Search Results (171)

Untreated sewage sludge (SS) and misused stabilization technologies have contributed to great contamination and the accumulation of various pollutants in agricultural soils. Regarding micro-pollutants’ degradation, scalable and effective technologies are still scarce. Although many attempts at composting adaptations have been discussed, only a few have been tested individually under outdoor conditions. To investigate different composting methods (bioaugmentation and semipermeable cover) for the removal of micro-pollutants frequently found in SS, we performed a set of on-site experiments. Windrows of SS and olive pruning were used as the compostable material and were subjected to (i) bioaugmentation with the fungus Penicillium oxalicum, (ii) covered composting, (iii) covered and bioaugmented composting, and (iv) a conventional composting pile, which was included as a control. The entire experiment lasted 99 days. Bioaugmentation without cover increased the phosphorus content, favored a reduction in heavy metal content, and was the only treatment that reduced carbamazepine at the end of the process. Moreover, the inoculation of P. oxalicum under semipermeable cover increased the richness, diversity, and dominance of specific microbial taxa and total bacterial abundance. The four mature composts obtained met the standards required to be classified in the B fertilizer category, showing that we reduced most of the micro-pollutants, and passed the germination test. Full article

This study evaluates the agronomic potential of two types of vermicompost—one produced solely from wine industry residues (WIR) and one incorporating sewage sludge (WIR + SS)—under rainfed and deficit irrigation conditions in Mediterranean vineyards. The vermicompost was obtained through a two-phase process involving initial thermophilic pre-composting, followed by vermicomposting using Eisenia fetida for 90 days. The conditions were optimized to ensure aerobic decomposition and maintain proper moisture levels (70–85%) and temperature control. This resulted in end products that met the legal standards required for agricultural use. However, population dynamics revealed significantly higher worm reproduction and biomass in the WIR treatment, suggesting superior substrate quality. When applied to grapevines, WIR vermicompost increased soil organic matter, nitrogen availability, and overall fertility. Under rainfed conditions, it improved vegetative growth, yield, and must quality, with increases in yeast assimilable nitrogen (YAN), sugar content, and amino acid levels comparable to those achieved using chemical fertilizers, as opposed to the no-fertilizer trial. Foliar analyses at veraison revealed stronger nutrient uptake, particularly of nitrogen and potassium, which was correlated with improved oenological parameters compared to the no-fertilizer trial. In contrast, WIR + SS compost was less favorable due to lower worm activity and elevated trace elements, despite remaining within legal limits. These results support the use of vermicompost derived solely from wine residues as a sustainable alternative to chemical fertilizers, in line with the goals of the circular economy in viticulture. Full article

Deployment of nature-based systems for mine water treatment is constrained by system size, and the evidence suggests decreasing hydraulic conductivity (K_sat) of organic substrates over time compromises performance. In lab-scale continuous-flow reactors, we investigated (1) the geochemical and hydraulic performance of organic substrates used in nature-based systems for metals removal (via bacterial sulfate reduction) from mine water, and then (2) the potential to operate systems modestly contaminated with Zn (0.5 mg/L) at reduced hydraulic residence times (HRTs). Bioreactors containing limestone, straw, and wood chips, with and without compost and/or sewage sludge all achieved 88%–90% Zn removal, but those without compost/sludge had higher K_sat (929–1546 m/d). Using a high K_sat substrate, decreasing the HRT from 15 to 9 h had no impact on Zn removal (92.5% to 97.5%). Although the sulfate reduction rate decreased at a shorter HRT, microbial analysis showed high relative abundance (2%–7%) of sulfate reducing bacteria, and geochemical modelling pointed to ZnS(s) precipitation as the main attenuation mechanism (mean ZnS saturation index = 3.91–4.23). High permeability organic substrate treatment systems operated at a short HRT may offer potential for wider deployment of such systems, but pilot-scale testing under ambient environmental conditions is advisable. Full article

This study evaluates the agronomic and environmental performance of pelletized compost derived from olive mill waste as a sustainable alternative to mineral fertilizers for cultivating wheat (Triticum turgidum L.) under conventional tillage methods. A field experiment was conducted in semi-arid Spain, employing three fertilization strategies: inorganic (MAP + Urea), sewage sludge (SS), and organic compost pellets (OCP), each providing 150 kg N ha⁻¹. The parameters analyzed included wheat yield, grain quality, soil properties, and greenhouse gas (GHG) emissions. Inorganic fertilization yielded the highest productivity and nutrient uptake. However, the OCP treatment reduced grain yield by only 15%, while improving soil microbial activity and enzymatic responses. The SS and OCP treatments showed increased CO₂ and N₂O emissions compared to the control and inorganic plots. However, the OCP treatment also acted as a CH₄ sink. Nutrient use efficiency was greatest under mineral fertilization, though the OCP treatment outperformed the SS treatment. These results highlight the potential of OCP as a circular bio-based fertilizer that can enhance soil function and partially replace mineral inputs. Optimizing application timing is critical to aligning nutrient release with crop demand. Further long-term trials are necessary to evaluate their impact on the soil and improve environmental outcomes. Full article

The rising cost of mineral fertilizers and the decreasing availability of manure in vegetable farming highlight the need for alternative fertilization strategies. To examine the possibility of applying byproducts from the food processing industry, sugar beet molasses, and compost from brewery sewage sludge in celery production, the field experiment was conducted over two years, using a randomized complete block design with three replications. The examined variants were T0—control (without fertilizer); T1—mineral fertilizer; T2—cattle manure; T3—sheep manure; T4—poultry manure; T5—supercompost; and T6—molasses. In the first year, there was no significant difference between T1 and T5 in thickened root yield, while these two variants achieved significantly higher yield compared with other variants. In both years, the highest leaf yield was achieved with T1, while no significant difference was found between T5, T6, and conventional organic fertilizers of animal origin. The highest amount of N was absorbed by roots in T1 (42.0 kg/ha and 51.2 kg/ha, respectively), while the lowest amount was absorbed in T0 (25.5 kg/ha and 26.7 kg/ha, respectively). A significantly higher amount of P₂O₅ was absorbed by roots in all organic fertilizer variants compared to T0 and T1. In both years, of all the nutrients, K₂O was the most absorbed nutrient by the celery root, while CaO was absorbed in greater quantities than N. Based on two years of research, it can be concluded that compost from brewery sludge and sugar beet molasses can be used as an alternative source of nutrients for plants. Full article

The treatment of wastewater and the utilization of the by-products of these processes are an important part of the circular economy. The sewage sludge, a result of wastewater treatment, could be used as a material for plant nutrient supply and/or soil-improving products. The city of Nyíregyháza, Hungary, with 120,000 citizens, has a well-planned water treatment plant operated by Nyírségvíz Ltd., which, in cooperation with the Research Institute of Nyíregyháza, developed a municipal sewage sludge compost (SSC). The closed loop of sewage water treatment and the agricultural utilization of its by-product has been developed and managed. The compost product called Nyírkomposzt was planned for acidic sandy soils. Beyond the agronomic benefits, the sustainable and environmentally sound utilization of SSC reduces sewage sludge disposal. This active involvement of a water utility company demonstrates the potential of cross-sectoral cooperation in solving environmental problems. The quality of the compost fits the Hungarian legislation. To study the effects of 0, 9, 18, and 27 t ha⁻¹ doses of compost on acidic sandy soil, a long-term small plot experiment was started in 2003. The cumulative effects of the regular (every third year, last treatment before sampling in 2021) application of the SSC showed positive changes in basic soil properties, depending on the doses used. Increasing values were found in the case of pH from 4.5 to 6, plant available P₂O₅ from 240 to 690 ppm, and plant available K₂O from 180 to 200 ppm. The plant-available zinc and copper content also increased. Soil organic matter and total N content stabilized at around 0.9% and 0.08%, respectively. The grain yields of winter rye also increased in both investigated years. The yields of 18 t ha⁻¹ treatment were about two times higher compared to the control, but only in 2022 was the difference significant. Our findings underscore the potential of well-planned SSC applications to improve the fertility of ploughed, acidic sandy soil, taking into account the theory of the circular economy by utilizing wastes and decreasing landfilling. Full article

This study evaluated the physiological and antioxidative responses of maize to non-composted (NCSS) and composted sewage sludge (CSS) from Debrecen and Kecskemét, applied at 25%, 50%, and 75% (m/m) concentrations. Measurements were taken 21 and 35 days after sowing (DAS). Debrecen NCSS significantly enhanced plant height at all concentrations and at both sampling times, while higher doses of Kecskemét NCSS reduced growth by 35 DAS. Chlorophyll-a, chlorophyll-b, and carotenoid contents were notably enhanced by Kecskemét treatments, especially at lower concentrations, whereas Debrecen treatments showed less effect. Photosystem II (PSII) efficiency parameters varied with origin: Kecskemét NCSS notably increased minimal fluorescence (F_o), while Debrecen CSS occasionally reduced maximum fluorescence (F_m) and variable fluorescence (F_v) at 75% dose (21 DAS). The superoxide dismutase activity (SOD) was significantly elevated in Kecskemét treatments—by 101%, 148% and 149% at 25%, 50% and 75% CSS applications. Correlation analysis further highlighted that NCSS treatments often showed negative associations between plant height and chlorophyll content but positive correlations with antioxidant activity. In contrast, CSS treatments promoted balanced physiological responses. The results support the importance of sludge origin and application rate and suggest that composted sludge can be a safe, sustainable amendment when managed appropriately. Full article

Soil degradation is caused by climate change and some agricultural practices. The use of compost from organic waste can be a sustainable solution, but poses risks to soil, crops and fruit. This article examined vineyard yield, vine and wine composition when compost from sewage sludge and urban waste was applied to two soils. One rainfed plot received 80 UFN kg/ha, while two irrigated plots received 40 and 80 UFN kg/ha. Compared to mineral fertilizer, compost increased crop yield (+60% in rainfed conditions) and above-ground biomass (+15% in rainfed conditions). Aromatic series were obtained by grouping the aroma compounds according to their aroma descriptor. In both rainfed and irrigated trials, higher values were observed in the fruity, green, waxy and floral series in wines from vines fertilized with compost compared to the control and chemical fertilization. The compounds with a higher influence in such series were ethyl butanoate, ethyl hexanoate, ethyl octanoate, hexanal, phenylacetaldehyde and 2-phenylethanol. Organoleptically, wines from compost were preferred to those from mineral fertilizer, with ratings close to the control wine, particularly in aroma, flavor and overall impression. Although further studies are needed, compost fertilization appears on the one hand to improve wine quality and, on the other hand, is a suitable alternative that reduces municipal waste. Full article

This study evaluated the effects of Trichoderma harzianum strain T-22 on wheat (Triticum turgidum L. var. Durum, cv. Vitron) growth and soil microbial dynamics. Three inoculation levels (I0, I1, and I2) were applied to different soil substrates: Villacañas soil (V), Quero soil (Q), and composted sewage sludge (C) from Alcázar de San Juan. Over six months, soil physicochemical properties, fungal diversity, and plant development were analyzed. The results showed that Trichoderma significantly increased fungal diversity, particularly in compost-amended substrates. In treatments with composted sludge and Trichoderma (CVI2 and CQI2), Trichoderma colonization reached up to 112,000 propagules/g, enhancing microbial activity. Higher shoot biomass and spike weight were observed when combining compost with Trichoderma since it improved nutrient availability and plant growth. Additionally, Trichoderma inoculation reduced the presence of pathogenic fungi such as Helminthosporium and Fusarium, reinforcing its biocontrol potential. However, high salinity of the soil limited microbial proliferation and plant performance. In conclusion, composted sludge and Trichoderma improved soil microbiota, enhanced wheat growth, and increased resistance against pathogens. The results highlight the potential of Trichoderma as a sustainable alternative to chemical treatments in crop production. Further studies should further investigate field-scale applications to validate these findings under real agricultural conditions. Full article

This study investigates the impact of sewage sludge-based composts on the quality of sod-podzolic soils (Fluvisols, WRB), which are naturally acidic and low in fertility. A field experiment with eight variants was conducted, applying different doses of sewage sludge and composts mixed with organic materials to enhance soil properties. Energy crops, including Salix viminalis L., Miscanthus × giganteus, and Panicum virgatum L., along with Helianthus tuberosus, were cultivated in three replications to ensure research reliability. The study assessed changes in physicochemical soil properties, nutrient availability, and heavy metal accumulation within the soil-plant-ash continuum. Results indicated that compost application improved soil fertility, increased biomass yields, and influenced heavy metal dynamics, with variations depending on the applied compost type and dosage. The findings highlight the potential of sewage sludge composts to enhance soil productivity while maintaining environmental safety. Full article

This paper reviews methods of municipal sewage sludge (MSS) disposal in the Republic of Poland. The MSS amount produced in 2022 in sewage treatment plants is 580.7 thousand tons of total solids. This is related to the increase in the amount of treated sewage and the use of the co-digestion of sewage sludge with waste. MSS generated in municipal sewage treatment plants constitutes waste with code 19 08 05—stabilized MSS. It is subjected to the rules of conduct specified in the Act on Waste. According to data from the Central Statistical Office, in 2022, the most popular disposal method was its use in agriculture (27.1%). Approximately 18% of the MSS from treatment plants was thermally treated. A significant part of MSS is also used for crops, compost production, and reclamation. MSS management requires an individual approach from sewage treatment plant operators and the use of effective disposal methods. Considering the assumption of the circular economy, it is necessary to consider the possibility of recovering valuable raw materials from MSS and producing products for reuse. One of the possibilities of reusing MSS is to generate porous materials. Moreover, MSS can be transformed into multiple types of soil improvers and fertilizers. Full article

This study investigates the effects of compost and vermicompost derived from sewage sludge and moulded pulp on wheat yield, nutrient uptake, photosynthetic activity, and drought resistance. Optimal weather conditions in March facilitated timely wheat sowing, contributing to ideal yields, while subsequent higher temperatures and rainfall influenced grain formation and weight. The experiment demonstrated that vermicompost significantly enhances plant physiological and yield parameters, including photosynthetic activity, chlorophyll content, and water use efficiency. Fertilized variants exhibited improved soil properties, leading to higher grain and straw yields compared to the control. Macronutrient uptake was notably higher in vermicompost-treated variants, with variant VI showing the highest values. Enhanced photosynthetic activity and drought resistance were observed in fertilized variants, attributed to better stomatal regulation and osmotic adjustment under stress conditions. The study underscores the role of vermicompost in promoting sustainable agriculture by improving nutrient availability, soil structure, and plant resilience. These findings suggest that compost and especially vermicompost applications can effectively enhance wheat productivity and resilience, offering a sustainable approach to improving crop performance under varying environmental conditions. Full article

This article examines the process of pressure agglomeration of garden waste compost mixed with sewage sludge ash (SSA) to produce granulated fertilizer material, using a flat die rotating compaction roller system. The study evaluated the effects of adding SSA at mass fractions of 0%, 10%, 20%, 30%, 40%, and 50% on the process of pelleting and the quality of pellets. Increasing the SSA content from 0% to 50% reduced the power demand of the pellet mill by 13.5% (from 4.92 kW to 4.25 kW), decreased the kinetic strength of the pellets by 0.7% (from 98.21% to 97.56%), and slightly increased the pellet density, by 2.6% (from 1641.17 kg·m⁻³ to 1684.09 kg·m⁻³). The high density of the pellets, i.e., over 1600 kg·m⁻³, indicates that they are of market quality. A chemical analysis revealed that SSA addition positively influenced fertilizer properties. A higher SSA content (up to 50%) decreased the nitrogen content (1.4% to 0.73%) but significantly increased the phosphorus content (0.32% to 2.67%). The potassium content remained stable, at approximately 1.3%. The process of co-pelleting also diluted the heavy metals present in SSA, reducing the final product’s lead and cadmium levels to meet the standards set for fertilizers. Although the SSA contained high levels of heavy metals (lead: 93.89 mg·kg_d.m.⁻¹, cadmium: 11.28 mg·kg_d.m.⁻¹), these elements were not detected in the compost. Co-pelleting of compost and SSA produces high-density, high-quality fertilizer pellets with favorable nutrient profiles and heavy metal contents, complying with regulatory standards. Moreover, by converting garden waste and SSA into valuable agricultural products, the process supports sustainable waste management. This study evaluated the impact of SSA additives on the composition and water absorption of the granulate, providing insights into its suitability as an eco-friendly fertilizer alternative and its potential implications for sustainable agricultural practices. Full article

The use of some organic fertilizers may raise concerns about the transfer of hazardous substances to soil and plants. This study examined the impact of soil amendment with compost and vermicompost derived from sewage sludge and straw pellets in different ratios on the accumulation of pharmaceuticals and personal care products (PPCPs) by hemp (Cannabis sativa L.). The concentrations of fifty different PPCPs were measured in compost-treated soil, and in the roots and above-ground biomass of cannabis grown on the soil. The highest bioaccumulation of PPCPs was recorded in plants from previously unfertilized soils low in organic matter, while the lowest concentrations were measured in soil amended with compost or vermicompost made from straw pellets only, without sewage sludge. The effect of sludge-derived compost and vermicompost application on the absorption of PPCPs was statistically determined by measurements in soil samples, roots and shoots of carbamazepine, cetirizine, lamotrigine, telmisartan, paraxanthine, tramadol, triclosan, and venlafaxine. The above-ground biomass exhibited lower PPCP content than roots, suggesting a potential plant defense mechanism for limiting contaminant translocation. Only tramadol and carbamazepine showed significantly increased content in above-ground biomass. Full article

This study evaluates the environmental performance of stabilised sewage sludge used as a circular fertiliser across three European regions: Central, Mediterranean, and Northern Europe, comparing its performance against non-renewable fertilisers. The research applies a life cycle assessment approach, considering a mix of the most used stabilisation technologies in each region, such as anaerobic digestion, chemical treatment, thermal drying, composting, and aerobic digestion. Environmental impacts were assessed based on key categories, including climate change, acidification, eutrophication, and resource use. The environmental performance of circular fertiliser production outperformed non-renewable fertilisers in all assessed categories, showcasing its potential as a sustainable alternative. Findings reveal that the choice of stabilisation process is key to the overall environmental performance of the region. High energy-driven technologies such as thermal drying present the bigger impacts. Regional disparities highlight the need for context-specific technology selection to optimise environmental outcomes. The study underscores the importance of integrating energy recovery and nutrient recycling in sludge management practices. These findings advocate for the promotion of circular fertilisers within a sustainable agricultural framework, emphasising technology adaptation based on local conditions to enhance ecological and economic benefits. Full article