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).     

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.     

Anaerobic Degradation of PCB in Soils

Abstract

The anaerobic degradation of PCB in loamy and clayey soils containing indigeneous microflora was studied. The anaerobic conditions were created by an argon atmosphere in the flasks containing soil flooded by a liquid medium with glucose. GC-ECD analysis of soil extracts after 40 day incubation showed, in addition to the concentration changes of the less chlorinated PCB congeners, a significant decrease in the concentration of highly chlorinated congeners in both soils. The results indicate that in both soil types reductive dehalogenation of PCB congeners was encountered.     

Bioaccumulation of Heavy Metals in Some Wild‐Grown Edible Mushrooms

Abstract

In this study some heavy metal uptake in mushroom species, their metal content in soil substrate and the relation in between metal concentration in mushroom and soil were investigated. Mushroom species and soil in which mushroom species were grown were collected from Tokat region of Turkey. Six different mushroom species and their underlying soil (0–10 cm layer) samples were analyzed for some heavy metals (Cu, Pb, Fe, Zn, Cd, Mn, Ni, Cr and Co). The analysis was performed with an atomic absorption spectrometer. The results indicate that in general, heavy metal contents in all mushroom species were lower than the underlying soil substrates except for some mushroom species. The results obtained from the analyses of mushroom and underlying soil samples were evaluated using linear correlation analysis and concentration factors to identify the metal accumulation of mushrooms.     

Behavior of14C-DDE in the soil of subtropical conditions

The behaviour of p,p-DDE in upland and flooded soil conditions was studied by using¹⁴C-p,p-DDE in Hangzhou, China. The dissipation speed of¹⁴C-DDE from upland soil is faster than that from flooded soil, especially in the second phase. In flooded soil, 0–8 week T_1/2=3.42 (methanol extractable); 8–43 week, T_1/2=10.10; in uplan soil, 0–8 week, T_1/2=3.22; 8–43 week, T_1/2=7.22. There is not too much difference in the distribution patten between upland and flooded soil. Most of the¹⁴C-residue is within 2 cm layer of soil column. DDE is very stable in both upland and flooded soil conditions. Experiments were carried out under natural conditions in a net house. LSC (Pachard 1900TR) was used for¹⁴C-counting. TLC technique^[4] was engaged for the analyzing of its degradation products.     

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.     

Effect of Liquid Animal Manure Application on the Solubilization of Heavy Metals from Soil

Abstract

The effect of liquid animal manure on heavy metal solubilization in soil has been studied in the laboratory; three different types of experiments were carried out:

1) aerobic and anaerobic incubation of soil/manure mixtures

2) desorption of heavy metals from soil, as affected by manure liquid fraction

3) gel permeation chromatography of soil/manure aqueous extracts to identify components responsible for heavy metal solubilization.

Alf three different approaches showed that complexation involving high molecular weight dissolved organic matter from the soil/manure matrix is (together with pH) the most important driving force for heavy metal solubilization. As a consequence, chemical and microbial processes (e.g. nitrification) that influence dissolved organic matter concentrations in the soil solution, determine the degree of heavy metal solubilization in manured soil.     

Use of chemometrics methods and multicriteria decision-making for site selection for sustainable on-site sewage effluent disposal

This paper presents a study undertaken to evaluate site suitability for sewage effluent renovation based on physico-chemical characteristics of the soil. The results obtained showed that as the soil becomes acidic, the phosphorus concentration in the soil reduces accordingly. The chloride ion concentration was found to be a reliable indicator for evaluating the soil capacity to remove nitrogen. A high cation exchange capacity (CEC) can enhance the renovation of sewage effluent. Soils with high quartz content had a low CEC with high organic matter content (OM) being able to compensate. Therefore, an understanding of the micro-nutrients in the soil, organic matter content and chloride ion concentration are important.To facilitate a multi-variate approach for site selection, multicriteria decision-making (MCDM) methods, PROMETHEE and GAIA, were applied for analysis of a sequence of three matrices consisting of 8, 16, and 48 soil site objects, respectively, and seven soil property parameters. Matrix models and the interpretation of results are discussed in detail. From these analyses, PROMETHEE II net outranking flows, ?, found that two sites were always among the top three ranks of the three matrix models, which suggested that they were the most suitable for sewage effluent renovation. The criteria CEC and OM, were particularly important for the selection of these better sites, but pH and Cl⁻ attributes discriminated the weaker performing sites from the better ones; as well the PO₄³⁻ and the NH₃-N criteria were in general opposition to CEC, OM, pH and Cl⁻ but were much less effective as discriminators. Consideration of net outranking flows suggested an approach method for the selection of other possibly suitable sites for sewage effluent renovation.     

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.     

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.     

Soil Contamination by some Organic Micropollutants Related to Sewage Sludge Spreading

Abstract

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 reserch shown an accumulation of light molecular weight PAHs and PCBs, DEHP and 4-NP just after spreading, but one month later the con-centration of these micropollutant groups fall to the concentration detected just before the sludge spreding.

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 increse 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.     

Determination of Nitrilotriacetic Acid in Waters and Waste Waters by Gas-Liquid Chromatography,Differential Pulse Polarography and a Colorimetric Method

Abstract

A comparison of gas-liquid chromatography, differential-pulse polarography and a colorimetric method for the determination of nitrilotriacetic acid in settled sewage, sewage effluent, potable water, soil extracted water and deionised water has been undertaken. Differential-pulse polarography has also been applied to the determination of nitrilotriacetic acid in saline samples. By statistical analysis of replicate determinations, accuracy and precision have been evaluated, and calibration linearity assessed. Interferences were observed for sewage samples when analysed by all three methods. Precision was generally higher for differential-pulse polarography down to 100 μgl^?1, although only gas-liquid chromatography is applicable to concentrations below 25μgl^?1 in non-saline samples. The colorimetric method was not applicable to concentrations below 500 μgl^?1 of nitrilotriacetic acid.     

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.     

Use of the diffusive gradients in thin films technique (DGT) with various diffusive gels for characterization of sewage sludge-contaminated soils

The diffusive gradients in thin film technique (DGT) was used for characterization of South Moravian arable soils (sampling sites Zlín, Tuřany, and Chrlice) amended by sewage sludge in the 1980s. Two types of polyacrylamide diffusive gel with different pore size (APA gels—cross-linked with agarose and RG gels—cross-linked with bis-acrylamide) were employed. The (bio)available parts of Cd, Cu, and Ni and the proportions of inorganically and organically complexed species of these metals were assessed. The degree of metal resupply from the soil solid phase to the soil solution was also determined. Metal concentrations obtained by the DGT technique were lower by almost 4 to 5 orders of magnitude in comparison with those obtained by extraction with aqua regia. DGT concentrations of metals were also lower by approximately 1 to 2 orders of magnitude in comparison with those obtained by extraction with sodium nitrate (commonly used for assessment of the (bio)available part of metals). Results obtained by DGT measurement were expected to be closer to the actual content of available metal species than results obtained by extraction with sodium nitrate. Using RG gels together with APA gels provided resolution of inorganically and organically complexed metal species and their proportional representation. Inorganic metal species (particles smaller than 1 nm) formed a predominant part of assessed metal content in all studied soil samples and horizons. However, there was the exception of the cadmium content in the middle profile of Chrlice sandy soil sample. Ratio R values indicated that resupply of Cd, Cu, and Ni from the solid phase to the soil solution varied for individual soil samples and individual depth profiles. Mobile and labile species of Cd, Cu, and Ni were much more closely related to upper rather than deeper horizons. This observation correlates very well with the mechanical treatment and amendment of the studied soils.     

Pollution Potential of Some Triazole Pesticides

Abstract

The widespread occurrence of pesticides, especially in the groundwater has stimulated research into the behavior of these agrochemicals in the environment. In this work a simple model to describe the fate of the two triazole fungicides Flutriafol and Flusilazol in a silt soil is presented. For this purpose we constructed mini-columns of soil, on which we applied the two fungicides, the percolation waters and the soils were collected at different times and the pesticides quantified in these samples. In the first part, these experiments were carried out outdoors during a period of 6 months on the silt soil and in a second part, we did similar indoor experiments with the same soil and with two others. To complete our work, we studied the adsorption of these two compounds on these three types of soil with batch equilibrium experiments. The results demonstrate that the fungicide Flusilazol is an immobile compound in soil, being strongly adsorbed whatever the nature of the soil. The Flutriafol is slightly to moderately mobile in the different soils, being less adsorbed.     

Competitive sorption and desorption of heavy metals in mine soils: influence of mine soil characteristics

Many mine soils are chemically, physically, and biologically unstable and deficient. They are sometimes amended with sewage sludge and ashes but often contain heavy metals that increase the already high mine soils' heavy metal contents. Cd, Cr, Cu, Ni, Pb, and Zn in mutual competition were added to five mine soils (Galicia, Spain). Soil capacities for heavy metal sorption and retention were determined by means of distribution coefficients and selectivity sequences among metals. Influence of soil characteristics on sorption and retention was also examined. Retention selectivity sequences indicate that, in most of the soils, Pb is the preferred retained metal, followed by Cr. The last metals in these sequences are Ni, Cd, and Zn. Soil organic matter content plays a fundamental role in control of Pb sorption. Gibbsite, goethite, and mica influence Cr retention. Soil organic matter, oxides, and chlorite contents are correlated with K(d sigma sp medium). Heavy metals are weakly adsorbed by soils and then desorbed in high amounts. To recover these soils it is necessary to avoid the use of residues or ashes that contain heavy metals due to their low heavy metal retention capacity.     

Development of Resin Membranes as a Sensitive Indicator of Heavy Metal Toxicity in the Soil Environment

Abstract

Ion exchange resins in contact with soil can act as a sink for metal cations, thereby simulate the action of plant roots. Ion exchange resins in membrane form offer additional advantages in ease of use and handling. A procedure was developed to assess the bioavailability of four heavy metals Cd, Cr, Ni and Pb via direct in soil burial. A growth chamber experiment with three representative crops (oats, radish and lettuce) was set up to determine the phytotoxic levels of the four heavy metals. The critical levels varied widely from crop to crop, and soil to soil. Lettuce was most sensitive to high concentration of metals. The toxic effects are more pronounced on sandier textured soils.     

Electrically conductive composites of polyethylene filled with polyamide particles coated with silver

New types of electrically conductive polymeric composites were prepared on a base of high-density polyethylene (HDPE) matrix filled with silver-coated polyamide (PA) particles. The electrical, mechanical and adhesive properties of those composites are reported in this paper. The percolation concentration of the filler within a matrix was found to be 4 vol.%. Composites filled with high filler content were highly electrically conductive; their electrical conductivity reached the value of 6.8 × 10² S cm⁻¹. Mechanical properties and rheology of these composites were discussed. The adhesive properties of the composites to metal sharply increased with an increase in the filler content.     

Study of the pyrolysis liquids obtained from different sewage sludge

Pyrolysis of sewage sludge in fluidized bed to produce bio-oil is under study as a useful way to valorise this waste. Sewage sludge is the waste produced in the wastewater treatment plants. Its composition may change due to the origin and to the non-standardized treatments in the wastewater treatment plants. The pyrolysis of three samples of anaerobically digested sewage sludge obtained from three different urban wastewater treatment plants was studied in this work. The organic and inorganic matter composition, and the volatile and ash content of these sewage sludge samples were different. The influence of these parameters on the pyrolysis product distribution and on some characteristics of these products was studied. It was determined that the ash content of the raw material had an enormous influence on the sewage sludge pyrolysis. An increase in the ash content of the sewage sludge caused an increase in the gas yield and a decrease in the liquid and the solid yield with the operational conditions studied. The increase of the volatile content of the sewage sludge samples caused an increase in the liquid yield. The H₂ proportion was the most influenced non-condensable gas. It increased significantly with the ash content. The viscosity of the pyrolysis oils decreased when the ash content augmented. On the other hand, the water content depended on the organic composition of the sewage sludge samples. The chemical composition of the pyrolysis oils was also affected by the sewage sludge ash content above all the proportion of polyaromatic hydrocarbons and nitrogen-containing aromatic compounds. These compound groups increased with the augment of the sewage sludge ash content. The oxygen-containing aliphatic compounds and the steroids decreased with the ash content, although its proportion in the sewage sludge liquid was also influenced by the organic matter composition of the sewage sludge samples.