Enhancing agricultural output: Investigating the impact of advanced organic formulations on crop productivity, nutrient use efficiency, and profitability in a multi-crop system.

The significance of integrating agricultural by-products such as paddy husk ash (PHA) and potato peels with organic fertilizers lies in enhancing soil fertility, increasing crop yields, and reducing reliance on traditional organic fertilizers like farmyard manure (FYM) or compost alone. Grounded in sustainable agriculture and nutrient management frameworks, this study examines the impact of diverse formulations derived from agricultural waste on productivity, nutrient efficiency, and profitability in a pigeon pea-vegetable mustard-okra cropping system. A two-year field experiment (2020-2022) at ICAR-IARI, New Delhi tested seven nutrient sources viz., (T1) control, (T2) 100% RDN through FYM, (T3) 100% RDN through improved RRC, (T4) 100% RDN through PHA based formulation, (T5) 75% RDN through PHA based formulation, (T6) 100% RDN through PPC based formulation and (T7) 75% RDN through PPC based formulation that were tested in RBD and replicated thrice. Treatment T4 had significant effect on seed yield of pigeon pea (1.89 ± 0.09 and 1.97 ± 0.12 t ha-1), leaf yield of vegetable mustard (81.57 ± 4.59 and 82.97 ± 4.17 t ha-1), and fruit yield of okra (13.54 ± 0.82 and 13.78 ± 0.81 t ha-1) grown in rotation, followed by treatment T6 and T2 during both the years respectively over control. Enhanced system uptake of N, P and K along with system gross and net returns in T4, showed increases of 78.9%, 83.8%, 72.4%, 54.4% and 56.8% in the first year and 77.5%, 80.8%, 77.7%, 54.8% and 57.4% in the second year, respectively, over control. Treatment T4 significantly improved apparent recovery by 66.3% and 69.2% in pigeon pea, 64.7% and 47.9% in vegetable mustard, and 72.7% and 79.4% in okra over T3, averaged across two years. Based on the above findings, (T4) 100% RDN through PHA-based formulation, and (T6) 100% RDN through PPC-based formulation can be recommended for areas with a shortage of FYM but availability of rice husk ash/potato peels for sustainable agricultural wastes and improved sustainability.

Streamlined screening of extracellularly expressed PETase libraries for improved polyethylene terephthalate degradation.

Enzyme-mediated polyethylene terephthalate (PET) depolymerization has recently emerged as a sustainable solution for PET recycling. Towards an industrial-scale implementation of this technology, various strategies are being explored to enhance PET depolymerization (PETase) activity and improve enzyme stability, expression, and purification processes. Recently, rational engineering of a known PET hydrolase (LCC-leaf compost cutinase) has resulted in the isolation of a variant harboring four-point mutations (LCC-ICCG), presenting increased PETase activity and thermal stability. Here, we revealed the enzyme's natural extracellular expression and used it to efficiently screen error-prone genetic libraries based on LCC-ICCG for enhanced activity toward consumer-grade PET. Following multiple rounds of mutagenesis and screening, we successfully isolated variants that exhibited up to a 60% increase in PETase activity. Among other mutations, the improved variants showed a histidine to tyrosine substitution at position 218, a residue known to be involved in substrate binding and stabilization. Introducing H218Y mutation on the background of LCC-ICCG (named here LCC-ICCG/H218Y) resulted in a similar level of activity improvement. Analysis of the solved structure of LCC-ICCG/H218Y compared to other known PETases featuring different amino acids at the equivalent position suggests that H218Y substitution promotes enhanced PETase activity. The expression and screening processes developed in this study can be further used to optimize additional enzymatic parameters crucial for efficient enzymatic degradation of consumer-grade PET.

Application of Sensory Methods to Evaluate the Effectiveness of Solutions to Reduce the Exposure to Odour Nuisance and Ammonia Emissions from the Compost Heaps.

Exposure to high concentrations of odours can result in health effects associated with direct health risks and irritation from nuisance. This investigation aimed to correlate aspects of the waste composting process with the emission levels of malodourous compounds. An essential optimisation criterion is the reduction of negative environmental impacts, particularly odour emissions. This study characterises odour concentration variations across various technological variants over different weeks of the composting process. A secondary objective is evaluating the efficacy of these variants, which differ in inoculation substances and compost heap composition. Olfactometric analyses were conducted using portable field olfactometers, enabling precise dilutions by mixing contaminated and purified air. The primary aim was to examine the correlation between selected odour parameters, determined via sensory analysis, and ammonia concentration during different composting weeks. Ammonia levels were measured using an RAE electrochemical sensor. Research shows that odour concentration is a significant indicator of compost maturity. In situ, olfactometric testing can effectively monitor the aerobic stabilisation process alone or with other methods. The most effective technological solution was identified by combining olfactometric and ammonia measurements and monitoring composting parameters, ensuring minimal odour emissions and the safety of employees and nearby residents.

Application of municipal solid waste (MSW) char during rotary drum co-composting (RDC) of vegetable waste and its characterization.

Composting, a sustainable method for handling biodegradable waste constituting nearly 50% of municipal solid waste (MSW), can be enhanced by incorporating char produced from MSW pyrolysis. This study investigates the impact of MSW char (0% char-Control, 2.5% char-Trial 1, 5% char-Trial 2) on the physicochemical properties of vegetable waste compost. A thermophilic temperature range of 53.8 °C was detected in Trial 2, 50.8 °C in Trial 1, and 46.8 °C in Control. The pH of the mixes increased at day 20 to 7.5, 7.87, and 8.2 in Control, Trial 1, and Trial 2, respectively. The highest drop of total organic carbon (TOC) and volatile solids in Trial 2 is about 21.18% and 21.02%, respectively. Total Kjeldahl nitrogen (TKN) increased, particularly in Trial 2 (2.35%), while NH4-N concentrations decreased, and phosphorus levels rose notably to 23.48 mg/kg, with 2.49 mg/kg available phosphorus in Trial 2. The C/N was reduced to 10 in Trial 2. Total potassium increase was highest for Trial 1 (6.9 g/kg). Trial 2 had the highest overall macronutrient concentration and correspondingly showed the greatest decrease in volatile solids. Furthermore, Trial 1 demonstrated a reduction in heavy metal concentration in comparison to Control and Trial 2. Consequently, the utilization of MSW char during rotary drum composting enhances the process of composting and significantly improves compost quality, making it a sustainable waste management solution.

Physiological and genomic insights into a psychrotrophic drought-tolerant bacterial consortium for crop improvement in cold, semiarid regions.

The agricultural land in the Indian Himalayan region (IHR) is susceptible to various spells of snowfall, which can cause nutrient leaching, low temperatures, and drought conditions. The current study, therefore, sought an indigenous psychrotrophic plant growth-promoting (PGP) bacterial inoculant with the potential to alleviate crop productivity under cold and drought stress. Psychrotrophic bacteria preisolated from the night-soil compost of the Lahaul Valley of northwestern Himalaya were screened for phosphate (P) and potash (K) solubilization, nitrogen fixation, indole acetic acid (IAA) production, siderophore and HCN production) in addition to their tolerance to drought conditions for consortia development. Furthermore, the effects of the selected consortium on the growth and development of wheat (Triticum aestivum L.) and maize (Zea mays L.) were assessed in pot experiments under cold semiarid conditions (50 % field capacity). Among 57 bacteria with P and K solubilization, nitrogen fixation, IAA production, siderophore and HCN production, Pseudomonas protegens LPH60, Pseudomonas atacamensis LSH24, Psychrobacter faecalis LUR13, Serratia proteamaculans LUR44, Pseudomonas mucidolens LUR70, and Glutamicibacter bergerei LUR77 exhibited tolerance to drought stress (-0.73 MPa). The colonization of wheat and maize seeds with these drought-tolerant PGP strains resulted in a germination index >150, indicating no phytotoxicity under drought stress. Remarkably, a particular strain, Pseudomonas sp. LPH60 demonstrated antagonistic activity against three phytopathogens Ustilago maydis, Fusarium oxysporum, and Fusarium graminearum. Treatment with the consortium significantly increased the foliage (100 % and 160 %) and root (200 % and 133 %) biomasses of the wheat and maize plants, respectively. Furthermore, whole-genome sequence comparisons of LPH60 and LUR13 with closely related strains revealed genes associated with plant nutrient uptake, phytohormone synthesis, siderophore production, hydrogen cyanide (HCN) synthesis, volatile organic compound production, trehalose and glycine betaine transport, cold shock response, superoxide dismutase activity, and gene clusters for nonribosomal peptide synthases and polyketide synthetases. With their PGP qualities, biocontrol activity, and ability to withstand environmental challenges, the developed consortium represents a promising cold- and drought-active PGP bioinoculant for cereal crops grown in cold semiarid regions.

Nano(micro)plastic mobility in soil: Metallic additives and Sr isotopes as potential tracers.

Metal contaminants were found in a soil amended with a compost produced from household waste that included plastic debris. A strong correlation between the microplastics (MPs) distribution and the metal concentrations in the soil profile. Metals in the highest concentrations corresponded to the most significant plastic additives. As the total amount of plastic debris and the loss of metals and plastic particles were unknown, it was not possible to conclude that plastic debris is responsible for all of the metal contamination. Amount of calcium (Ca) in MPs (24.5 g kg-1 of MPs) are high in response to it use as filler in plastic formulation. As strontium (Sr) is an analogous of Ca, the potential of 87Sr/86Sr ratios to quantify MPs and nanoplastics (NPs) was tested. Elemental concentrations (Ca, Cd, Cr Pb, Ni and Sr) coupled with Sr isotopic ratios were compared in both amended soil and a reference soil without amendment. The 87Sr/86Sr ratios of the amended soil were less radiogenic than for the reference soil (0.724296 ± 0.000010 against 0.726610 ± 0.00009 for the 0-5 cm soil layer, respectively). The Sr isotopic ratio of MPs was also significantly less radiogenic (0.711527 ± 0.000010 for the 0-5 cm soil layer) than for soils. The MPs< 2 mm occurred in the ploughed soil depth with concentration varying from 1.19 to 0.09 mg kg-1. The NPs concentration stayed quite constant from 0 to 55 cm at around 0.25 µg kg-1. The presence of NPs until 55 cm soil depth was attested by the detection of polypropylene NPs by Py-GCMS in the soil solution < 0.8 µm. These results highlighted, for the first time, the NPs mobility throughout the soil depth and their ability to reach hydrosystems. It also demonstrated that Sr could be a potential tracer of the MPs< 2 mm and NPs amount occurring in soils.

Optimizing agricultural sustainability: enriched organic formulations for growth, yield, and soil quality in a multi-crop system.

Utilizing agricultural and industrial wastes, potent reservoirs of nutrients, for nourishing the soil and crops through composting embodies a sustainable approach to waste management and organic agriculture. To investigate this, a 2-year field experiment was conducted at ICAR-IARI, New Delhi, focusing on a pigeon pea-vegetable mustard-okra cropping system. Seven nutrient sources were tested, including a control (T1), 100% recommended dose of nitrogen (RDN) through farmyard manure (T2), 100% RDN through improved rice residue compost (T3), 100% RDN through a paddy husk ash (PHA)-based formulation (T4), 75% RDN through PHA-based formulation (T5), 100% RDN through a potato peel compost (PPC)-based formulation (T6), and 75% RDN through PPC-based formulation (T7). Employing a randomized block design with three replications, the results revealed that treatment T4 exhibited the significantly highest seed (1.89 ± 0.09 and 1.97 ± 0.12 t ha-1) and stover (7.83 ± 0.41 and 8.03 ± 0.58 t ha-1) yield of pigeon pea, leaf yield (81.57 ± 4.69 and 82.97 ± 4.17 t ha-1) of vegetable mustard, and fruit (13.54 ± 0.82 and 13.78 ± 0.81 t ha-1) and stover (21.64 ± 1.31 and 22.03 ± 1.30 t ha-1) yield of okra during both study years compared to the control (T1). Treatment T4 was on par with T2 and T6 for seed and stover yield in pigeon pea, as well as okra, and leaf yield in vegetable mustard over both years. Moreover, T4 demonstrated notable increase of 124.1% and 158.2% in NH4-N and NO3-N levels in the soil, respectively, over the control. The enhanced status of available nitrogen (N) and phosphorus (P) in the soil, coupled with increased soil organic carbon (0.41%), total bacteria population (21.1%), fungi (37.2%), actinomycetes (44.6%), and microbial biomass carbon (28.5%), further emphasized the positive impact of T4 compared to the control. Treatments T2 and T6 exhibited comparable outcomes to T4 concerning changes in available N, P, soil organic carbon, total bacteria population, fungi, actinomycetes, and microbial biomass carbon. In conclusion, treatments T4 and T6 emerge as viable sources of organic fertilizer, particularly in regions confronting farmyard manure shortages. These formulations offer substantial advantages, including enhanced yield, soil quality improvement, and efficient fertilizer utilization, thus contributing significantly to sustainable agricultural practices.

Temporal trends of polycyclic aromatic hydrocarbons in soils amended with sludge, compost, and manure in a Scotland pasture: An 8-year field experiment.

To optimize the effective utilization of organic waste in agricultural practices, a comprehensive assessment of associated risks and benefits is crucial. This study investigated the impact of three types of organic wastes (sludge, compost, and manure) on polycyclic aromatic hydrocarbons (PAHs) in contaminated soil in a Scottish pasture. The experimental setup comprised 16 plots with four treatments (compost, manure, sludge, and inorganic fertilizer) and four replicates. After eight years of this study, notable disparities in ΣPAH16 concentrations were observed among the different treatments, with compost-amended soil at 378 µg kg-1, sludge-amended soil at 331 µg kg-1, and manure-amended soil at 223 µg kg-1. The concentrations of ΣPAH16 in soil amended with compost and sludge exhibited a linear increase with extended sampling time. Significant changes in ΣPAH16 concentration were evident in the compost treatment plot, with an increase of 20% in the first year and 82% in the eighth year. Risk assessment suggested a low level of health risk from exposure to PAHs at the measured concentrations in the three organic wastes. In conclusion, this study highlights the importance of considering the effects of organic waste amendments on soil PAH levels to make informed decisions in sustainable agricultural practices. It also underscores the need for ongoing research to fully understand the implications of different organic waste applications on soil health and environmental quality.

Visible intruders: Tracing (micro-) plastic in organic fertilizers.

Agricultural soils have been identified as potential reservoirs for plastic pollution, with adverse effects on soil properties. Primary sources of plastic input in agricultural landscapes are associated with the application of sewage sludge or compost. Understanding the sources and anticipated plastic content is crucial in mitigating plastic pollution in agricultural fields. This study presents one of the first investigations into the plastic content and other impurities, e.g. glass, of seven organic fertilizers (biowaste compost, digested pig slurry, sewage sludge compost, dry chicken manure, green waste compost, sewage sludge, and a mixed digestate comprising pig slurry, chicken manure, and 74 % renewable raw materials). Potentially visible foreign substances were assessed on the surface of each fertilizer pile. No impurities could be detected in digested pig slurry, chicken manure, and mixed digestate. For the remaining fertilizers, visible potential foreign substances were collected, cleaned, visually described, weighed, photographed, size measured, and chemically characterized using ATR-FTIR. The quantification revealed that plastic particles are the most abundant and are contained in all other fertilizers, in contrast to glass and metal. An increasing trend in plastic particle number per m2: green waste < biowaste < sewage sludge compost < sewage sludge, which is about 4 times greater in sewage sludge than in green waste compost, could be observed. However, sewage sludge compost has the largest plastic mass and surface area per square meter. This illustrates that sewage sludge compost application can be a significant entry pathway for visual plastics into agricultural soils.

Bulk and Mapping Speciation Analyses Unveil the Pattern and Heterogeneity of Cu Species during Organic Waste Treatment.

Organic wastes (OWs) can be a common source of copper (Cu) contamination of agricultural soils. Here we conducted a comprehensive study of 22 raw and treated OWs sampled at 6 different full-scale OW treatment plants. Bulk XANES analysis findings indicated that the Cu oxidation state was subject to changes throughout the OW treatment process, mostly depending on the anaerobic/aerobic conditions prevailing in each treatment stage. These changes were independent of the OW origin (agricultural, urban or industrial). Cu(I) prevailed in raw OWs and digestates (88-100%), whereas Cu(II) dominated in composts (46-100%). Bulk EXAFS analysis confirmed these observations and revealed that Cu(I) species in raw OWs and digestates consisted mainly of Cu(I)-sulfide (76-100%), while Cu(II) species (60-100%) in composts were Cu(II)-citrate, Cu(II)-carbonate and amorphous Cu(II)-phosphate. Interestingly, we observed that anaerobic digestion was conducive to the formation of crystallized Cu(I)-sulfides at the expense of nanosized and poorly crystalline Cu(I)-sulfide species, and that the recalcitrant Cu(I) species in composts was always crystallized Cu(I)-sulfide. XANES imaging analysis revealed Cu(II) species present in low proportions (2-4%) that were not detected using bulk XAS analysis in raw OWs and digestates. This demonstrated the potential of XANES imaging for probing minor species in complex matrices.

Efficacy of various amendments for immobilization of potentially toxic elements in wastewater contaminated soils.

Farmers are using municipal wastewater either treated or untreated for irrigation because of limited fresh water resources. Wastewater extensively used for irrigation purposes is enriched with many nutrients. The reuse of wastewater is imposing a negative impact on human health and the ecosystem. It is a need of the day to identify and assess issues of the reuse of wastewater. In the current experiment, impact of organic/inorganic amendments was studied to mitigate the toxic effects of pollutants present in wastewater. Soil was brought from the site having consistent use of wastewater and different treatments were applied as per plan. The experiment has 28 treatments with 04 replications. Nine different amendments were used at 3 varying levels. Incubation time of 30 days was given after the addition of all treatments. The results of the study showed the application of FYM @ 5.0% w/w soil reduced soil pH (7.44), EC (2.16 dS m-1), SAR (8.14), lead (8.48 mg kg-1), cadmium (1.14 mg kg-1), nickel (10.55 mg kg-1) and arsenic (2.03 mg kg-1) when compared with control and other treatments. Usage of compost and horse waste followed FYM. On the basis of this study, it is recommended that wastewater can be used for irrigation purpose after treating with FYM preferably and compost in general.

Soil fertility and plant nutrition in an organic olive orchard after 5 years of amendment with compost, biochar or their blend.

The agronomic use of compost and biochar as soil amendments may exhibit contrasting results in terms of soil fertility and plant nutrition. The effects of the biennial application of biochar, compost and a blend of compost:biochar (90:10; % dw:dw) on the agronomical performance of an organically managed and well established 25-year-old olive orchard was assessed 5 years after the initial application. The agronomical evaluation was based on the assessment of the soil physical, chemical, and biological characteristics, and the assessment of the soil fertility by both crop production and nutritional status of the orchard, and the bioassay with olive plantlets. Biochar mainly benefited the physical properties (bulk density, total porosity, aeration, water retention capacity) of soil, especially in the top 0-5 cm. Compost and its blend with biochar improved microbial activity, soil nutritional status (increasing the content of soluble organic C, N, and P) and favoured the formation of aggregates in soil. The bioassay conducted with young plantlets confirmed the enhanced soil fertility status in the three amended treatments, particularly in the case of biochar and its blend with compost. However, this effect was not significantly observed in the adult plants after 5 years of application, reflecting the slow response of adult olive trees to changes in fertilization. Based on these results, alongside the desirable long-residence time of biochar in soil and the ready availability of compost, the blend of biochar with compost assayed in this study is defined as a valid strategy for preparing high quality soil organic amendments.

A comprehensive review on agricultural waste utilization through sustainable conversion techniques, with a focus on the additives effect on the fate of phosphorus and toxic elements during composting process.

The increasing trend of using agricultural wastes follows the concept of "waste to wealth" and is closely related to the themes of sustainable development goals (SDGs). Carbon-neutral technologies for waste management have not been critically reviewed yet. This paper reviews the technological trend of agricultural waste utilization, including composting, thermal conversion, and anaerobic digestion. Specifically, the effects of exogenous additives on the contents, fractionation, and fate of phosphorus (P) and potentially toxic elements (PTEs) during the composting process have been comprehensively reviewed in this article. The composting process can transform biomass-P and additive-born P into plant available forms. PTEs can be passivated during the composting process. Biochar can accelerate the passivation of PTEs in the composting process through different physiochemical interactions such as surface adsorption, precipitation, and cation exchange reactions. The addition of exogenous calcium, magnesium and phosphate in the compost can reduce the mobility of PTEs such as copper, cadmium, and zinc. Based on critical analysis, this paper recommends an eco-innovative perspective for the improvement and practical application of composting technology for the utilization of agricultural biowastes to meet the circular economy approach and achieve the SDGs.

Engineered biochar combined clay for microplastic biodegradation during pig manure composting.

This study pursued to regulate bacterial community succession pattern and expedited biodegradation of microplastics (MP) during pig manure (PM) composting employing walnut shell biochar (WSB) and montmorillonite (M). The WSB with concentration of 0%, 2.5%, 5%, 7.5%, 10% and 12% along with 10% M participated into PM for 42 days compost to search the optimal solution. The results confirmed the most prosperous bacterial phylum consisted of Firmicutes (3.02%-91.80%), Proteobacteria (2.08%-48.54%), Chloroflexi (0-44.62%) and Bacteroidetes (0.85%-40.93%). The addition of biochar has dramatically arranged bacterial community at different stages of composting. Energy Dispersive Spectrometer (EDS) revealed that carbon element in MPs decreased since the chemical bond fracture, under the intervention of high-temperature composting and WSB, the carbon content of MPs was maximum reduced by 20.25%. Fourier transform infrared spectrum indicated that CC, C-O, C-H and -COOH abundance of MPs in 10% and 12% dose biochar addition sharply reduced, interestingly, explicating WSB and composting made MP biodegradable. This experiment possesses affirmatory practical meaning for elimination of potential hazards by composting.

A method for the extraction of microplastics from solid biowastes including biosolids, compost, and soil for analysis by µ-FTIR.

Few methods exist detailing the extraction of microplastics from organic matrices. A validated method for the successful extraction of microplastics from solid biowastes including biosolids, compost, and soil for spectroscopic analysis by micro-Fourier transform infrared spectroscopy (µ-FTIR) was developed. Solid dry biowastes were first digested with a wet peroxide oxidation (WPO) with iron (II) solution and 30% hydrogen peroxide followed by sequential density separations with ultra-pure water and 1.8 g cm-3 NaI in an optimised sediment-microplastic isolation (SMI) unit. The average recoveries for spiked microplastics were 92, 95 and 98% for bagged compost, biosolids, and soil, respectively. This method ensures a high microplastic recovery by first chemically disintegrating biowaste aggregates without employing destructive methods like milling and allows for successful density separations where the settled fraction is isolated off from the supernatant, allowing thorough rinsing of the equipment and thus a greater transferal of particles into the vacuum filtering device. Minimal processing steps reduce the instance of introducing contamination and particle loss.•Digestion as a first step to disintegrate aggregates to release entrapped microplastics•Density separation with SMI unit with the method adapted for biowastes•Minimal steps to reduce contamination and particle loss.

Effect of thermal treatment of illite on the bioavailability of copper and zinc in the aerobic composting of pig manure with corn straw.

The large amount of various types of heavy metals in animal manure applied to agricultural field has caused severe threat to the ecosystems of soil environments. In this study, the effect of thermal treatment of illite on the bioavailability of copper (Cu) and zinc (Zn) in the aerobic composting of pig manure with corn straw biochar was investigated. The objectives of this study were to characterize the variations in the bioavailability of Cu and Zn in the aerobic composting of pig manure added with illite treated with high temperatures and to identify the relatively dominant microbes involved in the formation of humus and passivation of heavy metals in pig manure composting based on 16S rRNA high-throughput sequencing analysis. The results showed that in comparison with the raw materials of pig manure, the bioavailability of Zn and Cu in the control and three experimental composting groups, i.e., group I (with untreated illite), group I-2 (with illite treated under 200°C), and group I-5 (with illite treated under 500°C), was decreased by 27.66 and 71.54%, 47.05 and 79.80%, 51.56 and 81.93%, and 58.15 and 86.60%, respectively. The results of 16S rRNA sequencing analysis revealed that in the I-5 group, the highest relative abundance was detected in Fermentimonas, which was associated with the degradation of glucose and fructose, and the increased relative abundances were revealed in the microbes associated with the formation of humus, which chelated with Zn and Cu to ultimately reduce the bioavailability of heavy metals and their biotoxicity in the compost. This study provided strong experimental evidence to support the application of illite in pig manure composting and novel insights into the selection of appropriate additives (i.e., illite) to promote humification and passivation of different heavy metals in pig manure composting.

Bio-chelate assisted leaching for enhanced heavy metal remediation in municipal solid waste compost.

Municipal solid waste compost, the circular economy's closed-loop product often contains excessive amounts of toxic heavy metals, leading to market rejection and disposal as waste material. To address this issue, the study develops a novel approach based on: (i) utilizing plant-based biodegradable chelating agent, L-glutamic acid, N,N-diacetic acid (GLDA) to remediate heavy metals from contaminated MSW compost, (ii) comparative assessment of GLDA removal efficiency at optimal conditions with conventional nonbiodegradable chelator EDTA, and (iii) enhanced pre- and post-leaching to evaluate the mobility, toxicity, and bioavailability of heavy metals. The impact of treatment variables, such as GLDA concentration, pH, and retention time, on the removal of heavy metals was investigated. The process was optimized using response surface methodology to achieve the highest removal effectiveness. The findings indicated that under optimal conditions (GLDA concentration of 150 mM, pH of 2.9, retention time for 120 min), the maximum removal efficiencies were as follows: Cd-90.32%, Cu-81.96%, Pb-91.62%, and Zn-80.34%. This process followed a pseudo-second-order kinetic equation. Following GLDA-assisted leaching, the geochemical fractions were studied and the distribution highlighted Cd, Cu, and Pb's potential remobilization in exchangeable fractions, while Zn displayed integration with the compost matrix. GLDA-assisted leaching and subsequent fractions illustrated transformation and stability. Therefore, this process could be a sustainable alternative for industrial applications (agricultural fertilizers and bioenergy) and social benefits (waste reduction, urban landscaping, and carbon sequestration) as it has controlled environmental footprints. Hence, the proposed remediation strategy, chemically assisted leaching, could be a practical option for extracting heavy metals from MSW compost, thereby boosting circular economy.

Simultaneous biofiltration of H2S, NH3, and toluene using compost made of chicken manure and sugarcane bagasse as packing material.

Offensive odors from wastewater treatment plants (WWTP) are caused by volatile inorganic compounds such as hydrogen sulfide and ammonia and volatile organic compounds (VOCs), such as toluene. To treat these pollutants, biofiltration is an effective and economical technology used worldwide due to its low investment and environmental impact. In this work, a laboratory-scale prototype biofilter unit for the simultaneous biofiltration of hydrogen sulfide, ammonia, and toluene was evaluated by simulating the emission concentrations of the El Salitre WWTP Bogotá, Colombia, using a compost of chicken manure and sugarcane bagasse as packing material for the biofilter. The prototype biofilter unit was set to an operation flow rate of 0.089 m3/h, an empty bed residence time (EBRT) of 60 s, and a volume of 0.007 m3 (6.6 L). The maximum removal efficiency were 96.9 ± 1.2% for H2S, at a loading rate of 4.7 g/m3 h and a concentration of 79.1 mg/m3, 68 ± 2% for NH3, at a loading rate of 1.2 g/m3 h and a concentration of 2.0 mg/m3, and 71.5 ± 4.0% for toluene, at a loading rate of 1.32 g/m3 h and a concentration of 2.3 mg/m3. The removal efficiency of the three compounds decreased when the toluene concentration was increased above 40 mg/m3. However, a recovery of the system was observed after reducing the toluene concentration and after 7 days of inactivity, indicating an inhibitory effect of toluene. These results demonstrate the potential use of the prototype biofilter unit for odor treatment in a WWTP.

Optimizing germination: comparative assessment of various growth media on dragon fruit germination and early growth.

Dragon fruit (Selenicereus undatus), known for its captivating appearance and remarkable nutritional profile, has garnered considerable attention in recent years. Despite its popularity, there's a dearth of research on optimal conditions for seed germination and early growth stages such as seedling shoot length, which are crucial for optimal crop yield. This study aims to bridge this gap by evaluating various growing media's performance on dragon fruit germination and early growth stages. Dragon fruit seeds were obtained from local markets in Pakistan and evaluated in five different growing media: cocopeat, peat moss, sand, vermiculite, and compost. Germination parameters were observed for 45 days, including seed germination percentage, mean germination time, and mean daily germination percentage, among others while early growth was monitored for 240 days. Statistical analysis was conducted using ANOVA and Tukey's HSD test. Significant differences were found among the growing media regarding germination percentage, mean germination time, and mean daily germination. Vermiculite exhibited the highest germination rate (93.33%), while compost showed the least (70%). Peat moss and sand media facilitated rapid germination, while compost showed slower rates. Stem length was significantly influenced by the growth media, with compost supporting the longest stems. Vermiculite emerged as the most effective medium for dragon fruit seed germination, while compost showed slower but steady growth. These findings provide valuable insights for optimizing dragon fruit cultivation, aiding commercial growers and enthusiasts in achieving higher yields and quality. Further research could explore additional factors influencing dragon fruit growth and development.

Prediction of compost organic matter via color sensor.

Composted materials serve as an effective soil nutrient amendment. Organic matter in compost plays an important role in quantifying composted materials overall quality and nutrient content. Measuring organic matter content traditionally takes considerable time, resources, and various laboratory equipment (e.g., oven, muffle furnace, crucibles, precision balance). Much like the quantitative color indices (e.g., sRGB R, sRGB G, sRGB B, CIEL*a* b*) derived from the low-cost NixPro2 color sensor have proven adept at predicting soil organic matter in-situ, the NixPro2 color sensor has the potential to be effective for predicting organic matter in composted materials without the need for traditional laboratory methods. In this study, a total of 200 compost samples (13 different compost types) were measured for organic matter content via traditional loss-on-ignition (LOI) and via the NixPro2 color sensor. The NixPro2 color sensor showed promising results with an LOI-prediction model utilizing the CIEL*a* b* color model through the application of the Generalized Additive Model (GAM) algorithm yielding an excellent prediction accuracy (validation R2 = 0.87, validation RMSE = 4.66 %). Moreover, the PCA scoreplot differentiated the three lowest organic matter compost types from the remaining 10 compost types. These results have valuable practical significance for the compost industry by predicting compost organic matter in real time without the need for laborious, time-consuming methods.