Search Results (13)

Microbial fuel cells (MFCs) are environmentally friendly energy converters that use electrochemically active bacteria (EAB) as catalysts to break down organic matter while producing bioelectricity. Traditionally, MFC research has relied on simple organic substrates, such as acetate, glucose, sucrose, butyrate, and glutamate, the production of which involves energy-intensive, CO₂-dependent processes and chemically aggressive methods. In contrast, nonconventional waste streams offer a more sustainable alternative as feedstocks, aligning with zero-waste and regenerative agricultural principles. This review highlights the potential of nonconventional organic wastes, such as fruit and vegetable wastes, raw human and livestock urine, and farm manure, as globally available and low-cost substrates for MFCs, particularly in household and farming applications at small-scale waste levels. Furthermore, complex waste sources, including hydrocarbon-contaminated effluents and lignin-rich industrial wood waste, which present unique challenges and opportunities for their integration into MFC systems, were examined in depth. The findings of this review reveal that MFCs utilizing nonconventional substrates can achieve power outputs comparable to traditional substrates (e.g., 8314 mW m⁻²–25,195 mW m⁻² for crude sugarcane effluent and raw distillery effluent, respectively) and even superior to them, reaching up to 88,990 mW m⁻² in MFCs utilizing vegetable waste. Additionally, MFCs utilizing hydrocarbon-containing petroleum sediment achieved one of the highest reported maximum power densities of 50,570 mW m⁻². By integrating diverse organic waste streams, MFCs can contribute to carbon-neutral energy generation and sustainable waste management practices. Full article

Agro-industrial activities generate significant amounts of organic waste and a variety of effluents thus posing environmental challenges. Viticulture in Argentina, which covered 204,847 ha in 2023, faces water scarcity as a limiting factor conditioning its production. This industry produces large volumes of grape marc, sediments, and stalks, which can be valorised into products like alcohol, tartaric acid, and compost. However, these valorisation processes generate effluents with high organic load and salinity, further stressing water resources. This study explores the potential of utilising these effluents to cultivate plant biomass in arid regions (sorghum or perennial pasture), which could serve as bioenergy, animal feed, or composting co-substrates, contributing to circular bioeconomy principles. The combined use of effluent as a water resource and the sowing of sorghum and pasture increased soil organic matter content and led to a slight reduction in pH (depth: 0.30–0.60 m) compared to the control treatment. The sorghum plots showed better establishment and higher dry biomass yield (32.6 Tn/ha) compared to the pasture plots (6.5 Tn/ha). Sorghum demonstrated better tolerance to saline soils and high salinity effluents, aligning with previous studies. Although pasture had a lower biomass yield, it was more efficient in nutrient uptake, concentrating more NPK, ash, and soluble salts. Sorghum’s higher yield compensated for its lower nutrient concentration. For biomass production, sorghum is preferable, but if nutrient capture from effluents is prioritised, summer polyphytic pastures are more suitable. These results suggest that the final selection between plant biomass alternatives highly depends on whether the goal is biomass generation or nutrient capture. Full article

With increasing global water scarcity, the reuse of treated wastewater for agricultural irrigation offers a promising solution, particularly in arid regions. This study evaluates the impact of distillery wastewater from Kinmen Kaoliang Liquor Inc. (KKL) on the growth of wheat and sorghum in the Kinmen region. The field experiment applied varying proportions of KKL wastewater to assess its effects on soil properties, nutrient distribution, and crop performance. The results showed that wastewater irrigation increased soil concentrations of key nutrients, such as potassium (K), sodium (Na), magnesium (Mg), and phosphorus (P), but also raised the electrical conductivity (EC) and sodium adsorption ratio (SAR) beyond acceptable irrigation standards. K, Mg, Ca, and P primarily accumulated in the stems and grains, while Na was concentrated in the roots. However, higher wastewater concentrations negatively affected soil permeability due to Na accumulation, and elevated salinity levels led to reduced plant biomass. This study concludes that although wastewater irrigation improves nutrient availability, careful management is essential to mitigate salinity risks and ensure sustainable agricultural practices. These findings offer valuable insights into the potential of wastewater reuse in water-scarce regions and provide practical recommendations for managing associated risks. Full article

The water resource crisis and concerns with environmental pollution prompt the necessity to upgrade conventional wastewater treatment processes. The microalgae-based wastewater treatment process has shown many advantages that can fulfill the stricter demands for improved wastewater treatment. Microalgae cultivation can be carried out in different photobioreactors and under different operational conditions. The cultivation of the microalgae biomass provides the bioremediation of some targeted pollutants through uptake/digestion or biosorption, resulting in treated effluent and the production of biomass. This paper reviews the progress in microalgae-biotechnology for industrial wastewater treatment. A brief overview of microalga types/classification, the cultivation photobioreactors type, and conditions was first provided. Next, a comprehensive review of the bioremediation of industrial wastewater, including distillery, heavy metals, textiles, and emerging contaminants, was provided. Finally, perspectives on the potential scale-up of the technology and some critical considerations were also discussed. Full article

This study aimed to enhance dark fermentative hydrogen production from co-digestion of distillery wastewater (DW) and glycerol waste (GW) through integration with microbial electrolysis cells. First, the optimal proportion of DW and GW in hydrogen production was investigated in batch mode. The results show that DW and GW co-digestion at a ratio of 99:1 (% v/v) gave the highest hydrogen yield of 149.5 mL-H₂/g − VS_added. Continuous hydrogen production using the optimal proportion was conducted in a continuously stirred tank reactor. As a result, a maximal hydrogen yield of 99.7 mL-H₂/g − VS_added was achieved, and the dominant hydrogen-producing bacterium was Clostridium sensu stricto 7. The dark fermentation effluent from the continuously stirred tank reactor was later used to produce methane using batch MECs. The maximum methane yield of 115.1 mL-CH₄/g − VS_added was obtained under an applied voltage of 1 V and continuous stirring at 120–140 rpm. Microbial community analysis revealed that Metahnobacterium, Methanomethylovorans, Methanoculleus, and Methanosarcina were the methanogenic archaea in the microbial electrolysis cell reactor. Full article

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. Full article

This study was conducted at the ethanol plant of Metehara sugar factory, at a laboratory scale, to assess the effect of recycling vinasse into the fermentation process on effluent reduction. Vinasse is an effluent produced from distilleries. The experimental design included vinasse concentrations at 4 dilution rates (0 (control), 20, 35, 50, and 65% of process water) with 2 replicates and 6 responses, as follows: ethanol yield, fermentation efficiency, residual sugar concentration, cell count, cell viability, and calcium oxide content. In this study, the actual operational parameters of the ethanol plant were maintained during the experiment. The result of the experiment indicates that, with up to 20% vinasse recycling, there was no influential impact on the ethanol yield, the fermentation efficiency, the residual sugar concentration, or the calcium oxide content, attributable to the recycling, as compared to the control. Above 20% vinasse recycling, ethanol yield and fermentation efficiency decreased sharply from those of the control. In addition, with 20% vinasse recycling put into practice, the amount of vinasse generated will be reduced by about 19.5% and about 114.2 tons of water will be saved per day. Moreover, the excess amount of vinasse produced by the distillery, which is beyond the handling capacity of bio-compost plant of the distillery, will reduce from 105 to 36.8 tons per day. Therefore, it is possible to recycle vinasse into the fermenter up to 20% on dilution water of Metehara distillery, without causing any impacts on the distillery’s performance. Full article

Implementation of anaerobic digestion of primary sludge in modern wastewater treatment plants (WWTPs) limits the availability of organic carbon for denitrification in conventional nitrification-denitrification (N/DN) systems. In order to ensure efficient denitrification, dosage of the external carbon source is commonly undertaken. However, application of commercial products, such us ethanol or acetate, greatly increases operational costs. As such, inexpensive and efficient alternative carbon sources are strongly desirable. In this study, the use of the fusel oil, a by-product from the distillery industry, was validated in terms of the denitrification process enhancement and impact on the activated sludge bacterial community structure. The experiment was conducted at a full scale biological nutrient removal facility (210,000 PE), in the set of the two technological lines: the experimental line (where fusel oil was introduced at 45 cm³/m³ dose) and the reference line (without an external carbon source addition). During the experimental period of 98 days, conventional nitrate utilization rate (NUR) measurements were carried out on a regular basis in order to assess the biomass adaptation to the fusel oil addition and denitrification process enhancement. While the NURs remained at a stable level in the reference line (1.4 ± 0.1 mg NO₃-N/g VSS·h) throughout the entire duration of the experiment, the addition of fusel oil gradually enhanced the denitrification process rate up to 2.7 mg NO₃-N/g VSS·h. Moreover, fusel oil contributed to the mitigation of the variability of NO₃-N concentrations in the effluent from the anoxic zone. The bacterial community structure, characterized by 16S rRNA PCR—DGGE and the clone libraries of the genes involved in the denitrification process (nirS and nirK), was comparable between the reference and the experimental line during the entire experimental period. In both analyzed lines, the most frequent occurrence of denitrifiers belonging to the genera Acidovorax, Alcaligenes, Azoarcus, Paracoccus and Thauera was noticed. Our results proved that fusel oil would a valuable substrate for denitrification. The addition of fusel oil enhances the process rate and does not reflect a severe selection pressure on the bacterial community at applicable doses. Practical application of fusel oil generates opportunities for the WWTPs to meet effluent standards and reduce operational costs, as well as optimizing waste management for the distillery industry. Full article

Although anaerobic digestion (AD) enables biogas production and facilitates renewable electricity production, its effluent must be post-treated before discarding it into the environment. However, during AD designing, the post-treatment step is often overlooked. This paper presents the kinetics and efficiency of nitrogen removal from effluent after AD of leachate from the aerobic stabilization of the organic fraction of municipal solid waste. A two-stage SBR system was used. An ammonium oxidation rate of 15.5 mg N-NH₄/(L·h) ensured a 98% nitrification efficiency (I stage). For denitrification (II stage), alternative carbon sources (ACS) (molasses, crude glycerine, or distillery stillage) were used. Two volumetric exchange rates (n) were tested: 0.35 1/d (COD/N-NO₃ ratio of 8) and 0.5 1/d (COD/N-NO₃ of 7). With all ACS and COD/N-NO₃ ratios, almost 100% of nitrate was denitrified; at the COD/N-NO₃ of 8, biodegradable organics remained in the effluents. At the COD/N-NO₃ of 7, the denitrification removal rates were lower (29.6-45.1 mg N-NO_x/(L·h)) than at the ratio of 8 (72.1–159.5 mg N-NO_x/(L·h)), because of temporal nitrite accumulation. The highest nitrate removal rates were obtained with molasses, the lowest with a distillery stillage. Considering the nitrate removal rate and the effluent COD concentration, molasses was recommended as the most effective carbon source for AD effluent treatment at the COD/N-NO₃ of 7. Full article

Sugarcane Distillery Spent Wash (DSW) is among the most pollutant industrial effluents, generally characterized by high Chemical Oxygen Demand (COD), high mineral matters and acidic pH, causing strong environmental impacts. Bioremediation is considered to be a good and cheap alternative to DSW treatment. In this study, 37 strains of yeasts and filamentous fungi were performed to assess their potential to significantly reduce four parameters characterizing the organic load of vinasses (COD, pH, minerals and OD_475nm). In all cases, a pH increase (until a final pH higher than 8.5, being an increase superior to 3.5 units, as compared to initial pH) and a COD and minerals removal could be observed, respectively (until 76.53% using Aspergillus terreus var. africanus and 77.57% using Aspergillus niger). Depending on the microorganism, the OD_475nm could decrease (generally when filamentous fungi were used) or increase (generally when yeasts were used). Among the strains tested, the species from Aspergillus and Trametes genus offered the best results in the depollution of DSW. Concomitant with the pollutant load removal, fungal biomass, with yields exceeding 20 g·L⁻¹, was produced. Full article

The production of brandy from wine and bioethanol from sugarcane in distilleries generates vinasses, which are effluents that are rich in organic matter. Since they have a high pollution load characterized by high chemical and biological oxygen demands and a dark color, the depollution of these effluents is inevitable. Pt and Ru catalysts supported on titania and zirconia were explored in the catalytic wet air oxidation (CWAO) processing of cognac and sugarcane wastewaters, in batch mode and in a trickle-bed reactor, at a temperature condition of 190 °C and a pressure condition of 70 bar air. The addition of a catalyst promoted total organic carbon (TOC) abatement and the oxidation of ammonium ions formed from organic nitrogen in the effluents to dinitrogen or nitrates. The best results in terms of selectivity to N₂ were obtained by using Pt catalysts; a selectivity of 92% to N₂ and a TOC removal of 90% were observed in continuous oxidation of the sugarcane vinasse. Full article

Industrial production of biodiesel from microbial catalysts requires large volume of low-cost feedstock for lipid production. Vinasse, also known as distillery spent wash (DSW), is a liquid waste produced in large amounts by ethanol distilleries. This effluent is particularly rich in organic matter, and may be considered as a potential resource for the production of fungal lipids. The present study aimed at evaluating the potential of vinasse from a distillery located in Reunion Island for yeast and fungal growth, lipid production, and suitability for biodiesel requirements. Among the 28 different strains tested, we found that Aspergillus niger grown on pure vinasse allowed biomass production of up to 24.05 g/L (dry weight), whereas Aspergillus awamori produced the maximum amount of lipid, at 2.27 g/L. Nutrient removal and vinasse remediation were found to be the best for A. niger and Cryptococcus curvatus, reaching a maximum of 50% for nitrogen, and A. awamori showed 50% carbon removal. Lipids produced were principally composed of C16:0, C18:1 (n-9), and C18:2 (n-6), thus resembling the vegetal oil used in the biodiesel production. This work has shown that vinasse can support production of biomass and lipids from fungi and yeast suitable for energetic use and that its polluting charge can be significantly reduced through this process. Full article

One of the most important factors determining the profitability of microalgae biomass production is the use of inexpensive and available source of nutrients. The aim of the study was to determine the possibility of using anaerobic digestion effluents (ADE) from the fermentation of distillery stillage, maize silage and bovine slurry as a nutrient in the production of microalgae Chlorella vulgaris biomass. The highest biomass production of 2319 mg TS/dm³ was obtained during the cultivation of microalgae in the medium consisting of the effluents originating from the fermentation with a high share of bovine slurry. Significantly lower Chlorella vulgaris biomass growth was noted during cultivation in the medium composed of effluents obtained after dewatering of anaerobic sludge from the methane fermentation reactor fed with distillery stillage. In these series, an increase of the initial concentration of N-NH₄ in the medium to a level of 160 mg/dm³ significantly reduced microalgae growth. The high efficiency of P-PO₄ removal from 87–100% was noted. The study proved that anaerobic digestion effluents might be used as a nutrient source for efficient biomass production of Chlorella vulgaris after optimization of ammonium nitrogen dose. Full article