Full-scale assessment of biological performance of modified glass fiber reinforced polymer disk aerator in wastewater treatment plant

In this work, the conventional high-density polyethylene (HDPE) disk aerators in wastewater treatment plants (WWTPs) were replaced by newly developed glass fiber reinforced polymer (GFRP). Six composite samples were prepared of varying fiber reinforcement chopped strand mat (CSM) “E-glass” content (25 %, 33 %, and 50 %). Three samples were fabricated using resilient isophthalic resin, while the other three samples were fabricated using vinyl ester resin. The mechanical behavior of both aerators was compared by applying different mechanical tests. Sample D fabricated from vinyl ester resin with a 50 % fiber volume fraction showed the best mechanical properties with 95.5 N/mm² for hardness, 333.9 MPa for flexural strength, 113.15 N/mm² for tensile strength, and 137.77 kJ/m² for impact-strength. GFRP disk aerators were manufactured based on sample D specifications and installed on a WWTP with a capacity of 25,000 m³/day. The biological performance of the GFRP disk aerators was evaluated over 200 days. The results also showed that the aeration efficiency was not affected by changing the disk material from HDPE to GFRP, where roughly similar removal efficiencies were reported for chemical‑oxygen-demand (COD), biological‑oxygen-demand (BOD), total suspended solids (TSS), ammonia (NH₃) using both disks material. Additionally, the dissolved oxygen (DO) concentration is very close using both disk materials: 4.60 mg/L for HDPE disks and 4.74 mg/L for GFRP disks. The new GFRP composite disk aerators not only improved the mechanical properties but also reduced disk cost and ensured continuous operation of the treatment plant without failure.