Agricultural Use Of Sewage Sludge Research Articles

The Assessment of Sewage Sludge Utilization in Closed-Loop Economy from an Environmental Perspective

Sewage sludge, a by-product of wastewater treatment, is garnering increasing attention in the pursuit of closed-loop economy practices due to its highly beneficial fertilizing properties. However, like any technique, using sewage sludge as fertilizer has potential and limitations. Heavy metals within sewage sludge are a primary limitation curtailing its application as a fertilizer. This study collected sewage sludge samples from four wastewater treatment plants and soil from potential application sites. The mobility of heavy metals was then examined using a sequential BCR analysis. Furthermore, a comprehensive environmental risk assessment associated with the agricultural use of sewage sludge was conducted, using various risk indicators such as Igeo and Nemerov, to compare the cumulative metal concentrations in the sewage sludge and soil. Additionally, risk assessment codes, ecological risk indices of metal mobility, and environmental risk indices were calculated, specifically focusing on the mobility of metals in the soil environment. This research demonstrates that sewage sludge failing to meet conventional criteria for agricultural use based on total metal content does not necessarily pose a high-risk application. Understanding the mobility forms of metals in sewage sludge is crucial, influencing the analysis of their potential utilization. Importantly, sewage sludge from wastewater treatment plants utilizing biological bed technology tends to exhibit a higher tendency of heavy metals to exist in mobile forms, migrating within the soil environment.

Laggard by Design: The Case of the Implementation of the EU Directive on the Agricultural Use of Sewage Sludge in Italy

The literature on EU environmental policy implementation shows that Italy’s low administrative capacity prevents it from fully complying with EU provisions. This paper builds on this literature and, through a comprehensive documentary analysis, utilises a process tracing methodology to analyse the implementation process of the sewage sludge directive. This policy has implications for public health and the environment, causing widespread concern. Empirical findings show that the poor performance in this sector results from specific, customised policy decisions made by national and regional authorities at different points in time. The conclusions suggest that, rather than being incompetent, Italy can be defined as a laggard by design.

Measuring the environmental impacts of sewage sludge use in agriculture in comparison with the incineration alternative

This study compares two scenarios for sewage sludge treatment i.e., agricultural-land application (LA) and incineration (INC), in an Italian context (Pavia province, Po Valley). The study was realised within a regional project aiming to obtain useful data to better address future sludge management policies. To do so, an attributional Life Cycle Assessment (LCA) approach was chosen and the multi-functionality was addressed by using system expansion. Results indicated that the scenario INC had higher impacts than scenario LA for the categories linked to process inputs and to the direct emissions of incineration, such as Global warming potential (= + 60 %)., Stratospheric Ozone Depletion, Ozone Formation, Mineral Resource Scarcity and Fossil Resource Scarcity. System expansion i.e., the production of non-renewable fertilisers, played a large role (higher impacts) in the categories related to resource scarcity in the INC scenario. On the other hand, LA scenario showed higher impacts than INC for direct emissions due to fertilisation (Marine and Freshwater Eutrophication, and Particulate Matter).In conclusion, the use of sewage sludge in agriculture seemed to be competitive with the alternative of incineration but both sludge quality and emission reduction during sludge distribution in the field play an important role in the reduction of environmental impacts.

Spatial multicriteria analysis to select suitable sites for sewage sludge use in agriculture: a case study in southeast Brazil

Spatial multicriteria analysis to select suitable sites for sewage sludge use in agriculture: a case study in southeast Brazil

How cautious should we be? The role of the precautionary principle in the regulation of sewage sludge in Sweden

Drawing a line between what constitutes a potentially hazardous waste and what is instead a possible resource is complicated. A case in point is the use of sewage sludge, whose use not least in agriculture, has long been subject of debate. In Sweden, the issue has been investigated for possible legislative changes four times in the past decades. The latest of these investigations propose to introduce either a total or a partial ban on agricultural use of sewage sludge. In this paper, the legality of these proposals is analyzed with particular focus on their compatibility with the precautionary principle and the EU principle of free movement of goods and services, using a traditional legal method. The analysis indicates that a partial ban may well be considered proportionate to the risks that the use entails for human health and the environment, whilst a total ban would likely be found in breach of EU law, despite the scope for Member States to take stricter measures than prescribed by secondary legislation.

Effects of Co-Digestion Sludge Application on Soil Productivity

Anaerobic digestion and agricultural use of sewage sludge are effective methods to treat and dispose of sewage sludge, respectively. Then, the anaerobic digested sewage sludge is applied in agricultural land and the improvement of soil properties can be expected. In this study, with the purpose of evaluating the potential of co-digestion sludge for agricultural use, plot experiments with two vegetable species (radish and Chinese cabbage) and three application dosages were carried out in a short term of six months. Focus was on soil physical properties, soil nutrient change and plant growth responses during the whole process. Results showed that application of co-digestion sludge had little effect on soil physical properties, including the bulk density, porosity, capillary porosity and non-capillary porosity. However, after the application of co-digestion sludge, the maximum increase in content of organic matter, total nitrogen, hydrolysable nitrogen, total phosphorus and available phosphorus in soil reached 51%, 125%, 212%, 15% and 87%, respectively, which supplied the available nutrients quickly and continuously. The application of co-digestion sludge promoted the growth of radish and Chinese cabbage, which was observed through increase of the leaf, root biomass and plants height. Consequently, co-digestion sludge has a good application prospect for improving soil productivity as fertilizer.

From Sewage Sludge to the Soil-Transfer of Pharmaceuticals: A Review.

Sewage sludge, produced in the process of wastewater treatment and managed for agriculture, poses the risk of disseminating all the pollutants contained in it. It is tested for heavy metals or parasites, but the concentration of pharmaceuticals in the sludge is not controlled. The presence of these micropollutants in sludge is proven and there is no doubt about their negative impact on the environment. The fate of these micropollutants in the soil is a new and important issue that needs to be known to finally assess the safety of the agricultural use of sewage sludge. The article will discuss issues related to the presence of pharmaceuticals in sewage sludge and their physicochemical properties. The changes that pharmaceuticals undergo have a significant impact on living organisms. This is important for the implementation of a circular economy, which fits perfectly into the agricultural use of stabilized sewage sludge. Research should be undertaken that clearly shows that there is no risk from pharmaceuticals or vice versa: they contribute to the strict definition of maximum allowable concentrations in sludge, which will become an additional criterion in the legislation on municipal sewage sludge.

Risk Assessment and Potential Analysis of the Agricultural Use of Sewage Sludge in Central Shanxi Province.

The agricultural use of sewage sludge has become an economic disposal method used worldwide. However, heavy metals contained in sewage sludge have become the crucial limiting factors for this way of disposal. This study showed that regulatory limit values are not enough to determine whether sewage sludge is suitable for agricultural use; risk assessment and potential analysis should be applied. Correlation analysis and hierarchical cluster analysis (HCA) should also be performed to identify heavy metals’ sources and show their influence on sewage sludge utilization. Samples were collected from 13 wastewater treatment plants (WWTPs) located in central Shanxi Province. Results indicated that the mean contents of heavy metals in sewage sludge were all less than the limit threshold of China. According to the monomial potential ecological risk coefficient (), the agricultural use of sewage sludge had low ecological risks for all heavy metals, except for Hg and Cd. Based on the potential ecological risk index (RI), only three stations had moderate risk, other nine stations all had higher potential risk. The mean potentials by all heavy metals were all beyond 10 years, which is the limit of the maximum application time specified by China. Combining all heavy metals, only one station’s potential was less than 10 years. Although the contents of heavy metals were all within the threshold values, large quantities of sewage sludge are not suitable for agricultural use. Coal-related industries, which were the main sources of Hg and Cd, greatly affected the agricultural use of sewage sludge.

Plot-level field monitoring with Sentinel-2 and PlanetScope data for examination of sewage sludge disposal impact

Agricultural use of sewage sludge is one of the means of sustainable environmental management. In order to monitor the short-term effects of sludge disposal a multi-year, high-resolution data collection was planned on arable land in south-eastern Hungary. Data acquisition was applied at the highest temporal and spatial resolution using Sentinel-2 and PlanetScope satellite imagery observing the vegetation period based on vegetation indices (EVI, NDVI) from 2016 to 2021. There were statistical differences in the case of sunflower and maize biomass productions but the spatial and statistical deviations between the affected and non-affected areas of sludge disposal were generally not significant. The sensitivity of EVI in the dense vegetation period and its applicability might be emphasized in a comparative analysis.

Agricultural Use of Sewage Sludge as a Threat of Microplastic (MP) Spread in the Environment and the Role of Governance

Sewage sludge from wastewater treatment plants is commonly used as a soil amendment on agricultural land. Unfortunately, more and more research indicates that large amounts of microplastic (MP) are re-introduced to soil with sludge. This study aims to present the impact MP has on soil ecosystems, global trends in agricultural sludge management resulting from a high concentration of micropollutants in sludge, and finally propose a high-level strategy for sustainable sludge management. This strategy is mostly dedicated to the European Union and involves multiple stakeholders and the links between each of them to achieve appropriate sludge management to avoid soil pollution with MP. Governance, Technology, Consumer Acceptance, and Economy and Commercial Viability is explored in depth. To the author’s knowledge, this is the first paper to discuss these topics in the context of a changing agricultural scene and identifies ways of which sewage sludge can limit MP pollution whilst still fitting into a circular economy. As total elimination of agriculturally used sludge is not a viable option, more stringent regulation on sludge quality before its use is necessary, especially on contaminant concentrations. This includes MPs limits, to improve sludge quality, in turn improving soil health. More alternative management options for sludge that does not meet land usage requirements are necessary and will be explored in this study. Overall, the combination of factors discussed will inevitably lead to more emphasis on sewage sludge management, therefore it can be expected that the information presented in this review will be of high demand and importance for sludge producers and serves as a comprehensive foundation for researchers to build off.

Economic cost\u2013benefit analysis for the agricultural use of sewage sludge treated with lime and fly ash

A tool for calculating the economic and environmental impacts of the use of byproducts of industrial processes that can substitute for perishable resources was presented. This was exemplified by fly ash (the fine fraction of ash originating from coal burned to generate electricity and collected by filtering exhaust gases leaving the furnace), added to soil as a component of sewage sludge stabilized with fly ash and lime (NVS). Application to soil of NVS has potential agricultural and environmental advantages and disadvantages. The costs and benefits of such application were calculated using both a database and expert opinions. The calculations assumed a representative assemblage of soils and crops, with weights assigned to each crop type and soil characteristic. The annual weighted benefits (additional income for the farmer) and costs per hectare reached 324 $/ha and 131 $/ha respectively. Major potential benefits include: Chemical fertilizer replacement, 159 $/ha; Improvement to the soil's physical properties, 75 $/ha; Supply of vital trace elements, 33 $/ha. Major potential costs were: Regulatory limitations on marketing of crops pending proof of absence of risk of heavy metals or radionuclides accumulation in these crops, (17 $/ha and 36 $/ha respectively); Application and incorporation cost, 50 $/ha. The presented estimates of the costs and benefits refer to the array of soils and conditions typical to Israel. It is possible to maximize potential benefits by applying fly ash only to the most suitable agricultural soils while improper use of fly ash will increase the costs incurred from its use.

Risk Assessment of Soil Contamination with Heavy Metals from Municipal Sewage Sludge

Sewage sludge (SS) is a by-product of processes conducted during the treatment of wastewater. It can be used in many different ways. One of them is the use of SS in agriculture as an organic fertiliser, but the main criterion for such use is the heavy metals (HMs) content. Knowledge of the total content of HMs in SS does not translate into the danger it may pose. The toxicity of metals is largely dependent on their mobility. The mobility of SS from three different wastewater treatment plants (WWTP) of the Świętokrzyskie Voivodeship, which were characterised by an increased zinc content, was examined in this study. The aim of the study was to prove whether the high level of zinc in SS actually disqualifies the possibility of its natural use. Calculations were made for five environmental hazard indicators: the geoaccumulation index of heavy metals in soil (Igeo), potential environmental risk indicator (PERI), risk assessment code (RAC), environmental risk factor (ERF), and the authors’ own environmental risk determinant (ERD) indicator. The obtained results show how important mobility analysis is when assessing the possibility of natural use of SS.

Long-term effects of sewage sludge-derived biochar on the accumulation and availability of trace elements in a tropical soil.

Thermal treatment by pyrolysis has been proposed as a sustainable alternative to enable the agricultural use of sewage sludge. The solid product obtained via pyrolysis of sewage sludge is called sewage sludge biochar and presents several advantages for its use as a fertilizer or soil conditioner. However, there are concerns about the accumulation and dynamics of trace elements in soil amended with sewage sludge biochar over the years. This study examined the effect of sewage sludge biochar, under field conditions for 5 yr, on the accumulation and availability of trace elements in a tropical soil. For this, 15 t ha-1 of sewage sludge biochar produced at 300 and 500°C were applied in the first two growing seasons. Application was interrupted from the third to the fifth seasons to assess the residual effect of sewage sludge biochar in the soil. The total and available trace element concentrations were determined. The total contents of trace elements showed the following variation in the soil over the 5 yr (mg kg-1): Cd (16.8-20.0), Co (19.5-21.5), Cr (98.2-125.7), Cu (8.1-17.1), Mn (62.9-85.7), Ni (20.3-35.0), Pb (27.0-52.4), and Zn (20.3-35.8). There was no change in the availability of Cd, Cr, Ni, and Pb over the years. Additionally, a residual effect of the sewage sludge biochar was the increase in availability of trace elements that are considered essential (Cu, Mn, and Zn) and beneficial elements (Co) for plants. Therefore, in relation to contamination by trace elements, the pyrolysis of sewage sludge of domestic origin proved to be an adequate strategy to enable the safe use of this residue in tropical agriculture.

ASSESSMENT OF THE POSSIBILITIES OF AGRICULTURAL USE OF SEWAGE SLUDGE FROM SMALL, MEDIUM AND LARGE WASTEWATER TREATMENT PLANTS

The management of sewage sludge, generated at various stages of wastewater treatment, is still a significant problem. One of the possibilities of using sewage sludge, which is a valuable source of nutrients (carbon, nitrogen, phosphorus), is its use for agricultural purposes. Sludge can be used for fertilising when it meets the requirements with regard to the content of heavy metals, the number of eggs of intestinal parasites and Salmonella bacteria, and when the amount of organic substances and fertilising components is sufficient. That is why it is so important to know exactly the characteristics of sewage sludge. This allows determination of whether it can be used as fertiliser in agriculture. The study assesses the agricultural use of sewage sludge from three mechanical and biological wastewater treatment plants of different PE, produced in 2016-2018. The analysis was carried out on the basis of the physicochemical parameters of the sludge. Particular attention was paid to the fertilisation and sanitary properties, as well as the presence of heavy metals, which were largely influenced by such factors as: the size of the wastewater treatment plant, the method of sewage sludge treatment and sludge management, and the nature of the catchment area. The concentrations of particular substances in sludge from wastewater treatment plants differed from one another, and sometimes these were very large differences. The conducted analysis showed that sewage sludge, from both small and large wastewater treatment plants, has a significant potential as agricultural fertiliser due to the presence of minerals such as nitrogen, phosphorus and calcium.

Analysis of the comprehensive management of sewage sludge in Poland

The methods of sewage sludge management in Poland have largely been determined by the legal requirements related to the Poland’s membership in the European Union. Since 1st January 2016, sewage sludge landfilling is prohibited. It must be emphasised that legal changes regarding wastewater management, along with the systematic increase in the volume of produced sludge, entail the necessity to change the existing method of sewage sludge management. This paper contains an analysis of solutions for management of sewage sludge produced in Poland over the period of 8 years. The goal of the work was an assessment of comprehensive management of sewage sludge produced in Poland from 2009 to 2016. Despite the decrease in the agricultural use of sewage sludge, their average share of 32% was the highest among other forms of sewage sludge management in Poland. Another form, related with the final stage of sewage sludge management, concerned its thermal processing. It was treated as a promising method, with a 19% increase over the analysed period. An optimal solution should be found to ensure safe management of sewage sludge.

Sustainable Production of Sweet Sorghum as a Bioenergy Crop Using Biosolids Taking into Account Greenhouse Gas Emissions

Currently, little data are available on greenhouse gas (GHG) emissions from sweet sorghum production under temperate climate. Similarly, information on the effect of bio-based waste products use on the carbon (C) footprint of sorghum cultivation is rare in the literature. The aim of this study was to evaluate the agronomical and environmental effects of the application of biosolids as a nitrogen source in the production of sweet sorghum as a bioenergy crop. The yield of sorghum biomass was assessed and the GHG emissions arising from crop production were quantified. The present study focused on whether agricultural use of sewage sludge and digestate could be considered an option to improve the C footprint of sorghum production. Biosolids—sewage sludge and digestate—could be recognized as a nutrient substitute without crop yield losses. Nitrogen application had the greatest impact on the external GHG emissions and it was responsible for 54% of these emissions. CO2eq emissions decreased by 14 and 11%, respectively, when sewage sludge and digestate were applied. This fertilization practice represents a promising strategy for low C agriculture and could be recommended to provide sustainable sorghum production as a bioenergy crop to mitigate GHG emissions.

Biochar na produção e nutrição da beterraba

ABSTRACT: The biomass pyrolysis process may be an alternative for the agricultural use of sewage sludge. This study aimed to evaluate the use of of biochars from mixture of sewage sludge and sugarcane bagasse (BB, 1:1 relationship sewage sludge and sugarcane bagasse) on sugar beet (Beta vulgaris L.) production and nutrition. A greenhouse experiment was conducted with five application rates of BB: 0, 2.5, 5, 7.5, and 10% (v/v), and two additional treatments, biochar from sewage sludge (BS, application rate 5% (v/v)) and conventional treatment (CV) that received lime and mineral fertilizer. The treated soils were incubated for 45 days, after which, seedlings were cultivated for 55 days. Biochar produce from sewage sludge and sugarcane bagasse is an alternative technology to reduce the potential for contamination of sewage sludge and to incorporate more stable carbon forms in the soil. Although, biochar has increased soil fertility, fine roots and nutrient uptake efficiency by sugar beet plants, total dry matter yield was significantly lower than that obtained in conventional treatment.

Agricultural use of sewage sludge under sub-humid Mediterranean conditions: effect on growth, yield, and metal content of a forage plant

A field experiment was carried out in order to investigate the effects of sewage sludge application on the growth and yield components of triticale (X Triticosecale Wittmack). Five treatments were compared: a control (C) without application of sludge or nitrogen fertilization; a mineral fertilization treatment (MF) applied as ammonium nitrate; and three sewage sludge treatments (SS), 6, 12, and 18 t ha−1, applied 15 days prior to triticale sowing. The main results showed that SS application improved plant growth by increasing leaf area index, tillering capacity, accumulated aboveground dry matter, and plant height of triticale. As a result, 18 t ha−1 of SS could be recommended the suitable dose for triticale, where dry matter production was more than twofold above the control value. No toxic effects arising from the heavy metals in triticale plants were observed. The Cu concentration was the only trace element that increased in the straw tissues with sludge application, although the values recorded were below critical environmental thresholds. Furthermore, growth and yield responses of triticale to all SS rates are comparable even sometimes more important than those for mineral fertilizer.

Agricultural Use of Sewage Sludge in Paraná State, Brazil: A Decade of National Regulation

The agricultural use of sewage sludge brings benefits to soil and plant crops, but due to the possible presence of contaminating substances and pathogenic organisms it is necessary to follow the criteria for safe use for health and the environment. In Brazil, the Conama 375/06 Resolution established criteria and procedures for agricultural use of sewage sludge and Paraná is one of the few states in the country to use this alternative. This case study presents the management process and the results of the agricultural destination of the sludge in Paraná State, Brazil, from 2007, year in which the resolution came into force, to 2017. The management is carried out in two spheres of action: one in the context of the sludge management units (SMU) and another in the agricultural sphere. The sludge is provided free of charge to farmers, which reduces expenses with fertilizers and soil acidity correctives, resulting in economic and social benefits to the communities where it is used. However, from the year 2011 there was a reduction in the amount destined for agricultural use. The requirements of the national regulation make the process complex, overly bureaucratic and burdensome, requiring a review of its criteria.

Characterization of composted sewage sludge during the maturation process: a pilot scale study

This paper determines the impact of the maturation process of composted sewage sludge on the quality of the final product and assesses the stabilization effect. The samples of composted sewage sludge were taken from a wastewater treatment plant located in Pomerania in northern Poland. The sewage sludge was composted in an open windrow composting plant with the addition of straw and wood chips in the turning windrow. The aeration of the sewage sludge mixture was conducted based on two methods. The first phase (intensive degradation phase of 6 to 8 weeks) was characterized by frequently turning; the second phase for maturation used aeration channels (2 to 3 months). In three sampling campaigns samples were taken from the same windrow after 2 (no. 1), 8 (no. 2), and 12 weeks (no. 3) of maturation. Fresh samples were used for analyzing the stabilization parameter as static respiration activity (AT4). Furthermore, the values of pH, organic matter (OM), total organic carbon (TOC), elementary composition, nutrients, total content, and mobile forms of heavy metals were analyzed in the compost samples. A significant decrease was found in the stabilization parameter (AT4) during the maturation of tested materials. In turn, no significant differences were found in the elementary composition. The concentration of most metals increased in the final product. The total content of heavy metals in the final product did not exceed the limit values for the agricultural use of sewage sludge, compost from municipal waste, and for organic fertilizers. There were no significant changes in the percentage of bioavailable and mobile forms of heavy metals during compost maturation. Zinc was characterized by the highest level of mobile and bioavailable forms, which may cause bioaccumulation after the fertilization of soil. The study has shown that the process of maturation of compost from sewage sludge not affects changes in the content of heavy metal forms. The scope of this study has been planned on a wider scale for different variants of sewage sludge composting, in order to evaluate the process.