Sustainable wastewater treatment in the U. S: Bio-flocculation of laundry fibers using calcium ions

This research investigates calcium-enhanced bio-flocculation as a sustainable approach for removing synthetic and natural laundry fibers from wastewater streams. With conventional wastewater treatment systems removing only 65-99.9% of microfibers and an estimated 700,000-12,000,000 fibers released per 6 kg wash load, innovative methods are urgently needed to address this growing environmental concern. This review examines the fundamental mechanisms through which calcium ions promote bio-flocculation of textile fibers, particularly focusing on interactions between calcium and extracellular polymeric substances (EPS) in activated sludge systems. By exploring various literature studies, we compare the efficiency of calcium-enhanced bio-flocculation with traditional chemical coagulants, analyzing fiber removal rates, effluent quality, and sludge properties. Results indicate that calcium ions significantly improve flocculation efficiency through charge neutralization, bridging mechanisms, and cross-linking with biopolymers, achieving removal rates of 85-97% for various fiber types under optimized conditions. The optimal operational parameters include calcium concentrations of 50-75 mg/L, pH range of 6.5-8.0, and temperature between 20-35°C. This paper demonstrates that calcium-based bio-flocculation represents a cost-effective, environmentally friendly alternative to conventional chemical flocculants, offering a scalable solution that can be integrated into existing wastewater infrastructure while reducing energy consumption and chemical usage in treatment processes.