Search Results (195)

Application of CFA-treated biosolids (NVS) offers multiple benefits to agricultural soils, including fertilizer replacement, soil rehabilitation, and disinfection. It also poses a heavy metal(loid)s threat to the agro-environment. NVS (and CFA to some extent) was tested in lysimeter and field trials, using soils differing in physicochemical properties and a large selection of crops. Consistently, As, Pb, and Cd concentrations in leachate were at or below detection limit, and these and other heavy metal(loid)s (and P) were within the permitted range in plant tissue. Foliage Mo (occasionally also Se, P) concentrations often increased significantly, especially in crops (legumes, potatoes) grown on marginal soils, which also displayed significantly higher yields. CFA and NVS reduced lettuce and legumes foliage Mn (and occasionally Zn) concentrations, which remained, however, adequate. NVS (214 and 642 mT ha⁻¹), digested sewage sludge (ADS) and its compost (24 and 72 mT ha⁻¹), temporarily increased the DTPA-extractability of some elements (NVS: B, Cr; ADS: Cu, Ni, Zn; Compost: Zn) 10–30-fold. The extractabilities of Fe and P increased by up to six times. These increases vanished soon after additive application, supporting the hypothesis of ‘self-attenuation’ by applied biosolids. Our data indicate that long-term application of NVS (and CFA) to calcareous soils poses no heavy metal(loid)s-related threat to the agro-environment. Full article

The growing medium is one of the key factors determining the yield and quality of lavender oil. The research conducted in greenhouse conditions aimed to assess the impact of a substrate with a reduced peat content enriched with compost from sewage sludge and bark on the growth, yield, and chemical composition of the oil from the inflorescences and leafy stems of English lavender ‘Sentivia Blue’. The plants were grown in pots filled with peat and chemical fertilizer, or in a substrate containing bark and sewage sludge compost, with or without fertilizer. Media affected the growth, leaf greenness index, and biomass production of lavender. Plants growing in peat with fertilizer were the tallest and widest. In turn, the highest number of inflorescences and the highest dry weight of inflorescences and leafy stems were found in plants grown in a mixture of bark and sewage sludge compost, with the addition of fertilizer. A significant interaction between the plant organ and the type of substrate was demonstrated, which affected the content of specific oil components. The content of essential oil was higher in inflorescences (1.15%) than in leaves (0.21%). The oil from the inflorescences was dominated by linalool, caryophyllene oxide, and linalyl acetate, while caryophyllene oxide, borneol, and geranyl acetate dominated in the leafy stems. The highest linalool content was found in oil obtained from inflorescences of plants grown in both media, based on bark and sewage sludge compost. The results show that the best quality parameters of the raw material and oil, including particularly high dry weight and linalool content, were obtained when the plants were grown in a medium consisting of bark, sewage sludge compost, and chemical fertilizer. Full article

The excessive use of synthetic fertilizers in agriculture has raised environmental concerns, prompting the search for sustainable alternatives, such as organic amendments. This study evaluated the agronomic performance, nutrient use efficiency and metabolomic profiles of lettuce (Lactuca sativa L. var. baby leaf) cultivated using synthetic and organic (olive mill waste-based compost pellets and sewage sludge) in a controlled pot experiment. The treatments included three doses of inorganic fertilizer and two organic fertilizers applied at equivalent nitrogen (N) rates, alongside an unfertilized control. Soil physicochemical properties, plant biomass, nutrient uptake and metabolite profiles, including amino acids, sugars and organic acids, were analyzed. Inorganic fertilization rapidly increased soil mineral N and phosphorus (P), enhancing leaf chlorophyll, canopy development and fresh biomass, and promoting the accumulation of reducing sugars (p < 0.05). However, it reduced amino acid and phenolic levels, indicating a metabolic shift towards growth at the expense of stress and antioxidant compounds. Sewage sludge increased soil organic matter and amino acid and sucrose accumulation, but also induced stress-related metabolites. Pelletized compost maintained an intermediate level of nutrient availability, preserved phenolic compounds and improved phosphorus use efficiency. This surpassed the results achieved with sewage sludge in terms of dry matter yield, despite limited short-term growth stimulation. These findings highlight the potential of integrating moderate mineral fertilization with pelletized compost to balance immediate productivity, nutrient efficiency and long-term soil and metabolic quality in lettuce cultivation. Full article

Composted sewage sludge (CSS) applications and the use of plant growth-promoting bacteria (PGPB) are emerging as sustainable alternatives in tropical agriculture. However, no studies have validated the combined use of these practices. This study aimed to evaluate the residual effect of three CSS applications on soil fertility (0.0–0.2 m and 0.2–0.4 m layer), plant nutrition, morphological and yield components, and grain yield and quality of soybean, with and without co-inoculation of Bradyrhizobium japonicum combined with Azospirillum brasilense, under a no-tillage system (NTS) in the Cerrado region. The field experiment was conducted over a six-year period in Selvíria, Mato Grosso do Sul, Brazil. This research was evaluated during the 2022/23 first cropping season. The experimental design was a randomized complete block with four replicates, arranged in a 5 × 2 + 1 factorial scheme, consisting of five cumulative CSS rates (0.0, 15.0, 22.5, 30.0, and 37.5 Mg ha⁻¹, wet basis), with and without co-inoculation of A. brasilense, plus an additional control treatment with conventional mineral fertilization (CMF). The residual effect of the cumulative CSS rates improved soil fertility in both layers, similarly to CMF, regardless of co-inoculation. Co-inoculation with Bradyrhizobium japonicum and Azospirillum brasilense did not influence the soybean variables assessed. We found that the 24.7 Mg ha⁻¹ CSS accumulated rate yielded the highest soybean yield (4990 kg ha⁻¹). CSS can be used as an organic fertilizer in soybean cultivation, helping to improve the efficiency of mineral fertilizers while ensuring environmentally friendly disposal of municipal sewage sludge. Full article

Linear alkylbenzene sulfonates (LAS) are one of the organic pollutants of most concern in sewage sludge due to their widespread occurrence in domestic sewage. In this work, the occurrence of LAS was assessed in 15 wastewater treatment plants (WWTPs), with different sludge stabilization treatments, from September 2023 to March 2024. Samples were analyzed by ultrasound-assisted extraction and LC-MS/MS. In primary sludge, LAS homologues displayed the typical fingerprint of laundry detergents, suggesting these products are a primary source in influent wastewater. There was no clear correlation between the population served and the LAS concentrations in the studied WWTPs. The highest concentrations of LAS (sum of the homologues C10–C13) were found in anaerobic lagoons, followed by aerobically (6438 mg/kg) and anaerobically digested (5521 mg/kg) sludge. The lower levels were observed in composted sludge (215 mg/kg). 100% of the composted samples showed concentrations lower than 2600 mg/kg (concentration limit currently proposed by the EU for LAS), while these percentages were reduced to 25 and 13% in the case of aerobically and anaerobically digested sludges. These results showed that composting could be an effective method for ensuring compliance with a future EU Directive on sludge application to the soil. Full article

In recent decades, the urban population of Ecuador has grown, increasing the need for wastewater sanitation in cities. Wastewater treatment in this country generates sewage sludge (SS), which is mainly deposited on land near wastewater treatment plants or in sanitary landfills, generating significant environmental impacts. In view of this, composting or vermicomposting of SS can be suitable treatments for this waste, and the final materials obtained can be used as organic amendments. The objective of this study was to compare the agronomic and economic aspects of composting and vermicomposting using the same SS mixtures with different plant residues. For this purpose, the evolution of various physicochemical and biological parameters of both processes, the quality of the materials obtained, and the costs of their production were evaluated. The results revealed that all the amendments presented characteristics suitable for safe agricultural use. The vermicomposts had significantly lower levels of salts and higher levels of most macro- and micronutrients than the composts, thus increasing their economic value. However, the average production cost of composts was lower than that of vermicomposts, with faster stabilization of organic matter. All of this indicates that both techniques could be suitable for treating SS, but in order to choose the most appropriate technique for the study area, further studies with other waste mixtures and agricultural validation of the composts and vermicomposts obtained, as well as control of possible contaminants, would be required. Full article

The replacement of peat in horticultural substrates is a priority for sustainable plant production. This study evaluated compost and vermicompost, derived from vine pruning and sewage sludge, as partial peat substitutes in cucumber (Cucumis sativus L.) seedling production. Germination, early growth traits, growth efficiency indices, and leaf nutrient contents were assessed, and the relationships among variables were explored using correlation analysis and principal component analysis. Five substrates were tested: peat-perlite alone (control) and mixtures containing 10%, 20%, or 40% compost or vermicompost as peat replacements. Results showed that incorporating 10% vermicompost significantly improved germination, seedling vigor, and biomass accumulation, with performance comparable to, or exceeding, the control. In contrast, higher proportions of compost or vermicompost negatively affected germination and seedling quality. Nutrient analysis revealed that 10% vermicompost enhanced Ca and K accumulation, traits positively correlated with growth, whereas 20% compost and 20% vermicompost were associated with higher P and Mg contents but reduced seedling performance. Overall, these promising findings demonstrate that a low proportion of vermicompost (10%) is sufficient to successfully partially replace peat in cucumber seedling production, benefiting both performance and sustainability, whereas higher compost or vermicompost levels disrupt nutrient balance and limit this species’ growth. Full article

The rising demand for sustainable agriculture and circular resource management has intensified interest in converting wastewater sludge into value-added products. This review explores the transformation of sewage sludge into slow- and controlled-release fertilizers (CRFs), with a focus on biochar production and encapsulation technologies. Sewage sludge is rich in essential macronutrients (N, P, K), micronutrients, and organic matter, making it a promising feedstock for agricultural applications. However, its use is constrained by challenges including compositional variability, presence of heavy metals, pathogens, and emerging contaminants such as microplastics and PFAS (Per- and Polyfluoroalkyl Substances). The manuscript discusses a range of stabilization and conversion techniques, such as composting, anaerobic digestion, pyrolysis, hydrothermal carbonization, and nutrient recovery from incinerated sludge ash. Special emphasis is placed on coating and encapsulation technologies that regulate nutrient release, improve fertilizer efficiency, and reduce environmental losses. The role of natural, synthetic, and biodegradable polymers in enhancing release mechanisms is analyzed in the context of agricultural performance and soil health. While these technologies offer environmental and agronomic benefits, large-scale adoption is hindered by technical, economic, and regulatory barriers. The review highlights key challenges and outlines future perspectives, including the need for advanced coating materials, improved contaminant mitigation strategies, harmonized regulations, and field-scale validation of CRFs. Overall, the valorisation of sewage sludge into CRFs presents a viable strategy for nutrient recovery, waste minimization, and sustainable food production. With continued innovation and policy support, sludge-based fertilizers can become a critical component of the green transition in agriculture. Full article

Mining activities often result in ecosystem degradation and landscape destruction. The restoration of abandoned mine lands is particularly challenging due to the poor physicochemical properties and low fertility of the soil, which necessitate the use of soil amendments. Sewage sludge, which contains abundant nutrients, has potential for use in mine soil restoration. Four separate piles of sewage sludge, each weighing 5 tons, were subjected to aerobic composting and then applied at different rates (0%, 2%, 5%, 10%, and 20%) to reclaim an abandoned mine land site (500 m²). During the composting process, the pH, moisture content, organic matter (OM), and dissolved organic matter (DOM) of the sewage sludge all decreased, while electrical conductivity (EC) and germination index (GI) increased. The sewage sludge compost reached maturity after 83 days. Soil pH and bulk density decreased with increasing application levels, whereas soil fertility, such as OM, alkali-hydrolyzable nitrogen, available phosphorus (AP), and available potassium (AK), significantly improved after application of sewage sludge compost. Vegetation coverage (ryegrass and alfalfa) reached 100% after 2 months at the 20% application level. Fresh biomass and plant height were significantly higher at all application levels compared to the control (p < 0.05). Results from Pearson’s correlation, redundancy analysis (RDA), and the random forest model indicated that soil fertility, particularly AP, OM, and alkali-hydrolyzable nitrogen, rather than soil physicochemical properties, was the key factor influencing the restoration success of the mine site. The use of sewage sludge compost as a soil amendment for reclaiming abandoned mine lands is feasible and can help reduce the ecological restoration costs of mining. Full article

Organic fertilisers release nutrients more slowly than mineral fertilisers, which is why combining organic and mineral fertilisation gives good results in crop cultivation. In the conducted pot experiment, the reaction of oats to compost fertilisation with or without additional nitrogen mineral fertilisation was examined. The following treatments were used: A, control (no fertilisation); B, compost (sewage sludge 80% + sawdust 20%); C, compost (garden and park waste 80% + sawdust 20%); D, compost (sewage sludge 40% + garden and park waste 40% + sawdust 20%); E, compost B with nitrogen fertilisation (30 N kg ha⁻¹); F, compost C with nitrogen fertilisation (30 N kg ha⁻¹); and G, compost D with nitrogen fertilisation (30 N kg ha⁻¹). The study results indicated that the composts used had an altering impact on the soil’s chemical composition by the end of the experiment. Overall, the lowest levels of nutrients were recorded in the control group, indicating that the composts increased soil fertility. Oat plants were better nourished (SPAD—soil–plant analysis development) after fertilisation with sewage sludge composts than garden and park waste composts. However, the most favourable results were obtained in the treatments where organic fertilisation (composts) was combined with mineral fertilisation (nitrogen). All fertilisation treatments significantly enhanced plant height and the number of panicles in the pot compared to the control. The highest values for the number of grains in the panicle, thousand-grain weight, grain mass from the pot, and protein content in the grain were observed after applying organic–mineral fertilisation. Therefore, fertilisation with composts, especially composts combined with mineral nitrogen, can be recommended for oat cultivation. Full article

Composting organic waste enhances soil fertility, supports plant growth, and offers a sustainable waste management strategy. This study evaluated the agronomic potential of three compost types derived from unconventional sources: (i) sewage sludge, (ii) slaughterhouse animal by-products (ABPs), and (iii) cheese industry waste. The impact of Trichoderma harzianum strain T-22 inoculation was also assessed in relation to the early development of durum wheat (Triticum turgidum subsp. durum) under greenhouse conditions. Compost type significantly influenced plant emergence and growth, with sewage sludge-based compost showing the best performance. T. harzianum T-22 inoculation produced mixed results; it improved growth in specific combinations (CS-1/3 and CA-1/4) but inhibited it in others (particularly CW-based composts). These findings underscore the importance of compost source selection and highlight that microbial inoculation effects are substrate-dependent. This work supports sustainable composting practices and fungal waste valorization to optimize plant growth in sustainable agriculture. Full article

Antimicrobial resistance (AMR) has emerged as a planetary health emergency, driven not only by the clinical misuse of antibiotics but also by diverse environmental dissemination pathways. This review critically examines the role of environmental compartments—water, soil, and air—as dynamic reservoirs and transmission routes for antibiotic-resistant bacteria (ARB) and resistance genes (ARGs). Recent metagenomic, epidemiological, and mechanistic evidence demonstrates that anthropogenic pressures—including pharmaceutical effluents, agricultural runoff, untreated sewage, and airborne emissions—amplify resistance evolution and interspecies gene transfer via horizontal gene transfer mechanisms, biofilms, and mobile genetic elements. Importantly, it is not only highly polluted rivers such as the Ganges that contribute to the spread of AMR; even low concentrations of antibiotics and their metabolites, formed during or after treatment, can significantly promote the selection and dissemination of resistance. Environmental hotspots such as European agricultural soils and airborne particulate zones near wastewater treatment plants further illustrate the complexity and global scope of pollution-driven AMR. The synergistic roles of co-selective agents, including heavy metals, disinfectants, and microplastics, are highlighted for their impact in exacerbating resistance gene propagation across ecological and geographical boundaries. The efficacy and limitations of current mitigation strategies, including advanced wastewater treatments, thermophilic composting, biosensor-based surveillance, and emerging regulatory frameworks, are evaluated. By integrating a One Health perspective, this review underscores the imperative of including environmental considerations in global AMR containment policies and proposes a multidisciplinary roadmap to mitigate resistance spread across interconnected human, animal, and environmental domains. Full article

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