Soil Application Of Sewage Sludge Research Articles

Soil Application of Sewage Sludge Treated with Clay Minerals or Biochar and Its Effect on Soil Properties and White Clover’s (Trifolium repens L.) Growth and Arbuscular Mycorrhizal Fungal Root Colonization

From the perspective of finding new, more environmental-friendly methods for the stabilization of sewage sludge to be used in agriculture, sludge treated with 15% bentonite, vermiculite or biochar was investigated as a soil amendment for white clover (Trifolium repens L.) growth, by means of a pot experiment. The sludge treatments, which were applied to two soils (an acid and an alkaline soil), in three replications, were the addition of 2% (≈80 Mg ha−1) treated sludge with the clay minerals or biochar, as well as limed or untreated (air-dried) sludge (for comparison reasons). Additional treatments with inorganic fertilization or neither organic nor inorganic fertilization (control) were also included. The application of 2% sludge to both soils significantly increased salinity compared to the control, which remained below harmful levels for sensitive crops, except for the case of untreated sludge. Furthermore, it significantly increased the soil-available macronutrients N, P and K, and micronutrients Cu, Zn (several times, especially in the case of untreated sludge) and B (up to three times) compared with the control. Moreover, the pH of the acid soil was improved, except for the case of limed sludge, where an undesirable pH increase close to 8.5 was observed. Addition of the treated sludge with the clay minerals or biochar and untreated sludge to the acid and alkaline soil significantly increased the aboveground biomass yield of white clover by 117–233% and 114–153%, respectively, compared to the control, whereas limed sludge had no effect. Plant nutrient uptake increased as well. In general, the effect of sludge on soil microbiological properties and arbuscular mycorrhizal fungal root colonization was ambiguous. It was concluded that 2% soil addition of sewage sludge treated with 15% bentonite, vermiculite or biochar could improve soil fertility and enhance plant growth; however, caution is needed with respect to potential risks of soil salinization or Zn and B phytotoxicities.

Evaluation of newly reclaimed areas in Saudi Arabia for cultivation of the leguminous crop Phaseolus vulgaris under sewage sludge amendment

Herein, the cultivation of Phaseolus vulgaris was evaluated in newly reclaimed areas in Abha City, Saudi Arabia, following amendment with different rates of sewage sludge (SS) collected from a nearby municipal wastewater treatment plant. A pot experiment was designed to assess the soil heavy metal (HM) pools, growth, yield and HM uptake by P. vulgaris plants cultivated under different SS amendment rates (0, 10, 20, 30, 40 and 50 g kg−1). SS application was found to significantly change all of the chemical properties of the reclaimed soil (except Fe and Mn). The application of SS caused a gradual significant elevation in the soil organic matter content. The application of SS also led to a meaningful increase in the soil electrical conductivity and the Cd, Co, Cr, Cu, Mo, Ni, Pb and Zn contents. However, the soil pH decreased in reaction to the treatments. However, the measured HMs (except Fe) in the soil mixtures in all treatments after harvesting P. vulgaris plants were below the maximum permissible limits in agricultural soil. Generally, SS application up to 20 g kg−1 caused a significant increase in most of the morphological parameters and biomass of P. vulgaris compared to the plants grown in the control soil, followed by a decreasing trend at SS application rates of 30, 40 and 50 g kg−1. P. vulgaris flower production decreased with an increase in the SS application rate, and fruiting was only successful at rates of 10 and 20 g kg−1. All the HM contents in different tissues of P. vulgaris were meaningfully higher for plants treated with different SS levels matched to those grown in control soil. The highest contents of all of the HMs were documented at 50 g kg−1 SS in all P. vulgaris tissues. However, all HM contents (excluding Fe and Mn in the roots) were within safe limits, with most of the absorbed HMs persisting in roots. The regression analysis showed that P. vulgaris plants have an increasing ability to absorb more HMs with an increase in the SS amendment rate. Calculations of bioaccumulation factor (BAF) showed that the BAF for most investigated HM was < 1. This means that P. vulgaris is an excluder for these HMs. In addition, calculations of the translocation factor (TF) indicated that the capacity of P. vulgaris to translocate HMs from roots to shoots or pods is < 1 for most of the investigated HMs, indicating that the amounts of HMs that persisted in roots were always higher than those that travelled to the stems, leaves or pods. Taken together, our findings suggest that soil application of SS up to 20 g kg−1 can provide a sustainable safe practice for SS disposal and improve P. vulgaris growth and yield, while exerting no environmental threats provided there is no accumulation of HMs to toxic levels in shoots of the grown P. vulgaris plants or in the amended soils.

Sewage Sludge Application Enhances the Growth of Corchorus olitorius Plants and Provides a Sustainable Practice for Nutrient Recirculation in Agricultural Soils

The current study aimed at evaluating the effects of different sewage sludge (SS) amendment rates as biofertilizers on growth of Corchorus olitorius plants and soil properties, with an emphasis on heavy metal (HM) allocation in plant parts and postharvest soil. Then, the soil was supplemented with various SS rates (0, 10, 20, 30, and 40 g kg−1). The effects of these SS amendment rates on different growth parameters of Corchorus olitorius and soil properties were investigated. The SS amendment rate of 20 g kg−1 triggered the highest growth rates of Corchorus plants. Micronutrient HMs, including Co, Cu, Mn, and Ni, increased in the shoots of plants grown in soils amended with 20 g kg−1, but with levels sufficient for normal plant growth and below the phytotoxic limits. The sludge application significantly increased the content of organic matter in postharvest soil from 1.38 to 4.83% at the amendment rate of 20 g kg−1. Furthermore, our data showed that the quantities of the estimated HMs remaining in postharvest soils were below (Cu, Fe, Mn, Mo, Zn, and Pb) or within (Co, Ni, Cd, and Cr) the maximum permissible concentrations in agricultural soils at all of the SS amendment rates. Taken together, our findings suggest that soil application of SS can provide a sustainable safe practice for SS disposal and improve plant growth, while exerting no environmental threats provided there is no accumulation of HMs to toxic levels in shoots of the grown plants or in the amended soils.

Soil application of sewage sludge stabilized with steelmaking slag and its effect on soil properties and wheat growth

The effect of sewage sludge, stabilized with steelmaking slag, on soil chemical properties and fertility and on wheat (Triticum aestivum L.) growth was evaluated. Dewatered sewage sludge [75% (wet weight basis)] stabilized with steelmaking slag (25%) and three soils with different pH values were used in a pot experiment with winter wheat. The following treatments were applied: (i) sludge addition of 30gkg−1 (≈ 120Mgha−1, rate equivalent to the common inorganic N fertilization for wheat, based on sludge's water soluble NO3-N), (ii) sludge addition of 10gkg−1 (≈ 40Mgha−1, rate equivalent to the common inorganic N fertilization for wheat, based on sludge's Kjeldahl-N), (iii) addition of the common inorganic N fertilization for wheat (120kgNha−1) as NH4NO3, (iv) control (no fertilizer, no sludge). Sludge application at both rates to all soils resulted in a significant increase of pH, electrical conductivity of the saturation extract (ECse) and soil available NO3-N and P, in comparison to the other two treatments and this increase remained constant till the end of the pot experiment. In sludge treatments pH did not exceed the critical value of 8.5, whereas ECse, although it did not reach the limit of 4dSm−1, exceeded the value of 2dSm−1 at the rate of 30gkg−1. Concentrations of heavy metals, which regulate the agronomic use of sewage sludge according to the established legislation, ranged from not detectable to lower than the respective permissible levels. Both rates of sludge's addition in all soils improved wheat's growth, as judged by the significant increase of the aboveground biomass yield and the total plant uptake of almost all nutrients, compared to the other two treatments. It was concluded that sewage sludge stabilized with steelmaking slag could be used in agriculture, applied at rates based on sludge's Kjeldahl-N content and crop's demand for N. However, potential environmental impacts must also be considered.

Agricultural use of sewage sludge in India: benefits and potential risk of heavy metals contamination and possible remediation options - a review

Application of municipal sewage sludge in agriculture is one of the best options for its safe disposal as it provides an opportunity to recycle plant essential nutrients (N, P, secondary nutrients and micronutrients) and improves soil physical, chemical and biological properties due to high organic matter content. Yield and productivity of a wide range of crops has been improved due to soil application of sewage sludge than that of well-fertilised control. Depending upon the origin, sewage sludge often contains very high amount of potentially toxic heavy metals and as such their excessive use for a longer period increases metal bioavailability in soil and ultimately causes food chain contamination. In this article we reviewed the available information on various aspects of land application of municipal sewage sludges on crop yield, soil fertility and problems of heavy metals accumulation in edible portion of the crops as well as possible options for remediation of heavy metals toxicity in contaminated soils to explore the possibility of safe recycling this waste in agriculture.

Agricultural use of sewage sludge in India: benefits and potential risk of heavy metals contamination and possible remediation options - a review

Application of municipal sewage sludge in agriculture is one of the best options for its safe disposal as it provides an opportunity to recycle plant essential nutrients (N, P, secondary nutrients and micronutrients) and improves soil physical, chemical and biological properties due to high organic matter content. Yield and productivity of a wide range of crops has been improved due to soil application of sewage sludge than that of well-fertilised control. Depending upon the origin, sewage sludge often contains very high amount of potentially toxic heavy metals and as such their excessive use for a longer period increases metal bioavailability in soil and ultimately causes food chain contamination. In this article we reviewed the available information on various aspects of land application of municipal sewage sludges on crop yield, soil fertility and problems of heavy metals accumulation in edible portion of the crops as well as possible options for remediation of heavy metals toxicity in contaminated soils to explore the possibility of safe recycling this waste in agriculture.

Critical aspects of biomass ashes utilization in soils: Composition, leachability, PAH and PCDD/F

Bottom and fly ashes streams collected along a year in several biomass thermal plants were studied. The bulk composition of ashes and other chemical characteristics that may impact soil application showed a high variability depending on the ash stream, combustion technology and ash management practice at the power plants. The acid neutralization capacity (ANC) and metal’s availability for leaching at fixed pH 7 and 4 was performed according with EA NEN 7371, as a quick evaluation method to provide information on the long-term behavior of ashes, regarding heavy metals and also plant nutrients release. Also the pH dependence leachability study was performed according to CEN/TS 14429 for predicting the leaching behavior under different scenarios. Leachability profiles were established between pH 3 and 12, allowing to distinguish different solubility control phenomena of toxic heavy metals (Cu, Cr, Mn, Ni, Zn, Pb) as well as other salts (Ca, K, Mg, Na, Cl). The ANC of fly ashes at pH 4 (3.6–9.6molH+/kg) were higher than that observed for the bottom ashes (1.2–2.1molH+/kg). Ashes were also characterized for persistent organic pollutants (POP), such as polycyclic aromatic hydrocarbons (PAH) and paradibenzodioxines and furanes (PCDD/F). Contents were found to be much higher in fly ash than in bottom ash streams. None of the PAH levels did reach the current national limit value of sewage sludge application in soils or the guide value for ash in north European countries. However, PCDD/F contents, which are not regulated, varied from non-detectable levels to high amounts, regardless the level of loss on ignition (LOI) or unburned carbon content in fly ashes. Given the current ash management practices and possible use of blends of bottom and fly ash streams as soil conditioners resembles clear the urgent need to regulate ash utilization in soils, incorporating limit values both for heavy metals, PAH and PCDD/F.

Direct and residual effect of sewage sludge on yield, heavy metals content and soil fertility under rice–wheat system

Soil application of sewage sludge in crop production offers an alternative technique for its disposal and management. The present study was taken up to evaluate the effect of sewage sludge on yield of rice, soil fertility and heavy metals accumulation in grain and straw in a glass house. The residual effect of sludge application was evaluated in subsequent wheat crop in the sequence. Five doses of sludge i.e., 0, 10, 20, 30 and 40tha−1 were applied to rice and their effects were compared with the recommended dose of fertilizers i.e., 120, 60 and 60kgN, P2O5 and K2Oha−1, respectively. There was significant increase in straw and grain yields of both the crops with application of sludge. The grain yield of rice increased 45% at 40tha−1 sludge application over no sludge. The residual effect on wheat yield was more pronounced. Soil pH in post harvest rice soil increased with the application of sludge, however, it decreased in post harvest wheat soil at higher levels of sludge application. Increase in available nutrients content of soil was also recorded with increasing levels of sludge application after harvest of rice and wheat crops. Application of sludge also increased the heavy metals contents in soil and plant. The Cd content in rice grain was above the Indian safe limit at 20tha−1 or higher levels of sludge application. There was a significant build up of P, S, Zn, Fe, and Mn in post harvest wheat soil at 40tha−1 sludge application.

Residual and cumulative effects of soil application of sewage sludge on corn productivity

The objective of this study was to evaluate the effect of frequent and periodic applications of sewage sludge to the soil, on corn productivity. The experiment was carried out as part of an experiment that has been underway since 1999, using two types of sludge. One came from the Barueri Sewage Treatment Station (BS, which receives both household and industrial sludge) and the other came from the Franca Sewage Treatment Station (FS, which receives only household sludge). The Barueri sludge was applied from 1999 up to the agricultural year of 2003/2004. With the exception of the agricultural years of 2004/2005 and 2005/2006, the Franca sludge was applied up to 2008/2009. All the applications were made in November, with the exception of the first one which was made in April 1999. After harvesting the corn, the soil remained fallow until the next cultivation. The experiment was set up as a completely randomized block design with three replications and the following treatments: control without chemical fertilization or sludge application, mineral fertilization, and dose 1 and dose 2 of sludge (Franca and Barueri). The sludges were applied individually. Dose 1 was calculated by considering the recommended N application for corn. Dose 2 was twice dose 1. It was evident from this work that the successive application of sludge to the soil in doses sufficient to reach the productivity desired with the use of nitrogen fertilizers could cause environmental problems due to N losses to the environment and that the residual and cumulative effects should be considered when calculating the application of sludge to soil.

Potential of Gamma Irradiated Sewage Sludge as Fertilizer in Radish: Evaluating Heavy-Metal Accumulation in Sandy Loam Soil

Soil application of sewage sludge as an amendment in crop plants has became a popular method of municipal sewage-sludge disposal in many countries. However, the presence of heavy metals in untreated sewage sludge has raised concerns of adverse effects on crop growth, quality of product, and environmental health. Gamma irradiation is one of the treatments for hygienization of sewage sludge before use as fertilizer. To evaluate the potential of gamma-irradiated sewage sludge as fertilizer in vegetable crops, the field investigation was conducted in a root crop, radish (Raphanus sativus L.), during the 2005–06 and 2006–07 growing seasons in a sandy loam soil. Treatments consisted of three source of fertilizers [farmyard manure (FYM), gamma-irradiated sewage sludge (GISS), and nonirradiated sewage sludge (NISS)]; each were compared at six application levels (1, 3, 6, 7, 9, and 11 t ha−1). The physicochemical properties of all the three fertilizers used in this study were compared. Growth parameters and yields of radish were not significantly influenced by source of fertilizers or their application levels, except plant stand, which was influenced by type of fertilizers used. There was no significant difference observed between source of fertilizer treatments with respect to any of the measured soil properties, including major nutrients [nitrogen (N), phosphorus (P), and potassium (K)], metallic micronutrients [copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn)], and heavy metals [nickel (Ni), lead (Pb), cadmium (Cd), and cobalt (Co)]. Soil P and Zn were influenced by the various level of fertilizers. However, the interaction effect of source and level of fertilizer was absent for all the measured parameters. The maximum pollutant limits in sewage sludge and soil for agricultural use in different countries were compared. The concentration of metallic micronutrients and heavy metals in soil were less than the prescribed limit of the United States Environmental Protection Agency (USEPA), and no significant accumulation was noted after 2 years of application of GISS and NISS even at higher application rates.