Transforming Decentralized Wastewater Treatment with Fibrous Super-Bridging Agents and a Compact Reactor

Abstract

Ageing sewer networks and increasingly variable wastewater characteristics motivate the development of compact, versatile, and high-rate treatment strategies capable of operating with short residence times and reduced operational costs. Here, we present a decentralized fiber-assisted coagulation–flocculation–floc separation “3-in-1” approach that integrates rapid floc separation via settling and coarse screening to enable decentralized pretreatment. Floc size distribution analyses demonstrated that fibers markedly increased floc size compared with conventional treatment, enabling rapid clarification to ≤ 25 NTU and residual TSS as low as approximately 1 mg-TSS·L⁻¹. Screening through a 200 to 2000-µm mesh provides an additional safeguard when gravity separation is limited, while simultaneously facilitating in-line solids capture and sludge dewatering suitable for compact system designs. Modification of fibers with targeted surface chemistries further expands treatment capability by enabling nutrient-specific capture; namely, iron-grafted fibers reduced residual total phosphorus concentrations to approximately 1 mg-TP·L⁻¹. Pilot tests in a 178-L integrated module achieved ≤ 25 NTU on an extremely turbid wastewater stream (up to 4500 NTU; > 99 % removal), demonstrating process scalability and applicability. This study introduces a regenerable and tunable fiber-enabled platform for high-rate clarification using a simple separation approach, offering a practical pathway toward resilient, decentralized wastewater management while reducing reliance on conventional centralized treatment plants – which are already under increasing pressure from rising flows and treatment demands.