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The escalating production of biosolids from wastewater treatment plants presents significant environmental and health challenges due to the presence of pathogens, trace organic pollutants, and heavy metals. Transforming biosolids into biochar through pyrolysis offers a sustainable solution, enhancing soil fertility and mitigating greenhouse gas emissions. This review critically evaluates the pyrolysis processes (slow, fast, and flash) for biosolid conversion and examines the impact of biosolid-derived biochar on soil nutrient retention, crop productivity, and greenhouse gas emissions. Findings from various studies demonstrate that BDB can significantly reduce emissions of N2O, CH4, and CO2 while improving soil health. However, challenges such as standardizing production methods, addressing heavy metal content, and ensuring economic feasibility must be overcome. Future research should focus on optimizing pyrolysis conditions, developing regulatory frameworks, and conducting comprehensive economic analyses to support the large-scale implementation of BDB in sustainable agriculture. [ABSTRACT FROM AUTHOR]

Purpose: Sewage sludge compounds possess physical and chemical attributes that make them well-suited for formulating fertilizers intended for agricultural purposes. Within this framework, the research aimed to assess the effects of utilizing organomineral fertilizers derived from sludge on soil fertility and chickpea yield. Method: The study was conducted in a randomized complete block design, with five replications, in a 2×2+2 factorial scheme, consisting of two organic sources for organomineral fertilizer production (composted sludge - SC or sludge biochar - SB), two fertilizer forms (granular-GRA or powder-POW), and two additional controls (mineral fertilization with NPK at a 04:15:04 ratio, and unfertilized-NF). The chickpea production and soil chemical attributes were characterized. Results: The organomineral fertilization with composted sewage sludge and sewage sludge biochar, in the forms of powder or granules, increased soil fertility, and enhanced production characteristics. Fertilization with LC and BL resulted in soil organic carbon (OC) content of 8.00 and 8.60 g/kg, while treatments with NPK and without fertilization had 6.50 and 7.30 g/kg, respectively. Grain dry matter and total dry matter varied from 4.80 to 5.70 and 17.40 to 19.10 g per plant in fertilized treatments, respectively. In the unfertilized plots, the averages were 0.30 and 3.40 g per plant. Conclusion: The use of organomineral fertilizer consisting of composted sludge or in granulated form increased straw production by 19% and 5.70 times, compared to mineral fertilization and the control (no fertilization), respectively. This indicates the potential for chickpea production similar to that obtained in treatments receiving only mineral fertilization. Research Highlights • Fertilizers from composted sludge or sludge biochar enhance soil fertility. • Organomineral fertilizers increase soil organic matter content. • Organomineral fertilizers enhance soil cation exchange capacity. • Granulation of composted sludge increases chickpea residue production. • Stabilized sludge in powder or granulated form can serve as an alternative fertilizer source. • Organomineral and mineral NPK fertilizers are equivalent in chickpea production.

This study evaluated catabolic gene expression as an index of hydrocarbon breakdown in ultisol treated with Bacillus altitudinis-Cropped Biofertilizers derived from Biosolid and Brewer Spent Grain (BSG) using phenotypic and molecular methods. We observed significant reductions in Total Petroleum Hydrocarbons (TPH) concentrations with both amendments, albeit the biosolid based amendment was markedly more effective. Concurrently, there was a substantial increase in hydrocarbon-degrading bacteria. Notably, the bulk of Operational Taxonomic Units (OTUs) in biosolid (95.77 %) and BSG (93.00 %) amended Ultisol were Proteobacteria, Acidobacteria, Actinobacteria, and Planctomycetes, which are key players in hydrocarbon bioremediation. We observed the presence of eleven hydrocarbon-degrading genes through M5nr analysis. These genes encompass essential catalysts for aliphatic hydrocarbon degradation and hydrocarbon desulfurization. Notably, these enzymes/genes include Bacterial Flavin-bound Monooxygenase (AlmA), Alkane Monooxygenase (AlkM), Alpha Ketoglutarate Dependent Dioxygenase (alkB), Propane Monooxygenase (PrM), Cytochrome P450 (cP450), Methane Monooxygenase/Ammonia Monooxygenase (MMO/AMO) subunits A, B, and C, Alkane Sulfonate Monooxygenase (ssuD), Alkane Sulfonates Transport System Permease Protein (ssuC), Dibenzothiophene Monooxygenase (dszC), Dibenzothiophene-Sulfone Monooxygenase (dszA), and Dibenzothiophene-5,5-Dioxide Monooxygenase (dszB). These genes play pivotal roles in the degradation of aliphatic hydrocarbons and hydrocarbon desulfurization. Interestingly, unique gene expression patterns were observed for each amendment, with Actinomycetales and Bulkhoderiales orders expressing the majority of identified genes. These findings have revealed the amendment-specific microbial and genetic alterations and, the diversity and potential of the annotated genes induced by the Bacillus altitudinis-Cropped Biofertilizers (biosolid and BSG amendments) for effective remediation of hydrocarbon-contaminated soils.

• Pulp and paper mill sludge (PPMS) landfill sites have GHG assessment challenges. • GHG fluxes measured by chambers with (F +) and without (F-) a frame were compared. • Flux relationships up to 80 % were shown between F- and F + chambers (the standard) • Correction factors for F- chambers were built to estimate fluxes from F + chambers. • The approach can refine GHG inventories on PPMS landfill sites. Assessments of greenhouse gas (GHG) emissions in managed areas are facing various challenges. A non-flow-through, non-steady-state (NFT-NSS) chamber coupled to a frame permanently inserted into the landfilled substrates is a standard method for quantifying GHG emissions in managed areas, such as pulp and paper mill sludge (PPMS) landfill sites. Frequent measurements are needed to minimize uncertainties on GHG emission factors at the landfill site scale. However, maintaining a frame inserted into the substrates for a long time period is often impossible due to landfilling management operations. Therefore, GHG measurements using NFT-NSS chambers placed directly on substrates' surface could be an interesting option. Our objectives were to determine the relationships between CO 2 , CH 4 , and N 2 O fluxes measured with (F +) and without (F-) a frame inserted in the substrates' surface and to develop correction factors for fluxes measured without a frame. Measurements were made at different PPMS landfill sites in the province of Québec, Canada. Stronger GHG flux relationships were observed at the provincial (across sites) than the specific site scale: the variance in GHG fluxes from F- chambers explained up to 80 % of variance in fluxes from F + chambers. The measured CO 2 , CH 4 , and N 2 O fluxes in F- chambers were on average 53, 78, and 63 % lower, respectively, than those estimated by the models at provincial scale. The correction factors developed with this approach could greatly extend the number of sites where in situ GHG measurements can be done and would help refining GHG inventories at the provincial and national levels. [ABSTRACT FROM AUTHOR]

Organo-mineral fertilizers (OMFs) can have higher efficiency than mineral fertilizers. In Europe, peat is commonly used as an organic matrix in OMFs, as it is a highly stable organic material. However, peat extraction releases long-term stored organic C. Stabilized biowaste materials could replace peat in OMFs. Thus, this study aimed to understand how the variety of chemical properties in biowastes can influence OMF-soil interactions and nutrient availability to plants. Peat, green compost (GC), municipal solid waste compost (MSWC), and vermicompost (VC) were used as the organic matrix of OMFs with a C-N-P2O5 content of 7.5, 10, and 5%, respectively. OMFs were tested first in a ten-day plant-free incubation to measure Hedley P fractionation, nitrate, ammonium, total N in the soil, and CO2 and NH3 emissions. Further, a 30-day greenhouse trial measured maize yield and N and P use efficiencies. Controls included no fertilization (N0P0) and mineral N and P fertilization (MFNP). No differences were found in the incubation experiment for mineral N fractions in the soil. Fertilization significantly increased CO2 emissions, which were slightly higher in OMFs over MFNP, whereas OMFs significantly increased ammonia volatilization compared to MFNP. Available P had consistent results in the incubation and the greenhouse trials. Peat and MFNP had the highest water-and bicarbonate-P pools in the first experiment and higher yield and P use efficiency by maize. Therefore, OMFs from biowaste materials exhibited limited suitability for short growth cycles due to lower P use efficiency and higher ammonia volatilization. [ABSTRACT FROM AUTHOR]

The stabilized sewage sludge, biosolid, has been widely investigated but despite numerous studies few ones have monitored the retention potential of metal ions of this material. This study aimed to investigate the zinc retention in biosolid-soil mixtures with different biosolid contents. The potential of zinc retention was evaluated using a physical model in a geotechnical centrifuge. The physical model was designed to represent a waste barrier of 3.75 m and to simulate a 1-year zinc percolation through the biosolid-soil layer. During the percolation, the zinc effluent was collected to monitoring its concentration over the time. Results show that the addition of 50% of biosolid in the soil, among other investigated proportions provided reductions up to 95% of the initial zinc concentration, considering a 300 days zinc percolation, while the natural soil, for the same period, provided reduction of 33%. The results clearly demonstrate that the incorporation of biosolid in the soil improved the zinc retention capacity. Chemical analysis suggested that the retention behavior of the biosolid is associated with the presence of organic matter and the pH value. The results are promising regarding the use of biosolid-soil mixtures in waste landfill barriers. [ABSTRACT FROM AUTHOR]

This study evaluated the levels of heavy metals in the soil and castor bean plant after fertilization with sewage sludge (SS) subjected to different stabilization processes. The study was conducted in a Haplic Cambisol with the following treatments: control (CO), fertilization with solarized sewage sludge (SSS), composted sewage sludge (CSS), vermi composted sewage sludge (VSS), limed sewage sludge (LSS), and mineral fertilizer (MF). The experimental design included a subdivided plot scheme with fertilization being the primary factor and soil layers or leaf parts being the secondary factor. The data obtained were analyzed using analysis of variance and the Scott-Knott test with 5% significance. Fertilization with SSS, CSS, and LSS led to the highest increase in Zn in the soil, mainly in the surface layer. In the leaf tissues, Zn and Cu levels were higher with the CO and SSS treatments, whereas the Ni level was higher with SSS, CSS, VSS, and MF treatments. In general, Zn and Cu levels were higher in the leaf limb than in the petiole, whereas Ni, Pb, and Cr levels were higher in the petiole than in the leaf limb. In any case, no symptoms of toxicity in the plants and no risk of soil contamination were observed with any of the fertilization treatments. [ABSTRACT FROM AUTHOR]

Organo-mineral fertilizers (OMFs) can have higher efficiency than mineral fertilizers. In Europe, peat is commonly used as an organic matrix in OMFs, as it is a highly stable organic material. However, peat extraction releases long-term stored organic C. Stabilized biowaste materials could replace peat in OMFs. Thus, this study aimed to understand how the variety of chemical properties in biowastes can influence OMF-soil interactions and nutrient availability to plants. Peat, green compost (GC), municipal solid waste compost (MSWC), and vermicompost (VC) were used as the organic matrix of OMFs with a C-N-P2O5 content of 7.5, 10, and 5%, respectively. OMFs were tested first in a ten-day plant-free incubation to measure Hedley P fractionation, nitrate, ammonium, total N in the soil, and CO2 and NH3 emissions. Further, a 30-day greenhouse trial measured maize yield and N and P use efficiencies. Controls included no fertilization (N0P0) and mineral N and P fertilization (MFNP). No differences were found in the incubation experiment for mineral N fractions in the soil. Fertilization significantly increased CO2 emissions, which were slightly higher in OMFs over MFNP, whereas OMFs significantly increased ammonia volatilization compared to MFNP. Available P had consistent results in the incubation and the greenhouse trials. Peat and MFNP had the highest water-and bicarbonate-P pools in the first experiment and higher yield and P use efficiency by maize. Therefore, OMFs from biowaste materials exhibited limited suitability for short growth cycles due to lower P use efficiency and higher ammonia volatilization.

Biosolid applications based on crop nitrogen (N) demand have been widely adopted to attenuate nitrate leaching. However, due to the dependence of N supply on the mineralization rate and the early release of the majority of the mineralizable N, there are concerns about a compromise in crop yield and groundwater. A two-year field lysimeter study was conducted to verify whether higher nitrate leaching from biosolid at the early growth stage would compromise maize yield compared to a two-split inorganic N fertilizer application. Four treatments (biosolid + humid rainfall, inorganic fertilizer + humid rainfall, biosolid + subhumid rainfall, inorganic fertilizer + subhumid rainfall) replicated three times were randomly allocated to 12 lysimeters. Overall, the cumulative nitrate leaching from biosolid application was comparable to inorganic fertilization. Nitrate leaching at the early (V0–V14) growth stage of maize from biosolid was lower than inorganic fertilizer, except in the second year under humid rainfall. However, nitrate leaching did not compromise maize yield. Thus, biosolid application based on crop and site specificity can replace inorganic fertilizer in maize cultivation. Further studies may need to ascertain the findings in the humid agro-ecological zone because of the high soil N residue observed under biosolid-humid rainfall treatment.

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Objetivou-se avaliar o crescimento inicial de Citharexyllum myrianthum sob a influência de três fontes de adubos de plantio, em condições de vasos de 18 L. Os tratamentos utilizados foram: testemunha absoluta; 5 L de biossólido/vaso; 300 g de fosfato natural de rocha (FNR) e 200 gramas de NPK 06-29-06. As mudas foram cultivadas nos vasos a pleno sol, complementados com Latossolo Vermelho Amarelo distrófico. Aos 150 dias após transplantio, as plantas foram mensuradas, obtendo-se a altura da parte aérea e o diâmetro do coleto. Em seguida foi calculado o incremento dessas duas variáveis. Posteriormente, as folhas foram retiradas para determinação da área foliar (AF), separando-se a parte aérea do sistema radicular, sendo acondicionados em saco de papel e colocados em estufa a 65°C, para secagem até atingir peso constante. Após pesagem deste material para obtenção da massa seca da parte aérea (MSPA) e radicular (MSR), as folhas foram moídas para a determinação dos teores foliares de N, P, K, Ca e Mg. Para avaliar o efeito dos tratamentos sobre o solo, retirou-se amostras dos vasos para a determinação dos teores de macronutrientes, matéria orgânica e CTC(t). Foi constatado que a AF e MSPA das plantas adubadas com NPK apresentaram valores significativamente superiores quando comparado as plantas cultivadas no tratamento testemunha. Indica-se adubar as plantas de Citharexyllum myrianthum com 200 gramas de N-P-K 06-29-06/cova ou com 5 L de biossolido/cova. [ABSTRACT FROM AUTHOR]

[Display omitted] • Microplastics (MPs) properties in biosolid and biosolid-amended soils were assessed. • Higher MPs fibres than fragments observed in biosolids and biosolid-amended soils. • PET and PE were major MPs in biosolids and biosolid-amended soils, respectively. • Biosolid amendment had higher impact on fitness of Eisenia than Amynthas species. • Earthworms had no preference for ingestion of different MPs sizes from biosolid. Microplastics (MPs) are a major emerging contaminant in agroecosystems, due to their significant resistance to degradation in terrestrial environments. Although previous investigations have reported the harmful effects of MPs contamination on soil biological properties, still little is known about the characteristics and fate of MPs in biosolid-amended soils and their risks to soil biota, particularly earthworms. We determined microplastics' concentration, size distribution, and chemical composition in 3 sewage sludge biosolids and 6 biosolid-amended agricultural soils. In addition, we assessed the potential short-term risks of MPs to earthworms' (Amynthas Gracilis and Eisenia Fetida) survival rate and fitness in an environmentally relevant exposure study (28 days). Biosolid-amended soils (1000–3100 MPs kg−1 dry mass) showed ≈30 times lower MPs content than investigated biosolids (55400–73800 MPs kg−1 dry mass), with microplastic fragment to fibre ratios between 0.2 and 0.6 and 0.3–0.4 in soils and biosolids, respectively. Total MPs dry mass was also ≈19 times lower in assessed soils (12–26 mg kg−1) than biosolids (328–440 mg kg−1). On average 77% and 80% of plastic fragments had a lower dimension than 500 µm, while 50% and 67% of plastic fibres had a length of less than 1000 µm in soil and biosolid samples, respectively. Polyethylene (23.6%) was the major source of microplastic contamination in biosolid-amended soils, while polyethylene terephthalate (41.6%) showed the highest concentration in biosolid samples. Spiked polyethylene MPs did not show any significant effect on earthworms' survival rate (93–99%). However, biosolid application significantly (P < 0.05) decreased survival rate of Eisenia Fetida (81%) but showed no significant effect on Amynthas Gracilis (93%). Biosolid amendment significantly (P < 0.05) decreased earthworms' growth rate, with higher impact on Eisenia Fetida than Amynthas Gracilis , while there were no significant differences between control and microplastic spiked treatments. The overall decrease in MPs concentration of earthworm casts, compared with initial MPs concentrations in soil, indicated that the investigated species did not bioaccumulate MPs during the exposure experiment. [ABSTRACT FROM AUTHOR]

Biomethanation and dewaterability characteristics of primary sludge (PS), secondary sludge (SS) and mixed sludge (MS) fractions were assessed after anaerobic stabilization under parallel batch and continuous mixing conditions at 35°C in order to investigate the performance of the separate digestion system. Similar methane conversion/yield values were obtained in PS, SS and MS digestion with continuous mixing's positive effect only in PS digestion. Continuous mixing resulted in 50% increase in the methane yield (600(+/-100) mL/g VSadd.d. SS digestion produced a comparable methane yield at 650(+/-100) mL/g VSadd.d showing no effect due to mixing pattern. Settling and dewaterability characteristics of the stabilized PS were superior to stabilized SS samples. A reverse relationship was obtained between settling and dewaterability characteristics where intermittent mixing enhanced settling ability while continuous mixing resulted in higher dewaterability of the stabilized sludges. Polyelectrolyte (PE) addition showed a negative effect on the settleability of the sludges. Low degree mixing resulted in 50% sludge volume reduction and an SVI of 64 mL/g VS compared to 25% volume reduction and 82 mL/g SVI in the continuous mixing mode for the stabilized PS. A similar trend for the stabilized SS but weaker values with 25% volume reduction and an SVI 182 mL/g in the intermittent mixing mode compared to 15% volume reduction and 200 mL/g VS SVI indicated a much lower settleability in the continuous mixing mode and compared to stabilized PS. [ABSTRACT FROM AUTHOR]

This paper presents the influence of sewage sludge (SS) on the biometric parameters, absorption of mineral elements and thermal characteristics of sweet sorghum (Sorghum bicolor L.) grown on Technosol. Two types of sewage sludge were used: unmodified and modified with DAMET flocculant. Each type of sludge was applied in three doses (expressed as dry matter basis, DM): 20 t DM/ha, 40 t DM/ha and 60 t DM/ha, respectively. The yield of fresh biomass depended on the dose of sewage sludge: it increased by 14.5–41% and reached 104.6 t/ha after application of the sewage sludge with flocculant at a maximum rate of 60 t/ha. Sorghum biomass actively absorbs nutrients from the soil. Nitrogen was absorbed more actively; depending on the type and dose of sewage sludge application, its content in biomass increased from 12–40% (dose of 20 t/ha) to 80–112% (dose of 60 t/ha). By content in sorghum biomass, essential elements can be arranged in descending order as follows: Fe → Mn → Zn → Cu. Sorghum shows a low ability to accumulate some heavy metals in aboveground biomass. Despite the fact that large doses of sewage sludge contributed to an increase in the content of nickel, cadmium and lead in the substrate by 1.8–5.6 times, the ratio of the content of these elements in plants to the content in the substrate remained low. Sewage sludge affects the process of thermal degradation of sorghum biomass. The decomposition of the main components occurs at lower temperatures, and, as a rule, at higher rates. Sewage sludge (especially with flocculant) contributes to a more complete combustion of biomass. The results showed that sewage sludge with flocculant at a dose of 40 t/ha is the most optimal fertilizer option for growing sweet sorghum on such Technosols as loess-like loam. [ABSTRACT FROM AUTHOR]

In the state of Paraná, Brazil, calcined sewage sludge (biosolid) without remediation is used as a fertilizer in different crops, such as soybeans and corn. Evaluated the chemical composition, pathogenic potential, and toxic potential to plants and E. fetida of biosolid produced in the state. The analysis of metals and pathogens, based on the Brazilian Resolution 498/2020 of the National Council for the Environment (CONAMA), classified the residue as suitable for incorporation into crop soils in Brazil. However, all concentrations of the biosolid (6.25, 25, 50, and 100%) caused phytotoxicity to Lactuca sativa, Allium cepa, Cucumis sativus, and Triticum aestivum. A. cepa meristematic cells exposed to the residue revealed division disruption, including clastogenic damage to chromosomes, and death. All concentrations promoted swelling in onion roots, drastic inhibition of ascorbate peroxidase and superoxide dismutase, activation of guaiacol peroxidase, and lipid peroxidation in their meristems. Studies with Eisenia fetida showed biosolid has strong repellent effects and higher concentrations caused 100% mortality. In surviving animals, catalase and guaiacol peroxidase showed higher tissue levels of activity, suggesting a response to increased environmental free radicals, including reactive oxygen species. Therefore, in Paraná, the current and recurring incorporation of biosolids, without adequate remediation, into cropping soils has the potential to trigger extensive oxidative stress in plants and animals, representing an environmental risk. Furthermore, this study brings important elements that advance the understanding of how biosolids trigger phytotoxicity and cellular toxicity in different organisms. [ABSTRACT FROM AUTHOR]

At a strategic moment for agricultural soils, which are expected to contribute to climate change mitigation through carbon storage while safely feeding a growing world population, the fertiliser strategies used will be key. In a calcareous soil with extensive rainfed agricultural use and straw removal, different fertiliser strategies were evaluated with the aim of determining their effects on crop yield, nitrogen agronomic efficiency, and the storage of organic carbon and total nitrogen in the soil. Different doses of mineral fertiliser, expressed as kg of mineral nitrogen ha−1 year−1 (0, 60, 120, 180, and 240 nitrogen fertilising units (NFUs)), were applied to plots with and without biosolid amendment. The biosolid, applied at a rate of 40 Mg ha−1 every 3 years for 18 years, complied with national and European regulations to be applied on agricultural soil. The use of combined fertilisation reduced the amount of mineral fertiliser applied between 33 and 67% and the total fertiliser units between 7 and 40%, while maintaining similar yields to the reference mineral fertilisation (180 NFUs). These results could be related to a higher nitrogen agronomic efficiency in the combined fertilisation treatments that do not exceed the total NFUs required by the crop. Combined fertilisation was also an effective fertiliser technique to store total nitrogen and organic carbon in the soil. However, compared to the reference mineral fertilisation (180 NFUs), no significant changes in the soil organic carbon were observed, probably due to the crop management method in which the straw is removed and to higher gas emissions. Our results support the need to assess the efficacy of each agricultural technique at local scales in order not to overestimate or underestimate the potential of each agricultural technique to store soil organic carbon. [ABSTRACT FROM AUTHOR]

Plastics smaller than 5 mm that end up in a soil environment are known as microplastics (MPs). Microplastics have become a common contaminant in agricultural areas in addition to metals. However, the effect of cadmium (Cd) on soil organisms has not been clearly defined in the presence of MPs. In addition to MPs, biosolid application as a soil amendment in agricultural lands is also leading to shifts in soil conditions, such as the concentrations of nutrients and organic matter. Therefore, the aim of this study is to investigate the toxicity and bioaccumulation of Cd for Enchytraeus crypticus in the presence of polystyrene (PS)‐MPs and biosolids to provide insight into their possible interactions. The lethal toxic concentration (LC50) for Cd was higher than 650 mg Cd/kg dry soil for all conditions. The presence of PS‐MPs increased the toxicity of Cd for which EC50 was 102 and 38 mg Cd/kg dry soil without and with Cd, respectively, which may be the result of an increased exposure rate through adsorption of Cd on PS‐MPs. On the contrary, the presence of biosolids decreased the toxicity of Cd where EC50 was 193 and 473 mg Cd/kg dry soil for the sets applied with 0.6 and 0.9 g biosolids, respectively. Coexistence of biosolids and PS‐MPs decreased the reproduction toxicity of Cd, which is similar to the biosolid effect (EC50 is 305 mg Cd/kg dry soil). Bioaccumulation of Cd only positively correlated with its initial concentration in soil and was not affected by the presence of PS‐MPs or biosolids. Integr Environ Assess Manag 2023;19:489–500. © 2022 SETAC Key Points: Cadmium (Cd) tends to be more toxic for Enchytraeus crypticus when it is found in the soil with polystyrene microplastics (PS‐MPs) than when it is present by itself or combined with biosolids.Polystyrene microplastics can play a vector role for Cd in the soil environment for the other organisms as well.Contrary to the presence of PS‐MPs, high biosolid application (500:22 g dry soil/g dry biosolid) decreased the toxicity of Cd significantly.Bioaccumulation of Cd in E. crypticus is directly related to soil Cd concentration, and the presence of other contaminants does not alter the bioaccumulation potential. [ABSTRACT FROM AUTHOR]

The byproduct of wastewater treatment is called as ‘Biosolid’ whereas the byproduct of infrastructure sector produces construction and demolition (C&D) waste, both leading to major waste disposal problem. The present study evaluates the usage of biosolid as a potential fill material for embankments constructed over soft subgrade. Geotechnical and geochemical characterization of the virgin biosolid (VB) and 40% C&D waste modified biosolid (CNMB) has been conducted to evaluate their potential as fill materials. Consolidation and creep settlement behaviour of a 3m embankment under a traffic load of 20 kPa with VB and CNMB is investigated using Finite Element analysis (Plaxis 2D). Due to the organic nature of VB and CNMB, biodegradation settlement of the embankment is also analytically examined. The embankment with CNMB layer undergoes a settlement of 18.3 mm which is 62.3% lesser than embankment with VB layer over 365 days. The CNMB layer also attains constant rate of biodegradation after 20 years with 48.5 mm settlement which is within permissible limit. It is concluded that 40% C&D waste with biosolid can be used as fill material in embankment over soft subgrade. However, use of virgin biosolid as fill material is not recommended.

Waste from the human food system includes a large quantity of nutrients that pose environmental and human health risks. If these nutrients can be captured and repurposed, they could potentially offset synthetic fertilizer demands. This study reviews several technologies—including anaerobic digestion, hydrothermal carbonization (HTC), and composting—that can be used to process wastes from the human food system. This study also assesses the quantity of nutrient resources that are available from wastes, including food waste, biosolids, manure, and yard waste. Three geographic scales were analyzed. At a national level in the United States, up to 27% of nitrogen and 33% of phosphorus demands for agriculture could be met with wastes from the human food system, primarily from food waste and biosolids. Some rural localities have a greater potential for circular economies of nutrients in the food system, with the potential to meet 100% of nitrogen and phosphorus fertilizer demands using waste nutrients, as in the case of Athens County, Ohio. Benefits of offsetting synthetic fertilizer use with waste nutrients include reduced greenhouse gas (GHG) emissions, with up to 64% reduction in GHG emissions per unit of nitrogen fertilizer produced with HTC.

A large quantity of biosolid is produced worldwide from treated wastewater plants, and it is considered a big challenge to eliminate it in proper and environmentally safe ways. On the other hand, a large quantity of forage needed and was imported from outside to overcome the decrease in local forage production. The objective of this study was to increase the water use efficiency for production of barley biomass as forage crops using biosolid. HIGHLIGHTS Biosolid from treated wastewater plants was introduced at different rates designed to meet nitrogen needs of the plant.; The release of biosolid from treated wastewater plants is the main source of environmental contamination.; Diverse treatments used to improve biomass production and yield of barley were summarized.; Barley biomass yield production with an increase in biosolid application rate was shown to be positive.;

Global waste production is significantly rising with the increase in population. Efforts are being made to utilize waste in meaningful ways and increase its economic value. This research makes one such effort by utilizing gas-to-liquid (GTL)-derived biosolids, a significant waste produced from the wastewater treatment process. To understand the surface properties, the biosolid waste (BS) that is activated directly using potassium carbonate, labelled as KBS, has been characterized using scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), and Brunauer–Emmett–Teller (BET). The characterization shows that the surface area of BS increased from 0.010 to 156 m2/g upon activation. The EDS and XPS results show an increase in the metal content after activation (especially iron); additionally, XRD revealed the presence of magnetite and potassium iron oxide upon activation. Furthermore, the magnetic field was recorded to be 0.1 mT using a tesla meter. The magnetic properties present in the activated carbon show potential for pollutant removal. Adsorption studies of methylene blue using KBS show a maximum adsorption capacity of 59.27 mg/g; the adsorption process is rapid and reaches equilibrium after 9 h. Modelling using seven different isotherm and kinetic models reveals the best fit for the Langmuir-Freundlich and Diffusion-chemisorptionmodels, respectively. Additional thermodynamic calculations conclude the adsorption system to be exothermic, spontaneous, and favoring physisorption. [ABSTRACT FROM AUTHOR]

Recirculating aquaculture systems (RAS) are efficient at solid waste capture and collection but generate a concentrated waste stream. Anaerobic digestion (AD) could be one potential treatment option for RAS facilities. However, the concentration of organic matter in the sludge can significantly affect the biogas quality from AD. This study evaluated the effect of fish sludge (FS) solid concentration on biogas quality. Three FS treatments consisted of different initial total solid concentrations (1.5%, 2.5%, and 3.5%) from a mixture of sludge produced by Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss). Methane (CH4) production was measured, quantified, and normalized on a volatile solids (VS) basis. The highest solid concentration treatment produced 23% more CH4 than the lowest solid concentration (519 mL/g VS versus 422 mL/g VS, respectively). Peak CH4 production occurred on Day 7 for the lowest FS concentration (78.2 mL/day), while the highest FS concentration peaked on Day 11 (96 mL/day). Peak hydrogen sulfide (H2S) concentrations ranged from 1803–2074 ppm across treatments, signifying the requirement of downstream unit processes for H2S removal from biogas. Overall, this study demonstrated that increasing the FS concentration can significantly enhance CH4 production without affecting the stability of the digestion process. [ABSTRACT FROM AUTHOR]

Aims: The present study aimed at: (i) verifying the suitability of pure sewage sludge (SS) as growing medium for the hyperaccumulator species (Pteris vittata, Odontarrhena chalcidica, Astragalus bisulcatus and Noccaea caerulescens); (ii) evaluating the removal of As, Ni, Se and Zn operated by the chosen species; (iii) estimating the potential metal yields (bio-ore production) and connected monetary rewards in a small-scale field experiment. Methods: Hyperaccumulator plants were first tested under controlled conditions, on three different SS (P1, P2, P3) characterized by the presence of one or more contaminants among As, Ni, Se and Zn. P1 sludge was then chosen for a small-scale field experiment. Hyperaccumulator seedlings were transferred on SS and cultivated for 16 weeks before harvesting. Results: All hyperaccumulator species grew healthy on P1 SS, with A. bisulcatus and O. chalcidica reaching an average biomass of 40.2 and 21.5 g DW/plant. Trace metal concentrations in aerial parts were: As (P. vittata) 380 mg/kg DW, Ni (O. chalcidica) 683 mg/kg DW, Se (A. bisulcatus) 165 mg/kg DW, Zn (N. caerulescens) 461 mg/kg DW. The total removal of As, Ni, Se and Zn from SS due to phytoextraction was 5.8, 19, 18, 29% respectively. Conclusions: This study demonstrated that phytoextraction can be applied to SS for the removal contaminants while recovering valuable metals. Se and As were identified as the most promising target element, while Ni and Zn removal was poorly efficient under the present experimental conditions. [ABSTRACT FROM AUTHOR]

The increasing production of biosolids (BS) as a result of urban wastewater treatment generates pollution problems in their management and final disposal, and a better management is needed for their disposal. The composting of BS is an alternative process for obtaining a product with potential application as an organic amendment in the recovery of agricultural soils. As a biotechnological contribution, this study analyzed a composting process with BS, bovine manure (BM) and rice husks using four treatments T1 (C/N = 24); T2 (C/N = 34); T3 (C/N = 44); T4 (C/N = 54) for 120 days, in order to develop compost quality indexes (CQIs) through the analysis of 18 physicochemical, biological and ecophysiological indicators. Subsequently, three methodologies—successfully used on soils—were implemented for the development of the CQIs called "unified", "additive" and "nemoro". The indicators that comprised the CQIs were nitrification index (NI) and synthetic enzymatic index (SEI). The CQIs made it possible to differentiate the quality of the compost according to the treatments applied. The treatments used resulted in composts considered phytonutritious whose average quality value depending on the CQI developed was considered high (CQIw = 0.62), moderate (CQIa = 0.56) and low (CQIn = 0.30). The developed CQIs can be applied to determine the quality of BS composting systems reducing the cost of monitoring. [ABSTRACT FROM AUTHOR]

Through pyrolysis it is possible to transform sewage sludge (SS) into a product called biochar, which can be used safely in agriculture as a soil amendment. Among the advantages of using SS biochar (SSB) are the supply of nutrients and carbon sequestration in the soil. However, there is still a lack of information on the supply of nutrients and the nutritional balance provided by SSB application. The objective of this study was to evaluate the nutritional status of corn plants fertilized with SS biochar by the DRIS method. Soil and plant data from a three-year field experiment were assessed. The field experiment, with four replications, consisted of the following treatments: 1) control, no biochar and no mineral fertilization; 2) mineral fertilization; 3) biochar produced at 300°C; 4) BC300 associated with mineral fertilization; 5) biochar produced at 500°C; 6) BC500 associated with mineral fertilization. In the present study, leaf samples of corn cultivated for three consecutive harvests were used. From the DRIS indexes, it was concluded that potassium is the most limiting nutrient for SSB. Despite that, according to outputs from DRIS, SSB has a good potential as a fertilizer, especially if supplemented with K. [ABSTRACT FROM AUTHOR]

Plastics, which occupy a large place in our lives, have also brought along various environmental problems with their widespread use. Microplastics can accumulate in the sewage sludge of Wastewater Treatment Plants, and then the use of these sludges in agricultural lands may cause the spread of pollutants such as heavy metals and microplastics for which the toxic effects are not clear, yet. Nickel is one of the heavy metals that pose a risk in agricultural lands, and it is also limited by the relevant regulations. However, the change in the toxicity of Nickel in the presence of potential pollutants such as microplastics and biosolids, whose effects have just begun to be investigated, has not been examined. In this context, nickel toxicity was investigated in the presence of microplastics and biosolids. The effects on reproduction on E. Crypticus, which is used as a representative of living things living in the soil, were determined by EC50 values. Accordingly, both microplastics and biosolids applications had a decreasing effect on Nickel toxicity. This can be explained by the neutralization of Nickel for which toxicity is sourced from ion forms by complexing with organic substances in the biosolid or interacting with charged surface groups that may be present on the microplastic surface. [ABSTRACT FROM AUTHOR]

ABSTRACT The cultivation of grasses in sewage sludge (SS) with aeration has the potential for stabilization of sludge organic matter in the production of organic fertilizer. Thus, the objective of this work was to evaluate the cultivation of Urochloa brizantha and Pennisetum purpureum under aerated system on the chemical and biological attributes of SS to obtain a matured organic fertilizer. The study was conducted in a randomized block design in a 2x2+2 factorial scheme with four replications. Factors consisted of cultivation of P. purpureum or U. brizantha in SS, with or without intermittent aeration. Control treatments were SS without cultivation, with or without aeration. Sewage sludge was collected in layers and the chemical and microbial attributes were evaluated. There was no significant difference between treatments for grass dry matter. The C/N ratio was not matched with organic fertilizer stabilization due to similar losses of C and N (~7%). However, microbial activity was reduced in the presence of plant cultivation demonstrating improvement in the properties of the organic fertilizer produced. Through uni- and multivariate analysis, organic fertilizer produced from SS aerated and cultivated with P. purpureum showed matured organic matter.

Struvite from nutrient-rich wastewaters has been identified as a potential substitute for commercial mineral fertilisers, with the added benefit of reducing threats to global food security by prolonging phosphate rock reserves. A fertilisation test using grass (Brachiaria brizantha Marandú) and a sand column leaching test was conducted to determine the agronomic effectiveness of struvite precipitates produced from the supernatant of dewatered sewage sludge (centrate) from a municipal Wastewater Treatment Plant (WWTP). The performance of this struvite as a fertiliser was compared with biosolids and commercial fertilisers (Urea and Triple15). The results show that the concentration of heavy metals in struvite was lower than in biosolids and below the limits of Colombia and European fertiliser regulations. Struvite increased the uptake of N and P in grass, resulting in crop yields similar to other treatments tested. Struvite use as an effective slow-release fertiliser is highly dependent on the size of crystal particles, particularly in achieving low P losses, but resulted in high N loss in the sand columns tested; N loses from struvite were higher than in the commercial fertilisers due to the struvite small particle size. Therefore, struvite represents a suitable opportunity to recover and recycle nutrients from municipal sewage sludge, facilitating the effective reuse of P and N in agriculture and uptake by plants. HIGHLIGHTS Heavy metal concentrations of the struvite from the studied centrate of a WWTP were below the threshold limits.; P uptake and apparent P recovery efficiency by the grass were significantly higher in two struvite treatments than in the commercial fertilised tested.; N and P leaching depend on particle size. Smaller crystals can produce greater N uptake by the grass but at the same time more significant N losses by leaching.;

The germination of Agave salmiana requires optimal conditions of water, temperature, and well-drained soils, along with soil microbiome synergy. Three substrates were evaluated: black soil, worm humus, and biosolid. Using 200 seeds and the filter paper germination method, a germination rate of 85-90% was achieved. Seedlings grown in humus reached greater heights, showing vigorous growth, while development in biosolid was slower. After 25 days, they were transplanted with a survival rate of 90% in humus, 75% in black soil, and 60% in biosolid, highlighting the effectiveness of humus in greenhouse conditions. [ABSTRACT FROM AUTHOR]

Stabilized sewage sludge could be used as a fertilizer in the soil because of nitrogen, phosphorus, and other micronutrition material to improve the properties of the soil. In this study, clover and fodder corn plants were planted in the soil to which stabilized sewage sludge was applied. The soil was analyzed and evaluated by collecting samples to determine changes in the application fields before plantation and one year after the harvest. To monitor changes in the soil and after the application of stabilized sludge to the soil, the stabilized sewage sludge was evaluated for the suitability of parameters such as heavy metals, halogenated organic compounds including adsorbable organic halogens (AOX), nonylphenol ethoxylates (NPE), polycyclic aromatic hydrocarbon compounds (PAH), polychlorinated biphenyls (PCB), di(2-ethylhexyl) phthalate (DEHP), linear alkylbenzene sulphonates (LAS), polychlorinated dibenzo-p-dioxins and dibenzo-p-furans (PCDD/F), and pathogens and other parameters containing organic matter (OM), pH, conductivity (EC), total nitrogen (TN), and total phosphorus (TP). After the sludge application, the heavy metal content increased, except for Zn. The application of stabilized sludge as a soil conditioner and humus caused a significant increase in the TN and TP content since the product increased the harvest that increased soil nutrition. After the sludge application to the soil, the concentration of organic micropollutants in the soil did not change. The concentration of AOX and PCDD/F in the soil increased by 141% and 125%, respectively. [ABSTRACT FROM AUTHOR]

ABSTRACT The present work aimed to develop mathematical fuzzy models to evaluate the effects of different doses of sewage sludge and irrigation with wastewater and potable water. Such models were elaborated from an experiment carried out at the Faculty of Agronomic Sciences, in the Department of Soil and Environmental Resources, from the Sao Paulo State University, in Brazil. The experiment was carried out in a randomized block design, in a 6 × 2 factorial scheme, with 6 doses of sewage sludge (0, 25, 50, 75, 100 and 125 of the recommended dose of N), and in the presence and absence of wastewater. In the development of the fuzzy model, the Mamdani method was used for the defuzzification. As input variables, the doses of sewage sludge and the types of water were used. For the output variables, it was sought to evaluate the biometric and developmental components of the culture. It can be inferred that the model developed presented a good fit when compared to the regression model, and that the use of sewage sludge may prove to be a potential future replacement of mineral nitrogen.

A chemical leaching process was used for the cleanup of two municipal biosolids (MOS and BES) spiked with Cd, Cu, Zn or their mixture prior to agricultural use. Non-cleaned, cleaned and washed biosolids were compared as soil amendments for corn cultivation in greenhouse. Corn growth, biosorption and metal leaching were measured. Results showed that biosolid amendments tend to produce more aerial biomass. Cleanup and washing of BES biosolid significantly increased total biomass of roots and stalks, respectively. Regarding biosorption of metals, Cd accumulated in roots (0.06–1.13 mg kg−1) and leaves (0.06–0.63 mg kg−1), but not in seeds nor in stalks. Larger amounts of Cu were detected in roots (10.7–18.2 mg kg−1), stalks (1.29–3.78 mg kg−1) and leaves (6.77–20.2 mg kg−1). However, Zn was more accumulated in roots (17.9–74.9 mg kg−1), stalks (6.15–17.1 mg kg−1) and leaves (47.9–90.1 mg kg−1). Whereas Cd and Cu decreased in the order roots > leaves > stalks, Zn decreased from leaves > roots > stalks. Cleanup and washing of MOS and BES biosolids significantly lowered biosorption of Cd (up to 84%), Cu (up to 38%), Zn (up to 63%), and other metals. Concentrations in leachate draining into outlet water varied over time, but on average were moderately low. Significant amounts of metal leached from MOS biosolid. The effects of cleanup and washing of both biosolids on biosorption and leaching depended on the initial metallic charge and the biosolid type.

Composting and vermicomposting are an environmentally friendly way to reduce pathogens in organic wastes and generate a valuable product that provides nutrients for crops. However, how the bacterial community structure changes during these different processes and if the bacteria applied with the (vermi)composted products survive in an arable cultivated soil is still largely unknown. In this study, we monitored how the bacterial community structure changed during conditioning, composting with and without Eisenia fetida, and when the end-product was applied to arable soil cultivated with wheat Triticum sp. L. The organic wastes used were biosolid, cow manure, and a mixture of both. Large changes occurred in the relative abundance of some of the most abundant bacterial genera during conditioning, but the changes were much smaller during composting or vermicomposting. The bacterial community structure was significantly different in the organic wastes during conditioning and (vermi)composting but adding E. fetida had no significant effect on it. Changes in the relative abundance of the bacterial groups in the (vermi)composted waste applied to the arable soil cultivated with wheat were small, suggesting that most survived even after 140 days. As such, applying (vermi)composted organic wastes not only adds nutrients to a crop but also contributes to the survival of plant growth-promoting bacteria found in the (vermi)compost. However, putative human pathogens found in the biosolid also survived in the arable soil, and their relative abundance remained high but mixing the biosolid with cow manure reduced that risk. It was found that applying (vermi)composted organic wastes to an arable soil not only provides plant nutrients and adds bacteria with plant growth-promoting capacities, but some putative pathogens also survived. [ABSTRACT FROM AUTHOR]

The effect of treated wastewater (TMWW) and biosolid (BSD) on the available soil metal levels was studied through a field experiment conducted in Amfissa, Greece (Geo. Coordinates X 360,030.956 and Y 4,265,145.376), using a randomized block design and applying the following treatments, in 4 replications: (i) TMWW, (ii) BSD, (iii) TMWW + BSD, and (iv) CONTROL. The perennial Ryegrass (Lolium perenne L.) was chosen as a test crop. Under these treatments, the differences in soil metal concentration between pre- and post-application were statistically significant. A considerable metal contribution to soil and plant was attained by the following interactions: (a) between "soil chemical and physical characteristics with metals" and with essential nutrients, (b) between "metals and essential nutrients" occurring in the soil, and (c) between "metals and essential nutrients" within the plant tissues. It is suggested that the interactions between metals and soil characteristics must be further studied to attain a more accurate knowledge in relation to soil fertility and productivity. Highlights: • The treatments of reclaimed wastewater and biosolid increased the biomass yields and the crude protein content up to 25%. • The biomass yields were statistically significantly related to the Ryegrass plant height. • The treatment increased significantly the soil metals and essential nutrients content. • The soil's physical and chemical characteristics interacted synergistically with metals and essential nutrients. • Significant elemental interactions occurred in soil and within the plant tissues contributing metals and nutrients, respectively. • Ryegrass plants accumulated relatively high Cd levels, suggesting that they may act as toxic metal accumulators. [ABSTRACT FROM AUTHOR]

Abstract If not managed properly, mining waste can be detrimental to the environment. In addition, sewage treatment plants produce sludge, a biowaste rich in organic matter which is often sent to landfills. The present study evaluated the use of sewage sludge as an amendment for mine waste from a basalt quarry as an alternative to the use of soil from borrow areas during environmental restoration. An ex situ experiment was developed at the Federal University of Rio Grande do Sul - UFRGS. The experimental delineation compared the addition of two sources of organic matter (sewage sludge - SS and cover soil from that same region - CS) to basalt waste rock (BWR) against the sole use of cover soil, which a current restoration technique. The graminoid Avena strigosa (black oats) and soil fertility tests were used as indicators of soil conditions. Amending BWR with SS led to the best physical and chemical conditions and the highest production of dry matter in comparison to the use of CS as amendment or its single use as cover soil. These results show that mixing SS to BWR can be used as a substitute for cover soil during the environmental restoration of basalt quarries, further contributing to the final disposal of these materials.

ABSTRACT The use of residues for agricultural production is an alternative for the achievement of sustainability. When mixed with diatomaceous earth (DE) from biofuel filtration, sewage sludge (SS) plays an important role as soil conditioning agent. As a result, the objective of this work was to make a DE vermicompost at different proportions: 0; 7.53; 15.06; 22.59 and 30.12% v/v in relation to a SS pre-compost (PC) and gardening pruning residues. The experiment was carried out in 100-L containers in a randomized block design, with 5 treatments and 5 replications, in which Eisenia foetida earthworms were used in the pre-composting and vermicomposting processes. After four months, the physical characteristics of the vermicompost were analyzed. It was verified that the diatomaceous earth can be vermicomposted, even when soaked in biofuel oil, at amounts of up to 30.12% v/v, with no visible physical damage to earthworms and plants, and this proportion of DE reduced the concentration of nutrients, but improved the physical properties of the vermicompost, making it an excellent physical conditioner for use as a substrate of plants and fertilization of soils.

This paper presents the influence of sewage sludge (SS) on the biometric parameters, absorption of mineral elements and thermal characteristics of sweet sorghum (Sorghum bicolor L.) grown on Technosol. Two types of sewage sludge were used: unmodified and modified with DAMET flocculant. Each type of sludge was applied in three doses (expressed as dry matter basis, DM): 20 t DM/ha, 40 t DM/ha and 60 t DM/ha, respectively. The yield of fresh biomass depended on the dose of sewage sludge: it increased by 14.5–41% and reached 104.6 t/ha after application of the sewage sludge with flocculant at a maximum rate of 60 t/ha. Sorghum biomass actively absorbs nutrients from the soil. Nitrogen was absorbed more actively; depending on the type and dose of sewage sludge application, its content in biomass increased from 12–40% (dose of 20 t/ha) to 80–112% (dose of 60 t/ha). By content in sorghum biomass, essential elements can be arranged in descending order as follows: Fe → Mn → Zn → Cu. Sorghum shows a low ability to accumulate some heavy metals in aboveground biomass. Despite the fact that large doses of sewage sludge contributed to an increase in the content of nickel, cadmium and lead in the substrate by 1.8–5.6 times, the ratio of the content of these elements in plants to the content in the substrate remained low. Sewage sludge affects the process of thermal degradation of sorghum biomass. The decomposition of the main components occurs at lower temperatures, and, as a rule, at higher rates. Sewage sludge (especially with flocculant) contributes to a more complete combustion of biomass. The results showed that sewage sludge with flocculant at a dose of 40 t/ha is the most optimal fertilizer option for growing sweet sorghum on such Technosols as loess-like loam.

At a strategic moment for agricultural soils, which are expected to contribute to climate change mitigation through carbon storage while safely feeding a growing world population, the fertiliser strategies used will be key. In a calcareous soil with extensive rainfed agricultural use and straw removal, different fertiliser strategies were evaluated with the aim of determining their effects on crop yield, nitrogen agronomic efficiency, and the storage of organic carbon and total nitrogen in the soil. Different doses of mineral fertiliser, expressed as kg of mineral nitrogen ha−1 year−1 (0, 60, 120, 180, and 240 nitrogen fertilising units (NFUs)), were applied to plots with and without biosolid amendment. The biosolid, applied at a rate of 40 Mg ha−1 every 3 years for 18 years, complied with national and European regulations to be applied on agricultural soil. The use of combined fertilisation reduced the amount of mineral fertiliser applied between 33 and 67% and the total fertiliser units between 7 and 40%, while maintaining similar yields to the reference mineral fertilisation (180 NFUs). These results could be related to a higher nitrogen agronomic efficiency in the combined fertilisation treatments that do not exceed the total NFUs required by the crop. Combined fertilisation was also an effective fertiliser technique to store total nitrogen and organic carbon in the soil. However, compared to the reference mineral fertilisation (180 NFUs), no significant changes in the soil organic carbon were observed, probably due to the crop management method in which the straw is removed and to higher gas emissions. Our results support the need to assess the efficacy of each agricultural technique at local scales in order not to overestimate or underestimate the potential of each agricultural technique to store soil organic carbon.