Resource recovery from food-processing wastewaters in a circular economy: a methodology for the future

Microbial Electrochemical Technologies: Sustainable Solutions for Addressing Environmental Challenges

Addressing global challenges of waste management demands innovative approaches to turn biowaste into valuable resources. This chapter explores the potential of microbial electrochemical technologies (METs) as an alternative opportunity for biowaste valorisation and resource recovery due to their potential to address limitations associated with traditional methods. METs leverage microbial-driven oxidation and reduction reactions, enabling the conversion of different feedstocks into energy or value-added products. Their versatility spans across gas, food, water and soil streams, offering multiple solutions at different technological readiness levels to advance several sustainable development goals (SDGs) set out in the 2030 Agenda. By critically examining recent studies, this chapter uncovers challenges, optimisation strategies, and future research directions for real-world MET implementations. The integration of economic perspectives with technological developments provides a comprehensive understanding of the opportunities and demands associated with METs in advancing the circular economy agenda, emphasising their pivotal role in waste minimisation, resource efficiency promotion, and closed-loop system renovation.

Current trends and possibilities of typical microbial protein production approaches: a review

Global population growth and demographic restructuring are driving the food and agriculture sectors to provide greater quantities and varieties of food, of which protein resources are particularly important. Traditional animal-source proteins are becoming increasingly difficult to meet the demand of the current consumer market, and the search for alternative protein sources is urgent. Microbial proteins are biomass obtained from nonpathogenic single-celled organisms, such as bacteria, fungi, and microalgae. They contain large amounts of proteins and essential amino acids as well as a variety of other nutritive substances, which are considered to be promising sustainable alternatives to traditional proteins. In this review, typical approaches to microbial protein synthesis processes were highlighted and the characteristics and applications of different types of microbial proteins were described. Bacteria, fungi, and microalgae can be individually or co-cultured to obtain protein-rich biomass using starch-based raw materials, organic wastes, and one-carbon compounds as fermentation substrates. Microbial proteins have been gradually used in practical applications as foods, nutritional supplements, flavor modifiers, and animal feeds. However, further development and application of microbial proteins require more advanced biotechnological support, screening of good strains, and safety considerations. This review contributes to accelerating the practical application of microbial proteins as a promising alternative protein resource and provides a sustainable solution to the food crisis facing the world.

Towards planetary boundary sustainability of food processing wastewater, by resource recovery & emission reduction: A process system engineering perspective

Meeting the needs of a growing population calls for a change from linear production systems that exacerbate the depletion of finite natural resources and the emission of environmental pollutants. These linear production systems have resulted in the human-driven perturbation of the Earth's natural biogeochemical cycles and the transgression of environmentally safe operating limits. One solution that can help alleviate the environmental issues associated both with resource stress and harmful emissions is resource recovery from waste. In this review, we address the recovery of resources from food and beverage processing wastewater (FPWW), which offers a synergistic solution to some of the environmental issues with traditional food production. Research on resource recovery from FPWW typically focuses on technologies to recover specific resources without considering integrative process systems to recover multiple resources while simultaneously satisfying regulations on final effluent quality. Process Systems Engineering (PSE) offers methodologies able to address this holistic process design problem, including modelling the trade-offs between competing objectives. Optimisation of FPWW treatment and resource recovery has significant scope to reduce the environmental impacts of food production systems. There is significant potential to recover carbon, nitrogen, and phosphorus resources while respecting effluent quality limits, even when the significant uncertainties inherent to wastewater systems are considered. This review article gives an overview of the environmental challenges we face, discussed within the framework of the planetary boundary, and highlights the impacts caused by the agri-food sector. This paper also presents a comprehensive review of the characteristics of FPWW and available technologies to recover carbon and nutrient resources from wastewater streams with a particular focus on bioprocesses. PSE research and modelling advances are discussed in this review. Based on this discussion, we conclude the article with future research directions.

Microbial community-based protein from soybean-processing wastewater as a sustainable alternative fish feed ingredient

As the global demand for food increases, aquaculture plays a key role as the fastest growing animal protein sector. However, existing aquafeeds contain protein ingredients that are not sustainable under current production systems. We evaluated the use of microbial community-based single cell protein (SCP), produced from soybean processing wastewater, as a partial fishmeal protein substitute in juvenile Asian seabass (Lates calcarifer). A 24-day feeding trial was conducted with a control fishmeal diet and a 50% fishmeal replacement with microbial community-based SCP as an experimental group, in triplicate tanks containing 20 fish each. Both diets met the protein, essential amino acids (except for lysine), and fat requirements for juvenile Asian sea bass. The microbial composition of the SCP was dominated by the genera Acidipropionibacterium and Propioniciclava, which have potential as probiotics and producers of valuable metabolites. The growth performance in terms of percent weight gain, feed conversion ratio (FCR), specific growth rate (SGR), and survival were not significantly different between groups after 24 days. The experimental group had less variability in terms of weight gain and FCR than the control group. Overall, microbial community-based protein produced from soybean processing wastewater has potential as a value-added feed ingredient for sustainable aquaculture feeds.

Factors associated with citations of articles on circular economy in the Web of Science: modeling for main publishers

Introduction

The publication of articles on the circular economy has different associated factors to explain the citations registered in the Web of Science.

Method

Articles from the publishers Elsevier, MDPI, Taylor & Francis, Wiley, and Springer Nature were evaluated.

Results

It was expected that the older the article was, the more citations it had received, but this was not always the case. It was also recognized that there was a lower number of citations if the articles were too large or if they had too many references.

Discussion

This analysis helps to establish the factors that must be addressed in order to publish in journals that have a high citation rate. Conclusion: Based on speci?c articles and with speci?c references, it will be possible to increase the probability of citations.

Microbial community-based production of single cell protein from soybean-processing wastewater of variable chemical composition

The use of food-processing wastewaters to produce microbial biomass-derived single cell protein (SCP) is a sustainable way to meet the global food demand. Microbial community-based approaches to SCP production have the potential benefits of lower costs and greater resource recovery compared to pure cultures, yet they have received scarce attention. Here, SCP production from soybean-processing wastewaters using their existent microbial communities was evaluated. Six sequencing batch reactors of 4.5-L working volume were operated at 30 °C for 34 d in cycles consisting of 3-h anaerobic and 9-h aerobic phases. Four reactors received no microbial inoculum and the remaining two were amended with 1.5 L of a mixed culture from a prior SCP production cycle. Reactors produced more SCP when fed with wastewaters of higher soluble total Kjeldahl nitrogen (sTKN) content. The protein yield in biomass ranged from 0.53 to 3.13 g protein/g sTKN, with a maximum protein content of 50 %. The average removal of soluble chemical oxygen demand (sCOD) and soluble total nitrogen (sTN) was 92 % and 73 %, respectively. Distinct microbial genera were enriched in all six bioreactors, with Azospirillum, Rhodobacter, Lactococcus, and Novosphingobium dominating. The study showed that constituents in soybean wastewater can be converted to SCP and demonstrated the effect of variable influent wastewater composition on SCP production.

How can we possibly resolve the planet's nitrogen dilemma?

Nitrogen is the most crucial element in the production of nutritious feeds and foods. The production of reactive nitrogen by means of fossil fuel has thus far been able to guarantee the protein supply for the world population. Yet, the production and massive use of fertilizer nitrogen constitute a major threat in terms of environmental health and sustainability. It is crucial to promote consumer acceptance and awareness towards proteins produced by highly effective microorganisms, and their potential to replace proteins obtained with poor nitrogen efficiencies from plants and animals. The fact that reactive fertilizer nitrogen, produced by the Haber Bosch process, consumes a significant amount of fossil fuel worldwide is of concern. Moreover, recently, the prices of fossil fuels have increased the cost of reactive nitrogen by a factor of 3 to 5 times, while international policies are fostering the transition towards a more sustainable agro-ecology by reducing mineral fertilizers inputs and increasing organic farming. The combination of these pressures and challenges opens opportunities to use the reactive nitrogen nutrient more carefully. Time has come to effectively recover used nitrogen from secondary resources and to upgrade it to a legal status of fertilizer. Organic nitrogen is a slow-release fertilizer, it has a factor of 2.5 or higher economic value per unit nitrogen as fertilizer and thus adequate technologies to produce it, for instance by implementing photobiological processes, are promising. Finally, it appears wise to start the integration in our overall feed and food supply chains of the exceptional potential of biological nitrogen fixation. Nitrogen produced by the nitrogenase enzyme, either in the soil or in novel biotechnology reactor systems, deserves to have a 'renaissance' in the context of planetary governance in general and the increasing number of people who desire to be fed in a sustainable way in particular.