Studies on evaluation of surfactant coupled sonication pretreatment on Ulva fasciata (marine macroalgae) for enhanced biohydrogen production

Enhancing volatile fatty acid production through thermal hydrolysis of food waste with surfactant additives in anaerobic digestion

The hydrolysis phase is recognized as the bottleneck in the anaerobic conversion of food waste. This study firstly investigates an innovative surfactant-enhanced thermal hydrolysis (STH) process, using alkyl polyglucoside (APG), a bio-based surfactant, in combination with improved response surface methodology (RSM) to optimize pretreatment conditions for volatile fatty acids (VFAs) production in anaerobic digestion (AD) of food waste. The synergistic effects of the coupled technology and its impact on acid production were explored, and the contributions of the pretreatment techniques were quantified. Results show that STH significantly enhances the solubilization of organic matter and VFAs yield. Under optimal conditions (110 °C, 0.005 g APG/g TSS), fermentation time is reduced in half, and VFAs production increases to 33.72 g COD/L. Overall, this research solidifies the substantial potential of STH in improving the solubilization, hydrolysis, and VFAs production efficiency from food waste and sets the stage for its industrial-scale application in VFA production, offering valuable insights into optimizing food waste resource utilization.

Enhancing the High-Solid Anaerobic Digestion of Horticultural Waste by Adding Surfactants

The influence of adding surfactants on the performance of high-solid anaerobic digestion of horticultural waste was extensively investigated in batch systems. Adding Tween series and polyethylene glycol series non-ionic surfactants had positive effects on biogas production, resulting in 370.1 mL/g VS and 256.6 mL/g VS with Tween 60 and polyethylene glycol 300 at a surfactant-to-grass mass ratio of 0.20, while the biogas production of anaerobic digestion without surfactants was 107.54 mL/g VS. The optimal and economically feasible choice was adding Tween 20 at a ratio of 0.08 g/g grass in high-solid anaerobic digestion. A kinetics model reliably represented the relationship between surfactant concentration and biogas production. The mechanism of surfactants working on lignocellulose was investigated. The improvement in high-solid anaerobic digestion by adding surfactants was attributed to the interaction between lignocelluloses and surfactants and the extraction of biodegradable fractions from the porous structure. An economic analysis showed that adding Tween 20 was likely to make a profit and be more feasible than adding Tween 60 and polyethylene glycol 300. This study confirms the enhancement in biogas production from horticultural waste by adding non-ionic surfactants.

A review of volatile fatty acids production from organic wastes: Intensification techniques and separation methods

High value-added products from organic waste fermentation have garnered increasing concern in modern society. VFAs are short-chain fatty acids, produced as intermediate products during the anaerobic fermentation of organic matter. VFAs can serve as an essential organic carbon source to produce substitutable fuels, microbial fats and oils, and synthetic biodegradable plastics et al. Extracting VFAs from the fermentation broths is a challenging task as the composition of suspensions is rather complex. In this paper, a comprehensive review of methods for VFAs production, extraction and separation are provided. Firstly, the methods to enhance VFAs production and significant operating parameters are briefly reviewed. Secondly, the evaluation and detailed discussion of various VFAs extraction and separation technologies, including membrane separation, complex extraction, and adsorption methods, are presented, highlighting their specific advantages and limitations. Finally, the challenges encountered by different separation technologies and novel approaches to enhance process performance are highlighted, providing theoretical guidance for recycling VFAs from organic wastes efficiently.

Innovative strategies in algal biomass pretreatment for biohydrogen production

Biohydrogen is one of the cleanest renewable energies with a high calorific value. Algal biomass can be utilized as a sustainable feedstock for biohydrogen production via dark fermentation. However, the recovery of fermentable sugar from algal biomass is challenging because of the diversity and complex cell wall composition and therefore, requires an additional pretreatment step. However, most of the conventional pretreatment strategies suffer from limited technological feasibility and poor economic viability. In this context, this review aims to present the structural complexities of the cell wall of algae and highlight the innovative approaches such as the use of hybrid technologies, biosurfactants, nanoparticles, and genetic engineering approaches for the hydrolysis of algal biomass and improved biohydrogen production. Additionally, a comprehensive discussion of the comparative evaluation of various pretreatment methods, and the techno-economic and life cycle assessment of algal biohydrogen production is also presented in this review.

Effect of surfactant assisted ultrasonic pretreatment on production of volatile fatty acids from mixed food waste

In this study, the potential effect of surfactant assisted ultrasonic pretreatment on mixed food waste was investigated. Surfactants, such as Rhamnolipid, Sodium dodecyl sulfate; Glucopon and Triton X 100 were evaluated in this work. Among them, the maximum solubilization of chemical oxygen demand of 45.5 % and the highest release of soluble COD of 31 g/L were observed for ultrasonication assisted by Triton X 100 at a dose of 0.01 g/g TS in 30 min. The presence of a surfactant also reduced 27.5 % of energy demand when compared to ultrasonic pretreatment alone. Compared to the non-pretreated samples after anaerobic digestion, ultrasonication assisted by Triton X 100 led to 95 % increase of volatile fatty acid titers and 83 % increase of carbon conversion efficiency. Thus, sonication with the addition of Triton X 100 was proven to be highly effective toward increasing digestibility of and yield of volatile fatty acid from mixed food waste.

Sustainable production of biohydrogen from algae biomass: Critical review on pretreatment methods, mechanism and challenges

The production of chemicals and energy from sustainable biomass with an important objective decreasing carbon impressions has recently become one of the key areas of attention. Algae biomass have been recognized and researched as a potential renewable biomass of biohydrogen production attributed to their limited multiplying time, fast growing qualities and ability of lipid accumulation. This review additionally envelops various key perspectives such as composition and properties of algae biomass and pretreatment strategies such as physical, chemical and biological methods adopted for the algae biomass. This review is mainly focused on pretreatment strategies which have been developed to enhance biohydrogen production. The present review deals with methods and mechanism, enzymes involved and factors influencing on biohydrogen production which help to grasp various bottlenecks, challenges and constraints. Finally, the significant progressions and economical perspective on improving biohydrogen yield because of the expansion of co-substrates and the current trends are examined.

Ultrasonic Processing of Food Waste to Generate Value-Added Products

Ultrasonic processing has a great potential to transform waste from the food and agriculture industry into value-added products. In this review article, we discuss the use of ultrasound for the valorisation of food and agricultural waste. Ultrasonic processing is considered a green technology as compared to the conventional chemical extraction/processing methods. The influence of ultrasound pre-treatment on the soluble chemical oxygen demand (SCOD), particle size, and cell wall content of food waste is first discussed. The use of ultrasonic processing to produce/extract bioactives such as oil, polyphenolic, polysaccharides, fatty acids, organic acids, protein, lipids, and enzymes is highlighted. Moreover, ultrasonic processing in bioenergy production from food waste such as green methane, hydrogen, biodiesel, and ethanol through anaerobic digestion is also reviewed. The conversion of waste oils into biofuels with the use of ultrasound is presented. The latest developments and future prospective on the use of ultrasound in developing energy-efficient methods to convert food and agricultural waste into value-added products are summarised.

Carotenoid Production from Microalgae: The Portuguese Scenario

Microalgae have an outstanding capacity to efficiently produce value-added compounds. They have been inspiring researchers worldwide to develop a blue biorefinery, supporting the development of the bioeconomy, tackling the environmental crisis, and mitigating the depletion of natural resources. In this review, the characteristics of the carotenoids produced by microalgae are presented and the downstream processes developed to recover and purify them are analyzed, considering their main applications. The ongoing activities and initiatives taking place in Portugal regarding not only research, but also industrialization under the blue biorefinery concept are also discussed. The situation reported here shows that new techniques must be developed to make microalgae production more competitive. Downstream pigment purification technologies must be developed as they may have a considerable impact on the economic viability of the process. Government incentives are needed to encourage a constructive interaction between academics and businesses in order to develop a biorefinery that focuses on high-grade chemicals.