Application Of Municipal Biosolids Research Articles

Identification of microplastics extracted from field soils amended with municipal biosolids

Microplastic particles in arable soil are expected to impact the environment and potentially human health. The application of municipal biosolids (MBs) to agricultural land presents a further dilemma in that biosolids act as a fertilizer for crop growth, and a disposal pathway for wastewater treatment plants. They are also a direct path for emerging contaminants, such as microplastics to enter the terrestrial environment. Reliable methods are needed to identify and quantify microplastics, found in agricultural soils to determine how microplastics are being cycled in the terrestrial environment. In this study, we developed a method for extracting microplastics from soil, and characterized their composition and identity for particles sized 5 μm to 2 mm. Method development was initially completed using natural soils spiked with microplastics and MBs, followed by the analyses of soil sampled from an agricultural field where MBs were recently applied at a rate of 13 tons dw/ha. The procedures that used the spiked samples showed that microplastics can be reliably extracted from soil in a laboratory setting, and identified and semi-quantified by thermogravimetric analysis combined with Fourier-transform infrared spectroscopy (TGA-FTIR). However, when the same methods were applied to the soil samples collected from the agricultural field, reproducibility became a challenge, as the number and type of microplastics changed even within the same soils (i.e., collected the same day from the same exact location). The variation in reproducibility observed between laboratory and field samples underscores the significant heterogeneity present in the environment. This heterogeneity, in turn, affects the identification and quantity of microplastics detected, a phenomenon observed even when comparing different fields within a single treatment regimen.

Impact of biochar on plant growth and uptake of ciprofloxacin, triclocarban and triclosan from biosolids

Application of municipal biosolids in agriculture present a concern with potential uptake and bioaccumulation of pharmaceutical compounds from biosolids into agronomic plants. We evaluated the efficacy of biochar as a soil amendment to minimize uptake of antimicrobial agents (ciprofloxacin, triclocarban, and triclosan) in lettuce (Lactuca sativa) and carrot (Daucus carota) plants. Biochar reduced the concentration of ciprofloxacin and triclocarban in lettuce leaves and resulted in a 67% reduction of triclosan in carrot roots. There was no substantial difference in pharmaceutical concentrations in carrot and lettuce plant matter at low (2.0 g kg−1 soil) and high (20.4 g kg−1 soil) rates of applied biochar. The co-amendment of biochar and biosolids increased soil pH and nutrient content which were positively correlated with an increase in lettuce shoot biomass. Our results demonstrate the potential efficacy of using walnut shell biochar as a sorbent for pharmaceutical contaminants in soil without negatively affecting plant growth.

Transfer of perfluorooctanesulfonate (PFOS), decabrominated diphenyl ether (BDE-209) and Dechlorane Plus (DP) from biosolid-amended soils to leachate and runoff water

Environmental contextThe potential of pollutants to migrate from biosolids must be considered when assessing the environmental risk associated with the application of biosolids in agriculture. We conducted semi-field tests simulating natural conditions to determine the leaching and runoff capacity of emerging organic contaminants following fortification and application of municipal biosolids. We demonstrate the transfer of pollutants from biosolid-amended soil to leachate and runoff water generated by natural rainfall. AbstractAnthropogenic perfluoroalkyl substances, PFASs, and halogenated flame retardants, HFRs, have been detected in different environmental compartments. In order to determine the fate of these compounds in the soil–water system, a semi-field simulated runoff experiment was conducted following the application of municipal organic waste. Therefore, the application of four biosolids was carried out. The biosolids were fortified with perfluorooctanesulfonate (PFOS; ~1 mg PFOS per kg biosolid), decabromodiphenyl ether (c-decaBDE; ~10 mg kg−1) and Dechlorane Plus (DP; ~0.26 mg kg−1) commercial mixtures and were applied to soil packed in 15 runoff-leaching trays (2.5 × 2 × 0.05 m). These trays were designed to collect the leachate and runoff water generated by natural rainfall. PFASs and HFRs were detected in leachate and runoff water from several rainfall events from November 2011 to May 2012 (a first rainfall event of 10.5 × 10−3 m, a second event of 16.0 × 10−3 m and a third pool event with a cumulative amount of 113.1 × 10−3 m) occurring after the initial biosolid application. The total mass distribution calculated in water samples showed a higher content in runoff samples (PFOS, 91 ± 2 %; BDE-209, 76 ± 17 %; DP, 83 ± 14 %). The order of the loamy sand soil affinity for PFOS, BDE-209 and DP was as follows: PFOS < BDE-209 ≤ DP, which was predicted, either from the compounds’ water solubility, the octanol-water partition coefficient (Kow) or the organic carbon-water partition coefficient (Koc). The calculated leaching potential (Lp) index or the Groundwater Ubiquity Score (GUS), which are based on these Kocs, revealed the reverse order of potential transport to surface and groundwater respectively.

Long-term response of forest plantation productivity and soils to a single application of municipal biosolids

Ouimet, R., Pion, A.-P. and Hebert, M. 2015. Long-term response of forest plantation productivity and soils to a single application of municipal biosolids. Can. J. Soil Sci. 95: 187-199. After 16 to 19 yr, we revisited four experimental trials set up in the early 1990s to evaluate the long-term impact of municipal biosolids applied in forest plantations. Tree growth and the soil were sampled to determine the effects of a single application of biosolids applied at (liquid equivalent) rates of 0, 130, 200, and 400 m3 ha-1. Tree radial growth responded markedly to biosolids in the young plantations, increasing from 18 % for Pinus resinosa to 62 % for Picea glauca, and up to 700 % for Quercus sp. Increases in phosphorus (P) concentrations in the tree foliage in response to biosolids could still be detected in the conifer trials. In the top 0-5 cm soil layer, organic carbon (C), total nitrogen (N), P, and copper (Cu) concentrations and pools increased, while soil compaction and bulk density decreased. In the deepest soil layer sampled (20-40 cm depth), the total N and calcium (Ca) pools were reduced by the biosolids treatments, while the pool of exchangeable acidity increased. Our observations indicate that a single application of liquid biosolids up to 400 m3 ha-1 (30 t ha-1 DM) in young forest plantations is a sustainable practice without undue risk to such podzolic soils.

Uptake and retention of amitriptyline by kaolinite

As the most commonly prescribed tricyclic antidepressant, amitriptyline (AT) is frequently detected in wastewater, surface runoff, and effluents from sewage treatment plants, and could potentially reach agriculture land through the application of municipal biosolids or reclaimed water. Kaolinite is one of the most important soil components under warm and humid climate conditions. In this study, the uptake and retention of AT by kaolinite from aqueous solution were investigated by batch tests, XRD, and FTIR analyses. The uptake of AT on kaolinite was instantaneous, attributed to surface adsorption as confirmed by XRD analyses. Quantitative correlation between desorption of exchangeable cations and AT adsorption confirmed experimentally that cation exchange was the dominant mechanism of AT uptake on kaolinite. The values for free energy of adsorption also suggested physi-sorption such as cation exchange. Solution pH had minimal influence at pH 5–11 even though the pKa value of AT was 9.4 and the surface charge of kaolinite was pH-dependent.

Persistence and dissipation pathways of the antidepressant sertraline in agricultural soils

Sertraline is a widely-used antidepressant that is one of the selective serotonin reuptake inhibitors. It has been detected in biosolids and effluents from sewage treatment plants. Since sertraline can reach agriculture land through the application of municipal biosolids or reclaimed water, the persistence and dissipation pathways of 3H-sertraline were determined in laboratory incubations using three agriculture soils varying in textures and properties. The total solvent extractable radioactivity decreased in all three soils with times to dissipate 50% of material (DT50) ranging from 48.1±3.5 (loam soil) to 84.5±13.8 (clay soil) days. Two hydroxylated sertraline transformation products were identified in all three soils by high performance liquid chromatography with time-of-flight mass spectrometry (HPLC–TOF-MS), but the accumulation did not exceed 10% of the initial parent concentration. The addition of liquid municipal biosolids to the loam soil had no effect on the rate of sertraline dissipation, or production of transformation products. In summary, sertraline was persistent in agricultural soils with major dissipation pathways including the production of non-extractable soil-bound residues, and accumulation of hydroxylated transformation products. The biologically active sertraline transformation product norsertraline was not detected in soil.

Persistence of the tricyclic antidepressant drugs amitriptyline and nortriptyline in agriculture soils

Amitriptyline and nortriptyline are widely used tricyclic antidepressant drugs. They have been detected in wastewater, surface runoff, and effluents from sewage treatment plants. As such, they could potentially reach agriculture land through the application of municipal biosolids or reclaimed water. In the absence of data on their fate in the environment, the persistence and dissipation pathways of radiolabeled amitriptyline were determined in three agriculture soils varying widely in texture and chemical properties (loam soil, clay loam soil, and sandy loam soil). Tritiated amitriptyline was added to laboratory microcosms containing soils, and the metabolism of the extractable (3) H was monitored during incubation at 30°C. The total solvent extractable radioactivity decreased in all three soils with times to dissipate 50% of material (DT50) ranging from 34.1 ± 3.2 (loam soil) to 85.3 ± 3.2 d (sandy soil). Nortriptyline (N-desmethyl amitriptyline) and amitriptyline-N-oxide were identified as major transformation products in all three soils by high performance liquid chromatography with photodiode array detector and time-of-flight mass spectrometry (HPLC-TOF-MS/UV). The addition of liquid municipal biosolids to the loam soil had no effect on the dissipation of amitriptyline. The persistence of nortriptyline was evaluated in the loam soil. The DT50 of nortriptyline was 40.5 ± 3.2 d estimated with HPLC-TOF-MS/UV. Approximately 10% of added nortriptyline was converted to hydroxylated products after 50 d of incubation. In summary, amitriptyline persisted in agricultural soils with major dissipation mechanisms, including forming nonextractable residues and producing various transformation products including the psychoactive drug nortriptyline.

Incorporation of Municipal Biosolids Affects Organic Nitrogen Mineralization and Elephantgrass Biomass Production

Municipal biosolids (MBS) represents an alternative source of nutrients for the production of bioenergy crops like elephantgrass (Pennisetum purpureum Schum.). Two experiments were conducted during 2 yr in Florida to evaluate the effect of soil incorporation vs. surface application of MBS on: (i) elephantgrass dry matter (DM) yield, tissue N and P concentration and removal, and soil C and P (Exp. 1); and (ii) organic N mineralization and DM decomposition rates of MBS measured in the field using a litter bag incubation technique (Exp. 2). In Exp. 1, three treatments supplied 350 kg total N ha−1 yr−1 from surface‐applied municipal biosolids (MBS‐SA), soil‐incorporated municipal biosolids (MBS‐INC), and surface‐applied ammonium nitrate (NH4NO3). A fourth treatment provided 700 kg total N ha−1 yr−1 from MBS‐SA (double rate of municipal biosolids, 2x‐MBS). In Exp. 2, MBS was field incubated in litter bags placed on the soil surface or at a 5‐cm soil depth. Elephantgrass DM yield, and N and P removal were greater for MBS‐INC than MBS‐SA. Dry matter yield for MBS‐INC was not different than for NH4NO3 fertilizer (22.5 vs. 24.3 Mg ha−1). Removal of N and P increased 39 and 10 kg ha−1 yr−1, respectively, for MBS‐INC and MBS‐SA. Total organic N mineralized was greater for MBS‐INC (386 g kg−1) than MBS‐SA (308 g kg−1). Incorporation of MBS increases elephantgrass DM yield and nutrient removal compared to surface application and allows MBS to replace a greater proportion of inorganic N fertilizer.

Fate of the antifungal drug clotrimazole in agricultural soil

Clotrimazole is a broad-spectrum antimycotic drug used for the treatment of dermatological and gynecological infections; it is incompletely broken down during sewage treatment and could potentially reach agricultural land through the application of municipal biosolids or wastewater. In the absence of any environmental fate data, we evaluated the persistence and dissipation pathways of (3)H-clotrimazole during laboratory incubations of agricultural soils. Clotrimazole was removed from a loam (time to dissipate 50% = 68 d), a sandy loam (time to dissipate 50% = 36 d), and a clay loam (time to dissipate 50% = 55 d), with formation of nonextractable residues being the major sink for (3) H. Their parent compound had no significant mineralization, as evidenced by the lack of formation of (3) H(2) O. Up to 15% of the applied radioactivity was recovered in the form of [(3)H]-(2-chlorophenyl)diphenyl methanol. The rate of clotrimazole dissipation in the loam soil did not vary with moisture content, but it was slower at a lower temperature (number of days to dissipate 50% = 275.6 d at 4°C). Addition of municipal biosolids to the loam soil did not vary the clotrimazole dissipation rate. In summary, the present study has established that clotrimazole is dissipated in soil, at rates that varied with soil texture and temperature. Clotrimazole dissipation was accompanied by the formation of nonextractable residues and detectable extractable residues of the transformation product (2-chlorophenyl)diphenyl methanol.

The non-steroidal anti-inflammatory drug diclofenac is readily biodegradable in agricultural soils

Diclofenac, 2-[2-[(2,6-dichlorophenyl)amino]phenyl]acetic acid, is an important non-steroidal anti-inflammatory drug widely used for human and animals to reduce inflammation and pain. Diclofenac could potentially reach agricultural lands through the application of municipal biosolids or wastewater, and in the absence of any environmental fate data, we evaluated its persistence in agricultural soils incubated in the laboratory. 14C-Diclofenac was rapidly mineralized without a lag when added to soils varying widely in texture (sandy loam, loam, clay loam). Over a range of temperature and moisture conditions extractable 14C-diclofenac residues decreased with half lives < 5 days. No extractable transformation products were detectable by HPLC. Diclofenac mineralization in the loam soil was abolished by heat sterilization. Addition of biosolids to sterile or non-sterile soil did not accelerate the dissipation of diclofenac. These findings indicate that diclofenac is readily biodegradable in agricultural soils.

Fate of the antiretroviral drug tenofovir in agricultural soil

Tenofovir (9-(R)-(2-phosphonylmethoxypropyl)-adenine) is an antiretroviral drug widely used for the treatment of human immunodeficiency virus (HIV-1) and Hepatitis B virus (HBV) infections. Tenofovir is extensively and rapidly excreted unchanged in the urine. In the expectation that tenofovir could potentially reach agricultural lands through the application of municipal biosolids or wastewater, and in the absence of any environmental fate data, we evaluated its persistence in selected agricultural soils. Less than 10% of [adenine-8- 14C]-tenofovir added to soils varying widely in texture (sand, loam, clay loam) was mineralized in a 2-month incubation under laboratory conditions. Tenofovir was less readily extractable from clay soils than from a loam or a sandy loam soil. Radioactive residues of tenofovir were removed from the soil extractable fraction with DT 50s ranging from 24 ± 2 to 67 + 22 days (first order kinetic model) or 44 + 9 to 127 + 55 days (zero order model). No extractable transformation products were detectable by HPLC. Tenofovir mineralization in the loam soil increased with temperature (range 4 °C to 30 °C), and did not occur in autoclaved soil, suggesting a microbial basis. Mineralization rates increased with soil moisture content, ranging from air-dried to saturated. In summary, tenofovir was relatively persistent in soils, there were no extractable transformation products detected, and the response of [adenine-8- 14C]-tenofovir mineralization to soil temperature and heat sterilization indicated that the molecule was biodegraded by aerobic microorganisms. Sorption isotherms with dewatered biosolids suggested that tenofovir residues could potentially partition into the particulate fraction during sewage treatment.

Municipal Biosolids as an Alternative Nutrient Source for Bioenergy Crops: II. Decomposition and Organic Nitrogen Mineralization

High‐yielding biomass crops remove significant quantities of soil nutrients, and nutrient replacement using inorganic fertilizers may not be sustainable. Municipal biosolids (MBS) are an alternative nutrient source. Organic N is the primary N form in MBS, and patterns of N mineralization can determine the effectiveness of MBS as an N source. The objectives of this experiment were to: (i) determine the effect of season of application on organic N mineralization rate and dry matter (DM) decomposition of Class A MBS measured in the field with litter bags and (ii) compare N mineralization measured using a field‐based technique with that predicted from the DECOMPOSITION model. Treatments were season of MBS application (spring and summer) during 2 yr. Organic N mineralization measured using litter bags followed the same pattern and arrived at a similar endpoint as predicted by the DECOMPOSITION model in three of four seasons. Lower spring temperatures and rainfall were associated with lower rates of N mineralization and DM decomposition during the 50 d following spring vs. summer application of MBS. When MBS were applied in summer, organic N mineralization leveled off approximately 50 d after application compared with 150 to 250 d following spring application. Seasonal weather conditions and N mineralization patterns should be considered when determining whether to apply MBS as the source of N, the timing of MBS application, and if single or split applications are best.

Effects of land application of municipal biosolids on nitrogen-fixing bacteria in agricultural soil

Effects of municipal biosolids on microbial N2-fixation in agricultural soil were assessed in a 3-month laboratory study which included analysis of metals, pharmaceuticals, and personal care products. Reference agricultural soil was amended with organic manure or municipal biosolids from a southern Ontario wastewater plant, with a biosolids-only treatment included to evaluate metabolic activity in this inoculum. Microbial N2-fixation in reference and manure-amended soils were similar (p = 0.144) over 3 months and lower than in biosolids-amended soil (p = 0.001); however, differences among soil treatments decreased over time, with no significant difference at test termination. In general, one-time application of biosolids caused short-term stimulation of N2-fixing activity with a return to reference conditions within 3 months. Although no residual effects were detected, biosolids introduced elevated levels of metals, pharmaceuticals, personal care products (particularly analgesics), and viable bacteria; long-term effects caused by repeat applications (as commonly practiced) requires further investigation.

Nitrogen, Phosphorus, and Bacteria Tile and Groundwater Quality Following Direct Injection of Dewatered Municipal Biosolids into Soil

Application of municipal biosolids (sewage) to agricultural land is a common practice to improve soil physical quality and fertility. The chosen method of land application can have a strong impact on the extent of adjacent water contamination by nutrients and bacteria. Dewatered municipal biosolids (DMB) were applied to silt-clay loam experimental field plots in Ontario, Canada using two application methods: (i) surface spreading followed by shallow incorporation (SS) and (ii) a newly developed implement that directly injects DMB into the topsoil (DI). The objective of this study was to compare N, P, and bacteria quality of tile drainage and shallow groundwater associated with each land application technique. There were no significant differences (P > 0.05) in N, P, and bacteria tile mass loads among the application treatments for time periods <100 d postapplication, when the greatest peak loads and peak tile water concentrations were observed. Both land application treatments caused groundwater Escherichia coli contamination to at least 1.2 m depth below surface after the first postapplication rainfall event, and NO(3)-N contamination to at least 2.0 m depth below surface. The DI treatment did, however, have significantly (P < 0.05) higher tile mass loads of total Kjeldahl N (TKN), total phosphorus (TP), E. coli, Enterococci, and Clostridium perfringens relative to the SS treatment for time periods >100 d postapplication. Nevertheless, relative to tile effluent data collected <100 d postapplication (no application treatment differences), peak loads, and concentrations during this time were, overall, considerably lower for both treatments. This finding, along with no significant differences in N, P, and bacteria groundwater concentrations among the application treatments, and that the direct injection technique could potentially reduce vector attraction problems and odor, suggests that the direct injection technique should be considered a dewatered municipal biosolid land application option.

Fate of the nonsteroidal anti‐inflammatory drug naproxen in agricultural soil receiving liquid municipal biosolids

Naproxen (2-(6-methoxy-2-naphthyl) propionic acid) is widely used for the treatment of pain and swelling associated with arthritis, gout, and other inflammatory conditions. Naproxen has been detected in municipal sewage outflows and in surface waters and could reach agricultural land through the application of municipal biosolids or reclaimed water. The persistence characteristics of naproxen in three agricultural soils were investigated. In laboratory microcosms of moist soil incubated at 30 degrees C, [O-14CH3]naproxen was rapidly and thoroughly mineralized to 14CO2 with comparable kinetics in a sandy loam soil, a loam soil, and a silt loam soil. Naproxen mineralization was responsive to soil temperature and soil moisture content, consistent with the primary mechanism of dissipation being biodegradation. Mineralization of naproxen was hastened by the addition of liquid municipal biosolids (LMBs) from a municipal sewage treatment plant that aerated this material. Naproxen was stable in autoclaved soils with or without addition of autoclaved LMBs, whereas naproxen was rapidly mineralized in sterile soil supplemented with nonsterile LMBs. An enrichment culture was obtained from aerobically digested LMBs in a mineral salts medium with naproxen as the sole source of carbon. The culture converted the parent compound to the corresponding naphthol, O-desmethyl naproxen. In summary, naproxen was rapidly removed from soil, with mesophilic aerobic biodegradation being the primary mechanism of dissipation. Microorganisms carried in biosolids enhanced naproxen dissipation in soil, with the initial mechanism of attack likely being O-demethylation. We conclude on this basis that naproxen in soils receiving biosolids would be readily biodegradable and, in the absence of preferential flow or runoff, pose little risk for contamination of adjacent water or crops.

Response of Three Young Douglas-Fir Plantations to Forest Fertilization with Low Rates of Municipal Biosolids

The growth of three young (5-6 years since planting) Douglas-fir plantations fertilized with a single low-rate application of municipal biosolids, ranging from 17-19 dry Mg ha-1, was studied. Stand measurements showed increases in DBH, height, average and total basal area, average and total volume and average and total dry-weight differences in the biosolids-fertilized vs. control. For instance, average per tree DBH was 14.7% greater than the controls, height by 2.7%, per stem basal area by 27%, per stem average volume by 33%, per stem average dry weight by 38%, basal area per hectare by 28%, volume per hectare by 32% and dry weight per hectare by 36% compared to untreated controls. Comparing differences in volume increases from initial growth periods with the latest growth period indicates that volume increases due to the biosolids treatment are continuing and apparently increasing over time. However, none of these observed differences were statistically significant (0.05 level) due to high variation within and between stands.

Persistence of Municipal Biosolids in a Chihuahuan Desert Rangeland 18 Years After Application

The experimental application of municipal biosolids to degraded arid and semiarid rangelands has been practiced for many years and is becoming more common in the western United States. Previous studies have examined the effects of applying biosolids to land areas that have been degraded by one or more different factors including overgrazing, fire suppression, and increased drought frequency, duration, or intensity. However, few of these studies have measured the persistence of biosolids in the soil. This study is an attempt to recover information from an abandoned reclamation effort in which municipal biosolids were spread on a degraded rangeland on the Jornada Experimental Range in southern New Mexico. The biosolids were applied in 1979 and were still present in substantial amounts when soil samples were taken in 1997. An estimated 32% of the applied biosolids persisted as fragments greater than 2 mm in diameter for almost 20 years. There were no apparent benefits of biosolid application at this site in terms of vegetation establishment within the first four years, and there was no correlation between vegetation patterns and the concentration of biosolids remaining in the soil in 1997. It is hypothesized that much of the applied sludge remains in the soil because of the recalcitrant nature of digested biosolids combined with the environmental conditions of soil in arid systems. Long-term results from biosolid addition experiments in arid and semiarid rangelands should be considered before the practice is widely used for reclamation of degraded rangeland sites.

Yield of Tomatoes as Influenced by Time of Application of Municipal Biosolids

A trial evaluating the use of municipal biosolids application in 1996 resulted in stunted transplants, delayed fruit set, season-long reduction in plant vigor, and reduced yield of `Mt. Pride' tomatoes. Hypotheses for these effects include nitrogen (N) immobilization, increased salinity, and acetic acid phytotoxicity. Subsequently, a trial was initiated in 1997 at The Univ. of Tennessee Plateau Experiment Station near Crossville to evaluate the effect of timing of biosolid application on `Mt. Fresh' tomato plant growth and fruit yield. Treatments included an inorganic control consisting of 134, 67, and 67 kg·ha-1 N, P2O5, and K2O, respectively and a municipal biosolid at a rate of 168 kg·ha-1 N applied at transplanting, 2 months prior to transplanting, or 3 months prior to transplanting. The rationale for these treatments is that time would allow for mineralization of N and leaching of salts and/or acetic acid. Stunting of transplants was observed in all treatments receiving applications of municipal biosolids, with the degree of stunting increasing as length of delay decreased. Marketable and total yields were not influenced by treatment. Municipal biosolids applied at transplanting resulted in the greatest fruiting delays and increased the amount of blossom end rot observed. Plants receiving inorganic fertilization produced the highest percentage of cracked and rotten fruit. Recommendations for municipal biosolid use include applying a rate based on N in the fall prior to production or applying a rate based on phosphorus with supplemental inorganic N in the spring.

BUNKER HILL SUPERFUND SITE: ECOLOGICAL RESTORATION PROGRAM

Bunker Hill ID was the site of mining and smelting activities for many decades. As a result of these activities, soils on the hillsides adjacent to the site became contaminated with Pb, Zn, and Cd. In addition to metal contamination, pH of the soils became highly acidic. Native vegetation has died off and the soils have become highly erosive. An application of municipal biosolids in combination with wood ash and log yard wood waste was made to test the potential of this remediation mixture to reduce erosion, correct soil pH, and support a self sustaining vegetative cover. Biosolids improve soil physical properties and provide macro and micro nutrients. Wood ash serves as a lime substitute and a source of nutrients. Log yard waste improves physical properties and has a high C:N ratio that reduces the potential for N leaching. Initial results are promising. A healthy stand of grasses and legumes has been established. In addition, the application mixture has proven itself to be highly resistant to erosion.

Effect of a one-time application of municipal biosolids on plant growth at a metal mine tailings impoundment in a semi-arid climate, Utah, USA

Vegetation growth is often limited in metal mine spoils under semi-arid climatic conditions. This study was conducted to determine whether a one-time biosolids application, limestone and wood residue addition could enhance the establishment of vegetation on metal mine spoil under these conditions. Municipal sewage sludge (as biosolids) were applied at a rate of 0 tons/acre (control), 10 dry tons/acre, 20 dry tons/acre, and 30 dry tons/acre (0, 22.4, 44.8, and 67,2 Mg/ha, respectively), to the Kennecott Utah Copper Corporation tailings impoundment located near Magna, Utah. Five test sites on the impoundment were monitored for 12 months from August 1994 to August 1995 during the first growing season. Above ground biomass production, percent cover of individual plant species, and the concentration of heavy metals in plant tissue were evaluated. A conclusion of the study is that biosolids application enhanced the plant growth capability of the tailings significantly. The N, P, Ca and Zn contents of the tailings were significantly higher after the addition of biosolids. The increase in biomass and percent cover was proportional from the control rate to the 30 dry tons/acre (67.2 Mg/ha) application rate.