Soil contamination by some organic micropollutants related to sewage sludge spreading

The aim of the present publication is to give some information on soil contamination by 4 different micropollutant classes due to sewage sludge spreading. The soil under research shows an accumulation of light molecular weight PAHs and PCBs, DEHP and 4-NP just after spreading, but one month later the concentration of these micropollutant groups fall to the concentration detected just before the sludge spreading. As far as the soil concentration is concerned, only PAHs and PCBs are precipitation dependent. Some test plots, enriched during 10 years with fertilisers, pig-dung or sewage sludges show only an increase of the PAH concentrations of the plots amended with sludges. In the same way, the sewage sludge is chiefly responsible for the increase of PCBs in the soils, but pig-dung seems to contain quantities of these micropollutants which have to be taken into consideration.     

Persistence of Metal Residues in Sewage Sludge Treated Soils Over Seventeen Years

Abstract

Results from two long-term sewage sludge experiments conducted on different soil types are presented. Sewage sludges highly contaminated with Cr, Cu, Ni or Zn and a relatively uncontaminated sludge were applied at both sites at the same rates and metal contents in 1968. The Cr-rich sludge also had a high Cd content. Plot soils were sampled in 1972, 1976 or 1977, 1981 and 1985 and total and extractable metal contents determined. Metals added in sewage sludge may change their form but persist in soils in an extractable and plant available form for many years. There is little difference in soil extractable contents or plant uptake of Cu and Zn whether sludge is applied as one single application or as its equivalent in four separate annual applications of one quarter the amount. The percentages of the total chromium contents extractable by both EDTA and acetic acid were small and this was reflected in a low uptake of this element by pasture herbage species (<0.3 mg Cr/kg DM).     

Quantitative determination of polycyclic aromatic hydrocarbons, polychlorinated biphenyls and organochlorine pesticides in sewage sludges using supercritical fluid extraction and mass spectrometric detection.

Supercritical CO2 extraction (SFE) proved to be a valuable, fast, quantitative and partly selective extraction technique for determining polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and chlorinated pesticides (OCPs) in sewage sludges of different catchment areas based on a comparison study with certified reference materials (CRMs) and on recovery data. Most PCB extracts could be measured directly after SFE whereas for PAHs a short clean-up improved the final separation by high-resolution capillary gas chromatography. Due to the amount of coextracted compounds and the low levels of OCPs, extracts obtained by SFE had to be submitted to a multistep clean-up for final measurement. Average concentrations of 6.9 mg/kg dry mass (dm) for the sum of the 16 Environmental Protection Agency PAHs, 0.1 mg/kg dm for the sum of the seven PCB congeners and 0.002-0.072 mg/kg dm for the OCPs were found in the sewage sludges. Compared to studies performed earlier in our laboratory PAHs are still present in similar concentrations whereas PCB levels have decreased significantly. OCPs could be detected in only low amounts. A correlation between sludge type and degree of contamination could only be found for PAHs.     

Speciation of Metals in Soils

Abstract

Our studies have centred around the speciation of cadmium and manganese in three soils, one of which has been amended with sewage sludge. We report here some of our preliminary results, obtained by a coupled high performance liquid chromatography (HPLC)—graphite furnace atomic absorption spectroscopy (GFAAS) technique.

The results indicate that cadmium may exist in different forms in soil, but only one form in soil-pore waters. Manganese is present in different soil-pore waters in different forms. The presence of sewage sludge in the soil can also affect the quantity and form of metals in water extracts.     

The Importance of Long and Short-Term Air-Soil Exchanges of Organic Contaminants

Abstract

Retrospective analysis of archived soil samples collected and stored from long-term agricultural experiments in the UK has shown how soil organic chemical composition has changed over time. High molecular weight polycyclic aromatic hydrocarbons (e.g. benzo[a]pyrene) and polychlorinated dibenzo-p-dioxins and -furans have increased in concentration through this century as a result of cumulative atmospheric depositional inputs. Concentrations of polychlorinated biphenyls and low molecular weight hydrocarbons (e.g. phenanthrene) peaked in the late 1960s/early 1970s, but have declined subsequently. This reflects declining atmospheric inputs of these compounds and losses from surface soils by volatilisation back to the atmosphere and biodegradation. PCBs and low molecular weight PAHs exist predominantly in the vapour phase in air, whilst heavy PAHs and PCDD/Fs are predominantly particulate-bound. Outgassing from soils is probably the most important contemporary source of PCBs to the atmosphere in the UK. Future UK PCB air concentrations will presumably therefore be influenced (controlled) by the rate of desorption and outgassing, as soil and air concentrations move towards a condition of equilibrium partitioning. Archived soils collected and stored before the commercial manufacture of PCBs contain no PCBs indicating that there is no ‘natural production’ of these compounds. However, within a few hours of exposure to contemporary air these samples contain detectable quantities of PCBs. Short-term air-soil exchange, such as during soil drying in the laboratory, can lead to contamination of samples which contain low concentrations of PCBs and loss from samples which contain high concentrations.     

A field-scale demonstration of a novel bioremediation process for MGP sites

The Institute of Gas Technology (IGT) has developed and demonstrated an integrated chemical/biological treatment (CBT) process to efficiently remediate soils and sludges contaminated with hazardous compounds such as polynuclear aromatic hydrocarbons (PAHs), volatile hydrocarbons (e.g., BTEX), and polychlorinated biphenyls (PCBs). Bench-scale studies as well as the field-scale tests show that the CBT process is effective in significantly enhancing the rate as well as the extent of degradation of these contaminants.

In this paper, the results of bench-scale tests conducted with a variety of PAHs and a set of field-scale tests conducted with soils from a former manufactured gas plant (MGP) site (now a Superfund site) that contained coal-tar associated PAHs. The field tests results show that the chemically enhanced bioremediation using the CBT process results in up to 90% improvement over conventional bioremediation for total PAHs (2-6 ring compounds) degradation and over 100% improvement over conventional bioremediation for carcinogenic PAHs (4-6 ring compounds) degradation. In this paper, the preliminary results of the second field test being conducted using the contaminated soils from another MGP site are discussed.

     

Speciation of Heavy Metals in Sewage Sludge and Sludge-Amended Soil

Abstract

The presence of heavy metals in sewage sludge restricts their agricultural use. Sequential extraction procedures may provide an assessment of the mobility of these elements in sludge and sludge-amended soil, and may help to predict the release of metals in soil solution. Nevertheless, the “phases” in which an element occurs are operationally defined and it is necessary to standardize a procedure in order to allow the comparison of result from different laboratories.     

Sequential Extraction of Copper and Zinc from Sewage Sludges. Use of Organic Solvents

Abstract

Sequential extraction procedures were used to evaluate the bioavailability of metals from two sewage sludges after application in soils. Organic solvents were used prior to sequential extraction to evaluate the influence of oil and waxes on heavy metals extractability.

The preliminary results showed that a extraction of oil and waxes present in the sewage sludges by n-hexane followed by acetone increased the accessibility of Cu and Zn and did not remove substantial metal amounts.     

Chemical Aspects of Heavy Metal Solubility with Reference to Sewage Sludge Amended Soils

Abstract

The long term benefits of applications of sewage sludges to land as an alternative source for plant nutrients are frequently limited by potentially toxic contents of heavy metals. While upper limits for metal contents in amended soils have been defined in both North America and Europe, there has been little attention paid to the fate of the metals if soil management practices are changed and the solubility and hence the mobility of the metals increased. This study investigated the role of changes in pH and additions of chloride ions to the content of soluble Cd, Co, Cr, Cu, Pb, Ni, V and Zn in soils to which sewage sludge had been applied. The contents of soluble metals ranged from less than 1 μmol L^?1 for V to 500 μmol L^?1 for Zn. For all the metals, contents were greater in the presence of Cl^? ions and increased markedly as the pH decreased below about pH 5. Contents of V, Cr, Cu and Pb increased at pH's above 7. As all metal contents were undersaturated with respect to hydroxide or carbonate precipitates, the changes in their contents were probably related to desorption from variable charge sites on mineral and/or humic surfaces.     

Thermal analysis of soil amended with sewage sludge and biochar from sewage sludge pyrolysis

The main objective of the present study is to study the behaviour of sewage sludge and biochar from sewage sludge pyrolysis after addition to soil in a context of a temperate agricultural soil. For this, an incubation experiment was designed during 200 days. Carbon mineralization of soil amended with sewage sludge and biochar at two different rates (4 and 8 wt%) was evaluated. Differential thermal analysis, thermogravimetry and the first derivate of the TG were performed in oxidizing conditions on soil samples before and after incubation. Biochar obtained from sewage sludge pyrolysis at 500 °C was more stable in soil than original sewage sludge. After incubation experiment, the reduction of soil organic matter content was significantly lower in soil amended with biochar than in soil amended with sewage sludge. The thermostability index WL₃/WL₂ decreases after incubation in soil amended with biochar, however it increases in case of soil treated with sewage sludge.     

Sources of Errors Associated with the Determination of PAH and PCB Analytes in Water Samples

Abstract

This work describes the problems occurring in routine determination of polyaromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in water. On the basis of experiments carried out, sources of analyte losses in a particular step of the analytical procedure were identified and assessed. Primary attention has been paid to evaluation of the?following:

• degree of adsorption of analytes from the group of PCBs and PAHs on the walls of glass vessels used during sample pretreatment and storage

• influence of excess of solvent evaporation from extracts on analyte recoveries

• influence of material of extraction column (glass, polyethylene) on analyte recovery during the solid extraction process.

     

Simultaneous thermogravimetric-mass spectrometric study on the co-combustion of coal and sewage sludges

To combust coal together with a small percentage (<10%) of sewage sludge may be an option for the management of these wastes. Combustion of two different sewage sludge, one semianthracite coal and several sludges-coal blends (containing different dried mass% of each of the two sewage sludges) were studied by simultaneous TG/MS dynamic runs carried out at 5°C min^–1 in the temperature range 100–800°C. No interactions have been observed between coal and sludge during the blends combustion. Neither the combustion process, neither the studied emissions have changed appreciably for the mass% of sludge in the blends considered in this work.     

Comparison of ICP-AES and ICP-MS for the Analysis of Trace Elements in Soil Extracts

Abstract

The extraction of the chemical species Cr, Ni, Cu, Zn, Cd, and Pb, operationally defined, from a sewage sludge treated soil with various extractants (ammonium acetate, acetic acid and EDTA) has been studied by using two analytical techniques: inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma atomic emission spectroscopy (ICP-AES). A comparison of the mean values measured by the two techniques with the t-criterion reveal that the differences are not significant in all the extractants mentioned above.

Results are also compared with data from a laboratory intercomparison exercise organized in the BCR-programme (Bureau Communautaire de Reference) and discussed. A fast screening of the concentration of other trace metals could be provided by ICP-MS with good precision and low detection limits.     

Application of Leaching Tests for the Assessment of Available Heavy Metals from Domestic and Industrial Sludges

Various sludge samples from different domestic and industrial wastewater treatment plants were analyzed by Flame Atomic Absorption Spectrometry to evaluate their total and available contents of heavy metals (Cu, Cr, Ni, Pb, Zn and Fe). The EDTA and acetic acid single extraction procedures were applied to these samples with the aim to study the leaching behaviour of the metals in the different sludges and also to predict their possible mobility when these wastes are disposed on the environment and landfills. In acidic medium, a higher extraction efficiency was observed for the major part of the elements studied in the industrial sludges, except for Ni and Zn, which were also considerably released from domestic sludges. In contrast, in the presence of the EDTA complexing ligand, a more elevated mobility of metals was found in the domestic sludges and little or no metals were released from the industrial sludges. Moreover, the results of the microwave total digestions were compared, for all metals, with those obtained using a more simplified pseudototal digestion procedure (based on the EPA Method 3051, named microwave assisted acid digestion of sediments, sludges, soils and oils) and a good agreement was found between them, except for Cr and Ni in some particular samples. The between-batch precision (expressed as RSD) of both compared digestion methods was very similar and values lower than 7.7% were obtained in both cases. A certified domestic sludge material (SRM 2781) was employed to validate the two digestion procedures and no significant differences were found between the certified and experimental values for all the elements studied.     

A Simple Synthesis of Brominated Analogues of 3-Chloro-4-(dichloromethyl)-5-hydroxy- 2(5H)-furanone (MX)

Abstract

Three brominated analogues of the highly mutagenic drinking water micropollutant 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) have been synthesized from MX by halogen exchange reaction.     

Monitoring of di-(2-ethylhexyl)phthalate,nonylphenol, nonylphenol ethoxylates,and polychlorinated biphenyls in anaerobic and aerobic sewage sludge by gas chromatography–mass spectrometry

The occurrence of di-(2-ethyhexyl)phthalate (DEHP), nonylphenol and nonyphenol mono- and diethoxylates (NPEs) and seven polychlorinated biphenyl (PCB) congeners in different types of sludge samples is reported. The analysis of these compounds was carried out by sonication-assisted extraction and analytical determination by gas chromatography coupled with a mass spectrometry detector, following a previously described method. The applicability of the method was tested by monitoring the organic pollutants in primary, secondary, mixed, and digested-dehydrated sludge samples from two wastewater treatment plants (WWTPs) based on aerobic and on anaerobic biological stabilization. The occurrence of these compounds in sewage sludge and the influence of sludge stabilization process on the further farmland application of the sludge were evaluated. DEHP and NPEs were detected in all analysed sludge samples from both WWTPs at concentration levels in the range of 22.3–601?mg?kg^?1 and 136–2357?mg?kg^?1 dm (dry matter), respectively. PCBs were detected in all types of sludge analysed from the anaerobic WWTP but was not detected in any sludge sample from the aerobic WWTP. Concentration levels of the sum of the seven PCBs congeners were up to 1.5?mg?kg^?1 dm. The concentration of DEHP, sum of NPEs, and sum of the seven PCB congeners were higher than the limits fixed in the third draft of the future Sludge Directive for land application of sludge in the 67%, 100%, and 11% of samples from the anaerobic WWTP and in the 83%, 92%, and 0% of samples from the aerobic WWTP, respectively.     

Selective immunoclean-up followed by liquid or gas chromatography for the monitoring of polycyclic aromatic hydrocarbons in urban waste water and sewage sludges used for soil amendment

A selective clean-up procedure using immunoaffinity solid-phase extraction was applied for the trace-level determination of polycyclic aromatic hydrocarbons (PAHs) in urban waste water and sewage sludges used for soil amendment. Anti-pyrene antibodies have been immobilized on a silica-based sorbent and the cross-reactivity of the antibodies towards structurally related compounds were allowed to extract the whole class of priority PAHs. The selectivity of the antibodies provided clean extracts from sludges and, therefore, the identification and quantification were shown to be easier using either liquid chromatography (LC) with UV diode array and fluorescence detection in series or gas chromatography-mass spectrometry (GC-MS), although some loss of up to 50% was observed for the clean-up. The identification of the PAHs by matching of UV and MS spectra was greatly improved. The procedure, including immunoclean-up and LC coupled to diode array and fluorescence detection, was validated using certified reference materials with native PAHs of concentrations in the range of 0.57-2.16 mg/kg (dry sludges).     

Laboratory studies on waste water sludge application for acid soil remediation

In this work the effects of sludge disposal on pH values, buffer capacity and adsorption capacity of an acid soil were studied. A stabilized waste water sludge and a paper mill sludge were employed; the pH values of both sludges were higher than 8. The observed differences between soil-urban sludge and soil-paper mill sludge systems can be ascribed to the nature of the compounds present in the sludges and adsorbed on the soil. Both kinds of sludge are able to modify the natural pH of the soil, the buffer capacity and its capacity to retain metal. These modifications increase with increasing soil-sludge contact time and are higher for paper mill sludges. Temperature affects only the modifications due to urban sludge treatment.     

Solvent Composition Effects in the Chromatography of Alkaloids in the Systems Water + Methanol/Silanized Silica

Abstract

For systems of the type silanized silica/binary aquo-organic solvent, linear log k'vs. % H₂O plots are often obtained, the lines spreading fanwise in the direction of increased concentration of water. An example of such plots for a group of barbiturates is reported. For solutes which have more differentiated structures (especially in terms of the number and type of hydrophilic groups) less regular relationships can be obtained, as illustrated by log k' vs. % H₂O plots of eight alkaloids.     

Comparison of Methods for the Preparation of Sewage Sludge Samples Prior to the Spectrophotometric Determination of Phosphorus

Abstract

Three procedures for the preparation of sewage sludge samples prior to the colorimetric determination of phosphorus as “molybdenum blue” were evaluated. Using samples of the US EPA's municipal digested sludge as a reference material, sulfuric acid/ammonium persulfate digestion, muffle furnace ignition followed by extraction of the ash with hydrochloric acid, and direct extraction of the sewage sludge with sodium bicarbonate solution were compared in terms of phosphorus recovery as determined by colorimetric measurements. On the basisof phosphorus recovery, the samples prepared by muffle furnace ignition/hydrochloric acid extraction of the ash showed the best accuracy and precision. This procedure was also superior in terms of the time and effort expended in the preparation of the sewage sludge samples.