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This work evaluates the effect of agricultural plastic waste (APW) in two particle sizes, microplastic and film debris, and subjected to a pre-treatment by exposure to UV-C, in the development of the vermicomposting process. Eisenia fetida health status and metabolic response and the vermicompost quality and enzymatic activity were determined. The environmental significant of this study is mainly related to how can affect plastic presence (depending on plastic type, size and/or if it is partially degraded) not only to this biological process of organic waste degradation, but also to the vermicompost characteristics, since these organic materials will be reintroduced in the environment as organic amendments and/or fertilizers in agriculture. The plastic presence induced a significant negative effect in survival and body weight of E. fetida with an average decrease of 10% and 15%, respectively, and differences on the characteristics of the vermicomposts obtained, mainly related with NPK content. Although the plastic proportion tested (1.25% f. w.) did not induce acute toxicity in worms, effects of oxidative stress were found. Thus, the exposure of E. fetida to AWP with smaller size or pre-treated with UV seemed to induce a biochemical response, but the mechanism of oxidative stress response did not seem to be dependent on the size or shape of plastic fragments or pre-treated plastic.

Background: Since the state of alarm was declared due to the COVID-19 pandemic, hospitals have been the main ones in charge of registering the therapeutic follow-up of affected people. The analysis of these data has allowed those different biochemical markers have been identified as predictors of the severity of the disease, but most of the published studies tend to be eminently descriptive and do not propose a biochemical hypothesis to explain the alteration of the results they are showing. Our objective is to recognize the main metabolic processes that are occurring in COVID-19 patients, as well as the identification of clinical parameters that are decisive to predict the severity of the disease. Methods: A multivariate analysis was carried out from the clinical parameters collected in the database of the HM hospitals in Madrid, to determine the most relevant variables to predict the severity of the disease. Chemometric methods allow these variables to be obtained by applying a classification strategy with PLS-LDA. Findings and interpretation: The variables that most contribute to separation are age in men and, in both sexes, the concentration of lactate dehydrogenase, urea and C-reactive protein. Oxygen deficiency in the tissues, due to the loss of functionality of the lungs, could be affecting the muscle tissue with special severity. Inflammation and tissue damage is related to increased LDH and CRP. The loss of muscle mass and the increase in the concentration of urea and LDH is explained by the adaptation of muscle metabolism to this oxygen deficiency.

The global consumption of plastic is growing year by year, producing small plastic pieces known as microplastics (MPs) that adversely affect ecosystems. The use of organic amendments (compost and manure) polluted with MPs affects the quality of agricultural soils, and these MPs can be incorporated into the food chain and negatively impact human health. Current European legislation only considers large plastic particles in organic amendments. There is no information regarding MP pollution. Thus, the development of a methodology to support future legislation ensuring the quality of agricultural soils and food safety is necessary. This proposed methodology is based on thermogravimetry coupled with mass spectrometry to quantify polyethylene and polystyrene (PE and PS) MPs through their mass spectrometry signal intensity of characteristic PE (m/z 41, 43 and 56) and PS (m/z 78 and 104) ions. This method has been validated with several organic amendments where the MP content ranged from 52.6 to 4365.7 mg kg−1 for PE-MPs and from 1.1 to 64.3 mg kg−1 for PS-MPs. The proposed methodology is a quick and robust analytical method to quantify MPs in organic amendments that could support new legislation.

The agri-food industry is at the centre of the circular economy, since the co-composting of its residual flows allows their management and adds value producing fertilisers. In this work, six composting piles were prepared combining agri-food sludge (AS), different fresh vegetable wastes (pepper waste (P), tomato waste (T), and leek waste (L), and, as bulking agents, vine shoot pruning (VS), garlic stalks (GS) and avocado leaves (AL)). Classical physico-chemical and chemical determinations and advanced instrumental methods (excitation-emission fluorescence (EEM) and gravimetric (TG, DTG and DTA) techniques) were used and compared to assess organic matter evolution and evaluate the quality of the composts obtained. The thermal profiles of the composting processes were viable to show the stabilization of the agri-food sludge with the different materials tested in the mixtures, reaching adequate levels of stabilization of organic matter. Preferential degradation of peptides and proteins was observed by fluorescence. This seemed to induce a limitation in the biodegradation of the remaining organic matter, indicating that these biomolecules are key in composting dynamics, acting as limiting components during the process. The results from thermogravimetric analysis indicated the degradation of labile compounds (e.g., carbohydrates and proteins), the most recalcitrant material becoming predominant at the maturity stage of the composting process. The rise in the thermogravimetric parameter R2 was associated with the increase in the concentration of more refracting compounds, which need more energy for their decomposition.

The aim of this study was to evaluate the effect of considering different composting times on compost quality before the end of the bio-oxidative phase and after the maturation and storage phases. This study may provide useful information to optimize the composting process and increase the economic feasibility of the technology and its adoption without decreasing the quality of the end-product. In this study, three composts were prepared using chicken meat processing wastes mixed with urban tree trimmings, serving as a bulking agent, to evaluate the effect of reducing the durations of the bio-oxidative phase and the maturity stage on the different physico-chemical properties. Specifically, we evaluate water-soluble organic matter transformations by using excitation–emission matrix (EEM) fluorescence spectroscopy. The obtained results have shown that a composting time of 35 days combined with eight turnings was efficient for achieving the standard process control parameters for agro-industrial waste composting in the studied conditions and allowed for the production of stable and mature compost that is suitable for agricultural use.

This work evaluates several co-composting scenarios based on the use of Arundo donax biomass (AD) as bulking agent for the co-composting of sewage sludge (MS) and agri-food sludge (AS), to manage these organic wastes and to produce balanced organic fertilizers by optimizing the process. For this, six piles were prepared in commercial composting conditions, using AD in a range of 40%–80% (on a dry weight basis). Physico-chemical and chemical parameters and the thermal behaviour were evaluated during the process, as were the physical and chemical parameters of the final composts. The proportion of AD in the mixtures has a significant effect on the development of the thermophilic stage of composting, showing the piles with higher proportion of AD a quicker organic matter degradation. In addition, the evolution of the thermal indices R1 and R2 was different depending on the origin of the sludge used, indicating an increase in the relative concentration of more recalcitrant materials in the piles prepared with AS. The estimation of the global warming potential showed that the use of higher proportion of AD in the composting mixture may be a strategy to mitigate the emission of greenhouse gases during the composting process. Moreover, the end-products obtained had an additional marketable value, with a balanced nutrient content and a good degree of maturity, which indicates the viability of the composting process as a method for the stabilization of these organic wastes.

In the Mediterranean countries, there is an increasing production of date palm wastes (Phoenix dactylifera L.), not only due to the raising production of date palm fruits, but also derived from the maintenance of urban and peri-urban green areas, especially in those affected by red palm weevil (Rhynchophorus ferrugineus). The management of this increasing volume of green wastes usually concludes with a controlled disposal that implies an important loss of resources, in terms of organic matter, nutrients and energy. In addition, the rise of wastewater generation and the incentive of the wastewater treatment processes have derived in an increase of the amount of the sludge produced, which makes difficult its management. This work studies the feasibility of co-composting palm wastes with sludge from the urban and agri-food sectors as alternative treatment to manage these organic waste streams and to obtain added-value compost. For this, four mixtures (P1, P2, P3 and P4) were prepared using as main component palm leave waste (PL) mixed with different types of sludge. In the piles P1, P2 and P3, sewage sludge (SS) was used as co-composting agent, while agri-food sludge (AS) was used in P4. Throughout composting, the thermal profile of the composting piles was assessed, as were physical, chemical, physico-chemical and maturity parameters. In addition, the changes in water-soluble organic matter were assessed using chemical analytical methods and the excitation–emission matrix (EEM) fluorescence spectroscopy. The results obtained showed the viability of the co-composting process to obtain end-products with adequate maturity degree and physical characteristics for their potential use as substrates, except for the salt contents that can limit their use in some agricultural sectors.

The growth of the agri-food industry has resulted in a strong increase in its sludge generation. This type of waste is often produced in high amounts, concentrated in certain areas, and shows characteristics similar to those of municipal sewage sludge (except for the absence of heavy metals). Composting has been widely studied as a viable alternative for the treatment and recycling of municipal sewage sludge, but little information is currently available concerning the composting of agri-food sludge. Thus, the aim of this work was to increase our knowledge of how the vegetable-derived sludge produced by the agri-food sector can be managed using different co-composting strategies. The work was concerned mainly with the characteristics of the bulking agents used (type and particle size) and their effects on the development of the process and on the potential added value of the composts obtained. For this, four composting piles were prepared using agri-food sludge and two bulking agents (vine shoot prunings and pepper plant pruning waste) at two particle sizes (<1 cm and <3 cm). The evolution of the process and the final properties of the composts obtained were studied using classical analytical methods together with advanced instrumental methods (thermal analysis and excitation–emission matrix (EEM) fluorescence spectroscopy). In addition, their physical characteristics and potential suppression of phytopathogens (Fusarium oxysporum f. sp. melonis) were determined. The results showed differences according to the type and size of bulking agent, the mixtures with vine shoot prunings having a higher biodegradability, which was confirmed by thermogravimetry and EEM fluorescence spectroscopy. Melon plants grown in a mixture which included compost produced using vine pruning waste had a greater shoot weight than those grown on peat alone, while the mixture including compost derived from pepper pruning waste gave a shoot weight similar to that of peat-grown plants. Furthermo

Sewage sludge application to agricultural soils is a common practice in several countries in the European Union. Nevertheless, the application dose constitutes an essential aspect that must be taken into account in order to minimize environmental impacts. In this study, near infrared reflectance spectroscopy (NIRS) was used to estimate in sewage sludge samples several parameters related to agronomic and environmental issues, such as the contents in organic matter, nitrogen and other nutrients, metals and carbon fractions, among others. In our study (using 380 biosolid samples), two regression models were fitted: the common partial least square regression (PLSR) and the penalized signal regression (PSR). Using PLSR, NIRS became a feasible tool to estimate several parameters with good goodness of fit, such as total organic matter, total organic carbon, total nitrogen, water-soluble carbon, extractable organic carbon, fulvic acid-like carbon, electrical conductivity, Mg, Fe and Cr, among other parameters, in sewage sludge samples. For parameters such as C/N ratio, humic acid-like carbon, humification index, the percentage of humic acid-like carbon, the polymerization ratio, P, K, Cu, Pb, Zn, Ni and Hg, the performance of NIRS calibrations developed with PLSR was not sufficiently good. Nevertheless, the use of PSR provided successful calibrations for all parameters.