Poultry litter stabilization by two-stage composting-vermicomposting process: Environmental, energetic and economic performance

Enhancing biodegradation of vegetable oil-contaminated soil with soybean texturized waste, spent mushroom substrate, and stabilized poultry litter in microcosm systems

Industrial activities contribute to environmental pollution, particularly through unregulated effluent discharges, causing adverse effects on ecosystems. Vegetable oils, as insoluble substances, exacerbate this pollution, forming impermeable films and affecting the oxygen transfer, leading to serious habitat disruption. Organic wastes, such as soybean texturized waste, spent mushroom substrate, and stabilized poultry litter, were assessed for their efficacy in enhancing the degradation of vegetable oil in contaminated soil. For this purpose, contaminated soil was amended with each of the wastes (10% w/w) using microcosm systems, which were monitored physico-chemically, microbiologically and toxicologically. Results indicate that the wastes promoted significant oil degradation, achieving 83.1, 90.7, and 86.2% removal for soybean texturized waste, spent mushroom substrate, and stabilized poultry litter, respectively, within a 90-day period. Additionally, they positively influenced soil microbial activity, as evidenced by increased levels of culturable microorganisms and hydrolytic microbial activity. While bioassays indicated no phytotoxicity in most cases, soybean texturized waste exhibited inhibitory effects on seed germination and root elongation of Lactuca sativa. This study significantly enhances our comprehension of remediation techniques for sites tainted with vegetable oils, highlighting the critical role of organic waste as eco-friendly agents in soil restoration. Emphasizing the practical implications of these findings is imperative to underscore the relevance and urgency of addressing vegetable oil contamination in soil. Moving forward, tailored strategies considering both contaminant characteristics and soil ecosystem traits are vital for ensuring effective and sustainable soil remediation.

Application of life cycle assessment to high quality-soil conditioner production from biowaste

The recent large-scale urbanization and industrialization resulted in an impressive growth of solid waste generation worldwide. Organic fraction generally constitutes a large fraction of municipal solid waste and its peculiar chemical properties open to various valorization strategies. On this purpose, life cycle assessment is applied to an innovative industrial system that processes 18 kt/y of agricultural and livestock waste into a high-quality soil conditioner. The high-quality soil conditioner production system consists of a series of processes, including anaerobic digestion and vermicomposting, allowing the generation of a peat-like material with high carbon content, porosity, and water-holding capacity. The presence of a photovoltaic plant and a cogeneration plant, fed with the biogas produced in the anaerobic digestion, makes the system entirely self-sufficient from the national grid and generating a surplus of electricity of 1177MWh/y. The high-quality soil conditioner showed better environmental performances in 15 out of 18 impact categories when compared to alternative scenarios. In particular, the high-quality soil conditioner and the related biowaste management resulted in a carbon saving of around 397 kg CO2 eq/ton compared with a scenario involving the employment of peat in place of the high-quality soil conditioner and a traditional biowaste management, and 165 kg CO2 eq/ton compared with a scenario where cogeneration is replaced by biomethane upgrading. This study demonstrates the possibility of using organic waste as an environmentally sustainable and renewable source for energy and carbon to soil conditioning.

A Critical Review of Data Science Applications in Resource Recovery and Carbon Capture from Organic Waste

Municipal and agricultural organic waste can be treated to recover energy, nutrients, and carbon through resource recovery and carbon capture (RRCC) technologies such as anaerobic digestion, struvite precipitation, and pyrolysis. Data science could benefit such technologies by improving their efficiency through data-driven process modeling along with reducing environmental and economic burdens via life cycle assessment (LCA) and techno-economic analysis (TEA), respectively. We critically reviewed 616 peer-reviewed articles on the use of data science in RRCC published during 2002-2022. Although applications of machine learning (ML) methods have drastically increased over time for modeling RRCC technologies, the reviewed studies exhibited significant knowledge gaps at various model development stages. In terms of sustainability, an increasing number of studies included LCA with TEA to quantify both environmental and economic impacts of RRCC. Integration of ML methods with LCA and TEA has the potential to cost-effectively investigate the trade-off between efficiency and sustainability of RRCC, although the literature lacked such integration of techniques. Therefore, we propose an integrated data science framework to inform efficient and sustainable RRCC from organic waste based on the review. Overall, the findings from this review can inform practitioners about the effective utilization of various data science methods for real-world implementation of RRCC technologies.

Investigating the role of bulking agents in compost maturity

Kitchen waste is increasing globally, similarly in Pakistan bulk of municipal solid waste comprises of kitchen waste specifically, tea waste. Composting of kitchen waste is one of the promising ways to convert waste into useful product, resulting into zero waste. This study is aimed to convert waste (kitchen waste) in to a resource (compost) using bulking agents (tea waste and biochar) for reducing maturity time. Secondly, compost application on Solanum lycopersicum (tomato) was also tested. Four compost treatments were designed under aerobic composting conditions for 30 days. Tea waste and biochar have accelerated the maturity rate and produced a nutrient rich compost. Final compost had Electrical Conductivity of 2mS/cm, Carbon Nitrogen ration of 15, 54% of organic matter, 15% of moisture content, 48% of cellulose content, and 28% of Lignin content. With the use of Co-compost the Solanum lycopersicum showed 133% germination index, 100% germination, 235% Munoo-Liisa Vitality Index and 1238% seed vigor index. Co-compost also improved the soil total nitrogen by 1.4%, total phosphorous by 2%, total potassium by 2.1% and bulk density by 2.6 gcm-3. This study successfully used tea waste and biochar as bulking agents to reduce maturation time to 30 days. Tea waste and biochar enhanced the organic matter degradation, lignocellulose degradation, water holding capacity, porosity, seed's vigor, germination index. This research can be helpful in developing home composting and home gardening to combat solid waste management and food security issue in developing countries.

The Environmental Impact of Poplar Stand Management: A Life Cycle Assessment Study of Different Scenarios

The circular economy will play an important role in the reduction of carbon emissions and poplar might be one of the winning choices according to sustainable development. As for agricultural crops, high-quality production is strictly related to genetic variability and best management practice. The main objective of this study was to analyze different stand management options to quantify differences on carbon emission and environmental impacts. Moreover, the study was focused on the assessment of differences between standard poplar management for veneer and poplar management according to sustainable production (such as the PEFC certification scheme). The system boundaries embraced fertilization (inorganic or organic), agricultural operations, machinery, and field emissions associated with poplar cultivation. The environmental impacts were quantified by a life cycle assessment (LCA) calculation using SIMAPRO software v8.0 with different databases. The primary data of poplar stands were collected during a decades-long Italian experience. A reduction of carbon emissions was observed in the stand managed with MSA clones (Case “Mezzi PEFC”), and negative emissions were observed due to organic fertilization (scenarios 7m-29 t CO2-eq ha−1 and 26M-129 t CO2-eq ha−1). In all cultivation scenarios, the environmental impacts were lower than conventional crops in the study area, such as corn. A higher impact was observed in the 26M scenario with oversized machinery for stand management. These data can also contribute to poplar stand modeling and represent a basis for future research developments in this field.

Detoxification of coir pith through refined vermicomposting engaging Eudrilus eugeniae

Hazardous coir industrial waste, coir pith has been subjected to 50 days vermicomposting with Eudrilus eugeniae by amending nitrogenous legume plant, Gliricidia sepium together with cattle dung in different combinations, after 21 days precomposting using Pleurotus sajor-caju spawn. An increase in electrical conductivity, total NPK and calcium, and a decrease in organic matter, total organic carbon, C/N ratio, C/P ratio and total phenolic content in the final vermicompost were observed. Dehydrogenase, urease and cellulase activity peaked up to 30 days of vermicomposting and then declined. The phytotoxicity studies with Brassica juncea, C/N ratio and enzyme activities confirmed the stability and maturity of vermicompost. The results also demonstrated that the 2:3:1 ratio (coir pith + Gliricidia sepium + cow dung) is a suitable effective combination for nutrient-rich (N: 2.43%; P: 0.92%; K: 2.09%) vermicompost production. The total phenolic contents declined during the vermicomposting with a lower final content of 21.26 mg/g GAE in 2:3:1 combination of substrates from the initial level (105.56 mg/g GAE). Besides, the concentration of total phenol contents inversely related to the germination index of Brassica juncea (r = -0.761), indicating that the phenolic content could also play an important role in phytotoxicity. Growth and fecundity of Eudrilus eugeniae in 2:3:1 combination revealed the acceptability and rapid decomposition of coir pith substrate into vermifertilizer.

Toxicity and physicochemical parameters of composts including distinct residues from agribusiness and slaughterhouse sludge

Composting is useful for treatment of residues from agribusiness, but the potential toxicity of the final compost should be evaluated before its agricultural destination. The objective of this study was to evaluate the physicochemical characteristics and the toxicity of agribusiness residues using onion seeds as bioindicators. All tested treatments were composed by sludge from a swine slaughterhouse and sawdust. Besides the control, which included no additional materials, the other treatments included aviary bedding, rice husk and residue from tobacco industries as structuring materials. After 120 days of composting, for all treatments, the temperature inside the composting piles approached the environmental temperature, the physicochemical parameters indicated that the composts were stabilized and, except for the treatment including tobacco residues, that could be used for agriculture without impairing plant germination. Although the treatments including tobacco residues and rice husk showed evidence of cytotoxicity and genotoxicity at the beginning of the composting period, that was not observed for the treatment including aviary bedding. Such potential toxicity was not observed at the end of composting for any of the tested treatments.