Winery Wastewater Research Articles

Application of Electric Field Force for the Accumulation of Anthocyanins from Winery Wastewater

The recovery of anthocyanins from winery wastewater constitutes an attractive option for both environmental and commercial valorization, as food colorants and nutraceutical ingredients. In this study, the electric field induced ion drift method is proposed as a promising technique for the purification of wastewater solutions as well as for the accumulation of anthocyanins. The cation of the anthocyanidin malvidin (C17H15O7+) was selected as the most representative of winery waste, in order to develop a theoretical model. The main principle of the model is based on the displacement of charged anthocyanin ions, under the influence of an electric field vertical to the flow of the solution, and their accumulation on the side walls of a conductor. Apparatus inducing an electric field drift is described, and critical parameters (i.e., final spatial distribution of concentration, electric field intensity, surface charge density, and potential) were calculated. The proposed model succeeded in reducing anthocyanin concentration by more than 90%, for duct widths smaller than 1 mm in the bulk of the solution, for applied potentials φ(0) in the range of 0.2–0.4 V and target concentrations equal to 1.2 × 10−3 mol/m3.

Shear Enhanced Flotation Separation Technology in Winery Wastewater Treatment

The process of wine making is well known to produce large amounts of wastewater with highly variable characteristics. The disposal of untreated winery wastewater is strictly prohibited since it adversely affects the recipient environment. Due to the variability in characteristics of winery wastewater, developing a treatment system which can handle high organic and inorganic loads, especially during the vintage season, is a complex challenge. This study investigated the theory, methodology and implementation of a wastewater treatment technology called shear enhanced flotation separation (SEFS) as a potential primary treatment stage towards the treatment of winery wastewater. Winery effluent was subjected to a coagulation process in a high shear environment, with and without the introduction of air, followed by flocculation. Upon successful optimization of operating parameters, a polymeric-based coagulant AB121 and polyelectrolyte flocculant AB796 yielded the highest reduction in turbidity (95%) with typical values of 630 NTU for the raw wastewater and 25 NTU for the SEFS-treated effluent. A substantial reduction in total suspended solids (97%) was achieved with average raw winery wastewater values of 2275 mg/L compared to the 50 mg/L obtained for the SEFS-treated effluent. Furthermore, a notable reduction (54%) in COD (from 11,250 mg/L to 5220 mg/L) using SEFS technology was achieved.

Biosand reactors for remediation of winery effluent in support of a circular economy and the positive effect of sand fractionation on hydraulic and operational performance

There is an extensive body of knowledge pertaining to the treatment of winery wastewater and other acidic effluents in biosand reactors. This manuscript compares the performance of biosand reactors containing raw sand and fractionated sand. Fractionation of sand (particles <0.425 mm removed) increased the hydraulic conductivity of the sand matrix 9-fold when compared to raw sand: from 0.285 mm·s−1 to 2.50 mm·s−1 and 0.129 mm·s−1 to 1.11 mm mm·s−1 before and after start-up, respectively. Similar results for both sands were obtained in terms of organic removal performance (94 % and 95 %, respectively) and neutralization of acidic (pH 4.9) winery wastewater. Results indicate that one 5.6 m3 biosand reactor module containing 2.9 m3 of fractionated sand can theoretically treat 8102 L·d−1, which is the approximate volume generated from wineries crushing 329 to 547 t of grapes per annum. This is notably higher than the design flow rate of 1000 L·d−1 in used in a pilot system containing raw sand. Furthermore, a zero-waste biosand reactor model is presented for treatment of winery wastewater. The strategy includes reuse of treated effluent for irrigation, anaerobic digestion of primary winery wastewater sludge and use of the digestate as an agricultural fertilizer, and re-purposing of the residual sand.

Reuse of Pretreated Agro-Industrial Wastewaters for Hydroponic Production of Lettuce

The utilization of agro-industrial wastewaters (AIWWs), pretreated by immediate one-step lime precipitation + natural carbonation, as a nutritive solution for the hydroponic production of lettuce was evaluated. The AIWWs studied were olive mill wastewater (OMW), winery wastewater (WW), and cheese whey wastewater (CWW). Lettuces (Lactuca sativa L. var. crispa) were grown in a closed nutrient film technique hydroponic system, using the pretreated AIWWs (OMW-T, WW-T, and CWW-T) and a control nutrient solution (CNS). The growth and sensory analysis of lettuces and the environmental parameters of effluents after hydroponics were evaluated. The average number of lettuce leaves obtained with nutrient solutions prepared with AIWW-T was lower than that from CNS, but the highest lettuce chlorophyll content was attained with CWW-T, which also presented the best grow results. In general, sensory analysis did not show significant differences from the lettuces grown in the different pretreated AIWWs and CNS. As for the environmental parameters of the effluents from hydroponics, according to the Portuguese legislation, only the chemical oxygen demand of the OMW-T and WW-T presented slightly higher values than that of the environmental limit values for discharge in surface waters, showing the feasibility of using pretreated agro-industrial effluents in hydroponic lettuce cultivation, while obtaining a treated effluent, in a circular economy perspective.

Enhancement of EDDS-photo-Fenton process with plant-based coagulants for winery wastewater management

To achieve an efficient remediation of a winery wastewater (WW), it was studied a physical-chemical process (coagulation-flocculation-decantation – CFD) involving plant-based coagulants (PBC) with advanced oxidation processes (AOPs), aiming to achieve the Portuguese legal limits. Initially, one invasive (Acacia dealbata) and three native species (Quercus ilex, Platanus x acerifólia and Tanacetum vulgare) were collected and used as plant-based coagulants (PBCs). The combination of Platanus acerifólia (P.a.) seeds with polyvinylpolypyrrolidone (PVPP) achieved high turbidity (97.3%) and chemical oxygen demand (COD = 48.2%) removals, from raw WW, with [PBC] = 0.1 g/L, [PVPP] = 5 mg/L, pH = 3.0, fast mix = 150 rpm/3 min, slow mix = 20 rpm/20 min, sedimentation time = 12 h. Different AOPs were studied to treat raw WW, with photo-Fenton process revealing the highest COD efficiency (88.0%). To enhance the capabilities of photo-Fenton, ethylenediamine-N,N′-disuccinic acid trisodium salt (EDDS) was assessed as a chelation agent, reducing iron precipitation. The pre-treatment of WW by PBCs followed by EDDS/photo-Fenton (pH = 6.0, [H2O2] = 175 mM, [Fe2+] = 5 mM, [EDDS] = 1 mM, T = 298 K, time = 240 min) increased the COD removal, whatever the radiation source applied (UV–C, UV-A and solar). Among the different processes, the combined P. a. seeds and UV-C/EDDS/Fenton allowed increase the WW biodegradability from 0.26 to 0.46, and achieved a COD removal of 95.7%, reaching the Portuguese legal limits. As final remark, the synergy of PBCs and EDDS/photo-Fenton is considered effective and sustainable process for raw WW remediation and water reuse.

Co-Treatment of Winery and Domestic Wastewaters in Municipal Wastewater Treatment Plants: Analysis of Biodegradation Kinetics and Process Performance Impacts

Winery wastewater (WWW) handling strategies often include co-treatment at municipal wastewater treatment plants (WWTPs). Despite this, definitive information regarding oxidation kinetics and process and performance impacts due to co-treatment is lacking. A combined Michaelis–Menten–University of Cape Town kinetic model has been found to best describe the pH-inhibited aerobic biological oxidation of WWW by heterotrophs in activated sludge from four municipal WWTPs. The specific rate of substrate consumption was highest in biomass that had been exposed to WWW (57.3 mg COD/g MLVSS·h) compared to biomass that had not (20.7 mg COD/g MLVSS·h). Bench-scale aerobic co-treatment trials confirm that sorption is a key removal mechanism, with up to 98% chemical oxygen demand and 97% total organic carbon removal after 6 h of reaction time. The WWW solids are quickly incorporated into the biological floc and may improve settleability at loading rates above 75 mg WWW suspended solids/L bioreactor volume at the expense of significantly increasing the observed yield. The aerobic-activated sludge system at municipal WWTPs can effectively co-treat WWW, provided the organic loading rates are limited and the WWTP is designed to accommodate the seasonal loadings of winery wastewater. The identified mitigation measures can be used by co-treating facilities to optimize the co-treatment performance of WWW along with domestic wastewater.

Investigation on thermal pyrolysis of microalgae grown in winery wastewater: biofuels and chemicals production

Current innovations in microalgae technology include the use of wastewater as a cultivation medium for renewable energy generation and wastewater treatment. In this study, thermal pyrolysis was performed on a co-culture of Chlorella vulgaris and Arthrospira platensis grown in winery wastewater fed continuously into a membrane photobioreactor. The yield and composition of the reaction gases, reaction liquids, and solid residues collected at different reaction times and pyrolysis temperatures were compared with those of the same co-culture grown in its conventional medium. In general, the gaseous fraction resulted rich in combustible compounds. The highest yield in liquid products (55 %) was obtained by thermal pyrolysis of the co-culture grown in winery wastewater at 500 °C. Liquid fraction was made up of a mixture of oxygenated and nitrogenated compounds that are suitable as chemical intermediates and can therefore contribute to making the pyrolysis treatment economically feasible. For example, this fraction resulted particularly rich in crotonic acid, useful for the synthesis of copolymers (crotonic acid-vinyl acetate) and probably derived from the thermal cracking of polyhydroxy alkenoate. The results of this study suggest that thermal pyrolysis may be a good strategy to recover the energy potential of microalgae co-cultures used to treat wastewater.Graphical abstract

Experimental evaluation of temperature, nutrients, and initial concentration on medium-chain carboxylic acids production from winery wastes.

In the wine industry, grape processing is accompanied by waste generation, such as grape stalks, winery wastewater, and grape pomace (GP). GP can be used to produce value-added compounds such as medium-chain carboxylic acids (MCCA). This work aimed to determine the operational conditions (temperature, addition of nutrients, and initial waste concentration) to improve MCCA production using waste GP from the winery industry as a substrate. The electron donor (ethanol) and electron acceptor (acetate) were directly generated from the GP and consecutively used to produce MCCA. The treatment with high concentration, temperature, and nutrient addition promotes caproic acid's maximal yield and concentration (0.11 ± 0.02 g MCCA/g TS). Nutrients' presence and temperature significantly affected electron acceptor production. The addition of nutrients and 30 °C leads to elevated acetate production. However, at 37 °C, butyrate and MCCA were mainly produced without adding nutrients, and high ethanol consumption was observed. A higher metabolic diversification was observed at 37 °C than at 30 °C. Temperature and nutrient availability significantly affected the metabolic pathway and the type of carboxylic acid produced.

Recovery of Value-Added Compounds from Winery Wastewater: A Review and Bibliometric Analysis

Value-Added Compounds (VACs) are molecules that have attracted great attention in the literature regarding their potential for integration into existing processes or products. In Winery Wastewater (WW), VACs are valuable because of their antioxidant characteristics. Furthermore, integrated systems for recovery of these molecules and treatment of WW can be a powerful strategy towards an environmentally efficient way of wine production. Therefore, a bibliometric analysis was conducted to establish the status and trace research trends on that topic. The analysis investigated the Web of Science database from 1953–2023, where the software VOSviewer® and R were used. Secondly, an extensive literature review was carried out on VACs recovery from WW by membrane process, which was identified as a promising strategy. As a result, the historical evolution of publications has a growing behavior while citations take time to grow. The most productive authors, journals, and countries were analyzed, with Spain being the leading country in publications on that topic. Lastly, keyword mapping revealed the relevance of “circular economy” and “biorefinery” as knowledge transfer concepts where both traditional and emergent technologies are connected towards the achievement of sustainable development goals. The recovery of phenolic compounds from wine production through membrane processes stands out as a promising technology. Different recovery approaches using membrane processing were assessed in the review. Studies could achieve up to 100% phenolic compound and polysaccharide rejections and also addressed the possibility of fractioning these compounds.

Treatment of Winery Wastewater by Combined Almond Skin Coagulant and Sulfate Radicals: Assessment of HSO5- Activators.

The large production of wine and almonds leads to the generation of sub-products, such as winery wastewater (WW) and almond skin. WW is characterized by its high content of recalcitrant organic matter (biodegradability index < 0.30). Therefore, the aim of this work was to (1) apply the coagulation-flocculation-decantation (CFD) process with an organic coagulant based on almond skin extract (ASE), (2) treat the organic recalcitrant matter through sulfate radical advanced oxidation processes (SR-AOPs) and (3) evaluate the efficiency of combined CFD with UV-A, UV-C and ultrasound (US) reactors. The CFD process was applied with variation in the ASE concentration vs. pH, with results showing a chemical oxygen demand (COD) removal of 61.2% (0.5 g/L ASE, pH = 3.0). After CFD, the germination index (GI) of cucumber and corn seeds was ≥80%; thus, the sludge can be recycled as fertilizer. The SR-AOP initial conditions were achieved by the application of a Box-Behnken response surface methodology, which described the relationship between three independent variables (peroxymonosulfate (PMS) concentration, cobalt (Co2+) concentration and UV-A radiation intensity). Afterwards, the SR-AOPs were optimized by varying the pH, temperature, catalyst type and reagent addition manner. With the application of CFD as a pre-treatment followed by SR-AOP under optimal conditions (pH = 6.0, [PMS] = 5.88 mM, [Co2+] = 5 mM, T = 343 K, reaction time 240 min), the COD removal increased to 85.9, 82.6 and 80.2%, respectively, for UV-A, UV-C and US reactors. All treated wastewater met the Portuguese legislation for discharge in a municipal sewage network (COD ≤ 1000 mg O2/L). As a final remark, the combination of CFD with SR-AOPs is a sustainable, safe and clean strategy for WW treatment and subproduct valorization.

Photocatalytic treatment as a polishing step for the degradation of bio‐recalcitrant fractions of winery wastewater under solar, UVA‐LED, and blacklight irradiation

AbstractBACKGROUNDThis study investigates, for the first time, the most beneficial conditions for photocatalytic oxidation under ultraviolet (UV) irradiation provided by either a solar simulator, UVA light‐emitting diode (UVA‐LED), or UVA blacklight lamp (UVA‐BL) as a post‐treatment step for the degradation of the residual COD and color in winery wastewater (WiWW) after biological treatment.RESULTSThe effect of WiWW dilution (0, 50%), TiO2 concentration (0–1000 mg/L), catalyst type (TiO2, ZnO), pH (3, 6, 8.4), H2O2 addition (0–1000 mg/L), and treatment time on process efficiency was evaluated. At the best‐assayed conditions (1000 mg/L TiO2, 1000 mg/L H2O2), COD removal percentages in the range of 94–97% were obtained and color was removed by 99% within 180 min of treatment under all irradiation sources. The process was enhanced when the WiWW was subjected to 50% dilution and its pH was adjusted to 6. Among the three irradiation sources, UVA‐BL led to a marginally higher photocatalytic performance than solar and UVA‐LED, both of which achieved similar removal efficiencies. Regarding energy efficiency, UVA‐LED was found to be up to 1.7 times more energy efficient than UVA‐BL/TiO2. Finally, in most cases, the phytotoxicity of secondary effluent was eliminated during solar photocatalytic treatment.CONCLUSIONAlteration of basic operating parameters significantly improved process efficiency. In all cases, LED‐driven photocatalysis combined high removal performance and energy efficiency, proving to be an appropriate and sustainable alternative to solar photocatalysis for 24 h operation or for supplementary application during the harvest, when the majority of WiWW is generated. © 2022 Society of Chemical Industry (SCI).

Networks of action situations in point-source pollution: the case of winery wastewater in Aragon, Spain

In this article, we offer an analysis of point-source water pollution governance in the European agri-food sector. Specifically, we tackle the case study of the wine industry in Aragon (Spain) through the lenses of the networks of action situations approach. We unveil key strategic decisions of wine producers in relation to compliance with water discharge regulations and explore the feasibility and effectiveness of potential solutions. According to our quantitative and qualitative analyses, the problem of peak load discharges in the sector can be explained by the strategic behavior of wine producers in the context of enforcement deficits, as well as by particularities of the wine production process, and controversies around the construction and management of public treatment plants. Coordination among wine producers and public treatment plant managers to invest in in-house treatment infrastructure or to smooth discharges out so they fit the capacity of treatment plants would be a promising solution; however, economic incentives and tightened enforcement of discharge regulations would also be necessary.Graphical abstract

Combined organic coagulants and photocatalytic processes for winery wastewater treatment

Due to the consumers demand for quality wines, washing and disinfection operations are necessary in wine productions, leading to the generation of large volumes of winery wastewater (WW) with a high organic content which has the potential to cause irreversible environmental impacts. The aim and novelty of this work is the production of natural organic coagulants (NOCs) to be applied in coagulation-flocculation-decantation (CFD) process. To complement this treatment process, it is also aimed the performed a photo-Fenton process, combining hydrogen peroxide (H2O2) and potassium persulfate (KPS). The Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) showed that NOCs are carbon-based materials with adsorption capacity. Under the best operational conditions, NOCs achieved a turbidity removal between 86.2 and 98.9%, a total suspended solids (TSS) removal ranging between 85.0 and 94.9% and a dissolved organic carbon (DOC) removal ranging between 14.1 and 44.9%. To degrade the DOC present in the WW, different advanced oxidation processes (AOPs) were tested. Results showed that KPS-photo-Fenton, under the best operational conditions [Fe2+] = 2.5 mM, [KPS] = 1.0 mM, pH = 3.0, radiation UV-C mercury lamp (254 nm), agitation 350 rpm, temperature 298 K, reaction time 240 min achieved a DOC removal of 91.2 and 96.8%, with a H2O2 consumption of 156.9 and 199.0 mM, respectively for red and white WW. With application of combined CFD-KPS-photo-Fenton process, it was observed an increase of DOC removal with lower H2O2 consumptions. The energy consumption of the photosystem was evaluated by application of electric energy per mass (EEM). The application of KPS-photo-Fenton process achieved an EEM of 0.308 and 0.0309 kWh/g/L DOC, with a cost of 2.05 and 2.59 €/g/L DOC respectively for red and white WW. The combination of CFD-KPS-photo-Fenton decreased significantly the costs of treatment and the treated wastewater achieved the Portuguese legal values for wastewater discharge. This work shows that NOCs are a promising technology that can be an alternative to traditional metal salts, the combination of sulfate radicals with hydroxyl radicals can achieve high DOC removal and the combination of CFD with KPS-photo-Fenton process can decrease the operational costs.

Calcite Dissolution and Bioneutralization of Acidic Wastewater in Biosand Reactors

Acidic wastewaters such as winery wastewater require treatment to increase the pH before discharge into the environment. Biosand filters have been shown to reduce the organic load while simultaneously providing a buffering function. Previous research has shown increases in pH which was assumed to mainly take place via dissolution of calcite from the sand particles. This study investigated the possible role of biotic mechanisms for pH adjustment in sand column experiments by comparing results obtained from irradiated (biotic) and non-irradiated (biotic and abiotic) sand columns extracted from biosand filters used to treat winery wastewater. The columns were fed with either synthetic winery wastewater or filtered water (control). It was shown that the specific hydroxide concentrations in the eluant from the non-irradiated columns was significantly (p &lt; 0.05) higher than in the eluant from the irradiated columns (1.1 × 10−5 vs. 4.0 × 10−6 M/kgsand−1), indicating the presence of both biotic (average 4.5 ± 0.13%) and abiotic (average 95.5 ± 0.16%) pH increases. Using multivariate statistical tools to analyze a combination of parameters linked with biotic and abiotic pH adjustment, significant differences (ANOVA, p &lt; 0.05) were found between the four treatment groups (irradiated/non-irradiated SWW and control) and the groups showed good clustering in cluster plots (group average) linkages, and principal component analysis plots.

Effect of aeration on nitrogen removal-associated microbial community in an innovative vertical cork-based constructed wetland for winery wastewater treatment

The wine industry produces large quantities of wastewater that often contains high levels of organic matter and nutrients, like nitrogen and phosphorous. In particular, nitrogen pollution can be harmful, even at low levels, since infants are vulnerable to nitrates in drinking water, and excess nitrogen can harm the health of soils and waterways. Herein, an innovative compact, modular, and mobile treatment wetland (TW) using cork by product as the only granular media was used to treat the final effluents from the Codorniu winery (Sant Sadurní d'Anoia, Spain). The TW was operated during two 5-month periods with or without intermittent induced aeration (40 min cycles, 90 L/min air flow rate). Nitrate (N-NO3) and total nitrogen (TN) removal were higher (52.8% and 46.8%, respectively, p < 0.05) during TW operation under aerated-condition. Additionally, qPCR analysis of 16S rRNA, nirS and nosZ genes revealed that intermittent induced aeration facilitates N-NO3 reduction by the stimulation of denitrifying bacteria in the TW biofilm (11.4% increase in nirS copies number/g cork sample, p < 0.05) as well as increasing the number of heterotrophic bacteria adhered to cork (25.5% increase in 16S rRNA copies number/g cork sample, p < 0.05). Moreover, SEM images demonstrated the suitability of cork as a resistant filter media for TW after long-term system operation (1.5 years). In conclusion, our results suggest that aeration improved nitrogen compounds removal compared to the non-aerated period, without affecting phosphorous elimination. Additionally, residual cork is presented here in a circular bioeconomy view, as a suitable filling media to treat winery wastewater that can provide additional carbon source to increase C/N rate stimulating denitrification, as well as a reliable organic substrate for biomass growth.

Treatment of Winery Wastewater with PEG-600/PVDF Mixed Matrix Membranes Using Submerged Membrane Bioreactor and Process Optimization by Box–Behnken Design

Treatment of Winery Wastewater with PEG-600/PVDF Mixed Matrix Membranes Using Submerged Membrane Bioreactor and Process Optimization by Box–Behnken Design

Winery Wastewater Treatment Technologies: Current Trends and Future Perspective

Winery Wastewater Treatment Technologies: Current Trends and Future Perspective

Effect of Particle Character and Calcite Dissolution on the Hydraulic Conductivity and Longevity of Biosand Filters Treating Winery and Other Acidic Effluents

Acidic effluent such as winery wastewater is challenging to remediate. Biological sand reactors can simultaneously remove organics and neutralize winery wastewater via biotic and abiotic mechanisms. The systems have been shown to be suitable for treating the intermittent flow of wastewater at small wineries. It has been shown that dissolution of calcite is the most important abiotic mechanism for increasing the pH of the influent. In this study, sand column experiments were used to determine the effects of (i) sand particle size distribution on calcite dissolution kinetics, and (ii) the effects of calcite particle dissolution on the hydraulic conductivity. The results were then used to calculate the theoretical temporal abiotic neutralization capacity of biological sand reactors with differently sized sand fractions, including unfractionated (raw) sand. The results were compared with those determined from a pilot system treating winery wastewater over a period of 3 years. Sand fractions with larger particles contained lower amounts of calcite (using Ca as a proxy), but exhibited higher hydraulic conductivities (3.0 ± 0.05 %Ca and 2.57 to 2.75 mm·s−1, respectively) than those containing smaller particles and/or raw sand (4.8 ± 0.04 to 6.8 ± 0.03 %Ca and 0.19 to 1.25 mm·s−1, respectively). The theoretical abiotic neutralization capacity of biological sand reactors was compared with a pilot system with the same flow rates, and a temporal abiotic neutralization capacity of 37 years was calculated for biological sand reactors, which compared favorably with the theoretical results obtained for wastewater with pH values between 2 (8.2 years) and 3 (82 years). It was concluded that biological sand filters with around 10% calcite will be able to abiotically neutralize winery wastewater and other wastewaters with similar acidities for the projected life span of the system. Future work should focus on determining the effect of sand grain size on the bioremediation capacity, as well as the use of biological sand reactors for treating other acidic organic wastewaters such as fruit processing, food production and distillery wastewater.

Enhancing hydrogen production from winery wastewater through fermentative microbial culture selection

The present paper aims at enhancing the fermentative/co-fermentative hydrogen production from winery wastewater. Winery wastewater is a very abundant waste stream, with a high hydrogen production potential. On the other hand, it might exert toxic effects towards many hydrogen-producing bacteria. To optimize the process, a mixed microbial consortium was subject to microbial analysis to identify hydrogen-producing strains. These latter were isolated to obtain several pure cultures, either dark-fermentative, or photo-fermentative. Comparative fermentation tests were performed, using the isolated pure cultures, the initial mixed culture and a co-culture consisting of the two most performant dark fermentative and photo fermentative strains (i.e. Klebsiella pneumoniae strain MF101 and Rhodopseudomonas sp. strain BR0Y6). Results show that the initial mixed culture led to the highest production of 290 NmLH2 L−1. Further analyses on metabolic intermediates demonstrate the importance of synergies established in open fermentations to enhance the conversion of complex organic substrates to hydrogen.

Anaerobic digestion of primary winery wastewater sludge and evaluation of the character of the digestate as a potential fertilizer

Anaerobic digestion of primary winery wastewater sludge and evaluation of the character of the digestate as a potential fertilizer