Biosolids recycling impact on biofilm extracellular enzyme activity and performance of hybrid rotating biological reactors

Evaluation of textile industry wastes: Cellulose recovery from cotton/polyester blend shearing waste

In this study, the recovery efficiency of cellulose from shearing waste (SW), one of the textile industry wastes consisting of cotton/polyester blends, was investigated. Transforming textile industry wastes into high-value-added secondary products is important in terms of environmental sustainability and waste management. The main purpose of the study presented in this context is to reveal the economic and ecological potential of these wastes and to contribute to the development of a sustainable waste management model. Our study was carried out with a three-stage methodology. First, shearing wastes used as raw materials were supplied and characterized. In the second stage, cellulose was recovered using various chemical pretreatments (acid hydrolysis, alkaline hydrolysis, and organosolvent treatment), and the recovery efficiency was calculated. In the third stage, the recovered cellulose fractions were subjected to a detailed characterization process. It was determined that approximately 97% of the cellulose from the wastes could be recovered cumulatively as a result of the process carried out with the combination of the mentioned chemical pretreatments. The recovered cellulose showed varying crystallinity index (65-75%) and thermal stability depending on the process parameters. As a result, it was concluded that textile wastes have the potential to be converted into high-value products. It was revealed that it supports the protection of national natural resources and zero waste policies. In addition, the study tried to present evaluations regarding the complexity and applicability of the methodology and suggestions for improving textile waste management strategies. This research includes data and evaluations that can be important in terms of waste management and environmental policies in the textile industry and provide an important reference point. Future studies should focus on optimizing the solvent recovery system and increasing industrial-scale applicability.

Current recycling strategies and high-value utilization of waste cotton

The rapid development of the textile industry and improvement of people's living standards have led to the production of cotton textile and simultaneously increased the production of textile wastes. Cotton is one of the most common textile materials, and the waste cotton accounts for 24% of the total textile waste. To effectively manage the waste, recycling and reusing waste cotton are common practices to reduce global waste production. This paper summarizes the characteristics of waste cotton and high-value products derived from waste cotton (e.g., yarns, composite reinforcements, regenerated cellulose fibers, cellulose nanocrystals, adsorptive materials, flexible electronic devices, and biofuels) via mechanical, chemical, and biological recycling methods. The advantages and disadvantages of making high-value products from waste cotton are summarized and discussed. New technologies and products for recycling waste cotton are proposed, providing a guideline and direction for merchants and researchers. This review paper can shed light on converting textile wastes other than cotton (e.g., bast, silk, wool, and synthetic fibers) into value-added products.

A high-throughput assay to quantify protein hydrolysis in aerobic and anaerobic wastewater treatment processes

Proteins, an important fraction of the organic matter in wastewater, typically enter a treatment facility as high molecular weight components. These components are degraded by extracellular protein hydrolytic enzymes, denoted as proteases. Adequate protein hydrolysis monitoring is crucial, since protein hydrolysis is often a rate-limiting step in wastewater treatment. However, current monitoring tools lack a high sample throughput and reliable quantification. Here, we present an improved assay for high-throughput protein hydrolysis rate measurements in wastewater treatment applications. A BODIPY FL casein model substrate was implemented in a microplate format for continuous fluorescent quantification. Case studies on a conventional and a high-rate aerobic municipal wastewater treatment plant and a lab-scale, two-stage, anaerobic reactor provided proof-of-concept. The assay presented in this study can help to obtain monitoring-based process insights, which will in turn allow improving biological performance of wastewater treatment installations in the future. KEY POINTS: • Protein hydrolysis is a crucial step in biological wastewater treatment. • Quantification of the protein hydrolysis rate enables in-depth process knowledge. • BODIPY FL casein is a suitable model substrate for a protein hydrolysis assay. • High sample throughput was obtained with fluorescent hydrolysis quantification. Graphical abstract.