Critical evaluation of the use of the hydroxyapatite as a stabilizing agent to reduce the mobility of Zn and Ni in sewage sludge amended soils

The leachability of zinc (Zn) and nickel (Ni) was investigated in various soil types amended with sewage sludge and sewage sludge treated with hydroxyapatite. Sandy, clay and peat soils were investigated. For leachability tests, plastic columns (diameter 9 cm, height 50 cm) were filled with moist samples up to a height of 25 cm. Sewage sludge (1 kg) was mixed with 4.6 kg of clay and sandy soils and with 6.7 kg of peat soil. For sewage sludge mixtures treated with hydroxyapatite, 0.5 kg of the hydroxyapatite was added to 1 kg of the sewage sludge. Neutral (pH 7) and acid precipitation (pH 3.5) were applied. Acid precipitation was prepared from concentrated HNO(3), H(2)SO(4) and fresh doubly distilled water. The amount of precipitation corresponded to the average annual precipitation for the city of Ljubljana, Slovenia. It was divided into eight equal portions and applied sequentially on the top of the columns. The results indicated that the leachabilities of Zn in sewage sludge amended peat and clay soils were low (below 0.3% of total Zn content) and of Ni in sewage sludge amended sandy, clay and peat soil below 1.9% of total Ni content. In sewage sludge amended sandy soil, the leachability of Zn was higher (11% of Zn content). The pH of precipitation had no influence on the leachability of either metal. Treatment of sewage sludge with hydroxyapatite efficiently reduced the leachability of Zn in sewage sludge amended sandy soil (from 11% to 0.2% of total Zn content). In clay and peat sewage sludge amended soils, soil characteristics rather than hydroxyapatite treatment dominate Zn mobility.     

微生物降解重油的初步研究

丛石油污染的土壤中筛选出一株假单胞菌,考察了其对重油的降解效果。降解18d,重油的降解率达到42．8％,饱和烃、芳香烃、胶质、沥青质的降解率分别为42．95％,43．85％,44．5％,5．55％;质量浓度2．5g／L的表面活性剂Tween-80可使重油的18d降解率达到51．0％;弱碱性条件有利于重油的生物降解;生物泥浆法处理重油污染的土壤,1kg土壤中重油质量100g,降解45d,重油的降解率达到38．85％。     

Ammonia volatilization,N2O and CO2 emissions from landfill leachate-irrigated soils

Effects of leachate addition on ammonia volatilization and N₂O and CO₂ emissions from two different soils were investigated using the 10-day laboratory incubation method at two levels of moisture content. Ammonia volatilization was dominated by soil pH and only occurred in alkaline clay soil, where 0.26–0.32% of soil ammonia could be lost. The N₂O emission from the alkaline clay soil was one order of magnitude greater than that from the acidic sandy soil, when either water or leachate was irrigated. Increasing the moisture content from 46% water-filled pore space (WFPS) to 70% WFPS in the alkaline clay soil or the acidic sandy soil by either water or leachate irrigation increased the N₂O emission by over twofold. The CO₂ emission from each soil sample at the two WFPSs was almost the same. The CO₂ emission from the alkaline clay soil with leachate addition was 72% lower than that from the acidic sandy soil with leachate addition, and 6.7 times higher than that from the alkaline clay soil with distilled water addition. Ammonia volatilization and N₂O emission under leachate irrigation could be minimized by avoiding the excessively wet condition and by selecting the acidic sandy soil with low organic carbon and total nitrogen content.     

Petroleum biodegradation in soil: The effect of direct application of surfactants

The direct application of surfactants to petroleum-contaminated soil has been proposed as a mechanism to increase the bioavailability of insoluble compounds. Solubilization of hydrophobic compounds into the aqueous phase appears to be a significant rate limiting factor in petroleum biodegradation in soil. Nonionic surfactants have been developed to solubilize a variety of compounds, thus increasing the desorption of contaminants from the soil. In this study, laboratory scale land treatment scenarios were used to monitor the bioremediation of petroleum contaminated soils. In efforts to achieve the lowest levels of residual petroleum hydrocarbons in the soil following biotreatment, 0.5 and 1.0% (volume/weight) surfactant was blended into soils under treatment. Two soil types were studied, a high clay content soil and a sandy, silty soil. In both cases, the addition of surfactant (Adsee 799®, a blend of ethoxylated fatty acids, Witco Corporation) stimulated biological activity as indicated by increased heterotropbic colony forming units per gram of soil. However, the increased activity was not correlated with removal of petroleum hydrocarbons. The results suggest that the application of surfactants directly to the soil for the purpose of solubilizing hydropbobic compounds was not successful in achieving greater levels of petroleum hydrocarbon removal.     

Effect of Humic Acids and Fungal Inoculations on Cesium and Lead Concentrations in Lettuce Plants Grown in Contaminated Soils

A study was carried out to evaluate the effect of humic acid additives, applied either individually or in combination with Fusarium oxysporum fungi, on uptake and translocation of cesium and lead in cultivated Lettuce (Lactuca sativa) grown on Mostorud (clayey) and El‐Gabal El‐Asfar (sandy loam soil) soils in a complete randomized block experimental design. The selected soils from contaminated areas (Mostorud soil was irrigated with contaminated industrial water for more than 30 years and El‐Gabal EL‐Asfar soil was irrigated with sewage effluent for more than 50 years). The results indicated that the cesium and lead content was reduced by all treatments of humic acid application individually or when combined with Fusarium oxysporum inoculations, especially at 200 mmol/kg compared to a control and other treatments. On the other hand, retention of cesium and lead occurred in roots more than shoots. ©2016 Wiley Periodicals, Inc.     

Effects of municipal solid waste compost and sewage sludge on chemical and spectroscopic properties of humic acids from a sandy Haplic Podzol and a clay loam Calcic Vertisol in Portugal

The effects of amendment with municipal solid waste compost (MSWC) and anaerobically digested sewage sludge (SS) on the compositional and structural features of soil humic acids (HAs) were investigated. For this purpose, HAs were isolated from MSWC, SS, and two different Portuguese soils, a sandy Haplic Podzol and a clay loam Calcic Vertisol, which were either unamended or amended with MSWC or SS at a rate of 60tha(-1). The isolated HAs were analyzed for elemental and acidic functional group composition, and by ultraviolet/visible, Fourier transform infrared (FT IR), and fluorescence spectroscopies. The application of MSWC and especially SS to soils determined an increase of C, N, H, and S contents and E(4)/E(6) ratios (i.e., ratios of absorbances at 465 and 665nm), and a decrease of O, COOH, and phenolic OH contents and C/N, C/H, and O/C ratios of soil HAs. The FT IR and fluorescence results showed that the organic amendments, especially SS, caused an increase of the aliphatic character and a decrease of the degrees of aromatic polycondensation, polymerization, and humification of amended soil HAs. Both MSWC and SS affected more markedly the clayey soil HAs than the sandy soil HAs, possibly due to less extended mineralization processes and the protective action of clay minerals on amended soil HAs.     

萘降解菌的筛选及其对多环芳烃的降解

从柴油污染土壤中筛选分离出一株萘降解菌N-3,进行了菌种鉴定及萘双加氧酶基因(nah)验证,并考察了该菌对不同种类多环芳烃(PAHs)的降解能力及降解过程中脱氢酶活性的变化。实验结果表明:该菌为铜绿假单胞菌(Pseudomonas aeruginosa),含有nah基因;当分别对液体培养基中质量浓度为50 mg/L的萘、菲、蒽、芘、芴降解84 h时,菌株N-3对萘、菲、蒽、芘、芴的降解率分别为28.81%,34.83%,36.65%,27.50%,23.47%。菌株N-3的脱氢酶活性与其对不同PAHs的降解率呈一定的正相关性。该菌不仅能有效降解萘,且对其他种类PAHs也有一定降解作用。     

A risk assessment of chlorinated aliphatics in bioremediated soils

Natural microbes living in contaminated subsurface media can be enhanced to degrade large concentrations of contaminating compounds at a faster rate than the microbes could degrade under natural conditions. A feasibility study demonstrating this principle was performed on-site in southern Louisiana to evaluate the effectiveness of two microbial degradation remediation methods used to decrease the human carcinogenic risks associated with exposure to ethylene dichloride and vinyl chloride concentrations in contaminated clay and sludge soils at the site. The results of the study are compared to an acceptable Louisiana Department of Environmental Quality closure level to evaluate in-situ microbial enhancement in chlorinated aliphatic-contaminated sludge and clay soils as a remediation/cleanup alternative in similar industrial situations.     

高效石油烃降解菌的筛选及其对原油污染土壤的修复

从陕北原油污染土壤中筛选出7株高效石油烃降解菌,其中黄杆菌属CC-2、不动细菌属SC-5、假单胞菌属SC-6表现出较强的石油烃降解能力。通过单因素试验和正交试验考察总石油烃(TPH)降解效果的影响因素,得出各因素对TPH降解率影响程度的大小次序为:溶液p H降解温度降解菌接种量摇床转速,且在降解菌接种量为7%(φ)、溶液p H为7、降解温度为30℃、摇床转速为150 r/min的最适处理条件下,菌株SC-6的TPH降解率可达61.23%。原油污染土壤生物修复实验结果表明:高效石油烃降解菌的投加有利于土壤TPH降解率和酶活性的提高;"菌株SC-6+营养剂"组修复处理42 d后的TPH降解率可达57.59%。     

A Simple Assay for Monitoring Cellulose in Paper-Spiked Soil

We describe a simple method for measuring cellulose in soil. We used this method to measure the recovery of shredded office paper and pure medium fiber cellulose added to a Helvetia silt loam clay soil. This method consists of solvating cellulose from soil with 77% H₂SO₄ and analysis of the cellulose recovered by the phenol-sulfuric acid carbohydrate assay. Unlike previous related methods the modifications we propose allow good recovery of cellulose (~99%) and eliminate the need to autoclave the samples. We verified this method on soil spiked with up to 12% cellulose and found a good linear relationship between the amounts of cellulose added relative to that recovered. With proper fragmentation and dilution of the acid-treated soil samples, higher concentrations can be easily measured. We propose this technique as a robust and high throughput means to monitor the degradation of cellulose in paper spiked soil.     

Pneumatic fracturing to remove VOCS

A new process for enhancing in-situ remediation of low-permeability soil and rock formations is presently under development at the Hazardous Substance Management Research Center (HSMRC). The patented process, known as ?pneumatic fracturing,”? consists of injecting high-pressure air or other gas into contaminated geologic formations at controlled flow rates and pressures. In fine-grained soils such as clay, pneumatic fracturing creates conductive channels in the formation, thereby increasing the permeability and exposed surface area of the contaminated soil. The potential benefits of pneumatic fracturing are significant, since in-situ remedial technologies are essentially limited by the pore gas exchange rate of the soil being treated. This article describes the results of a recent demonstration of pneumatic fracturing at an industrial site to enhance a volatile organic compound (VOC) extraction system. After establishing the baseline removal rate of soil gas effluent from the clay, soil surrounding the extraction system was fractured to enhance VOC with drawal. A substantial improvement in the VOC removal rate was observed, including: (1) flush effluent concentrations that increased up to 200 times; and (2) air flows in the formation that increased up to 1,000 times.     

A research note on the assessment of optimum conditions for preparing soils for bioremediation feasibility testing

In this applied study, the effects of short‐term storage at 22°C, 6°C, and ?25°C on the numbers of microorganisms enumerated were examined with soils collected from a petrochemical contaminated soil containing multiple contaminants including phenol, polycyclic aromatic hydrocarbons, and petroleum hydrocarbons. Short term storage of soils at refrigerator temperature did not significantly change the number of microorganisms compared to those in the fresh soil (0 days of storage); however, at ?25°C there was a slight decrease in the phenol utilizers and total viable count (TVC). Long‐term storage caused a significant decrease in the number of phenol utilizers in the petrochemical‐contaminated soil samples. Chemical dispersing agents were used in an attempt to increase the extraction of microorganisms from naphthalene contaminated soil which were predominantly clay soils. These did not significantly change the enumeration of naphthalene utilizers or TVC. While these results are not unexpected from current research and knowledge of microbial community succession in laboratory environments, the results from the applied nature of this study confirm that it is best practice to keep soil samples designated for bacterial enumeration for the shortest possible time, and not longer than 1–2 weeks, and at refrigerated temperature (6°C) in preference to room (22°C) or deep freezer (?18°C) temperatures.     

百菌清污染土壤生物修复研究进展

针对百菌清具有在土壤中药效稳定、不易分解、代谢周期长、长期大量施加导致土壤严重污染等特点和问题,简要介绍了百菌清的毒性作用机制。总结了降解土壤中百菌清的物理法、化学法和生物法的原理及优缺点。重点阐述了生物修复百菌清污染土壤的主要降解菌株及其效果、降解途径以及降解产物及其毒性,分析了土壤性质、微生物种类、温度、土壤含水率等因素对百菌清降解效果的影响。指出今后的研究重点应为降解中间产物的毒性分析及其进一步的降解与转化问题,而复合菌制剂或多酶复合体系可实现百菌清的彻底降解和无害化。     

Remediation of Soil and Ground Water Contaminated with PAH using Heat and Fe(II)-EDTA Catalyzed Persulfate Oxidation

The feasibility of degrading 16 USEPA priority polycyclic aromatic (PAH) hydrocarbons (PAHs) with heat and Fe(II)-EDTA catalyzed persulfate oxidation was investigated in the laboratory. The experiments were conducted to determine the effects of temperature (i.e. 20 ^∘C, 30 ^∘C and 40 ^∘ C) and iron-chelate levels (i.e., 250 mg/L-, 375 mg/L- and 500 mg/L-Fe(II)) on the degradation of dissolved PAHs in aqueous systems, using a series of amber glass jars as the reactors that were placed on a shaker inside an incubator for temperature control. Each experiment was run in duplicate and had two controls (i.e., no persulfate in systems). Samples were collected after a reaction period of 144 hrs and measured for PAHs, pH and sodium persulfate levels. The extent of degradation of PAHs was determined by comparing the data for samples with the controls. The experimental results showed that persulfate oxidation under each of the tested conditions effectively degraded the 16 target PAHs. All of the targeted PAHs were degraded to below the instrument detection limits (∼4 μ/L) from a range of initial concentration (i.e., 5 μ/L for benzo(a)pyrene to 57 μ/L for Phenanthrene) within 144 hrs with 5 g/L of sodium persulfate at 20 ^∘ C, 30 ^∘C and 40 ^∘C. The data indicated that the persulfate oxidation was effective in degrading the PAHs and that external heat and iron catalysts might not be needed for the degradation of PAHs. The Fe(II)-EDTA catalyzed persulfate also effectively degraded PAHs in the study. In addition, the data on the variation of persulfate concentrations during the experiments indicated that Fe(II)-EDTA accelerated the consumption of persulfate ions. The obtained degradation data cannot be used to evaluate the influence of temperature and Fe(II) levels on the PAH degradation because the PAHs under each of the tested conditions were degraded to below the instrument detection limit within the first sampling point. However, these experiments have demonstrated the feasibility of degrading PAHs in aqueous systems with persulfate oxidation. Additional tests are being conducted to evaluate the effectiveness of treating PAHs in soils and obtaining the rate of degradation of PAHs with persulfate oxidation. Two sets of laboratory experiments were conducted to evaluate the ability of sodium persulfate in oxidizing real world PAH-contaminated soils collected from a Superfund site in Connecticut. The first set of soil sample were treated only with persulfate and to the second batch, mixture of persulfate and Fe(II)-EDTA solutions were added. The results of the second test showed that within 24 hours, 75% to 100% of the initial concentrations of seven PAH compounds detected in the soil samples were degraded by sodium persulfate mixed with FE(II)-EDTA.     

Limitations on infiltration and reinjection of treated groundwater to remove trace amounts of pesticides in groundwater and soil

Infiltration and reinjection of treated groundwater have been used to increase the recovery of pesticide-related constituents at a pesticide formulation plant that produces consumer pesticide products. The stratigraphy at the site consists of silty and sandy clay deposits overlying a shallow silt, sand, and gravel aquifer. The groundwater and soils in two areas in the northwest portion of the property have been identified as being significantly affected by pesticide and pesticide-related compounds. An integrated system of soil removal, recovery wells, injection wells, an infiltration gallery, and a cut-off wall was selected as the best remedial alternative. Groundwater modeling, column tests, biological jar tests, and a pilot test demonstrated the feasibility of the system. The affected groundwater is treated to drinking-water quality by a system of filtering and carbon adsorption. Approximately 75 percent of the treated water is reinjected or allowed to infiltrate through the vadose zone, and the remainder is discharged to the local sewer system. Initially, the system was effective in removing the dissolved, suspended, and weakly adsorbed constituents. Subsequently, the recovery rate of the chemical constituents became dependent on chemical and physical processes related to the presence of residual amounts of dense, nonaqueous phase liquids and the clay content of the strata. The rate of pesticide recovery has decreased because of the retarding effect of the clay and the low solubility of the pesticides.     

Alternative method of groundwater sparging for petroleum hydrocarbon remediation

An alternative method of in-situ groundwater sparging, termed density-driven convection (patent pending), is presented. This method has been successfully used to remediate eight underground storage tank releases involving a wide distillation range of petroleum hydrocarbons (gasoline to waste oil) and in a variety of site soils (clay to sandy gravel). Application of the density-driven convection method is detailed in a case study. The system, installed to remediate a gasoline and diesel release from an underground storage tank, was operated and monitored for a period of one year. Monitoring data indicate reductions in total petroleum hydrocarbon concentrations in groundwater and in soil. Concentrations of aromatic hydrocarbons (benzene, toluene, ethylbenzene, xylenes, and naphthalene) also decreased in both media. Stimulation of natural biodegradation, the primary mechanism of removal, occurred rapidly. Natural biological activity gradually declined over the subsequent 150 days. After one year of operation, the sparging system has achieved or is rapidly approaching the regulatory cleanup goals for both soil and groundwater, including reduction of dissolved concentrations below maximum contaminant levels established under the Safe Drinking Water Act.     

土壤氰化物污染生物修复技术研究进展

综述了植物修复、微生物修复和生物联合修复等土壤氰化物污染生物修复技术的降解机理、降解途径及降解影响因素的研究进展,探讨了氰化物生物修复技术的发展趋势和应用前景。指出基于提高修复时效和针对土壤复合污染类型的多技术融合研究、基于提高微生物耐受性和降解效率的菌株固定化及菌根真菌-植物联合技术研究以及基于工程化应用为导向的现场试验研究是未来研究的重点领域,为土壤氰化物污染的综合治理和修复提出了新思路。     

Integrated bioremediation of soil and groundwater at a superfund site

The soil and two aquifers under an active lumber mill in Libby, Montana, had been contaminated from 1946 to 1969 by uncontrolled releases of creosote and pentachlorophenol (PCP). In 1983, because the contaminated surface soil and the shallower aquifer posed immediate risks to human health and the natural environment, the U.S. Environmental Protection Agency placed the site on its National Priorities List. Feasibility studies in 1987 and 1988 determined that in situ bioremediation would help clean up this aquifer and that biological treatment would help clean up the contaminated soils. This article outlines the studies that led to a 1988 EPA record of decision and details the EPA-approved remedial plan implemented starting in 1989; EPA estimates a total cost of about $15 million (in 1988 dollars). The plan involves extensive excavation and biological treatment of shallow contaminated soils in two lined and bermed land treatment units, extraction of heavily contaminated groundwater, an aboveground bioreactor treatment system, and injection of oxygenated water to the contaminant source area, as well as to other on-site areas affected by the shallower aquifer's contaminant plume.     

The Effects of Additives on the Biodegradation of Polycaprolactone Composites

Because environmental pollution caused by plastic waste is a major problem investigations concerning biodegradable packaging are important and required. In this study, the biodegradation of PCL composite films with organic (glycerol monooleate and oleic acid) and inorganic additives (organo nano clay) was investigated to understand which additive and the amount of additive was more effective for biodegradation. The relationship between the degree of crystallinity and the effect of additives on the biodegradability of polycaprolactone (PCL) was examined. PCL composite films were prepared using organo nano clay (0.1–0.4–1–3 wt%) and oleic acid (1–3–5 wt%) or GMO (1–3–5 wt%). The 35 films prepared with PCL (P), clay (C), oleic acid (O), or glycerol monooleate (G) are coded as P_C#wt%_O (or G)#wt%. The composite films, P_C0.4_O5 contains 0.4 wt% clay and 5 wt% oleic acid and the P_C3_G1 contains 3 wt% clay and 1 wt% glycerol monooleate. The biodegradation of PCL films in simulated soil was studied for 36 months. The films were periodically removed from the simulated soil and film thicknesses, weight losses, visual changes, crystal structures, and a functional group analyses were performed. PCL composite films are separated into three groups, depending on degradation time, (1) films that degraded before 8 months (fast degradation), (2) films that degraded around 24 months (similar to neat PCL), and (3) films that take longer to degrade (slow degradation). The films in the first group are PCL films with 1 and 3 wt% clay additive and they begin to biodegrade at the 5th month. However, a composite film of PCL with only 0.4 wt% clay and 5 wt% GMO addition has the shortest degradation time and degraded in 5 months. The films in the last group are; P_G3, P_G5, P_C0.1, P_C0.1_O1, and P_C0.1_O5 and they took around 30 months for biodegradation. It was observed that increasing the organo nanoclay additive increases the biodegradability by disrupting the crystal structure and causing a defective crystal formation. The addition of GMO with organo nano clay also accelerates biodegradation. The addition of organo nano clay in an amount as small as 0.1 wt% acts as the nucleating agent, increases the degree of crystallinity of the PCL composites, and slows the biodegradation period by increasing the time.     

Evaluation of soil-washing process for “unwashable” clays and silts from the palmerton zinc site

The Palmerton Zinc Site is a Superfund site in Palmerton, Pennsylvania. Its former mineral processing operations have contaminated nearby wells and soils with zinc and cadmium. Preliminary analysis of soil and dust sampling conducted in May 1991 has revealed that the dust poses a potential threat to human health. Based on the results of a previous study, which showed a high percentage of silt and clay in soils from Palmerton residential properties, it was concluded that soil washing is not likely to be a viable method to treat the soil and dust contamination in Palmerton. However, since the completion of this study, a soil-washing process for “unwashable” clays and silts has been developed. A residential soil sample from Palmerton, which had low concentrations of arsenic, cadmium, and lead, and a somewhat high concentration of zinc, was washed in a bench-scale version of this process. The results showed that the new soil-washing process for “unwashable” clays and silts may be a viable method to treat the soil and dust contamination in Palmerton, depending on the soil quality criteria concentrations selected for site cleanup.