产绿地的含量普遍较低,不同绿地类型土壤重金属含量空间分布差异较大。公共绿地、居住绿地和道路交通绿地中,有机质是绿地土壤重金属的主要载体,Cd、Pb、Ni、Cu、Zn来源相同的可能性较大,公共绿地和道路交通绿地中Cd、Pb、Ni、Cu、Zn可能主要来源于交通活动产生的污染源,居住绿地中可能来源于生活垃圾污染源。4种绿地土壤重金属综合污染指数由高至低的排序为:道路交通绿地居住绿地公共绿地生产绿地,均处于轻度污染或警戒水平,Cd污染最为严重,Pb、Cu污染为其次,Mn、Zn、Ni污染较小。公共绿地、道路交通绿地Cd和Pb污染较重,居住绿地Cd和Cu污染较重。4种绿地土壤重金属潜在生态危害指数大小排序为:居住绿地道路交通绿地公共绿地生产绿地,均处于轻微生态危害程度,Cd的生态风险最大,Pb、Cu为其次,Zn、Mn最小。     

Potential of Chitosan (Chemically Modified Chitin) for Extraction of Lead-Arsenate Contaminated Soils

Arsenic, lead, and phosphorous contamination in soils represents a health risk. Chitosan (poly-N-acetyl glucosamine) inexpensive by-product derived from chitin has been used as a metals adsorbent. Objectives of this research were to evaluate the effectiveness of chitosan solution for arsenic, lead, and phosphorous extraction from lead-arsenate contaminated soils, and evaluate the effectiveness of protonated chitosan flakes (PCF) and ferric hydroxide chitosan beads (Fe(III)-CB) for water-soluble As removal from these soils. Percentage of arsenic, lead, and phosphorous removed from the soils by chitosan solution ranged from 0.96% to 17%, 1.80% to 31%, and 0.66% to 11%, respectively. Percentage of water-soluble arsenic removed by PCF and by Fe (III)-CB ranged from 12% to 47% and 36% to 77%, respectively. Averaged over soils, Fe (III)-CB removed slightly more arsenic (As) (42 mg kg^?1) compared to Mehlich III (40 mg kg^?1) extractant. Results indicate potential for the use of chitosan as an extraction for lead-arsenate contaminated soils.     

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.