Search Results (73)

Cheese whey, a byproduct of the dairy industry, has a high organic load and nutrient availability, associated with parameters such as chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP), representing an environmental problem when improperly disposed, and even considering the traditional biological wastewater treatment (secondary treatment), a polishing step (tertiary treatment) could be required in order to meet legislation parameters of discharge in water bodies. This study evaluated the efficiency of co-cultivation between the microalga Tetradesmus obliquus and the yeast Saccharomyces cerevisiae during the tertiary (advanced) treatment of dairy effluent. The process was operated in batch mode to optimize the COD:N ratio and, subsequently, in semicontinuous mode applying the volumetric replacement rates (VRRs) of 40% and 60%. In the batch stage, the COD:N ratio of 20 stood out as the most balanced in terms of nutritional requirement, achieving removal rates of 85.49% for COD, 96.23% for total Kjeldahl nitrogen (TKN), and 100% for TP. In the semicontinuous system, a VRR of 40% optimized nitrogen (91.67%) and phosphorus (95.93%) recovery while COD was also removed (71.68%). The pH remained stable within the range of 7.0 to 7.5 at the end of the process, indicating self-buffering of the consortium. Biomass production reached 915 mg·L⁻¹ (dry cell weight) in batch operation mode and 720 mg·L⁻¹ in semicontinuous mode (VRR of 40%). The results confirmed that the T. obliquus and S. cerevisiae co-cultivation constitutes a stable and sustainable strategy for nutrient recovery during dairy wastewater treatment, aligning with the principles of circular bioeconomy. Full article

The aim of the circular economy for plastics is to replace some of them with bio-based polymers in the future. In this work, second cheese whey (SCW) was used as a low-cost substrate for the production of the natural polyester poly(3-hydroxybutyrate)-hydroxybutyrate (PHB) by three Pseudomonas sp. phDV1 strains, namely, the wild type, a depolymerase PhaZ and PhaR knockout mutants. SCW has high polluting loads, characterized by high levels of lactose, phosphorus, nitrogen and salinity, as well as high turbidity due to the presence of whey solids. Initially, SCW was evaluated as the sole carbon source for the growth of the bacterial strains and the production of PHB. Fermentation conditions were screened to maximize polymer synthesis. Small-scale experiments showed that the strains could grow and produce PHB in SCW with and without enzymatic treatment. The formation and intracellular localization of PHB were determined with fluorescence microscopy, using Nile Red staining. Analytical HPLC was also used to quantify the PHB content in the cells and to optimize production. This study demonstrates the efficacy of Pseudomonas sp. phDV1 in SCW treatment and biomass valorization, providing a sustainable solution for dairy wastewater management while producing valuable resources. Full article

This study calculates the carbon footprint of chemical coagulants and operational energy for residential and industrial (whey digestion) wastewater treatment using ReCiPe 2016 methodology within a clearly defined system boundary from cradle to gate. Data from water treatment facilities have been analyzed to quantify environmental impacts and identify sensitive design parameters. The estimated emission of treating 1 m³ of wastewater from whey digestion (7.1195 kg CO₂ eq) is over 50 times higher than that of a residential one (0.1349 kg CO₂ eq). Life cycle impact assessment (LCIA) reveals that iron (III) chloride (40% in H₂O) and operational electricity consumption have higher impact categories compared to other design components. The uncertainty analysis indicates that electricity consumption (r = 0.4) is the dominant contributor to emissions, with a mean value of 4.22 kg CO₂-eq per m³ of wastewater treated. In contrast, iron (III) chloride emerges as the most sensitive parameter (r = 0.88) with small variations in dosing causing a disproportionately large impact on overall emissions. Therefore, the optimized use of an iron-based coagulant, the adoption of membrane electrolysis, and the integration of renewable electricity into the process supply chains have been identified as effective strategies for reducing emissions. Full article

The purpose of this study was to examine how hydraulic retention time (HRT) influences biohydrogen generation and the formation of end-products during the co-digestion of olive mill wastewater (OMW), cheese whey (CW), and sewage sludge (SS) mixed in a 40:40:20 (v/v/v) ratio. The relationship between the substrates, resulting metabolites, and microbial communities was also explored. Continuous fermentation trials were carried out under both mesophilic (37 °C) and thermophilic conditions using HRTs of 12, 24 and 48 h. Acetic, propionic, and butyric acids were identified as the main end-products. The highest hydrogen production rate (4.4 ± 0.5 L H₂/L_reactor/day) occurred under thermophilic conditions at an HRT of 24 h, whereas under mesophilic operation at the same HRT the hydrogen production reached 3.0 ± 0.3 L H₂/L_reactor/day. In contrast, the greatest accumulation of volatile fatty acids (VFAs) was observed under mesophilic conditions (10.02 g/L), while thermophilic operation at 24 h HRT resulted in 5.54 g/L of total VFAs. The improved performance under thermophilic fermentation is likely linked to the suppression of hydrogen-consuming bacteria at elevated temperatures, which favors rapid hydrogen producers. Microbial community analysis indicated dominance of Firmicutes and persistent Lactobacillus prevalence across conditions. Shorter HRT at 37 °C promoted community diversification with genera such as Olsenella, Dialister, and Prevotella increasing in relative contribution. Under thermophilic operation, consortia remained Lactobacillus-dominant but showed significant temporal restructuring. The predominance of acetic acid (~2.80 g/L) and butyric acid (~2.60 g/L) indicates that hydrogen generation mainly followed the acetic and butyric pathways. This study reveals how targeted control of HRT and temperature can steer microbial communities toward highly hydrogen-productive consortia in the continuous dark fermentation of mixed agro-industrial wastes. Full article

Large amounts of agro-industrial residues—such as grape pomace, olive mill wastewater, wheat straw, and cheese whey—pose disposal challenges and generate substantial environmental and economic burdens. Incorporating these by-products into ruminant diets may reduce feeding costs while supporting sustainability within a circular bioeconomy. Two experiments were conducted to evaluate: (i) the characteristics of a mixed raw agro-industrial by-product silage (BPS) in cylindrical bale silos (50 kg) and (ii) its effects as dietary supplementation on metabolic profile, oxidative status, milk yield, and milk quality in lactating goats. The BPS was formulated from raw wheat straw, grape pomace, olive mill wastewater, and cheese whey and tested at a 30% inclusion level (dry-matter basis). The combined by-products produced in 50 kg cylindrical bale silos were positively characterized and exhibited a nutritionally suitable silage with relevant antioxidant potential. Dietary BPS improved oxidative status, as evidenced by increased TAS and vitamin E and reduced ROMs, and positively influenced lipid and immunological blood markers of goats. Milk yield was higher in goats receiving the BPS. Moreover, milk quality was improved through a more favorable fatty acid profile, higher vitamin E content, reduced cholesterol levels, and enhanced oxidative stability, as evidenced by lower TBARS values. Overall, BPS supplementation enhanced animal health indicators and milk nutritional properties, demonstrating that this silage can contribute to more sustainable dairy goat production while offering potential benefits for human nutrition. Full article

A rapidly emerging approach within the scientific community involves the utilization of waste streams for renewable energy generation, particularly through biomethane production. A key aspect of this approach lies in the co-digestion of diverse waste streams, which can enhance process efficiency and contribute to a more effective reduction in the organic load. The present study investigates the anaerobic digestion of a mixture of food waste leachates and dairy waste (cheese whey wastewater), with a dual objective: to evaluate the reduction in organic-load efficiency of the mixed substrate and to assess the production of biogas enriched in biomethane content. Three distinct mixing ratios by volume of the two waste streams (25%/75%, 50%/50% and 75%/25%) were subjected to an anaerobic digestion process under the same SIR. The performance of each mixture was assessed in terms of both reduction in organic-load efficiency and biomethane yield, followed by a comparative analysis to identify the optimal mixing ratio. The results indicate that while the organic-load reduction remains consistently effective across all mixing ratios, the biomethane production potential is notably higher for the 25%/75% waste mixture, highlighting it as the most promising configuration for both energy recovery and waste treatment efficiency. Full article

This study investigates the implementation of an attached-growth pilot-scale biofilter for the biological treatment of mixed dairy wastewater derived from real industrial effluents, consisting of equal proportions of raw second cheese whey (SCW) and pudding dessert wastewater (PDW). The biofilter was inoculated with indigenous microorganisms derived from the mixed wastewater stream with initial dissolved Chemical Oxygen Demand (d-COD) concentrations ranged from 1000 to 12,500 mg/L. The removal performance of organic and inorganic components was evaluated at a recirculation rate of 1.0 L/min, resulting in d-COD reductions of up to 92.3% and removal rates reaching 194.6 mg/(L·h). High removal rates were recorded for ammonium (up to 99.9%) and TKN (92.2–98.7%), while nitrate removal varied (29.4–89.3%) and solids removal exceeded 92%. d-COD concentrations of treated effluent consistently met discharge or municipal disposal legislation values, demonstrating the system’s efficiency and stability and proposing it as an ideal solution for wastewater treatment in dairy facilities. Full article

Cheese whey, the major by-product of the dairy industry, poses an environmental challenge due to its high organic load but simultaneously represents a nutrient-dense matrix suitable for biotechnological valorization. This review synthesizes recent advances positioning whey as (i) a fermentation substrate for lactic acid bacteria, yeasts/fungi, and microalgae, enabling the production of functional biomass, organic acids, bioethanol, exopolysaccharides, enzymes, and wastewater bioremediation; (ii) a platform for postbiotic generation, supporting cell-free preparations with functional activities; and (iii) a food-grade encapsulating material, particularly through whey proteins (β-lactoglobulin, α-lactalbumin), which can form emulsions, gels, and films that protect biotics and bioactive compounds during processing, storage, and gastrointestinal transit. We analyze key operational variables (whey type and pretreatment, supplementation strategies, batch and continuous cultivation modes), encapsulation routes (spray drying, freeze-drying, and hybrid protein–polysaccharide systems), and performance trade-offs relevant to industrial scale-up. Finally, we outline future directions, including precision fermentation, mixed-culture processes with in situ lactase activity, microfluidics-enabled encapsulation, and life-cycle assessment, to integrate product yields with environmental performance. Collectively, these strategies reframe whey from a high-impact waste into a circular bioeconomy resource for the food, nutraceutical, and environmental sectors. Full article

Many individual wastewater streams exhibit imbalanced or poor nutrient profiles, limiting their suitability for efficient biological treatment. In regions where several agro-industrial activities coexist, these streams are often produced in small volumes and vary considerably in composition, making their combined use an effective way to obtain a more balanced influent. This study aimed to identify the optimal mixing ratio of two agro-industrial wastewaters, second cheese whey (SCW) and poultry wastewater (PW), for the cultivation of a Leptolyngbya-dominated consortium. Four mixing ratios of SCW:PW (50:50%, 60:40%, 70:30%, and 85:15%) were examined based on an initial dissolved chemical oxygen demand (d-COD) concentration of 3000 mg L⁻¹. The 70:30% ratio was led to significant biomass production (268.3 mg L⁻¹ d⁻¹), while simultaneously exhibiting the highest lipid content (14.0% d.w.), and the highest removal of d-COD (89.2%), total nitrogen (64%) and PO₄³⁻-P (60%). Overall, the experiments showed that using nutritionally balanced wastewater streams is a promising strategy to enhance biological treatment efficiency and lipid production. Full article

Phosphorus recovery from wastewater as struvite via electrochemical magnesium dosing is a promising approach to address the growing demand for fertilizers. However, its large-scale implementation is often constrained by energy requirements. To overcome this limitation, this study investigates electroless struvite precipitation from cheese whey wastewater using sacrificial magnesium anodes. Under optimal conditions, up to 90% of the phosphorus was recovered within 4–6 h. In this process, spontaneous magnesium dissolution acts as the driving force for phosphorus precipitation and is strongly influenced by the wastewater’s ionic composition. To identify conditions that favor efficient recovery, the effects of ammonium, chloride, and sulfate ions were evaluated by monitoring phosphorus removal and magnesium corrosion behavior. Sulfate ions enhanced magnesium corrosion more strongly than chloride during the initial stages, likely due to stronger coulombic interactions with Mg²⁺ at the electrode–electrolyte interface, whereas chloride ions were more effective at disrupting the passivation layer that develops over time. Based on these observations, a mechanistic interpretation of ion-specific effects on anodic corrosion is proposed. Solid-phase analyses using multiple characterization techniques confirmed struvite formation, with ammonium sulfate and ammonium chloride systems yielding the highest product purity. Overall, these findings improve the understanding of electroless struvite precipitation and highlight its potential as an energy-efficient approach for nutrient recovery. Full article

Whey, a by-product of cheese and casein manufacture, represents a major output in dairy processing and a valuable resource for the production of functional foods. This review examines the technological, environmental, and nutritional aspects of whey valorization, emphasizing its transformation from an ecological burden to a raw material with high economic potential. Over time, whey has evolved from being regarded as waste product to becoming a strategic ingredient in the formulation of modern functional foods and bio-based materials. Data from January 2015 to October 2025 were collected from PubMed, Web of Science, and Scopus to outline global whey production, utilization rates, and emerging processing methods. Modern membrane, enzymatic, and non-thermal technologies enable the recovery of valuable components, including proteins, lactose, and bioactive compounds. The use of these techniques reduces the biochemical and chemical oxygen demand in wastewater The review highlights the use of whey in functional beverages, milk and meat processing, edible films, bioplastics, and biofuels, as well as its microbiological and biotechnological potential. Results indicate that only about half of the 180–200 million tonnes of whey produced annually is effectively valorized, underscoring the need for integrated circular-economy approaches. Overall, whey valorization contributes to sustainable food production, environmental protection, and the development of innovative, health-promoting products that align with global strategies for waste reduction and the development of functional foods. Full article

In this study, two native microalgae, Chlorella sp. MC18 (CH) and Scenedesmus sp. MJ23-R (SC) were cultivated in bubble column photobioreactors for wastewater treatment. Domestic wastewater (DWW) was used as the main culture medium, alone (100%) and blended (10%) with vinasse, whey, or agro-food waste (AFW), respectively. Both species thrived in 100% DWW, achieving significantly high removal efficiencies for chemical oxygen demand, total nitrogen, and total phosphorus. Mineral removal exceeded 90% in all blended systems, highlighting the strong nutrient uptake capacity of both strains. The maximum specific growth rate (µ_max) in 100% DWW was higher for SC than in standard BG11 medium, and supplementation with vinasse, whey, or AFW further increased µ_max for both species. Blending DWW significantly enhanced microalgal biomass and lipid production compared to 100% DWW. Lipid production (max., 374 mg L⁻¹), proximate lipid composition (max., 30.4%), and lipid productivity (max., 52.9 mg L⁻¹ d⁻¹) significantly increased in all supplemented cultures relative to DWW alone, demonstrating the potential of co-substrate supplementation to optimize microalgal cultivation. This study contributes to reducing the water footprint and fills a gap in the bioprocessing potential of algae-based systems, highlighting wastewater blending as a circular economy-aligned approach that supports sustainable bioprocesses and resource recovery. Full article

Mesophilic anaerobic co-digestion of eight distinct substrate mixtures of agroindustrial and food wastes was assessed to determine the most efficient waste mixture for maximizing hydrogen production. To evaluate the impact of adding various mixtures on dark fermentation (DF), batch tests were conducted for 250 h at 37 °C and a pH range between 5.0 and 5.9. Ethanol, butyric, propionic, acetic, and isobutyric acids were identified as the principal fermentation end products. The hydrogen production rate reached in a decreasing order from a mixture comprising 55% Olive Mill Wastewater (OMW), 40% Cheese Whey (CW), and 5% Sewage Sludge (SS) or Liquid Pig Manure (LPM) (38 NmL/gVS) to 55% OMW, 40% CW and 5% diluted Food Waste (FW_dil) (30 NmL/gVS), 60% CW and 40% Grape Residues (GR) (27 NmL/gVS), 80% CW and 20% LPM (13 NmL/gVS), 60% OMW and 40% FW_dil. (10 NmL/gVS), 60% CW and 40% FW_dil, (8 NmL/gVS) and 70% OMW and 30% SS (5 NmL/gVS). These results indicated that H₂ was generated through mixed fermentation pathways, while the addition of OMW > 55% inhibited microbial activity and reduced hydrogen production. The highest hydrogen yield (38 NmL/gVS), accompanied by 27.6%, Volatile Solids (VS) reduction and the highest Volatile Fatty Acids (VFAs) concentration (6.1 g/L). The same substrate mixture resulted in the highest accumulation of acetic and butyric acid in the acidified effluent, indicating the dominance of hydrogen-producing metabolic routes. The data suggest that co-fermentation of the selected residues not only enhances hydrogen production but also creates more stable operational conditions -including improved pH regulation, increased carbohydrate conversion, and greater VFAs accumulation- making the process more robust and viable for practical application. Full article

Anaerobic co-digestion of agro-industrial and municipal biowastes can enhance methane production, but the optimal mixture depends on nonlinear interactions among substrates. This study evaluated swine wastewater (SW), cheese whey (CW), and the organic fraction of municipal solid waste (OFMSW) under mesophilic batch conditions to quantify composition–response relationships and identify a robust operating window. A restricted simplex-centroid mixture design was tested; linear, quadratic, and special cubic models were fitted and evaluated using ANOVA, diagnostic plots, and optimization with desirability mapping. Cumulative methane yield (CMY) ranged between 251 and 295 NmL CH₄ g VS⁻¹ in the mixtures, outperforming SW as single component. All mixtures maintained neutral pH and moderate alkalinity ratios. The special cubic model provided the best performance (high R² and R²pred) and revealed significant ternary interaction. The optimization indicated a composition near 63% SW, 10% CW, and 27% OFMSW with a predicted CMY of 300 NmL CH₄ g VS⁻¹; a high-performance band (desirability 0.90–1.00; corresponding to CMY ≥ 294.8) defined a robust window of ~60–66% SW, 6–20% CW, and 20–31% OFMSW. Overall, balanced ternary co-digestion showed synergistic effects beyond additive expectations, and the response surface model based on mixture design proved effective in capturing interactions and providing flexible guidance for practical implementation. Full article

The water sector faces a dual challenge: reducing energy consumption and carbon footprint while improving wastewater treatment efficiency. Anaerobic digestion (AD) remains the primary method for energy recovery in wastewater treatment plants (WWTPs). To enhance methane production and move toward carbon neutrality, co-digestion of sewage sludge with external substrates is gaining attention. This study evaluated nine organic substrates for their methane potential using the standardized Automatic Methane Potential Test System (AMPTS). The highest methane yield was obtained from sediment from a wine tank, reaching 1387 NmL CH₄/g VS, followed by yeast slurry, with 524 NmL CH₄/g VS. These values were over 6 and 2.5 times higher, respectively, compared to the methane potential of conventional mixed municipal sludge. Apple pomace, whey, food biowaste, and herbal maceration waste showed moderate improvements (301–388 NmL CH₄/gVS). When considering methane yield per gram of wet substrate, herbal maceration waste was the most efficient. A techno-economic analysis revealed that this substrate consistently achieved a net-positive energy balance (up to 170%) in large WWTPs, even at transport distances of 50 km. Other substrates also showed high potential, covering nearly 100% of energy demand under optimal conditions. In contrast, whey showed limited applicability due to transport constraints. These findings highlight the importance of substrate selection, particularly in practical efforts aimed at achieving energy self-sufficiency in wastewater treatment plants. It also provides WWTP operators with clear and practical insights into enhancing methane yields from anaerobic digesters while minimizing the risk of process inhibition. Full article