Food processing is among the greatest water-consuming industries with a significant role in the implementation of sustainable development goals. Waterconsuming industries such as food processing have become a threat to limited freshwater resources, and numerous attempts are being carried out in order to develop and apply novel approaches for water management in these industries. Studies have shown the positive impact of the new methods of process integration (e.g., water pinch, mathematical optimization, etc.) in maximizing water reuse and recycle. Applying these methods in food processing industries not only significantly supported water consumption minimization but also contributed to environmental protection by reducing wastewater generation. The methods can also increase the productivity of these industries and direct them to sustainable production. This interconnection led to a new subcategory in nexus studies known as water-food-environment nexus. The nexus assures sustainable food production with minimum freshwater consumption and minimizes the environmental destructions caused by untreated wastewater discharge. The aim of this study was to provide a thorough review of water-food-environment nexus application in food processing industries and explore the nexus from different aspects.The current study explored the process of food industries in different sectors regarding water consumption and wastewater generation, both qualitatively and quantitatively. The most recent wastewater treatment methods carried out in different food processing sectors were also reviewed. This review provided a comprehensive literature for choosing the optimum scenario of water and wastewater management in food processing industries.
K E Y W O R D Scircular economy, food processing, nexus, wastewater treatment, water management
INTRODUCTIONIncreased global demand for freshwater due to population growth has put the water resources under stress for the recent decades. Water scarcity is predicted to get more intensive in the forthcoming years (Piesse, 2020). Statistical data demonstrated that annual water consumption in three main different sectors of agriculture, industries, and
Plants deploy molecular, physiological, and anatomical adaptations to cope with long-term water-deficit exposure, and some of these processes are controlled by circadian clocks. Circadian clocks are endogenous timekeepers that autonomously modulate biological systems over the course of the day–night cycle. Plants’ responses to water deficiency vary with the time of the day. Opening and closing of stomata, which control water loss from plants, have diurnal responses based on the humidity level in the rhizosphere and the air surrounding the leaves. Abscisic acid (ABA), the main phytohormone modulating the stomatal response to water availability, is regulated by circadian clocks. The molecular mechanism of the plant’s circadian clock for regulating stress responses is composed not only of transcriptional but also posttranscriptional regulatory networks. Despite the importance of regulatory impact of circadian clock systems on ABA production and signaling, which is reflected in stomatal responses and as a consequence influences the drought tolerance response of the plants, the interrelationship between circadian clock, ABA homeostasis, and signaling and water-deficit responses has to date not been clearly described. In this review, we hypothesized that the circadian clock through ABA directs plants to modulate their responses and feedback mechanisms to ensure survival and to enhance their fitness under drought conditions. Different regulatory pathways and challenges in circadian-based rhythms and the possible adaptive advantage through them are also discussed.
BACKGROUND: This study aims to investigate the effect of simultaneous carbon dioxide (CO 2 ) addition and biomass recycling on specific performance parameters (including biomass productivity and harvestability, and species abundance) of the mixed culture of two freshwater microalgae species Chlorella vulgaris and Scenedesmus obliquus in a flat-panel photobioreactor grown semicontinuously using secondary effluent urban wastewater as the culture medium. Recycling a portion of the gravityharvested biomass back to the system has positive effects on biomass productivity and harvestability by letting microalgal cells utilize more of the available light energy and promoting the dominance of settleable microalgal species of S. obliquus (owing to their large cell sizes) in the mixed culture. Furthermore, CO 2 addition could supply the carbon limitation of urban wastewater and boost biomass production.
RESULTS:The work confirmed that simultaneous CO 2 addition and biomass recycling improved the biomass productivity by 314%, promoted the dominance of the larger algae species S. obliquus in the mixed culture by 38%, and increased the gravity sedimentation by 85% compared to the control that had no recycling and CO 2 addition. Concerning the secondary effluent urban wastewater, the interaction of CO 2 addition and biomass recycling was insignificant regarding the improvement in nutrient removal efficiency.CONCLUSION: The findings proved the potential benefits of simultaneous biomass recycling and CO 2 addition for reaching a high cell density, and demonstrated its potential for high biomass harvest efficiency in microalgae-based wastewater treatment systems.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.