Biosolids-amended Soils Research Articles

Mineralogy and Distribution of Cd, Ni, Cr, and Pb in Biosolids-Amended Soils From Castellón Province (NE, Spain)

Heavy metals can be transferred from soils to other portions of the ecosystem, with effects at both the ecosystem level and on human health from transmission through the web chain. For several years, this environmental issue has concerned scientists. In this context, heavy metal concentrations were studied in agricultural soils devoted to vegetable crops in the province of Castellón (NE Spain), in areas of intensive agriculture. Currently, the use of biosolids to improve the nutrient contents of the soil is a common practice. Contamination of soils by potentially toxic elements (e.g., Cd, Ni, Cr, Pb) from amendments of biosolids is subject to strict controls in relationship to total permissible metal concentrations, soil properties, and intended use within the European Community. This study is aimed at determining the chemical partitioning of Cd, Ni, Cr, and Pb in agricultural soils repeatedly amended with sludge. The distribution of chemical forms of Cd, Ni, Cr, and Pb in five biosolids-amended soils was studied using a sequential extraction procedure that fractionated the metal into soluble-exchangeable, specifically sorbed-carbonate bound, oxidizable, reducible, and residual forms. The biosolids incorporation has modified the soil composition, leading to the increment of heavy metals. The residual, reducible, and carbonate-sorbed forms were dominant. The mineralogical association of the clay fraction was illite, kaolinite, and chlorite.

Long-Term Assessments of Microconstituents Fate in Biosolids-Amended Soils

Long-Term Assessments of Microconstituents Fate in Biosolids-Amended Soils

The Agriculture and Agri-Food Canada Program to Assess and Manage the Transport of Microconstituents in Biosolids-Amended Soils

The Agriculture and Agri-Food Canada Program to Assess and Manage the Transport of Microconstituents in Biosolids-Amended Soils

Contamination of shallow groundwater system and soil–plant transfer of trace metals under amended irrigated fields

This study focuses on experimental pilot assessment of contamination of shallow groundwater systems and soil–plant transfer of trace metals under amended irrigated fields. The study approach involved a pilot experimental (greenhouse) set-up of organo-mineral amended test plots/troughs (40 cm × 47 cm × 46 cm) planted with two common vegetable crops ( Amaranthus hybridus and Abelmoschus esculentus) and irrigated with wastewater. In addition to the geochemical analyses of the primary un-amended and amended soils before planting as well as residual soils after harvesting, measurements of the physico-chemical parameters and chemical analyses of trace metals concentrations in irrigation leachates and harvested vegetable tissues were also undertaken following appropriate standard sample preparation and analytical methods. The results of the geochemical analyses carried out on irrigation leachate samples collected during the sprouting stage revealed that most of the analyzed trace metals in the collected leachates exhibited 2–10 folds depletion (except for Cu and Co with enrichment of about 1.5–3 folds) compared to the initial wastewater used for irrigation. A situation attributed to uptake/bioaccumulation of these metals and selective enrichment in the residual soils as well as to leaching by infiltrating irrigation water. Nonetheless, the observed higher trace elements concentrations in the second sets of leachates collected during harvesting stage compared to the first sets of leachates collected during the sprouting/vegetative stage is an indication of higher plant uptake during sprouting/vegetative stage or initial sorption/complexation of biosolids amendment before later vertical re-mobilization by infiltrating irrigation water. Although, virtually all of the analyzed metals exhibited elevated concentrations (2–173 ppm) in both A. hybridus and A. esculentus, a closer evaluation revealed 1.2–8.2 folds enrichment of Cr, Co, Ni, Cd, Cu, and Pb in A. esculentus compared to that of A. hybridus, an indication of the fact that phyto-accumulation of trace metal is plant-specific and dependent on physiological set-up. The overall evaluation had clearly demonstrated the potential danger of bioaccumulation of toxic trace metals under biosolid amended soils as well as impacts of irrigation-induced leaching on the shallow groundwater quality, while the need to evolve a sustainable agricultural practices is also highlighted. Capsule Organo-mineral amendment can lead to trace metal bioaccumulation (in plants) and irrigation-induced leaching to shallow groundwater system.

An Evaluative Screening Level Model of the Fate of Organic Chemicals in Sludge-Amended Soils Including Organic Matter Degradation

The Biosolids-Amended Soil: Level IV (BASL4) evaluative screening level model of the fate of organic chemicals introduced to a two-layer soil in association with contaminated biosolids amendments is described. The model is intended for use in assessing the likely month-to-month and year-to-year fate and possible build-up of chemicals in sludge-amended soils in which there can be relatively rapid degradation of the organic matter (OM) present in the applied sludge. To accomplish this goal, processes of chemical degradation, inter-layer transport, volatilization, leaching, diffusion, sorbed phase transport due to bioturbation, and degradation of both fast and slow degrading OM present in the soil and amendment are quantified. Chemical can be introduced as pure compound or in biosolids; it may be applied to the surface layer of the soil or injected into a deeper layer of soil, and it may be ploughed into the surface and deeper layer. BASL4 was applied illustratively to three dissimilar chemicals: DDT, benzene, and phenol for a 12-month simulation period. Several simulations of DDT fate in different amended and unamended soil scenarios demonstrate the capabilities of the model. Degradation of OM is shown to significantly affect partitioning between solids, pore water, and pore air and hence the fate of the chemicals. A preliminary evaluation of the model is described by simulating three field and laboratory studies and the results are regarded as being in reasonable accord with observations. A sensitivity analysis is included with the objective of determining the relative importance of the various parameters describing chemical and soil properties. The model is a useful tool for evaluating the potential for soil contamination under conditions of OM degradation, for identifying the need for soil monitoring studies, and as a basis for estimating concentrations in soil-dwelling organisms.

Levels of Dioxins in Soil and Corn Tissues after 30 Years of Biosolids Application

Detectable levels of dioxins have been reported in biosolids, but very little information is available on the effect of long-term application of biosolids on dioxins accumulation in soil and uptake by plants. We analyzed dioxins in soil and corn tissue samples from field plots after 30 continuous applications of biosolids at 0 (Control), 16.8, and 67.2 Mg biosolids ha(-1) yr(-1) resulting in 0, 504, and 2016 Mg ha(-1) cumulative loadings of biosolids, respectively. The levels of dioxins in soil were only 79.9, 115.5, and 247.5 ng toxic equivalents (TEQs) kg(-1) in the 0, 504, and 2016 Mg biosolids ha(-1) plots, respectively. Dioxins were not detected in the corn grain, and only trace levels (6.8-7.5 ng TEQs kg(-1)) were found in the corn stover; however, these values were not statistically different between control and biosolids-amended soils. These observations suggest that although long-term application of biosolids may increase the levels of dioxins in soil, it does not affect dioxins uptake by corn.

Influence of redox potential (Eh) on the availability of arsenic species in soils and soils amended with biosolid

A study was done on the influence of redox potential on the mobility and availability of the various arsenic chemical forms in a Mollisol soil from central Chile amended with biosolid. Arsenic availability was strongly dependent on the applied redox potential. As expected, under reducing conditions (−200mV vs Hg/Hg2Cl2) arsenic availability increased significantly, and arsenic was found mainly as arsenite. On the contrary under oxidizing conditions (200mV vs Hg/Hg2Cl2) arsenic solubility decreased markedly and was governed by the presence of arsenate. The greatest concentration of organic arsenic species was found under reducing conditions, which would indicate that methylated species may participate in the transformation of arsenate to arsenite. In biosolid-amended soils the concentrations of methylated species increased as a function of time under reducing conditions, which can be attributed to the greater microbial activity resulting from the organic matter supply from the biosolid to soil. In all the systems, a high concentration of As(V) was found under reducing conditions, indicating that the chemical kinetics for the conversion of arsenate to arsenite is slow. Along time, the content of As(V) increased in the control soils, which may be attributed to the possible dissolution of iron oxides and hydroxides under reducing conditions.

Long-term land application of biosolids–a case study

Impact of long-term land application of biosolids on groundwater and soil quality of an application site, which had been operated for 8-15 years, was evaluated in this study. During and after the biosolids application, biosolids-amended soil, groundwater, and background soil samples were collected mainly for pathogen, nitrogen, phosphorus, and heavy metal analyses. Soil test data showed that there was no heavy metal accumulation in the biosolids-amended soil even after 10 years of biosolids application. Similar results were also observed from the groundwater samples in which the heavy metal concentrations in all groundwater samples were well below the maximum contamination levels of the drinking water standards. In addition, bacteriological levels of the soil and groundwater samples were close to the background level and below the permissible limits, respectively, thereby showing no pathogen contamination. However, nitrate-nitrogen contamination of the groundwater was occasionally observed probably due to an excess loading of the biosolids in the past. This problem can be alleviated by applying biosolids at agronomic rates so that no excess nitrogen is available for leaching down to the groundwater.

Effect of treated zeolite, iron waste, and liming on phytoavailability of Zn, Cu, and Ni in long-term biosolids-amended soils

Two metal-contaminated biosolids-amended soils (moderately and highly contaminated) from the Bromley Sewage Treatment Farm, Christchurch, New Zealand, were used to evaluate the effect of remedial treatments on Ni, Zn, and Cu phytoavailability to sunflower (Helianthus annus L.). Two different chemical treatments (iron waste and treated zeolite), at 2 rates of application (5% and 10% w/w), in combination with 3 rates of a liming material (Ca(OH)2 at 0%, 0.33%, and 0.66% w/w) were evaluated for their metal remediation potential using pot experiments. Under the moderately acidic pH conditions of the original soils (pH 5.4–5.7), neither of the materials had substantial effects on plant metal concentrations, and the application of treated zeolite resulted in a large decrease in plant yield (>60% reduction). However, in the presence of Ca(OH)2, both materials showed some potential for reducing Ni and Zn concentrations in sunflowers compared with Ca(OH)2 alone. The best combinations of zeolite or iron waste with Ca(OH)2 resulted in reductions in shoot Ni concentrations to below the detection limit. For Zn, the best combinations of materials resulted in reductions in sunflower shoot Zn concentrations of 91% for the moderately contaminated soil and 75% for the highly contaminated soil. Combinations of iron waste and Ca(OH)2 in particular resulted in substantial decreases in soluble soil Zn concentrations (>90% reduction) and increases in plant yield (63% increase for highly contaminated soil), attributed to the remediation of Zn toxicity. There was little effect of any treatment on Cu concentration in the sunflower plants.

Influence of biosolids on phosphorus sorption characteristics of a Vertisol in comparison with manures and fertilizer

Regulation of manure application in Manitoba has raised the question of whether or not biosolids application should be regulated in the same way. This study examined the effects of biosolids (BIO) applications on P sorption characteristics of a Vertisol in comparison with dairy cattle (DAIRY) and hog (HOG) manures, and monoammonium phosphate (MAP) fertilizer using the classical sorption isotherm and single point sorption index. Pertinent chemical properties and degree of P saturation (DPS) were also determined. The sorption maximum (Smax) in the control was reduced from 655 mg kg-1, to a range of 536–655 mg kg-1 with BIO, 559–650 mg kg-1 with MAP, 402–568 mg kg-1 with DAIRY, and 350–587 mg kg-1 with HOG depending upon the rate of P added. The lower DPS in the soil amended with BIO suggests a lower risk of P loss with biosolids compared with manures. The higher P sorption capacity of biosolids-amended soils compared with soils amended with manures suggest that Ca added with BIO increased the number of P sorption sites by a similar proportion to the amount of P added. Key words: Biosolids, P sorption isotherm, degree of P saturation, labile P, non-labile P

Application of ultrasonic assisted extraction of chemically diverse organic compounds from soils and sediments

The objective of this research was the development, optimization, and demonstration of an ultrasonic assisted extraction (UAE) based method for organic anthropogenic waste indicators (AWIs) with a range of physicochemical properties from soil and sediment samples. The optimized method was designed to be cost effective compared to existing extraction methods, which may require large quantities of consumables, produce substantial volumes of organic waste, or require costly instrumentation or equipment. Reagent grade sand, soil collected from the native grassland in proximity to Eastern Washington University (EWU), and sediment samples collected from the Spokane river were used as sample matrices during method development. These matrices were fortified with eight AWIs of varying chemical properties that are representative of a variety of household, industrial, and agricultural sources. The recoveries of the AWIs spiked onto these matrices were determined in the extracts using gas chromatography/mass spectrometry (GC/MS). These values reflect the efficiency of the method for extraction of these analytes from representative environmental matrices. Recoveries ranged from 46.1% to 110% in the fortified soil and from 49.2% to 118.6% in the fortified sediment samples, which is comparable with existing methods for the study analytes. The optimized method was then used to quantify AWIs in a biosolid-amended soil. Indole and p-cresol were detected in the biosolid-amended soil.

Effect of Dissolved Organic Carbon on Zinc Solubility in Incubated Biosolids‐Amended Soils

Soil organic carbon (SOC) and dissolved organic carbon (DOC) affect long-term heavy metal solubility in biosolids-amended soils, but their role needs to be further studied under Mediterranean climatic conditions. We investigated Zn solubility, as assessed by water extraction, in two typical Greek soils amended with biosolids at 0, 20, and 100 Mg ha(-1) during a 310-d incubation period. It was found that SOC decreased by nearly 30% over time in the 100 Mg ha(-1) treatment. There was evidence that DOC affected Zn solubility, because DOC increased significantly on Day 23, probably due to a flush in microbial activity, and water-extractable Zn followed the same trend. After that, both DOC and water-extractable Zn decreased back to values similar to those of the unamended soils. Although Zn solubility did not increase overall even at high biosolids application rates, this study shows that time-limited fluctuations in Zn solubility due to sudden DOC flushes, can be significant, and need to be further investigated.

Nutrient and Microbial Dynamics in Biosolids Amended Soils Following Rainfall Simulation

Municipal waste treatment plants are mandated by U.S. EPA to treat domestic wastewater prior to releasing it to receiving streams. The dewatering and high temperature drying processes at the plant are considered effective in reducing microbial contaminants in the waste. The resulting solid material (biosolid) is rich in nutrients that may serve as a value-added product for plant growth. In this study, we examined the nutrient value of biosolids, their potential biological and chemical risks that could result from surface application to two Mid-Atlantic soils: Bojac (coarse-loamy, mixed, thermic Typic Hapludult) and Cullen (clayey, mixed, thermic Typic Hapludult). Soils were placed on tilt beds and packed to their respective bulk density. Biosolids were added at a rate of 2.24 Mg/ha equivalent and mixed with the top 5 cm of the soil bed. Simulated rain was applied at a rate of 65 mm h−1 for 45 minutes. Surface runoff and percolation water were collected and analyzed for elemental content, Escherichia coli (E. coli) and total coliform bacteria. Among the nutrient elements of concern (P, Zn, Mn, and Cu) in biosolids, none were found to be higher than the specified EPA limits. The concentration of P was highest in runoff and percolation water from beds packed with Bojac and biosolids. The combined effects of high clay (35%), Al (1.14%), and Fe (5.11%) in Cullen increased its P-adsorbing capacity. Low levels of E. coli and other coliform bacteria were present in samples from biosolids-treated beds packed with Cullen. Microbial counts in runoff and percolation samples varied with soil type; in some instances they were ten-fold higher in Bojac than in Cullen. The results obtained in this study suggest that surface runoff from land applications of biosolids might contribute to microbial contamination of receiving waters near agricultural fields.

Biosolids-amended soils: Part I. Effect of biosolids application on soil quality and ecotoxicity.

Investigations of potential risk from biosolids generally indicate that land application does not threaten human or ecosystem health, but questions continue to arise concerning the environmental effects of this practice. This research project was initiated to evaluate ecotoxicity resulting from the amendment of soils with biosolids from municipal wastewater treatment plants. Toxicity was evaluated using standard tests, including earthworm mortality, growth, and reproduction; seedling germination and root elongation; microbial respiration; and nematode mortality and reproduction. Nineteen municipal wastewater treatment plants were identified to participate in an initial screening of toxicity, and five were chosen for a more detailed evaluation. In addition, two soils with historically high applications of high-metal biosolids were evaluated. Contaminants examined were zinc, copper, nickel, chromium, arsenic, cadmium, lead, and coplanar polychlorinated biphenyls (PCBs). Single applications had no effect on soil metal concentrations. Coplanar PCBs were not detectable in any of the soils or biosolids. All target organisms were sensitive to reference toxicants. Limited toxicity was observed in a small number of the amended soils, but no patterns emerged. Approximately one-half of the negative effects of biosolids on bioindicators could be attributed to routine properties, such as slight depression of pH and/or elevated salinity. None of the accumulated metal concentrations were excessive, and most would not be considered elevated. These observations suggest that current regulations for application of biosolids to soils are providing adequate ecosystem protection.

Emission of carbon dioxide and dynamics of inorganic N in a gradient of alkaline saline soils of the former lake Texcoco

A plan was developed to apply biosolid to soil of the former lake Texcoco to fertilize the pioneer vegetation. Because, no information exists about how differences in electrolytic conductivity (EC) might affect mineralization of biosolid and dynamics of C and N in soil, 20 soil samples forming a gradient in EC ranging from 22 to 150 dS m −1 were characterized, amended with 500 mg biosolid C kg −1 dry soil and incubated aerobically at 22 ± 2 °C while production of CO 2, concentrations of ammonium (NH 4 +), nitrite (NO 2 −), and nitrate (NO 3 −), and NH 3 volatilization were monitored at 22 ± 2 °C for 70 days. Soil characteristics showed large variations with maximum values often >10-times larger than minimum values. The production of CO 2 in the unamended soil ranged from 25 to 159 mg CO 2-C kg −1 day −1 and NH 3 volatilization from 0 to 189 μg NH 3-N kg −1 day −1 . Application of biosolid increased production of CO 2 significantly 1.4-fold and volatilization of NH 3 11.5-fold. The EC explained most of the variation in production of CO 2, while particle size distribution explained most of the variation in volatilization of NH 3. The concentration of NH 4 + in the biosolid-amended soil decreased sharply in the first 14 days, with the EC explaining most of the variation found, and remained constant thereafter with a small increase at day 70. Significant increases in the concentration of NO 3 − were generally found in soil with EC < 64 dS m −1. The EC explained most of the variation in production of CO 2, and dynamics of NH 4 + and NO 3 − while clay positively and sand content negatively affected NH 3 volatilization. It was found that increases in EC inhibited C and N mineralization in soil of the former lake Texcoco.

Sorption–Desorption of Carbamazepine from Irrigated Soils

Th anti-seizure medication carbamazepine is often found in treated sewage effluent and environmental samples. Carbamazepine has been shown to be very persistent in sewage treatment, as well as ground water. Due to environmental persistence, irrigation with sewage effluent could result in carbamazepine contamination of surface and ground water. To determine the potential for leaching of carbamazepine, a series of adsorption and desorption batch equilibrium experiments were conducted on irrigated soils. It was found that carbamazepine adsorption to biosolid-amended (T) soils had a KD of 19.8 vs. 12.6 for unamended soil. Based on adsorption, carbamazepine leaching potential would be categorized as low. During desorption significant hysteresis was observed and KD increased for both soils. Desorption isotherms also indicate a potential for irreversibly bound carbamazepine in the T soil. Results indicate that initial removal of carbamazepine via adsorption from irrigation water is significant and that desorption characteristics would further limit the mobility of carbamazepine through the soil profile indicating that carbamazepine found in sewage effluent used for irrigation has a low leaching potential.

Utilization of Biosolids during the Phytoremediation of Hydrocarbon‐Contaminated Soil

Addition of anaerobically digested sewage sludge (biosolids) to soil may improve conditions for phytoremediation of petroleum hydrocarbons (PHCs) through improved soil chemical, biological, and physical properties. A 32-wk greenhouse study investigated three rates of biosolids addition (0, 13.34, and 26.68 g oven-dry biosolids kg(-1) oven-dry soil) and the presence or absence of smooth brome (Bromus inermis Leyss. cv. Carlton) plants on the removal of diesel (3.5 g kg(-1) oven-dry soil) in an industrial, sandy loam soil. Diesel PHCs were divided into two fractions based on equivalent normal straight-chain boiling point ranges (F2: nC10-nC16; F3: nC16-nC34). The addition of biosolids did not increase the extent of PHC degradation but did result in significantly greater first-order decay constants compared to unamended controls. Overall, the presence of plants did not increase the rate or extent of PHC degradation, relative to that observed in unamended, non-vegetated soils. Vegetation was, however, an important factor within the biosolids-amended soils as was observed by a greater extent of PHC degradation. Some of this decrease was attributed to plant-induced removal of biosolids components that were contributing to the F3 fraction. Overall, the low-amendment rate (13.34 g oven-dry biosolids kg(-1) oven-dry soil) was considered to be the most effective treatment because it produced the greatest overall PHC degradation rate (0.226 wk(-1) for total PHCs) and resulted in the greatest recovery of biosolids-derived N by smooth brome (26.6%).

Transport of molybdenum in a biosolid-amended alkaline soil

The transport of molybdenum (Mo) in a biosolid-amended, alkaline, agricultural soil was examined in the research reported herein. Batch-equilibrium and miscible-displacement experiments were conducted to examine the transport of Mo in soil with and without 10% by weight biosolid amendment. The results of geochemical modeling, conducted using PHREEQC, indicated that no mineral dissolution or precipitation reactions were expected for the system under the prevailing conditions. Sorption equilibrium coefficients ( K d ) obtained from moment analysis of the Mo breakthrough curves were similar to those calculated from the results of the batch-equilibrium experiments. Mo sorption was greater for the biosolid-amended soil ( K d of 1.3 versus 0.35). Sorption of Mo was shown to be linear, rate limited, and reversible for both unamended and amended soil. The results suggest that Mo associated with biosolid-amended soils is relatively bioavailable and mobile.

Long-term impacts of infrequent biosolids applications on chemical and microbial properties of a semi-arid rangeland soil

A plot study was conducted to quantify long-term (>12 years) impacts of a single biosolids application, and short-term impacts (<2 years) of a repeated application, on semi-arid rangeland soil chemical and microbial parameters. In 2003 and 2004, plots which had received 0, 2.5, 5, 10, 21, or 30 Mg biosolids ha−1 once in 1991 (long-term plots), or again in 2002 (short-term plots), were sampled and analyzed for soil chemical parameters, microbial biovolumes, C and N mineralization activities, Biolog EcoPlate substrate utilization potential, and plant productivity and tissue quality. Repeated applications temporarily exacerbated differences in soil chemical properties among treatments, but after 2 years, soil chemistry trends were similar between short-term and long-term plots. Soils which received a repeated application of 21 or 30 Mg biosolids ha−1 had greater bacterial biovolumes and C and N mineralization activities. In long-term plots, mineralization activities were stimulated only at the highest rate. Biosolids-amended soil communities also utilized Biolog substrates more quickly compared to communities from control plots. Plant biomass increased, whereas plant diversity and plant C/N ratio decreased with increasing application rate for both short- and long-term plots. Infrequent biosolids application had positive ecosystem effects in terms of site management objectives, with relatively low extractable metal levels in soil and greater plant biomass and tissue quality despite reduced species richness.

Potential Regrowth and Recolonization of Salmonellae and Indicators in Biosolids and Biosolid-Amended Soil

This study evaluated the potential for conversion of Class B to Class A biosolids with respect to salmonellae and fecal coliforms during solar drying in concrete lined drying beds. Anaerobically (8% solids) and aerobically (2% solids) digested Class B biosolids were pumped into field-scale drying beds, and microbial populations and environmental conditions were monitored. Numbers of fecal coliforms and salmonellae decreased as temperature and rate of desiccation increased. After 3 to 4 weeks, Class A requirements were achieved in both biosolids for the pathogens and the indicators. However, following rainfall events, significant increase in numbers was observed for both fecal coliforms and salmonellae. In laboratory studies, regrowth of fecal coliforms was observed in both biosolids and biosolid-amended soil, but the regrowth of salmonellae observed in the concrete-lined drying beds did not occur. These laboratory studies demonstrated that pathogens decreased in numbers when soil was amended with biosolids. Based on serotyping, the increased numbers of salmonellae seen in the concrete lined drying beds following rainfall events was most likely due to recolonization due to contamination from fecal matter introduced by animals and not from regrowth of salmonellae indigenous to biosolids. Overall, we conclude that the use of concrete-lined beds created a situation in which moisture added as rainfall accumulated in the beds, promoting the growth of fecal coliforms and salmonellae added from external sources.