Substrate Mixture Research Articles

Cascade [3 + 2]/[4 + 2] Cycloaddition of Enaminones with Vinylene Carbonate for the Synthesis of Functionalized Pyrrolo[2,1-a]isoquinoline Derivatives.

We developed a protocol for the synthesis of functionalized pyrrolo[2,1-a]isoquinoline derivatives (PIQDs) 3 from enaminones 1 using vinylene carbonate 2. This strategy involved [3 + 2] and [4 + 2] cycloadditions via heating a mixture of substrates 1 with vinylene carbonate 2 and DCE at 60 °C, catalyzed by [Cp*RhCl2]2 and oxidized with Cu(OAc)2 and AgSbF6 promoted by NaOAc. As we increased the reaction temperature to 110 °C under the same conditions, we synthesized PIQDs 4 through sequential C-H activation, alkene insertion, migratory insertion, C-N reductive elimination, β-O elimination, and finally dehydration. As a result, a series of PIQDs 3-4 were generated by forming four bonds (2 C-C and 2 C-N bonds) in a single step. This strategy realizes the synthesis of linear molecules with potential biological activity, specifically natural-like heterocycles (3-4). It expands the application of vinylene carbonate as a C2 synthon in the construction of pyrrole and isoquinoline skeletons for the synthesis of functionalized PIQDs in combinatorial and parallel syntheses via one-pot reactions.

Omega-3 and unsaturated Fatty Acid Enrichment of Shrimp Oil: Preparation, Characterization, and its Application in Salad Dressings

The effect of various lipase hydrolytic conditions on DHA/EPA and unsaturated fatty acids (USFAs) enrichment of shrimp (Litopenaeus vannamei) oil (SO) extracted from hepatopancreas was investigated. DHA/EPA and USFAs levels increased (40.96/22.61 and 27.83%, respectively) under optimized hydrolytic conditions of 20 U lipase, DMSO as a solvent (0.2:0.5), DMSO to water for the substrate mixture (SM), and water to SM (0.4:1) for 2 h at 50 °C. n3FAs and USFAs enriched shrimp oil (n3SO) were added to salad dressing (SD) at various concentrations (0, 5, 10, and 15%) (CON, SD5, SD10, and SD15, respectively) to offset the concentration of soybean oil. The addition of n3SO imparted an attractive orange color, enhancing the organoleptic properties of the SD, as indicated by higher likeness scores for color and appearance attributes than CON and commercial SD (CM). Samples added with n3SO exhibited a more uniform pattern and distribution of oil droplets, suggesting the formation of a stable emulsion system. The result was also supported by its enhanced viscoelastic and flow properties than the CON and CM. Overall, DHA/EPA enriched SO could be potential supplement or functional ingredient in SDs or other emulsion related products with superior health benefits.

Sustainable Synthesis of New Antioxidants from Hydroxytyrosol by Direct Biocatalytic Esterification in Ionic Liquids

Hydroxytyrosol (HT) is a nutraceutical compound, mainly found in the fruit, leaves and waste from the olive oil industry, known for exhibiting one of the highest antioxidant activities among molecules of natural origin. To harness this bioactivity in cosmetics, pharmaceuticals and the food industry, it is essential to modify the hydrophilicity of HT to enhance its compatibility with lipid-based mixtures. This chemical modification must be carried out with high selectivity to avoid compromising its radical scavenging activity. This work presents a highly efficient and selective approach to perform the biocatalytic esterification of free fatty acids (FFAs) of different alkyl chain lengths with HT in a reaction medium based on the SLIL [C12mim][NTf2]. By using a 1:2 (mol/mol) HT:FFA mixture of substrates, the HT-monoester derivative was obtained up to 77% yield after 2 h at 80 °C. The optimized molar ratio of substrates, combined with the ability to recover the SLIL for further reuse, significantly reduces waste accumulation compared to other reported strategies and results in a more sustainable approach as demonstrated by different green metrics. The antioxidant activity of HT-monoester products was fully maintained with respect to that presented by the natural HT, being stable for at least 3 months at 4 °C, as demonstrated by the DPPH and FRAP antioxidant analysis.

The Standardized Spectroscopic Mixture Model

The standardized spectral mixture model combines the specificity of a physically based representation of a spectrally mixed pixel with the generality and portability of a spectral index. Earlier studies have used spectrally and geographically diverse collections of broadband and spectroscopic imagery to show that the reflectance of the majority of ice-free landscapes on Earth can be represented as linear mixtures of rock and soil substrates (S), photosynthetic vegetation (V) and dark targets (D) composed of shadow and spectrally absorptive/transmissive materials. However, both broadband and spectroscopic studies of the topology of spectral mixing spaces raise questions about the completeness and generality of the Substrate, Vegetation, Dark (SVD) model for imaging spectrometer data. This study uses a spectrally diverse collection of 40 granules from the EMIT imaging spectrometer to verify the generality and stability of the spectroscopic SVD model and characterize the SVD topology and plane of substrates to assess linearity of spectral mixing. New endmembers for soil and non-photosynthetic vegetation (NPV; N) allow the planar SVD model to be extended to a tetrahedral SVDN model to better accommodate the 3D topology of the mixing space. The SVDN model achieves smaller misfit than the SVD, but does so at the expense of implausible fractions beyond [0, 1]. However, a refined spectroscopic SVD model still achieves small (<0.03) RMS misfit, negligible sensitivity to endmember variability and strongly linear scaling over more than an order of magnitude range of spatial resolution.

Effects of Active Dry Yeast Supplementation in In Vitro and In Vivo Nutrient Digestibility, Rumen Fermentation, and Bacterial Community.

This study assessed the impact of active dry yeast (ADY) on nutrient digestibility and rumen fermentation, using both in vitro and in vivo experiments with lambs. In vitro, ADYs were incubated with rumen fluid and a substrate mixture to assess gas production, pH, volatile fatty acid (VFA) profiles, and lactate concentration. In vivo, Hu lambs were randomly assigned to five dietary treatments: a control group and four groups receiving one of two dosages of either Vistacell or Procreatin7. Growth performance, nutrient digestibility, rumen fermentation parameters, and bacterial community composition were measured. Pro enhanced the propionate molar proportion while it decreased the n-butyrate molar proportion. Vis reduced the lactate concentration in vitro. In the in vivo experiment, Vis increased the propionate molar proportion and the Succinivibrionaceae_UCG-001 abundance while it decreased the n-butyrate molar proportion and the Lachnospiraceae_ND3007 abundance. Additionally, Vis showed a greater impact on improving the NDF digestibility and total VFA concentration in vivo compared to Pro. Overall, the effects of ADYs on rumen fermentation were found to vary depending on the specific ADY used, with Vis being the most suitable for lamb growth. It was observed that Vis promoted propionate fermentation and Succinivibrionaceae_UCG-001 abundance at the expense of reduced n-butyrate fermentation and Lachnospiraceae_ND3007 abundance. Importantly, differences were noted between the outcomes of the in vitro and in vivo experiments concerning the effects of ADYs on rumen fermentation, highlighting the need for caution when generalizing batch culture results to the in vivo effects of ADYs.

Solar-integrated biogas reactor for efficient kitchen waste conversion to biogas

This study aimed to improve biogas production by co-digesting kitchen waste and animal manure in a solar-integrated biogas reactor. The panel then heated the substrate mixture to the right temperature for the reactor after turning solar energy into electricity. The experiment was conducted at mesophilic (37°C) and thermophilic (40°C) conditions. After 45 days of co-digestion of animal dung, kitchen trash, cow manure, and grasses, the solar-integrated biogas plant generated 1,445 mL of biogas with 60% CH4, 14% CO, and 21% other gases; in comparison, the conventional biogas digester produced 501 mL, 479 mL, and 525 mL, respectively, with 35-50% Methane, 18% CO, and 22% other gases. The data show that a solar-integrated biogas plant may react faster produce more gas, and have a higher methane concentration using kitchen waste and animal manure. An environmental effect analysis and prediction of biogas plant construction has been accomplished. The proposed biogas plant, supported by a solar-integrated reactor strategy, appears economically viable, projecting a five-year payback period. This research evaluates efficient biogas production techniques, emphasizing their importance in advancing engineering sustainability. It promotes the role of renewable energy, energy efficiency, and environmental sustainability in solving global energy problems and reducing climate change.

CULTIVATION OF ALOE (ALOE ARBORÉSCENS) MEDICINAL PLANT IN OUTDOOR AND INDOOR CONDITIONS WITH SPRINKLER AND DRIP IRRIGATION METHODS

The article presents the results of scientific research on the cultivation of aloe medicinal plant (Aloe drevovidnoe (lat. Alóe arboréscens .)) in the conditions of Uzbekistan under sprinkler and drip irrigation methods in outdoor and indoor conditions. It was found that 2.039 kg/bush of green leaves can be obtained when grown in a mixture of substrates with manure-50%, sand-20%, soil-30% for 4 years under sprinkler irrigation.

Hydraulic Property Estimation of Green Roof Substrates from Soil Moisture Time Series

The adoption of green roofs is an effective practice for mitigating environmental issues in urban areas caused by extreme weather conditions. However, certain design aspects of green roofs, such as the characterization of the physical properties of their substrates, need a better understanding. This study proposes a simple method for estimating two hydraulic properties of green roof substrates based on the evolution of moisture during drying periods, or drydowns, where evaporative processes dominate: the weighted-mean diffusivity and the saturated hydraulic conductivity. Soil moisture was monitored using 12 in situ sensors from 2015 to 2020 in a study involving six different green roof plots composed of various mixtures of demolition-recycled aggregates and organic substrates. A universal parameterization for determining water diffusivity in soils was applied to estimate the weighted-mean hydraulic diffusivity. As a by-product, the saturated hydraulic conductivity was estimated from the evaluated diffusivity and the measured water retention data. The median values obtained for and range from 14.5 to 29.9 cm2d−1 and from 22 to 361 cmd−1, respectively. These values fall within the ranges reported by other research groups using direct measurement methods and supports the validity of Brutsaert’s model for green roof substrates. Furthermore, an increase in and a decrease in were observed as the percentage of recycled aggregates in the substrates increased, which could be considered for design purposes.

Hyperpolarized 13C NMR Reveals Pathway Regulation in Lactococcus lactis and Metabolic Similarities and Differences Across the Tree of Life.

The control of metabolic networks is incompletely understood, even for glycolysis in highly studied model organisms. Direct real-time observations of metabolic pathways can be achieved in cellular systems with 13C NMR using dissolution Dynamic Nuclear Polarization (dDNP NMR). The method relies on a short-lived boost of NMR sensitivity using a redistribution of nuclear spin states to increase the alignment of the magnetic moments by more than four orders of magnitude. This temporary boost in sensitivity allows detection of metabolism with sub-second time resolution. Here, we hypothesized that dDNP NMR would be able to investigate molecular phenotypes that are not easily accessible with more conventional methods. The use of dDNP NMR allows real-time insight into carbohydrate metabolism in a Gram-positive bacterium (Lactoccocus lactis), and comparison to other bacterial, yeast and mammalian cells shows differences in the kinetic barriers of glycolysis across the kingdoms of life. Nevertheless, the accumulation of non-toxic precursors for biomass at kinetic barriers is found to be shared across the kingdoms of life. We further find that the visualization of glycolysis using dDNP NMR reveals kinetic characteristics in transgenic strains that are not evident when monitoring the overall glycolytic rate only. Finally, dDNP NMR reveals that resting Lactococcus lactis cells use the influx of carbohydrate substrate to produce acetoin rather than lactate during the start of glycolysis. This metabolic regime can be emulated using suitably designed substrate mixtures to enhance the formation of the C4 product acetoin more than 400-fold. Overall, we find that dDNP NMR provides analytical capabilities that may help to clarify the intertwined mechanistic determinants of metabolism and the optimal usage of biotechnologically important bacteria.

Chemoselective and Triggered Decomposition of Diazo Esters by the [(IMes)Rh2(OAc)4] Complex: En Route to Assisted Tandem Catalysis from Mixtures of Diazo Compounds

AbstractDecomposition of aryl and unsubstituted diazo ester into Rh(II)‐carbenes by the [(IMes)Rh2(OAc)4] complex is shown to be slower than with Rh2(OAc)4. Diazo esters substituted by a second electron‐withdrawing group do not suffer nitrogen extrusion when exposed for several hours to this (NHC)Rh(II) complex at room temperature. This chemoselective decomposition of diazo esters depending on their substituent (Ar, H, EWG) can furthermore be achieved on a mixture of substrates. The catalytic activity of [(IMes)Rh2(OAc)4] towards electron‐poor diazo compounds is also restored by heating to reflux in chloroform, or after decomplexation of the NHC by addition of GaCl3. The [(IMes)Rh2(OAc)4] complex was then used to induce a fully selective reaction cascade from a mixture of two diazo esters. First, a donor/acceptor diazo compound was decomposed selectively at room temperature to give an intermolecular O−H insertion product without any decomposition of the electron poor diazo compound. Addition of GaGl3 then triggered nitrogen extrusion from the diazo malonate to give a 1,5‐C−H insertion product. This transformation, where decomposition of diazo compounds catalyzed by Rh(II) complexes can be externally controlled, represents the first example of assisted tandem catalysis with two metal carbene precursors.

Cycloaddition and Skeleton Rearrangement of Heterocyclic Ketene Aminals (HKAs) with 1-Diazonaphthalen-2(1H)-ones for the Synthesis of Functionalized 1,2,3-Triazoles.

We developed a protocol for the synthesis of highly functionalized 5,6-dihydro-imidazo[1,2-c][1,2,3]triazole derivatives 4-5 (DHITs) from 1-diazonaphthalen-2(1H)-one derivatives with heterocyclic ketene aminals (HKAs). This strategy involved cycloaddition and skeletal rearrangement entailing the heating of a mixture of substrates 1 with HKAs 2-3 and THF without any catalyst. As a result, a series of DHITs 4-5 were produced by cleaving one bond (1 C═N bond) and forming three bonds (1 N-N and 2 C-N bonds) in a single step. This protocol achieved the dual functionalization of diazo building blocks involving both the aromatic nitrogen alkylation reaction to form an ArC-N bond without any metal catalyst and the intermolecular cycloaddition of the N═N bond. These strategies can be used to synthesize functionalized DHITs for combinatorial and parallel syntheses via one-pot reactions without any catalyst.

Ecotoxicity of Tar from Coffee Grounds and Pine Pellet Gasification Process

This study determined the toxicity of the condensates produced during the gasification of two waste types. Coffee grounds, pine pellets, and a mixture of both substrates at a ratio of 1:1 were used in the study. Two microbiotests were applied for soil plants and aquatic macrophytes, and quantitative analysis of the soil microbiome for primary taxonomic groups of microorganisms was conducted. Three contamination rates were used in the Phytotoxkit test and the microbiological tests, 100, 1000, and 10,000 mg·kg−1 d.m. of soil, while in the aquatic organism studies, successive two-fold serial dilutions of condensates were used. The presence of liquid waste from the gasification process adversely affected the germination and development of terrestrial plants and the vegetative growth of aquatic plants. The condensate components modified the composition of the soil microbiome, adversely affecting soil fertility. The negative impact increased with increasing levels of contamination and primarily depended on the type of substrate from which the gasification process produced the liquid waste.

Trade-offs in biomethane production by substrate mixture optimization under German market conditions

BackgroundNew regulations and market conditions in Germany affect the profitability of biomethane upgrading as a repowering option for existing biogas plants following on-site CHP utilization. These conditions present trade-off challenges between higher sustainability requirements, maintaining production capacity and new revenue opportunities. Optimization methods, such as linear programming (LP), are essential for determining the ideal substrate mixture and profitable solutions amidst multiple market conditions, plant-specific process constraints, and substrate properties.MethodsWe updated a substrate mixture optimization model within an assessment framework for the repowering of existing biogas plants (BGPs), which focuses on the operator’s perspective. By integrating multiple German biomethane markets for various BGPs, we assessed changes in the substrate mixture, GHG emissions, contribution margins, and constraint parameters to derive conclusions for operators and future framework design.ResultsIntegrating market revenues and constraints can increase contribution margins by 12–55%. Additional gains can be achieved by considering multiple markets simultaneously but limited to a few BGPs. The plant-specific LP solution space and used benchmark market are decisive. The former limits the potential of high substrate-specific contribution margins, which has a significantly higher impact than the relation between plant-specific characteristics and process constraints. The advanced fuel market is currently the lead market for biomethane, incentivizing GHG-emission extensive substrates, decreasing gas production and GHG emissions but increasing levelized cost of energy (LCOE) and partially CO2 abatement costs.ConclusionsThe key to improve profitability and to supply an increasing biomethane demand while fulfilling new requirements is a large LP solution space. Increasing market options, substrate availability, and digestion system capacity achieve this on the operator’s side. Policy makers could reduce normative requirements such as the maize cap or double counting of advanced fuels and favor high but uniform GHG requirements. Operators can prepare robustly for the future substrate mixture by adding digester volume and pre-treatment tech, ensuring long-term and diverse substrate availability, and contracts with flexible components. Although current market conditions can improve specific GHG emissions, they do not necessarily increase manure usage when other options, such as straw, are viable. Other regulatory support systems will be required to do so.

The potential of processed mineral construction and demolition waste to increase the water capacity of urban tree substrates - A pilot scale study in Munich

Construction and demolition waste (CDW) represents one of the most significant waste streams worldwide. Due to a high brick content, CDW amended soil substrates are expected to improve water retention, benefitting urban trees.In this two-year field study evaluating the effects of CDW on the water holding capacities of urban tree substrates, six substrate mixtures are tested. Three test substrates contained a standard CDW mixture with 30 % and three 60 % bricks. Soil water contents were monitored and plant available water contents (PAWC) were analysed. From soil water contents and PAWC, the relative extractable water contents (REW), and subsequently the number of days with REW < 40 % and water stress intensity (WSI) are calculated.The substrates with enhanced brick content showed higher PAWC. However, the effect of brick on PAWC was only significant at a minimum of 30 % bricks in the substrate. Pore size distribution of the brick fraction confirmed the assumed relationship between addition of brick and increased PAWC. Substrates with an enhanced brick content showed reduced numbers of days with REW < 40 % and a reduction in WSI.Our findings demonstrate that CDW has potential to foster water holding capacities of urban tree substrates.

Optimization of Liquid-State Anaerobic Digestion by Defining the Optimal Composition of a Complex Mixture of Substrates Using a Simplex Centroid Design

This study aimed to define the optimal composition of three heterogeneous substrates of the anaerobic digestion process to maximize methane production. The investigated substrates were sewage sludge (SS), the organic fraction of municipal solid waste (OFMSW), and horse waste (HW). The optimal composition of these substrates was defined using the mixture design and, more specifically, the simplex–centroid mixture design. Customized methods and materials were employed to study the complex mixture design of these substrates. The findings revealed that the optimal mixture involved all three substrates with the composition 0.17 HW, 0.66 SS, and 0.17 OFMSW, which demonstrated the highest methane yield at 269 NmL·gVS−1. In addition, a mathematical model was developed to predict methane production based on a specific composition of co-substrates. The results were validated at the small pilot scale.

The effect of different peat-free growing media and fertilization levels on the plant nutrition of Leucanthemum vulgare (lam.) and Dianthus barbatus (L.)

Research on peat-free substrates is increasing due to the environmental concerns associated with peat extraction and with the aim of promoting sustainable horticultural practices. Previous research has shown that green compost mixed with coconut coir dust and stabilized wood fiber can be a valuable peat-free alternative for growing media. This study extends this knowledge by exploring the possibility of reducing fertilization levels by exploiting the nutrient content of green compost. In this paper we tested two ornamental herbaceous perennial plants, Leucanthemum vulgare Lam. and Dianthus barbatus L. For each species, we carried out five different substrate mixtures: 1) peat:pumice 70:30 v v−1; 2) coconut coir dust:pumice 70:30 v v−1; 3) coconut coir dust:green compost 55:45 v v−1; 4) green compost:stabilized wood fiber 60:40 v v−1; and 5) coconut coir dust:green compost:stabilized wood fiber 40:30:30 v v−1. For each mixture, we explored three different levels of fertilization: i) no fertilizer application; ii) low dosage of a controlled-release fertilizer at 2 g L−1; and iii) high dosage of the same controlled-release fertilizer at 4 g L−1. Plant biomass, biometric parameters, eco-physiological parameters, and plant mineral content were measured as performance indicators. The results showed that the nutrient surplus provided by the peat-free substrate, particularly when it contains green compost, can enhance the growth potential of the plants. Adding green compost to non-peat substrates can be an opportunity to optimize plant nutrition while reducing the presence of peat in plant nurseries and the use of chemical fertilizers.

Attenuation of the effect of salinity on redwood (Caesalpinia platyloba) by saline compost

The objective of this research is to evaluate the effect of saline compost on the attenuation of salinity stress in palo colorado (Caesalpinia platyloba). A representative sample of saline soil was taken at Ciudad Universitaria Intercultural, sieved (mesh &lt; 5mm) and composted with cattle manure and Cynodon dactylon garden grass pruning, in a 3:1:1 ratio (stubble: manure: saline soil), for 120 days, the characterization consisted of measuring the bulk density (DA), saturation point, pH and EC of the saturated paste extract. The effect of different concentrations of NaCl on the in vitro germination of palo colorado seeds was evaluated in a randomized complete block design with two substrates (blocks), B1) sand-perlite; B2) sand-perlite-salt compost, five treatments 0 M, 0.3 M, 0.4 M, 0.5 M and 0.6 M of NaCl, eight replicates per treatment. The control irrigation was with distilled water. The plants transference to polyethylene cups was fifteen days after sowing; the cups had the same substrate mixture. The variables measured were survival, leaf biomass and dry root biomass. The EC decreased during composting, from 9.45 dS/m low to 2.4 dS/m; the pH of the samples did not show a significant difference. It is concluded that neither the substrate nor the NaCl concentration significantly influenced the germination of palo colorado seeds, and that the saline compost had no effect on the mitigation of salt stress in palo colorado plants.

Effect of agricultural substrates mixtures on yield and components in oyster mushroom (Pleurotus ostreatus)

Effect of agricultural substrates mixtures on yield and components in oyster mushroom (Pleurotus ostreatus)

ANAEROBIC CO-DIGESTION OF DIFFERENT MIXTURES OF ORGANIC WASTES – OUR EXPERIENCE

Anaerobic digestion is a biotechnological method of biogas generation from organic wastes. Anaerobic co-digestion can be considered as the instantaneous anaerobic digestion of two or more substrate and co-substrate mixtures. Anaerobic co-digestion is a pragmatic method to resolve the difficulties related to substrate properties and system optimization in single-substrate anaerobic digestion. During the last two decades our multidisciplinary team performed a lot of experiments of anaerobic co-digestion of different organic wastes activated sludge, cattle manure, swine manure, milk whey, wasted fruits and vegetables etc. Different ratios of mixtures of these organic wastes, in binary and triple mixtures, have been investigated in view to maximize the obtained energy (methane) production. The time for reaching of the process steady state in laboratory anaerobic digesters have been determined to be ten days’ period. Results obtained have shown that some binary mixtures are more perspective in regards to biogas production optimization. It has been found that the addition of 3rd substrate to some binary mixtures could lead to decrease of bioprocess effectiveness.

Effects of different organic substrate compositions on the decontamination of aged PAH-polluted soils through outdoor co-composting

The effects of different organic substrate compositions on the efficiency of outdoor co-composting as a bioremediation technology for decontaminating soil polluted by polycyclic aromatic hydrocarbons (PAHs) were investigated. Four different substrate mixtures and two different aged PAH-contaminated soils were used in a semi-pilot-scale experiment that lasted nearly 700 days. The two soils (A and B) differed concerning both the initial concentrations of the Ʃ16 US EPA PAHs (5926 vs. 369 mg kg−1, respectively) and the type of predominant PAH group by molecular weight.The experiments revealed that while the composition of the organic substrate had an impact on the rate of PAH degradation, it did not significantly influence the final extent of PAH degradation. Notably, the organic substrate consisting of green waste and wood chips (GW) was found to facilitate the most rapid rate of PAH degradation (first-order rate constant k = 0.033 ± 0.000 d−1 with soil A over the initial 42 days of the experiment and k = 0.036 ± 0.000 d−1 with soil B over the initial 56 days). Despite the differences in organic substrate compositions and types of soil being treated, PAH degradation levels exceeded at least 95% in all the treatments after more than 680 days of co-composting.Regardless of the composition, the removal of low- and medium- molecular-weight (2-4 rings) PAHs was nearly complete by the end of the experiment. Furthermore, high-molecular-weight PAHs (5 rings and more) were significantly degraded during co-composting, with reductions ranging from 54% to 79% in soil A and from 59% to 68% in soil B. All composts were dominated by Proteobacteria, Firmicutes, and Actinobacteria, with significant differences in abundance between soils. Genera with PAH degradation potentials were detected in all samples. The results of a battery of toxicity tests showed that there was almost no toxicity associated with the final composts.