Sewage Sludge Application Research Articles

THE PHYSIOLOGICAL AND CELLULAR STUDY OF TRITICUM TURGIDUM GROWN IN AMENDED SOIL WITH SEWAGE SLUDGE (URBAN AND INDUSTRIAL) IN OPEN FIELDS UNDER SEMI-ARID CLIMATE CONDITIONS

A field experiment was conducted to demonstrate the beneficial and negative aspects of sewage sludge application on wheat and to determine the way of heavy metals in the sludge-soil-plant system. Two types of sewage sludge (urban and industrial) were applied at different rates (5, 25, 50 and 100 t dry matter (DM) per ha). Results showed that growth and yield have been improved by sewage sludge use. However, sewage sludge applications modified the content of heavy metals in plant tissues especially for industrial sewage sludge and high rates where significant accumulations including Co, Cr and Pb, were detected mainly in the roots. This has been coupled by an alteration of the root cellular ultra-structure and the presence of heavy metal deposition as electron-dense granules and crystals.

Characteristics of sewage sludge and its potential applications in the construction industry: a review

The treatment of wastewater in sewage treatment plants results in a by-product called sewage sludge. Sewage sludge has limited practical applications and hence its disposal is becoming a major environmental problem around the world. Over the years, sewage sludge has been used to recover energy, heavy metals and in agriculture after undergoing various treatment processes. In recent times, sewage sludge is being used in the construction industry to reduce the exploitation of natural resources. Based on the previously published research articles, treated sewage sludge has been used as lightweight coarse aggregate, as a pozzolanic material, in the manufacturing of cement and also in the production of bricks and cement blocks respectively. The applications are economically viable and help in the effective disposal of sewage sludge. Therefore, a critical review of the potential application of sewage sludge in the construction industry is presented in this article.

The formation of the leaf surface area and biomass of the miscanthus giganteus plants depending on the sewage sludge rate

The case study to determine the peculiarities of Miscanthus giganteus aboveground biomass formation depending on sewage sludge and composts rate carried out in the Precarpathian region of Ivano- Frankivsk province on sod-podzolic soils. The largest area of the leaf surface of miscanthus is formed in the trials where fresh sewage sludge was applied in the rate of 20 - 40 t/ha. The leaf surface area increases from 19 up to 24.0 cm2/plant, and the yield of raw mass of plants at the level of 23.5 - 25.1 t/ha due to increasing rates of sewage sludge application. The highest indicators of net photosynthesis productivity were found in the period of intensive growth, which amounted to 7.78 g/m²/day and in the maturation period of 7.56 g/m²/day in the trial SS - 40 t/ha + N10P14K58. The amount of dry mass of miscanthus plants significantly depends on the height of the shoot and the leaf surface area of the plants. The use of compost based on sewage sludge and straw in a ratio of 3: 1 at a rate of 30 t/ha contributes to the dry weight of miscanthus plants at the level of 15 t/ha.

Heavy Metals and Macronutrients Concentrations in Sewage Sludge Obtained from Decentralized Treatment Facility, Machakos Town, Kenya

With the increase of global population, wastewater treatment facilities face a major challenge of managing the large quantities of sewage sludge produced in urban areas. Due to this challenge many wastewater treatment plants have opted for use of sewage sludge as organic fertilizer to boost agricultural production. In Machakos Decentralized Treatment Facility (DFT), sewage sludge is usually sold to locals as fertilizer to boost crop production within the municipality. However, sewage sludge produced in municipal wastewater treatment plants is known to contain various heavy metals that may limit its usage as agricultural fertilizer. Studies have shown that sewage sludge has been associated with heavy metals which are linked to harmful effects on humans and environmental health. This study investigated the levels of various heavy metals and macronutrients from sewage sludge obtained from Machakos town wastewater treatment plant to test its suitability for use as fertilizer. Sewage sludge samples were obtained from the treatment plant at Mitheu and transported to Nairobi Agricultural Research Laboratory (NARL) for analysis of heavy metals (Cu, Zn, Mn, and Fe) and macronutrients (N, P, Ca, Mg and K). The results for the heavy metals were Zn=171.13±237mg/kg; Fe=17,877±15,700mg/kg; Mn=445.67±213mg/kg and Cu=41.1±16.71mg/kg) while the macronutrients were K=0.17±0.09%, P=1.26±1.75%, N=0.74±0.47%, Ca=0.48±0.72% and Mg=0.10±0.06%. The heavy metal concentrations were below Kenya Bureau of Standards (KEBS) and international permissible limits for sewage sludge application in agriculture and therefore deemed safe. The study concluded that the sewage sludge from Machakos Decentralized Treatment Facility is rich in nutrients and thus a potential fertilizing agent that can be used to boost plant growth in agricultural farms. However, it was noted that not all the wastewater produced in Machakos town gets into the DFT for treatment. Therefore, the study recommended that the county government of Machakos should endeavor to enlarge the small DFT treatment plant to accommodate the large quantities of wastewater generated within the town.

Soil Contamination by Microplastics in Relation to Local Agricultural Development as Revealed by FTIR, ICP-MS and Pyrolysis-GC/MS

Applying sewage sludge to improve soil, irrigated with wastewater, and grew crops inside polyethylene greenhouses in Tunisia, could introduce potential sources of microplastic pollution. To the best of knowledge, there is no data about the occurrence of microplastics in Tunisian farm soils which led to the study of the role of agricultural activities on microplastic pollution (MPs). The present study examined agricultural practices as a source of microplastics by sampling in a typical agricultural province named Moknine located in the center of Tunisia and characterized by intensive use of plastics mulches and extensive greenhouse coverage for growing vegetables and fruits. This study aims to investigate the MPs distribution and characteristics in the agriculture soil of Moknine farmlands. The evidence that agricultural soil is contaminated by MPs was evaluated by determining the total amount of MPs particles in soil at 16 sampling points. The total concentration of targeted MPs was 50-880 items/kg. White/transparent fibers and small sized particles (<0.3 mm) predominate in the studied area. SEM images of MPs surfaces revealed multiple features related to environmental exposures. Pyrolysis-GC-MS method enables us to a rapid identification of MPs incorporated in soil micro- and macro-aggregates based on spectral and mass spectrometry markers. ICP-MS technique analysis of soil samples revealed a broad range of metals. Trace metals are mainly adsorbed on the surface of MPs, inferring that MPs in the soil can be vectors for transporting trace metals which represent a risk to ecosystems and human health.

The use of sewage sludge and diatomite as growing medium in scots pine (Pinus sylvestris L.) seedling production and evaluation of its land performance

Although several organic and inorganic substrates are added to growing media for improving its physical and chemical characteristics, the need for search of new materials and/or mixtures that reduces the high-priced peat content in substrates is still interesting. This study evaluated the feasibility of reducing the peat content in substrates by replacing it with different amounts of diatomite and sewage sludge for Scots pine seedling (Pinus sylvestris L.) growth and their land performance. In order to evaluate the feasibility of reducing the peat content in substrates by replacing it with different amounts of diatomite and sewage sludge, an experiment was carried out in a temperature-controlled greenhouse under natural light. To evaluate the land performance of Scots pine seedlings grown in different substrates, a trial was established between the years 2013-2017 in Sar&amp;#305;kam&amp;#305;ş, Kars (NE Anatolia). Sewage sludge application, due to its high organic matter and macro and micronutrient content, has improved the composition of the rhizosphere, thereby resulting in growth acceleration. As a result of the evaluations made in terms of both seedling morphological characteristics and land performance; the best performance was determined in the 9&lt;sup&gt;th&lt;/sup&gt; (50%P+50%SS) and 3&lt;sup&gt;rd&lt;/sup&gt; (75%SS+25%DE) mixtures.

Soil microbial properties and functional diversity in response to sewage sludge amendments

ABSTRACT Soil organic matter has vital role in maintaining important soil functions. Consequently, using sewage sludge as soil organic amendment is considered one of the agricultural practices for improving soil fertility, which is also a safe approach for its disposal. The present research was carried out to analyze the different microbial activities and functional diversity of agricultural soil with regard to sewage sludge application. A laboratory experiment was set up by taking the agricultural soil from Haryana Agricultural University fields and amended with 5, 10, 20, 30 and 50 t ha−1 of sewage sludge. It was observed that soil microbial biomass increased upto 60% and potential activities of dehydrogenase, alkaline phosphatase and urease enzymes increased upto 50–55% with increasing application rates of sewage sludge. In addition the community-level physiological profiling technique (CLPP) based on carbon source utilization was used to determine the microbial functional diversity of soil. The results indicated higher functional diversity of microbial population capable of exploiting different carbon substrates with sewage sludge application. These results are imperative for improving the approach of sewage sludge application to the agricultural soil in consideration of increasing soil fertility with reducing the use of chemical fertilizers.

Global concentrations of microplastics in soils – a review

Abstract. Worldwide, microplastics (MPs) have been commonly recognized as a threat to soil ecosystems. Terrestrial soils are widely contaminated by MPs due to the application of sewage sludge and wastewater, plastic mulching, littering, the input of tire wear from roads and atmospheric deposition. Within the last decade, an increasing number of individual studies focused on item counts and masses of MPs in different global soil environments. We reviewed these studies to achieve a representative picture of common degrees of contamination. The majority of the prospected agricultural and horticultural sites were exposed to sewage sludge and mulching film application and showed concentrations of &lt;13 000 items kg−1 dry soil and 4.5 mg kg−1 dry soil. Microplastic concentrations in soils in the vicinity of municipal areas were thereby 10 times larger compared to rural sites. The measurement of masses was generally underrepresented compared to item numbers, and mass data were often generated from microscopic analyses by using shape-to-mass models instead of direct measurements. Extreme values, such as on industrial sites, exceed the common concentrations by 2 to 4 orders of magnitude, which might be attributed not only to the land use but also to the applied methods of measurement. Campaigns that focus on other entry pathways like composts, road dust runoff and littering or land uses like grassland, forest, fallow and wilderness as well as industrial sites and landfills were underrepresented or nonexistent. Background loads, such as atmospheric deposition, were often not excluded from the measurements and, thus, the studies might overestimate the contribution of the analyzed entry pathway to the total load. Other studies focused on light density MP, e.g., from mulching films, and therefore underestimated the amount of soil MP. Despite these limitations, the data give an impression of the spectrum of global MP concentrations and are a good basis for experiments examining the effects of MPs on exposed soils. Based on the collected data, we identified problems of past studies and recommend that future experimentation take into account standardized methods of extraction and quantification, a proper characterization of the sampling sites and their history as well as the exploration of as yet underrepresented entry pathways and land uses.

Land application of sewage sludge: Response of soil microbial communities and potential spread of antibiotic resistance.

The effect of land application of sewage sludge on soil microbial communities and the possible spread of antibiotic- and metal-resistant strains and resistance determinants were evaluated during a 720-day field experiment. Enzyme activities, the number of oligotrophic bacteria, the total number of bacteria (qPCR), functional diversity (BIOLOG) and genetic diversity (DGGE) were established. Antibiotic and metal resistance genes (ARGs, MRGs) were assessed, and the number of cultivable antibiotic- (ampicillin, tetracycline) and heavy metal- (Cd, Zn, Cu, Ni) resistant bacteria were monitored during the experiment. The application of 10tha-1 of sewage sludge to soil did not increase the organic matter content and caused only a temporary increase in the number of bacteria, as well as in the functional and structural biodiversity. In contrast to expectations, a general adverse effect on the tested microbial parameters was observed in the fertilized soil. The field experiment revealed a significant reduction in the activities of alkaline and acid phosphatases, urease and nitrification potential. Although sewage sludge was identified as the source of several ARGs and MRGs, these genes were not detected in the fertilized soil. The obtained results indicate that the effect of fertilization based on the recommended dose of sewage sludge was not achieved.

THE EFFECT OF SEWAGE SLUDGE APPLICATIONS ON YIELD AND QUALITY OF VETCH + BARLEY MIXTURE

This study was conducted in Bornova experimental fields of Department of Field Crops, Faculty of Agriculture, University of Ege, Turkey during 2015 and 2016, in order to determine the effects of treated sewage sludge on yield and quality of vetch + barley mixture. The experimental design was in complete randomized blocks, with four replications. In the trial some characteristics such as plant height, botanical composition, fresh herbage yield, dry matter rate, dry matter yield, the rates of crude protein and crude ash, the yields of crude protein and crude ash, NDF and ADF rates were determined. The results showed that plant height, botanical composition, fresh herbage yield and dry matter yield were significantly affected by the applications. In the study which the highest vetch and barley plant height and dry matter yield were obtained with sewage sludge applications of 20 and 30 t ha-1, the highest vetch botanical composition was obtained with control and mineral fertilizer applications. Sewage sludge application of 10-30 t ha-1 gave the highest barley botanical composition. Dry matter rate, crude ash rate and yield, crude protein rate and yield, NDF and ADF rates were not affected by mineral fertilizer and sewage sludge applications.

Influence of sewage sludge application on soil properties, carrot growth and heavy metal uptake

ABSTRACT A pot experiment with carrot (Daucus Carota L.) was conducted aiming to investigate some soil properties, growth and heavy metal uptake by carrot with the application of sewage sludge. The treatments used were as T1 Control (Soil only), T2 (Soil + NPK), T3 (Soil 50% and sewage sludge 50%), T4 (Soil 60% + sewage sludge 40%), T5 (Soil 70% + sewage sludge 30%) and T6 (100% Sewage sludge). The results showed that sewage sludge application significantly influenced soil pH, organic matter (OM), electrical conductivity (EC), exchangeable potassium (K) and available phosphorus (P). Heavy metals like lead (Pb), cadmium (Cd), nickel (Ni) and chromium (Cr) content in soil and plant were increased due to the application of sewage sludge. Heavy metal content in soils for different sludge treatments was lower and that in carrot samples was higher than the WHO/FAO permissible limit. The carrot was recognized by a translocation factor <1.0 for all of the heavy metals except Cd. Plant heavy metal concentrations were positively correlated with the soil organic matter content and negatively correlated with soil pH. The growth of carrot was influenced positively with sewage sludge application. Maximum fresh weight (66.3 g plant-1) was recorded in T5 treatment, and maximum dry weight (5.61 g plant-1) was in T3 treatment. The soil application of sludge improves soil fertility and enhances the better yield of carrot. Moreover, sewage sludge could be co-recycled to take simultaneously the best profit and minimize environmental pollution.

Efficiency of ethanol and hexane extraction of sunflower oil from seeds of plants inoculated with Azospirillum brasilense and fertilized with sewage sludge

Helianthus annuuss L. is an annual oilseed crop that grows well in various types of soil. Sunflower oil can be used for several purposes, including human consumption, biodiesel production, and as an ingredient in cosmetics, pharmaceuticals, and veterinary products. Sewage sludge application can provide essential nutrients for plant development. This study aimed to determine the efficiency of ethanol and hexane in extracting sunflower oil and assess the effects of sewage sludge application and inoculation with Azospirillum brasilense on sunflower oil yield. Sunflower oil was obtained from dried ground seeds by Soxhlet extraction. Thrity-eigth samples were used and the experiment was carried out in a completely randomized block design. Each treatment had four repetitions. The following doses were applied: 0 (control); 5,000; 10,000; 20,000; and 40,000 kg/ha sewage sludge. Seeds were either inoculated (150 mL per 50 kg of seed) or not. Hexane and ethanol did not differ in extraction efficiency. The seeds inoculated with the bacteria and the presence of sewage sludge showed a higher yield, being 42% with higher doses of sewage sludge. The results show that ethanol, an environmentally friendly and sustainable solvent, is as efficient in extracting sunflower oil as hexane. Sludge fertilization and inoculation of sunflower with A. brasilense improve oil yield, probably by enhancing nitrogen fixation and uptake. The results show that ethanol, an environmentally friendly and sustainable solvent, is as efficient in extracting sunflower oil as hexane. Sludge fertilization and inoculation of sunflower with A. brasilense improve oil yield, probably by enhancing nitrogen fixation and uptake.

Land application of sewage sludge biochar: Assessments of soil-plant-human health risks from potentially toxic metals

Effects of sewage sludge-derived biochar and its precursor on the accumulation of metals (Cd, Cu, Pb and Zn) in soil and their uptake by plants in a 1-year field experiment involving corn-radish rotation were comparatively studied. The human health risks were assessed, and the safe application period of biochar were estimated. The application of biochar, compares to sewage sludge, significantly enhanced the radish yield (p < 0.05; not corn yield) and significantly reduced the accumulation of metals in both plants (p < 0.05), especially the annual application at ≤15 t ha−1. The hazard quotient analyses of the metals showed there were no health risks to humans (Hazard Index < 1) in consuming the edible parts of the both plants. The application of sewage sludge at ≥15 t ha−1 resulted in Cd in radish exceeded the threshold for foodstuffs set by China (0.1 mg kg−1). The total contents of Cd, Cu, Pb and Zn in soil increased gradually as the application of sewage sludge or its biochar increased from 7.5 t ha−1 to 30 t ha−1. More metals were found to be introduced to soil by the land application of biochar than by its precursor at the same doses, because the metals were concentrated in biochar during the preparation process. The contamination risk assessment of soil based on the geo-accumulation index, the contamination factor and the pollution load index suggested the application of biochar on farmland should <15 t ha−1. Therefore, taking into account the yield of and metal concentrations in the radish and corn plants and the contamination risks in soil, it is recommended that the continuous safe application period at an application of 7.5 t ha−1 year−1 of biochar should not exceed 15 years, and that of its precursor sewage sludge should not exceed 17 years.

Appropriate human intervention stimulates the development of microbial communities and soil formation at a long-term weathered bauxite residue disposal area

Bauxite residue discharged to disposal areas, which could generate environmental pollution issues. Long-term natural restoration may improve the physicochemical properties of the residues, in turn supporting vegetation establishment, and effectively managing pollution. Nevertheless, the effects of short-term human intervention on soil formation in the weathered disposal areas are still relatively unknown. Thus, residue samples with different depths from different regions including no vegetation, sparse vegetation, complete vegetation coverage, and complete vegetation coverage following sewage sludge treatment were selected to analyze microbial community using Illumina high-throughput sequencing technology and evaluate soil formation process. Long-term weathering changed pH, the fraction of water-stable aggregates and nutrient concentrations, whilst promoting Proteobacteria, Chloroflexi, Acidobacteria and Planctomycete populations. Sewage sludge addition enhanced aggregate stability and significantly changed microbial community diversity. Sewage sludge application enriched the relative abundances of Proteobacteria and Bacteroidetes, whilst decreasing the relative abundance of Acidobacteria, which may be due to variation in environmental factors. Canonical correspondence analysis revealed that pH and EC were the main factors affecting microbial structure, followed by organic carbon content and aggregate stability. The results enhance the understanding of soil formation in bauxite residue and reveal the potential benefit of human intervention in ecological reconstruction at disposal areas.

Assessment of Copper and Iron Concentration in Water of Yamuna River, Delhi, India

The concentration of Copper (Cu) and Iron (Fe) in water from River Yamuna, Delhi, India, were determined by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Heavy metals are potentially toxic and are transferred to the surrounding environment through different pathways. Heavy metals are considered one of the most dangerous groups since they are non-degradable due to their persistent nature, toxicity, and tendency to accumulate in organisms and alters the food chain cycle and still more. Yamuna river water may become contaminated by the accumulation of trace metals and metalloids through emissions from the rapidly expanding industrial areas, disposal of high metal wastes, leaded gasoline and paints, land application of fertilizers, animal manures, sewage sludge, pesticides, wastewater irrigation, and Electronic waste. Trace element toxicity has proven to be a major threat, and there are several health risks associated with it. Even though they do not have any biological role, these metals' toxic effects remain present in some of the other forms harmful for the human body and its proper functioning. On comparison of these heavy metals concentration in water, it was found that Fe, Cu were higher than the permissible limits of WHO, which gives an indication of hazardous risk to human health.

Toxic metals in soil due to the land application of sewage sludge in China: Spatiotemporal variations and influencing factors

Land application has become a promising method for recycling energy and resources from sewage sludge; however, the changes that occur to the toxic metal concentrations in soil following the application of sewage sludge have been poorly investigated in China. The present study attempted to investigate the spatiotemporal variations of toxic metal concentrations in soil due to the land application of sewage sludge and the critical influencing factors. Overall, the results indicated that an increasing ratio of sewage sludge for land application, the concentrated disposal measures, and a shallower soil may lead to elevated toxic metal concentrations in soil. The worst scenario simulation showed that the cumulative discharge of toxic metals through sludge disposal were ranked as: Zn > Cu > Cr > Pb > Ni > As > Cd > Hg. After sewage sludge was applied to previously unaffected soil, i.e., background soil, the toxic metal concentrations in the soil increased annually over the period from 2006 to 2017. However, with respect to the affected soil, the concentrations of Zn and Cu increased, whereas the concentrations of As, Cd, Cr, and Pb decreased annually over the period from 2006 to 2017. The results indicate that, in practice, the selection of soil for sewage sludge disposal depends on the background and actual concentrations of toxic metals in a soil as well as the stress caused by the amount of sewage sludge application to cultivated land. We propose to use sewage sludge containing relatively lower concentrations of metals than the disposal soil for land application. Furthermore, land application of sewage sludge should be suited to local conditions in the future sewage sludge management.

Micronutrients accumulation under pearl millet-wheat cropping system in response of salinity levels amended with sewage sludge

Aim: The present study was undertaken to evaluate the effect of sewage sludge and saline water irrigation on micronutrients concentration in pearl millet- wheat cropping system. Methodology: The trial was conducted during 2017-2019 at Soil Research Farm, CCS Haryana Agricultural University, Haryana in a factorial random block design with three replications. There were three salinity levels of irrigation water, i.e., canal water (0.35 dS m-1), 8 and 10 dS m-1 EC of saline water; and five fertilization levels, i.e., control (no fertilizer), sewage sludge(5 t ha-1), SS (5 t ha-1) + 50% RDF, SS (5 t ha-1) + 75% RDF and 100 % RDF. However, sewage sludge was applied in Rabi seasons only. Results: Based on pooled analysis of two years, micronutrients (Fe, Mn and Cu) concentration in grain and stover/straw of pearl millet and wheat crops significantly reduced on application of saline water irrigation (ECiw 8 and 10 dS m-1) whereas, Zn concentration was non significantly affected with salinity levels. However, highest concentration of Fe, Mn and Cu was recorded with canal water irrigation. There was a significant increase in micronutrients (Fe, Mn and Cu) concentration in both crops with sewage sludge application in comparison of RDF and control treatments but in case of zinc treatment SS (5 t ha-1) + 75% RDF and 100% RDF were at par with each other. Among treatments, significantly higher concentration of micronutrients was recorded with SS (5 t ha-1) + 75% RDF treatment being at par with SS (5 t ha-1) + 50% RDF. Interpretation: Salinity affects micronutrient availability adversely. However, zinc content was not affected significantly. In such case, sewage sludge application may prove a feasible option that serves as a supplement of nutrients as well as sorting out the problem of dumping waste.

Approach to the Dynamic of Carbamazepine and its Main Metabolites in Soil Contamination through the Reuse of Wastewater and Sewage Sludge.

The release of pharmaceutically active compounds to the soils through the application of sewage sludge and the irrigation with wastewater, or even with surface water, is constant. The adsorption of these compounds onto the soil is one of the key factors affecting their fate in the environment and their potential environmental risks. In this work, the adsorption of carbamazepine (CBZ) and its metabolites, 3-hydroxy-carbamazepine (3OH-CBZ), carbamazepine-10,11-dihydro-10,11-epoxide (EP-CBZ), and 10,11-dihydro-10-hydroxycarbamazepine (10OH-CBZ), in three Mediterranean soils was evaluated using single-solute and four-solute experiments. The highest adsorptions were measured for 3OH-CBZ, followed by CBZ, EP-CBZ, and 10OH-CBZ, in that order. A high influence of the physicochemical characteristics of the compounds, pH, and soil characteristics in the adsorption of the studied compounds was observed and corroborated by the statistical analysis of the results. Moreover, a good fit was observed in the three isotherm models evaluated (linear, Freundlich, and Langmuir) in single-solute experiments (R2 > 0.90). However, a decrease of the measured adsorptions and a worse fit to the isotherm models were observed in the case of multiple-solute experiments. This could be mainly due to the competition established between the studied compounds for the active sites of the soils.

Effect of the direct use of biomass in agricultural soil on heavy metals __ activation or immobilization?

In recent years, the biomass was directly used extensively in agriculture due to its low cost and convenience. Increasingly serious soil pollution of heavy metals may pose threats and risks to human health. Directly addition of biomass to soil may affect the bioavailability and content of heavy metals. Here, we reviewed the impact of direct application of oil cake, manure, sewage sludge, straw and municipal waste to soil on the form and concentration of heavy metals in soil, and also emphasized the role of biomass in soil heavy metals remediation. Heavy metals can be activated in a short term by the content of heavy metals in biomass, the production of low-molecular-weight organic acids by biomass application, and the oxidation of sulfides (except for ammoniation). However, heavy metals in soil can be immobilized by humic substances. These can be produced by biomass during a long-term application to soil. Moreover, the degree of immobilization depended on the kind of biomass. Biomass contaminated by heavy metals cannot be returned to the field directly. Therefore, Mitigating the activation of heavy metals in the early stage of biomass application is meaningful, especially for application of these biomass such as straw, sewage sludge and municipal waste. Future researches should focus on the heavy metal control on direct use of biomass in agricultural.

Contamination of Soil with Diesel Oil, Application of Sewage Sludge and Content of Macroelements in Oats

The aim of the study was to determine the effect of soil contamination with diesel oil (0, 5, 10 and 15 mL/kg d.m. of soil) on the macroelement content (nitrogen, phosphorus, potassium, sodium, magnesium and calcium) in the above-ground parts of oats (Avena sativa L.). A remediation effect of sludge as a substance which reduces the negative impact of this petroleum product on its element content in oats was also evaluated. Sewage sludge was applied in doses 0, 4, 8 and 12 g/kg of soil. The macroelement content in the above-ground parts of oats depended on the soil contamination with diesel oil and on the addition of sewage sludge to the soil. Soil contamination with diesel oil caused significant changes in the content of all macroelements in the above-ground biomass of oats. Increasing doses of the petroleum product in the series without sewage sludge decreased the content of all macroelements, except phosphorus and calcium. The highest effect was observed for the content of sodium in oats. The addition of sewage sludge to the soil alleviated the negative impact of diesel oil on the chemical composition of the plants. The application of sewage sludge to soil resulted in an increase in average content of nitrogen, sodium and magnesium (as opposed to phosphorus and partly calcium) in the above-ground parts of oats, compared to the series without sewage sludge.