Search Results (73)

The dairy industry generates significant amounts of wastewater, including microfiltration (MF) retentate, a byproduct thickened with organic and inorganic pollutants. This study focuses on the treatment of two times concentrated MF retentate using a hybrid system based on biological treatment in a sequential batch reactor (SBR) and adsorption on activated carbon. The first stage involved cross-flow microfiltration using a 0.2 µm PVDF membrane at 0.5 bar, resulting in reductions of 99% in turbidity and 79% in chemical oxygen demand (COD), as well as a partial reduction in conductivity. The second stage involved 24-h biological treatment in a sequential batch reactor (SBR) with activated sludge (activated sludge index: 80 cm³/g, MLSS 2500 mg/dm³), resulting in further reductions in COD (62%) and TOC (30%), as well as the removal of 46% of total phosphorus (TP) and 35% of total nitrogen (TN). In the third stage, the decantate underwent adsorption in a column containing powdered activated carbon (PAC; 1 g; S_(BET) = 969 m² g⁻¹), reducing the concentrations of key indicators to the following levels: COD 84%, TOC 70%, TN 77%, TP 87% and suspended solids 97%. Total pollutant retention ranged from 24.6% to 97.0%. These results confirm that the MF–SBR–PAC system is an effective, compact solution that significantly reduces the load of organic and biogenic pollutants in MF retentates, paving the way for their reuse or safe discharge into the environment. Full article

This study investigates the efficiency of electrocoagulation–flotation (EC) as a pre-treatment method for industrial wastewater with a high chemical oxygen demand (COD), high levels of suspended solids (TSS), and different colors. Real wastewater from a brewery, dairy, winery, and marine oil processing industry was treated using aluminum electrodes under various current densities. Laboratory-scale experiments demonstrated significant COD, TSS, and color removal, with marine oils and dairy wastewater showing the highest COD removal efficiencies (up to 88.6%), while for all the examined wastewater samples, the TSSs removal exceeded 95%. The results confirm EC’s effectiveness and adaptability across diverse wastewater types, supporting its potential as a sustainable, low-cost alternative as a industrial wastewater pre-treatment process. Full article

This work describes the application of three different AgBr heterojunctions with TiO₂, SnO₂ and WO₃ in the treatment of two water sources: wastewater from a dairy industry facility (WDI) and water from a polluted river (WPR). All heterojunctions were widely characterised, and it was observed that the physicochemical properties of all the coupled materials were similar; however, the highest elimination of Enterobacteriaceae (>90%) was obtained with the AgBr/WO₃(20%) photocatalyst in WDI. Under the same conditions, with this photocatalyst, the complete removal of bacteria (i.e., E. coli, total coliforms and other Enterobacteriaceae) was achieved in WPR. The chlorides, hardness and colour in the two water samples decreased after photocatalytic treatment with all the coupled materials. However, nitrate levels and chemical oxygen demand increased due to the possible formation of intermediary species from the photodegradation of organic pollutants and the release of metabolic intermediates from bacterial degradation during the photocatalytic process. Overall, heterogeneous photocatalysis based on AgBr-coupled materials shows potential as a tertiary treatment for WDI and for the purification of vegetable irrigation water. However, it is still important to consider the need to optimise the integrity of photocatalytic materials in order to maintain their bactericidal effectiveness through continuous reuse. Full article

The dairy industry generates substantial quantities of wastewater, primarily whey wastewater, posing environmental challenges. Current treatment methods involve physical, chemical, and biological processes, but efficient solutions are still sought. Biological treatments using microalgae are gaining attention due to their potential to remove pollutants from wastewater and generate valuable products, making them an alternative way to improve environmental sustainability. The physicochemical characterization of whey effluents reveals a high organic content, an acidic pH, and elevated nutrient levels. This study investigates the potential of Chromochloris zofingiensis (formerly known as Chlorella zofingiensis) for treating whey wastewater using three concentrations, 10%, 20%, and 50%, over a 7-day culture period. The optimal concentration of whey wastewater for biomass, nutrient removal, astaxanthin, and lipid production was found to be 10%. At this concentration, C. zofingiensis achieved a biomass of 3.86 g L⁻¹ and a removal efficiency of nutrients between 77.08% and 99.90%. Analysis of pigment production revealed decreases in chlorophyll and carotenoid production with increasing whey wastewater concentration, while lipid and astaxanthin production peaked at the 10% dilution. The chlorophyll a, chlorophyll b, total carotenoid, astaxanthin, and lipid contents were, respectively, 11.49 mg g⁻¹, 4.56 mg g⁻¹, 4.04 mg g⁻¹, 0.71 mg g⁻¹, and 30.49% in 10% whey wastewater. The fatty acid profiles indicated the predominance of saturated and unsaturated fatty acids, enhancing the biofuel potential of C. zofingiensis cultivated in whey wastewater. These findings demonstrate the dual benefit of using C. zofingiensis for sustainable whey wastewater treatment and high-value bioproduct generation, supporting the development of circular biorefinery systems. Full article

The problem of the foul odor caused by H₂S in livestock farms has become a major complaints. In this study, optimal sulfur-oxidizing bacteria (SOB) strains were screened from dairy farm wastewater and the adjacent soil for odor treatment. The strains and physiological functions were determined by identification and genome comparison, and the optimal operating conditions were determined by experiments under different conditions. The identification results showed that the strain that had the highest homology with Halomonas mongoliensis was Halomonas sp. AEB2. The comparative genomic results showed that the average nucleotide identity and DNA–DNA hybridization value were 95.8% and 68.6%, respectively. The optimization results were as follows: sodium succinate-carbon (10 g/L) and ammonium chloride-nitrogen (0.07 g/L). The optimal operating conditions were as follows: seeding rate 4%, temperature 30 °C, stirring speed 90 rpm, and pH 8. The oxidation products of AEB2 were mainly elemental sulfur and tetrathionate, and the metabolic pathway of AEB2 was constructed accordingly. This study suggests a feasible path to reduce H₂S emissions from dairy farms, and it provides theoretical support for the restoration of livestock environment and sustainability. Full article

Enzyme immobilization plays a critical role in enhancing the efficiency and sustainability of biocatalysis, addressing key challenges such as limited enzyme stability, short shelf life, and difficulties in recovery and recycling, which are pivotal for green chemistry and industrial applications. Classical approaches, including adsorption, entrapment, encapsulation, and covalent bonding, as well as advanced site-specific methods that integrate enzyme engineering and bio-orthogonal chemistry, were discussed. These techniques enable precise control over enzyme orientation and interaction with carriers, optimizing catalytic activity and reusability. Key findings highlight the impact of immobilization on improving enzyme performance under various operational conditions and its role in reducing process costs through enhanced stability and recyclability. The review presents numerous practical applications of immobilized enzymes, including their use in the pharmaceutical industry for drug synthesis, in the food sector for dairy processing, and in environmental biotechnology for wastewater treatment and dye degradation. Despite the significant advantages, challenges such as activity loss due to conformational changes and mass transfer limitations remain, necessitating tailored immobilization protocols for specific applications. The integration of immobilization with modern biotechnological advancements, such as site-directed mutagenesis and recombinant DNA technology, offers a promising pathway for developing robust, efficient, and sustainable biocatalytic systems. This comprehensive guide aims to support researchers and industries in selecting and optimizing immobilization techniques for diverse applications in pharmaceuticals, food processing, and fine chemicals. Full article

The peculiarity of the wastewater produced in Polish dairies stems from the frequency and specific technology of cottage cheese production. The aim of this study was to determine the water consumption and the quantity and quality of wastewater and sewage sludge discharged from Polish dairies based on the size of the plant and the production profile of the plant to characterize the wastewater treatment plants (WWTPs). Data were collected from eighteen dairies. Most of them have their own WWTP. Water consumption ranged from 1.5 litres (L) of water per litre of milk processed to 3.71 L/L. The specific volume of wastewater ranged from 1.18 to 5.78 L per L of milk processed. The raw wastewater concentrations were comparable to those of dairy wastewater in other European countries. Despite the disposal of domestic wastewater in WWTPs, the results of the sanitary examinations of the sludge showed it was suitable for agricultural purposes. Its heavy metal also made it applicable on agricultural land. The ratio of the sludge to raw milk processing was between 0.137 and 7.927 kg of sludge per 100 L of milk processed. The amount of sludge produced per pollutant (BOD) load removed ranged from 0.404 to 18.895 kg/kg BOD_removed. Full article

This study explores the mixotrophic cultivation of Limnospira platensis using dairy byproducts, specifically scotta whey (SW), buttermilk wastewater (BMW), and dairy wastewater (DWW), to promote biomass production and enhance the composition of bioactive compounds. By assessing various concentrations (1%, 2%, and 4% v v⁻¹) of these byproducts in a modified growth medium, this study aims to evaluate their effect on L. platensis growth, phycocyanin (C-PC) content, and fatty acid methyl ester (FAME) profiles. The results show that the optimal biomass production was achieved with 2% scotta and dairy wastewater, reaching maximum concentrations of 3.30 g L⁻¹ and 3.19 g L⁻¹, respectively. Mixotrophic cultivation led to increased C-PC yields, especially in buttermilk and dairy wastewater treatments, highlighting the potential for producing valuable pigments. Additionally, the FAME profiles indicated minimal changes compared to the control, with oleic and γ-linolenic acids being dominant in mixotrophic conditions. These findings support the viability of utilizing dairy byproducts for sustainable L. platensis cultivation, contributing to a circular bioeconomy while producing bioactive compounds of nutritional and commercial interest. Full article

Organic waste has the potential to produce methane gas as a substitute for petrol-based fuels, while reducing landfilling and possible environmental pollution. Generally, anaerobic digestion (AD) is used only in wastewater treatment plants as a tertiary stage of sewage sludge treatment, generating a fraction of the energy that such process plants require. In this study, four different wastes—food waste (FW), dairy industry waste (DIW), brewery waste (BW), and cardboard waste (CBW)—were tested for biogas production. The biochemical methane potential (BMP) of each sample was evaluated using an automatic methane potential system (AMPTS). Operating parameters such as pH, temperature, total solids, and volatile solids were measured. Experiments on the anaerobic digestion of the samples were monitored under mesophilic conditions (temperature 37 °C, retention time 30 days). Specific methane yields (SMYs), as well as the theoretical methane potential (BMPth), were used to calculate the biodegradability of the substrates, obtaining the highest biodegradability for BW at 95.1% and producing 462.3 ± 1.25 NmL CH₄/g volatile solids (VS), followed by FW at an inoculum-to-substrate ratio (ISR) of 2 at 84% generating 391.3 NmLCH₄/g VS. The BMP test of the dairy industry waste at an inoculum-to-substrate ratio of 1 was heavily inhibited by bacteria overloading of the easily degradable organic matter, obtaining a total methane production of 106.3 NmL CH₄/g VS and a biodegradability index of 24.8%. The kinetic modeling study demonstrated that the best-fitting model was the modified Gompertz model, presenting the highest coefficient of determination (R²) values, the lowest root means square error (RMSE) values for five of the substrates, and the best specific biogas yield estimation with a percentage difference ranging from 0.3 to 3.6%. Full article

The cheese industry produces substantial amounts of raw cheese whey wastewater (RW), which requires effective treatment prior to environmental disposal. This study presents an innovative sequential batch system that combines macrophyte and microalgal cultivation for RW remediation. The efficacy of Lemna minor MO23 in first-line photobioreactors (PBR-1) and Chlorella sp. MC18 (CH) or Scenedesmus sp. MJ23-R (SC) in second-line photobioreactors (PBR-2) for pollutant removal was evaluated. The nutrient removal capacity of L. minor, CH, and SC was assessed at optimal tolerance concentrations, alongside nutrient recovery from treated RW (TRW) by PBR-1 for microalgae biomass production. The results demonstrate that all three species effectively purified the cheese whey wastewater. L. minor efficiently removed COD, nitrate, phosphate, and sulfate from RW, producing TRW effluent suitable for microalgal growth. CH and SC further purified TRW, enhancing biomass production. CH outperformed SC with a 4.79% higher maximum specific growth rate and 20.95% higher biomass yield. Biochemical analyses revealed the potential of CH and SC biomass for applications such as biofuels and aquaculture. After treatment, the physicochemical parameters of the effluent were within the regulatory limits. This demonstrates that the PBR-1 and PBR-2 series-coupled system effectively purifies and recovers dairy effluents while complying with discharge standards. Full article

This study explores the novel use of mixed cultures of microalgae—Spirulina platensis, Micractinium, and Chlorella—for nutrient removal from dairy wastewater (DW). Microalgae were isolated from a local wastewater treatment plant and cultivated under various light conditions. The results showed significant biomass production, with mixed cultures achieving the highest biomass (2.51 g/L), followed by Spirulina (1.98 g/L) and Chlorella (1.92 g/L). Supplementing DW (75%) with BG medium (25%) significantly enhanced biomass and pH levels, improving pathogenic bacteria removal. Spirulina and mixed cultures exhibited high nitrogen removal efficiencies of 92.56% and 93.34%, respectively, while Chlorella achieved 86.85% nitrogen and 83.45% phosphorus removal. Although growth rates were lower under phosphorus-limited conditions, the microalgae adapted well to real DW, which is essential for effective algal harvesting. Phosphorus removal efficiencies ranged from 69.56% to 86.67%, with mixed cultures achieving the highest removal. Microbial and coliform removal efficiencies reached 97.81%, with elevated pH levels contributing to significant reductions in fecal E. coli and coliform levels. These findings suggest that integrating microalgae cultivation into DW treatment systems can significantly enhance nutrient and pathogen removal, providing a sustainable solution for wastewater management. Full article

Cheese whey (CW), a byproduct resulting from dairy processing, requires proper treatment and disposal. The use of microalgae during tertiary treatment emerges as a promising option due to its efficiency to remove chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) from effluents obtained after secondary treatment processes. The present study was focused on treating CW effluent at two organic loads (C₁ and C₂—with different concentrations of COD, TN, and TP) (550–2200 mg·L⁻¹ of COD, 14–56 mg·L⁻¹ of TN, and 4.5–18 mg·L⁻¹ of TP) using the microalga Tetradesmus obliquus alone (C_M1 and C_M2) and in a consortium with the fungus Cuninghamella echinulata (C_MF1 and C_MF2), evaluating the residual values of COD, TN, and TP and removal efficiency. The experiments were carried out in an open system with a volumetric replacement ratio (VRR) of 40 and 60%. The C_M treatment showed residual values of COD in the range of 190–410 mg·L⁻¹ (removal efficiency: 57–68%), TN in the range of 6–24 mg·L⁻¹ (removal efficiency: 29–35%), and TP in the range of 0.90–3.0 mg·L⁻¹ (removal efficiency: 65–68%), after 7 days of volumetric replacement time (VRT) in a semicontinuous mode. In contrast, the consortium (C_MF) showed greater stability and efficiency in contaminant removal compared to the treatment system containing only the microalga, showing residual values of COD in the range of 61–226 mg·L⁻¹ (removal efficiency: 75–77%), TN in the range of 1.8–9.5 mg·L⁻¹ (removal efficiency: 70–74%), and TP in the range of 0.6–3.5 mg·L⁻¹ (removal efficiency: 66–70%), applying a lower VRT of 3 days and reaching the legislation standard for discharge to C_MF1 (VRR: 40 and 60%) and C_MF2 (VRR: 40%). The cell dry weight of 290–850 mg·L⁻¹ was obtained (microalga and microalga–fungus cultivation), which can be a valuable biomass for biotechnological applications. Finally, during microalga–fungus co-cultivation, there was greater system buffering (with less pH variation), ensuring a better system stability. Full article

Manure management emits large quantities of greenhouse gases (GHG) in California. Eminex^®, a manure additive, previously demonstrated significant GHG reductions in slurry. However, it has not been tested in lagoon wastewater. The aim of the present study was to investigate the effects of Eminex^® on GHG, ammonia (NH₃), and ethanol (EtOH) emissions from fresh dairy slurry and dairy lagoon wastewater. Both manures received the following treatments: high (1.0 kg Eminex^®/m³ manure), low (0.5 kg Eminex^®/m³ manure). Experiments were conducted in four replicates with an untreated manure control. The physical characteristics of the manure were determined during the monitoring periods of emissions: 7 days for slurry and 28 days for lagoon wastewater. All slurry emissions, except for N₂O, declined over time (p < 0.05). Lagoon wastewater total N increased with treatment (p < 0.05) possibly due to the urea provided by Eminex^®. Most lagoon wastewater emissions also decreased over time (p < 0.05). However, Eminex^®, compared to control, increased lagoon wastewater NH₃ volatilization (p < 0.05). With improvements to manure composition through increasing N content, as well as reductions in emissions, Eminex^® is a promising tool to mitigate the negative environmental impacts of manure management. Full article

Dairy wastewater (DW) contains a high concentration of organic and inorganic pollutants. In recent years, extensive research has been conducted to develop more efficient techniques for the treatment of DW. Electrochemical advanced oxidation processes (EAOPs) have gained significant attention among the various treatment approaches. EAOPs rely on electrochemical generation of hydroxyl radicals (•OH) which are considered highly potent oxidizing compounds for the degradation of pollutants in DW. In this paper, we provide an overview of the treatment of DW using various EAOPs, including anodic oxidation (AO), electro-Fenton (EF), photo electro-Fenton (PEF), and solar photo electro-Fenton (SPEF) processes, both individually and in combination with other techniques. Additionally, we discuss the reactor design and operating parameters employed in EAOPs. The variation in degradation efficiency is due to different oxidizing agents produced in specific approaches and their pollutant degradation abilities. In AO process, •OH radicals generated on electrode surfaces are influenced by electrode material and current density, while EF procedures use Fe²⁺ to create oxidizing agents both on electrodes and in the DW solution, with degradation mechanisms being affected by Fe²⁺, pH, and current density; additionally, PEF and SPEF approaches enhance oxidizing component production and pollutant degradation using ultraviolet (UV) light. Integration of EAOPs with other biological processes can enhance the pollutant removal efficiency of the treatment system. There is a scope of further research to exhibit the effectiveness of EAOPs for DW treatment in large scale implementation. Full article

The overuse of antibiotics has resulted in the prevalence of antibiotic resistance genes (ARGs) and antibiotic resistance bacteria (ARB) in the environment. High-density livestock farming is one of the major industries for antibiotic overuse. In this study, we sampled wastewater and manure at different stages of the feces treatment process from a dairy farm, as well as the soil in the farmland where the treated wastewater was being used for irrigation purpose. High-throughput Illumina sequencing was used to analyze the profiles of bacteria communities and ARGs. The results showed that the main ARG types were multidrug, aminoglycoside, glycopeptide, and tetracycline resistance genes, and Actinobacteria, Proteobacteria and Firmicutes were the main host bacteria phyla of these ARGs. The genus Nocardioides sp. and Ornithinimicrobium sp. were closely associated with the ARGs in the investigated samples. The relative abundances of ARGs in wastewater and manure were reduced by 68.5% and 62.1%, respectively, by the existing feces treatment process. Anaerobic fermentation and high-temperature fermentation were the most efficient treatment steps; the relative abundances of ARGs were reduced by 29.3% and 33.6% in the treated wastewater and manure, respectively. Irrigation with the treated wastewater significantly increased the abundance and diversity of ARGs and ARB in the surface soil of the farmland. The residual ARGs were found to transit through vertical gene transfer (VGT) and horizontal gene transfer (HGT) in soil. Therefore, the direct application of this inadequately treated wastewater and/or manure could risk spreading ARGs into the environment, and potentially impact human health. In order to effectively restrain the spread of ARGs, it is necessary to modify the wastewater and manure treatment processes and improve the regulations and guidelines of applying treated wastewater for irrigation. Full article