Study of the composting process of winery and distillery wastes using multivariate techniques

Compostaje de residuos vitivinícolas. Avanzando hacia una industria circular

En una vitivinicultura circular, mediante el compostaje de materia orgánica, se conservan los nutrientes, la estructura y la diversidad del suelo del viñedo, y se valorizan los residuos industriales. En este contexto, el objetivo de este trabajo fue optimizar la eficiencia y calidad de la producción de compost. En un proyecto colaborativo entre 3 bodegas, se evaluó un compostaje de volteo tradicional en conjunto con una tecnología de cubierta permeable, sustratos alternativos como residuos de tomate y manzana, así como estiércol y urea como fuente adicional de nitrógeno, y además el efecto de organismos comerciales como aceleradores del compostaje de residuos vitivinícolas. El uso de una cubierta permeable redujo el requerimiento de agua en un 17%. La adición de orujo de manzana y tomate generó un compost más estable y rico en N, en comparación con los sistemas que utilizan solo orujo. La aplicación de estiércol avícola y urea aumentó principalmente en el contenido respectivo de P y N. La inoculación adicional con microorganismos comerciales no generó diferencias en el compost. En cuanto a las poblaciones de microorganismos naturales, no se encontraron diferencias entre los tratamientos en bacterias beneficiosas fijadoras de nitrógeno como Nitrospira y Nitrosomas.

Utilización de lodos residuales en el compostaje de orujos y escobajo en la industria vitivinícola

Este estudio tiene por objetivo evaluar la factibilidad de integrar lodos provenientes de una planta de tratamiento de aguas vitivinícolas en el compostaje de orujos y escobajo. Los ensayos se llevaron a cabo en un viñedo de la zona central de Chile, se estudió la evolución del proceso de compostaje mediante el monitoreo de temperaturas, pH, humedad y densidad aparente. Se determinaron los efectos 3 distintas proporciones v/v de lodos (0, 10 y 20%), en las propiedades fisicoquímicas y el contenido de metales pesados durante la etapa mesófila inicial, termófila y mesófila tardía. Los resultados indican un incremento en el contenido de nutrientes y porcentaje de humedad al incorporar los lodos en las primeras etapas del proceso, además de mejorar la estructura física de las pilas. Sin embargo, existe un riesgo de fitotoxicidad asociado al contenido de metales pesados cuando el lodo es usado en mayores proporciones (20%). Con dosis menores (10%) se obtuvo un compost sin riesgos fitotóxicos y dentro de los parámetros establecidos por la normativa vigente en Chile. Por lo anterior, es factible integrar los lodos de la planta de tratamiento de aguas vitivinícolas, en una proporción de 10% de lodos y 90% de orujo y escobajo.

Increasing Value of Winery Residues through Integrated Biorefinery Processes: A Review

The wine industry is one of the most relevant socio-economic activities in Europe. However, this industry represents a growing problem with negative effects on the environment since it produces large quantities of residues that need appropriate valorization or management. From the perspective of biorefinery and circular economy, the winery residues show high potential to be used for the formulation of new products. Due to the substantial quantities of phenolic compounds, flavonoids, and anthocyanins with high antioxidant potential in their matrix, these residues can be exploited by extracting bioactive compounds before using the remaining biomass for energy purposes or for producing fertilizers. Currently, there is an emphasis on the use of new and greener technologies in order to recover bioactive molecules from solid and liquid winery residues. Once the bio compounds are recovered, the remaining residues can be used for the production of energy through bioprocesses (biogas, bioethanol, bio-oil), thermal processes (pyrolysis, gasification combustion), or biofertilizers (compost), according to the biorefinery concept. This review mainly focuses on the discussion of the feasibility of the application of the biorefinery concept for winery residues. The transition from the lab-scale to the industrial-scale of the different technologies is still lacking and urgent in this sector.

Recovery of polyphenols from distillery stillage by microwave-assisted, ultrasound-assisted and conventional solid-liquid extraction

Recovery of bioactive compounds from distillery waste could be an option for valorizing this waste. This study investigated how the extraction of polyphenols (which have antioxidant activity) from distillery stillage was affected by solvent type and concentration, extraction time, and method of extraction (conventional solid–liquid extraction, CSLE; ultrasound-assisted extraction, UAE; microwave-assisted extraction, MAE). Although recovery was similar with UAE and MAE, 3 min MAE with 80% ethanol and 80% methanol produced the highest yields of total phenolic content (TPC), total flavonoid content (TFC) and phenolic acids. With CSLE, TPC was 2.1–1.8-times lower than with MAE and 1.7–1.4-times lower than with UAE. Increasing the solvent concentration to 100% significantly decreased recovery. Six phenolic acids were recovered (ferulic and p-coumaric acid predominated), which were present mainly in the free form. There was a significant positive correlation between antioxidant activity, as measured with three methods (one based on the hydrogen atom transfer and two based on single electron transfer mechanisms), and phenolic acid content. With MAE and UAE, polyphenols were recovered more efficiently, with 2.1 times and 1.5 times higher antioxidant activity, and with 15 times and 9 times shorter extraction times, respectively, than with CSLE; thus, they can be considered "green" alternatives to CSLE.

Quantifying the effects of co-composting organic biomass mixtures with inorganic amendments to obtain value-added bio-products

Co-digestion of organic biomass mixed with inorganic amendments could have an impact on composting dynamics. Various studies highlighted fertilizers' role as an additive to lesser the nitrogen loss, while some studies focused on the addition of fertilizers to enhance the efficiency. The changes in carbon, nitrogen components, and humic substances during the organic-inorganic co-compost process were seldom studied. Clarifying these changes might help improve the production process and compost nutrients contents. Thus, this study's purpose is to investigate the effects of inorganic amendments on compost characteristics, compost temperature, biochemical methane production (BMP), and nutritional contents. The inorganic phosphorous (P), sulfur (S), and sulfur solubilizing agent (SSA) were added to Farmyard manure (FYM) mixed with biodegradable waste (BW), including wheat straw, corn stalks, and green lawn waste. The P and S amended treatments were carried out into two sets, with and without SSA. The mixed feedstocks were added in the insulated RBC composting pit (15 x 15 x 10 feet). The compost material's moisture content was maintained 50-65% during the entire composting process for optimum waste digestion i.e., the moisture content (MC) of FYM was 82.7% and for BW ranged 8.8-10.2%, while the C/N ratio was found 10.5 for FYM, 74.5 for wheat straw, 83.5 for corn stalks, and 84.8 for lawn waste. At the condition of compost maturity, the inorganic amendments have no significant effect on composted material's moisture content. The maximum organic matter of 69.7% and C/N ratio of 44.6 was measured in T1. On the 6th day of composting, the temperature reached to thermophilic range (>45 oC) in all the treatments due to aeration of compost increased microbial activities and waste decomposition rate and decreased gradually to mesophilic range (35-45 oC) because the supply of high-energy compounds becomes exhausted. The highest temperature was reached in T4 (58 oC) and lowest in CT (47 oC). The significantly maximum methane of 8.95 m3 and biogas burning was 818 minutes in CT, followed by T1 and T4. The results of this study revealed that P enriched compost is a feasible and sustainable way to overcome P deficiency in the soil as well as in plants and best way to use low-grade P and organic waste material.

Integrated biorefinery approach to valorize winery waste: A review from waste to energy perspectives

The ever-increasing environmental crisis, depleting natural resources, and uncertainties in fossil fuel availability have rekindled researchers' attention to develop green and environmentally friendlier strategies. In this context, a biorefinery approach with a zero-waste theme has stepped-up as the method of choice for sustainable production of an array of industrially important products to address bio-economy challenges. Grape winery results in substantial quantities of solid organic and effluent waste, which epitomizes an increasing concentration of pollution problems with direct damage to human health, economy and nature. From the perspective of integrated biorefinery and circular economy, winery waste could be exploited for multiple purpose value-added products before using the biomass for energy security. This review covers state-of-the-art biorefinery opportunities beyond traditional methods as a solution to overcome many current challenges such as waste minimization in grape leaves, stems, seeds, pomace, wine lees, vinasse etc. and the biosynthesis of various high-value bioproducts viz., phenolic compounds, hydroxybenzoic acids, hydroxycinnamic acids, flavonoids, tartaric acids, lignocellulosic substrates etc.. The critical discussion on the valorization of winery waste (solid, liquid, or gaseous) and life cycle assessment was deployed to find a sustainable solution with value added energy products in an integrated biorefinery approach, keeping the environment and circular economy in the background.

Impact of mesophilic co-composting conditions on the quality of substrates produced from winery waste activated sludge and grape stalks: Lab-scale and pilot-scale studies

In this study, different amounts of a mixture of winery waste activated sludge and grape stalks were co-composted for 8 weeks, at lab-scale under different temperatures and aeration rates, and at pilot-scale. None of the experiments showed the occurrence of a thermophilic stage, even when the composting temperature was kept at 34 °C, which might suggest biological suppression by the acclimated mesophilic microorganisms ubiquitous to the winery waste activated sludge. The composted substrates were fully characterized by physicochemical analysis, plant growth tests and germination indexes using parsley (Petroselinum crispum) seedlings and seeds. Surprisingly, despite the higher volume reduction at lab-scale, it was the initial mixture and the mixture composted outdoors which presented the best horticultural qualities, with seedling survival rates of 88.9% and 87.0% and modified germination indexes of 54% and 161%, respectively. These findings shed some light on previous contradictory results and allow the development of new recycling strategies.

Effect of bean dregs on nitrogen transformation and bacterial dynamics during pig manure composting

This work studied the nitrogen transformation and bacterial dynamics in the co-composting of bean dregs (BD) and pig manure (PM). Four treatments were performed with BD at 0% (CK), 5%, 10% and 15% (w/w dry basis of PM) amended for 49-days aerobic compost. Results revealed that the temperature, NH₄⁺-N and pH of end product all met the maturity requirement. The BD-amendment increased nitrogen losses (8.55%-55.92%) during composting compared to CK. However, this amendment also enhanced total nitrogen content (TKN) of end products (1.86%-12%). The highest content of TKN was in 10%BD-amended treatment with relatively lower nitrogen loss compared to 15%BD. Furthermore, the results of 16S rDNA showed that BD-amended changed the bacterial community composition compared with CK. Especially, 10%BD-amended was the optimum in promoting the diversity and abundance of bacteria. Additionally, Firmicutes, Actinobacteria, Proteobacteria, Bacteroidetes and Chloroflexi were dominant phyla and Bacilli was dominant class in BD-amended compost.

Strategies for recycling and valorization of grape marc

Grapes are one of the most cultivated fruit crops worldwide. Either for wine or juice production, grape processing generates a large amount of residues that must be treated, disposed of or reused properly to reduce their pollution load before being applied to the soil. In this review, a special focus is given to the treatment and valorization of the winemaking by-product like grape marc via anaerobic digestion, composting and vermicomposting at laboratory, pilot, and industrial scales. The impact of the final products (digestates, composts, and vermicomposts) on soil properties is briefly addressed. Moreover, the role of grape marc and seeds as a valuable source of natural phytochemicals that include polyphenols and other bioactive compounds of interest for pharmaceutical, cosmetic, and food industries is also discussed. This is of paramount importance given the fact that sustainability requires the use of management and valorization strategies that allow the recovery of valuable compounds (e.g. antioxidants) with minimum disposal of waste streams.

Development of organic fertilizers from food market waste and urban gardening by composting in Ecuador

Currently, the management of urban waste streams in developing countries is not optimized yet, and in many cases these wastes are disposed untreated in open dumps. This fact causes serious environmental and health problems due to the presence of contaminants and pathogens. Frequently, the use of specific low-cost strategies reduces the total amount of wastes. These strategies are mainly associated to the identification, separate collection and composting of specific organic waste streams, such as vegetable and fruit refuses from food markets and urban gardening activities. Concretely, in the Chimborazo Region (Ecuador), more than 80% of municipal solid waste is dumped into environment due to the lack of an efficient waste management strategy. Therefore, the aim of this study was to develop a demonstration project at field scale in this region to evaluate the feasibility of implanting the composting technology not only for the management of the organic waste fluxes from food market and gardening activities to be scaled-up in other developing regions, but also to obtain an end-product with a commercial value as organic fertilizer. Three co-composting mixtures were prepared using market wastes mixed with pruning of trees and ornamental palms as bulking agents. Two piles were created using different proportions of market waste and prunings of trees and ornamental palms: pile 1 (50:33:17) with a C/N ratio 25; pile 2: (60:30:10) with C/N ratio 24 and pile 3 (75:0:25) with C/N ratio 33), prepared with market waste and prunings of ornamental palm. Throughout the process, the temperature of the mixtures was monitored and organic matter evolution was determined using thermogravimetric and chemical techniques. Additionally, physico-chemical, chemical and agronomic parameters were determined to evaluate compost quality. The results obtained indicated that all the piles showed a suitable development of the composting process, with a significant organic matter decomposition, reached in a shorter period of time in pile 3. At the end of the process, all the composts showed absence of phytotoxicity and suitable agronomic properties for their use as organic fertilizers. This reflects the viability of the proposed alternative to be scaled-up in developing areas, not only to manage and recycle urban waste fluxes, but also to obtain organic fertilizers, including added value in economic terms related to nutrient contents.

Reducing nitrogen loss and phytotoxicity during beer vinasse composting with biochar addition

The aim of this study was to investigate the feasibility of composting of beer vinasse generated from brewing industry, the effect of biochar amendment on beer vinasse composting was also evaluated based on the changes of different physicochemical parameters, phytotoxicity and final compost quality. Four different treatments were performed of beer vinasse with biochar addition at 0, 5%, 10%, 15% (w/w dry basis). The final product obtained from beer vinasse composting was phytotoxicity-free (GI: 120.8%), mature (C/N: 19.88, NH₄⁺-N: 295.0mg/kg, DOC: 9.76g/kg) and nutrient-rich (especially for P: 1.92%) compost except high N loss (60.76%), which had the potential to be as soil amendment or fertilizer. Biochar addition contributed to decomposition of DOC indicating higher microbial activity and attain phytotoxicity-free standard rapidly. N loss significantly reduced by 27% with biochar at 15% addition. And 15% biochar addition ensured all parameters, which was involved in composts quality, to attain the mature standard. Therefore, it was suggested that biochar addition at 15% was optimal.

Addressing Facts and Gaps in the Phenolics Chemistry of Winery By-Products

Grape and wine phenolics display a noticeable structural diversity, encompassing distinct compounds ranging from simple molecules to oligomers, as well as polymers usually designated as tannins. Since these compounds contribute critically to the organoleptic properties of wines, their analysis and quantification are of primordial importance for winery industry operators. Besides, the occurrence of these compounds has been also extensively described in winery residues, which have been pointed as a valuable source of bioactive phytochemicals presenting potential for the development of new added value products that could fit the current market demands. Therefore, the cumulative knowledge generated during the last decades has allowed the identification of the most promising compounds displaying interesting biological functions, as well as the chemical features responsible for the observed bioactivities. In this regard, the present review explores the scope of the existing knowledge, concerning the compounds found in these winery by-products, as well as the chemical features presumably responsible for the biological functions already identified. Moreover, the present work will hopefully pave the way for further actions to develop new powerful applications to these materials, thus, contributing to more sustainable valorization procedures and the development of newly obtained compounds with enhanced biological properties.

Nitrification during extended co-composting of extreme mixtures of green waste and solid fraction of cattle slurry to obtain growing media

Next generation of waste management systems should apply product-oriented bioconversion processes that produce composts or biofertilisers of desired quality that can be sold in high priced markets such as horticulture. Natural acidification linked to nitrification can be promoted during composting. If nitrification is enhanced, suitable compost in terms of pH can be obtained for use in horticultural substrates. Green waste compost (GW) represents a potential suitable product for use in growing medium mixtures. However its low N provides very limited slow-release nitrogen fertilization for suitable plant growth; and GW should be composted with a complementary N-rich raw material such as the solid fraction of cattle slurry (SFCS). Therefore, it is important to determine how very different or extreme proportions of the two materials in the mixture can limit or otherwise affect the nitrification process. The objectives of this work were two-fold: (a) To assess the changes in chemical and physicochemical parameters during the prolonged composting of extreme mixtures of green waste (GW) and separated cattle slurry (SFCS) and the feasibility of using the composts as growing media. (b) To check for nitrification during composting in two different extreme mixtures of GW and SFCS and to describe the conditions under which this process can be maintained and its consequences. The physical and physicochemical properties of both composts obtained indicated that they were appropriate for use as ingredients in horticultural substrates. The nitrification process occurred in both mixtures in the medium-late thermophilic stage of the composting process. In particular, its feasibility has been demonstrated in the mixtures with a low N content. Nitrification led to the inversion of each mixture's initial pH.

Phosphorus availability from rock phosphate: Combined effect of green waste composting and sulfur addition

Rock phosphate constitutes a natural phosphorus (P) source for organic farming systems, but with a limiting direct agricultural use due to its poor inherent reactivity. Thus, this work studies the effect of the co-composting of rock phosphate with green wastes and elemental sulfur on phosphorus availability. Six composts were prepared combining different green wastes and rock phosphate in three different proportions (0%, 0.27% and 0.54% P fresh mass basis) and elemental sulfur in two proportions (0% and 0.5% S fresh mass basis). During composting, the temperature of the mixtures was monitored, as were physico-chemical and chemical parameters, especially those related to phosphorus. The co-composting of green wastes with rock phosphate improved phosphorus mobilization and also constituted a viable method to manage green wastes, obtaining P-enriched compost for organic farming systems. Sulfur addition favored the composting process and also phosphorus solubilization, especially in the mixture with the lowest proportion of rock phosphate.

Windrow composting as horticultural waste management strategy - A case study in Ecuador

In Ecuador, enormous quantities of vegetable wastes are produced annually from the horticultural industries. Composting can be a feasible treatment to stabilise horticultural wastes and, thus, to improve their properties for use as organic fertilisers. In this study, two different piles were prepared, using laying hen manure and sawdust mixed with broccoli or tomato waste, respectively, and composted by the turned windrow composting system. Throughout the composting process, the temperature of the mixtures was monitored and physico-chemical and chemical properties and the degree of maturity were determined. Also, principal component analysis was used to interpret the data set of compost characteristics. In both piles, the temperature exceeded 55°C for more than 2weeks, which ensured maximum pathogen reduction. Organic matter (OM) losses followed a first-order kinetic equation in both piles. The final composts showed a suitable degree of stability and maturity and an absence of phytotoxins, as observed in the evolution and final values of the total organic carbon/total nitrogen ratio (Corg/NT<20), water-soluble organic carbon (Cw<1.7%), germination index (GI>50%) and cation exchange capacity (CEC>67meq (100g OM)(-1)). As well, the evolution of different humification indexes during composting was a good indicator of the OM humification process. The type of vegetable waste used influenced OM and NT mineralisation and the final properties of the composts, showing the mixture with tomato waste a higher fertilising capacity and less environmental problems.

Tracking organic matter and microbiota dynamics during the stages of lignocellulosic waste composting

The dynamics of biologically meaningful soluble and polymeric carbon fractions and the combined relationships between physical, chemical and biological parameters during composting of lignocellulosic waste were evaluated. The first thermophilic stage is crucial in determining the further evolution of soluble and polymeric carbon fractions but the dynamics of carbon is still important at the maturation stage. Multivariate data analysis showed that not only are all parameters interrelated but also influence one another's variability. To discern completion of bio-oxidative stage other parameters in addition to temperature should be measured. Evaluation of soluble organic carbon, microbial biomass carbon, pH and inorganic nitrogen can be of great use in detecting the composting stage. This study offers new insights into the mechanisms involved in the biodegradation of organic matter and help to prioritize the parameters that contribute at critical stages of the process.

Valorization of winery waste vs. the costs of not recycling

Wine production generates huge amounts of waste. Before the 1990s, the most economical option for waste removal was the payment of a disposal fee usually being of around 3000 Euros. However, in recent years the disposal fee and fines for unauthorized discharges have increased considerably, often reaching 30,000-40,000 Euros, and a prison sentence is sometimes also imposed. Some environmental friendly technologies have been proposed for the valorization of winery waste products. Fermentation of grape marc, trimming vine shoot or vinification lees has been reported to produce lactic acid, biosurfactants, xylitol, ethanol and other compounds. Furthermore, grape marc and seeds are rich in phenolic compounds, which have antioxidants properties, and vinasse contains tartaric acid that can be extracted and commercialized. Companies must therefore invest in new technologies to decrease the impact of agro-industrial residues on the environment and to establish new processes that will provide additional sources of income.

Short-term stabilization of grape marc through earthworms

The winery industry generates vast amounts of organic waste during the various stages of wine production. Among the possible methodological alternatives available for its treatment, vermicomposting is one of the best-known processes for the biological stabilization of solid organic wastes by transforming them into safer and more stabilized materials suitable for application to soil. In this study we carried out a mesocosm experiment to evaluate the effectiveness of the active phase of vermicomposting for the stabilization of grape marc, an enriched lignocellulosic by-product obtained after the grape crushing and pressing stages in wine production. For this we analysed the chemical, biochemical and microbiological properties of the product resulting from this phase, in comparison with those in a control treatment. Earthworm activity reduced the abundance of both bacterial and fungal PLFA biomarkers. Decreases in microbial activity and in protease and cellulase activities were also attributed to the presence of earthworms. The differences in microbial communities were accompanied by a reduction in the labile C pool and the cellulose content. These results indicate that earthworms played a key role in the stabilization of the grape marc in the short-term, via its effects on organic matter decomposition and microbial biomass and activity.

Estimation of phosphorus content and dynamics during composting: use of near infrared spectroscopy

The content and chemical forms of P in compost are essential variables for its proper management with an agricultural purpose, especially considering the increasing P over-fertilization in agrosystems. In this study, the estimation of P content and dynamics in different composting scenarios was developed using near infrared reflectance spectroscopy (NIRS) coupled with a statistical tool for calibration, a penalized signal regression. Samples were analyzed on total P and partitioned using NaOH-solution (31)P NMR spectroscopy quantifying pyrophosphate, orthophosphate, orthophosphate diesters, phospholipids, and orthophosphate monoesters pools. According to the results obtained, total P content (r(2)=0.99 and root mean square error of cross-validation=0.53) and P forms can be estimated during composting using NIRS, as well as in the mature product, orthophosphate and orthophosphate monoesters being the most abundant P forms throughout the experiment. Penalized signal regression allows detecting the significant wavenumbers in each composting period, and also with the different P pools in the composting pile depending on time.