Dual-functional waste fungal pellets of Phanerochaete chrysosporium for textile wastewater treatment: A waste to treat waste strategy Bharat Bhushan Negi a,b , Hussein Znad b,* , Chandan Das a,* a Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India b WA School of Mines: Minerals, Energy and Chemical Engineering, Curtin University, GPO Box U1987, Perth, WA 6845, Australia A R T I C L E INFO Keywords: Waste fungal pellets Textile wastewater Methylene blue Adsorption Circular economy ABSTRACT Textile wastewater leads to large discharges containing synthetic dyes, posing severe environmental and health issues. This study explores a sustainable “waste to treat waste” strategy by repurposing Phanerochaete chrys- osporium waste fungal pellets (WFP) biomass previously used to treat refinery wastewater, heavy metals and selenite as an efficient removal of methylene blue (MB) dye from wastewater by adsorption. The characterization of WFP revealed a porous morphology and heterogeneous makeup rich in hydroxyl, carboxyl and amine groups, with a point of zero charge (pH PZC ) of 4.1. Key parameters (pH, temperature, dosage, contact time) were opti- mized using a batch experiment, achieving 95.25 % MB removal at neutral pH 7 and ambient temperature 25 ◦ C, with a rapid adsorption within 30 min. The adsorption rate was controlled by chemisorption based on pseudo- second-order kinetics (R 2 > 0.96), while the Sips isotherm (R 2 = 0.999) best described the adsorption process due to its minimum χ 2 value (0.91), indicating heterogeneous surface interaction combining monolayer and multilayer coverage on biomass. The thermodynamic analysis confirmed the process as spontaneous and exothermic. The WFP retained 71 % efficiency after completing the 4th adsorption-desorption cycle. The mechanistic studies identified the electrostatic attractions, π–π stacking, and hydrogen bonding of the MB dye with the fungal biomass. The WFP outperformed significantly compared to the standard adsorbent by operating at neutral pH, ambient temperature conditions and without any chemical activation. The work underscores the dual role of WFP in waste valorization and presents it as an economical and environmentally friendly adsorbent for textile wastewater management. 1. Introduction The textile industry is the cornerstone of global economic develop- ment. It is also one of the major contributors to environmental pollution, as it generates vast quantities of wastewater laden with synthetic dyes, chemicals, heavy metals, and recalcitrant organics [1,2]. During pro- cessing, recalcitrant dyes, such as azo dyes like methylene blue (MB) that are not bound to the fabrics and fibers, are released into wastewater [3]; the dyeing and finishing industry accounts for around 17 % of total industrial effluent, contaminating ground and surface water [4]. MB is one of the most widely employed dyes for coloring in textiles, paper, leather, and other sectors. Environmental processes do not quickly degrade these complex aromatic compounds; hence, they accumulate in the wastewater. Textile wastewater contains high chemical oxygen de- mand (COD), high color strength, and heavy metals; this hampers visual acceptability and disrupts aquatic ecosystems by inhibiting photosynthesis, reducing dissolved oxygen [1,5,6]. Heavy metals are toxic and bioaccumulate in marine life and humans [7–9]. This waste- water can cause significant ecological and health problems. Methylene blue and other dyes, as well as heavy metals like lead, cadmium, and mercury, are linked to cancer, liver disease, kidney failure, and neuro- logical disorders [1]. Long-term effects of exposure include respiratory problems, skin rash, and gastrointestinal disorders [10]. It also causes livestock and wildlife poisoning, reproductive disorders, and growth inhibition [1,11]. Therefore, treating such wastewater is very important to reduce its environmental impact. Hence, efficient and sustainable methods are necessary [12,13]. Conventional wastewater treatment methods, such as coagulation, flocculation, and advanced oxidation, are often expensive [14–17], inefficient in removing persistent dyes with low regeneration capacity, and also generate secondary pollutants [18–20]. Physical adsorption using activated carbons is widely adopted due to its high efficiency, but * Corresponding authors. E-mail addresses: h.znad@curtin.edu.au (H. Znad), cdas@iitg.ac.in (C. Das). Contents lists available at ScienceDirect Sustainable Materials and Technologies journal homepage: www.elsevier.com/locate/susmat https://doi.org/10.1016/j.susmat.2025.e01616 Received 13 May 2025; Received in revised form 7 August 2025; Accepted 21 August 2025 Sustainable Materials and Technologies 45 (2025) e01616 Available online 22 August 2025 2214-9937/© 2025 Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.