Innovative use of Barley Straw to control algal blooms and improve wastewater quality: Microbial community insights in a sustainable pre-filtration conditioning

Abstract

Returning to natural processes has become the central approach in modern wastewater treatment. This study investigates the effectiveness of barley straw (Hordeum vulgare) in mitigating algal blooms and reducing total suspended solids (TSS) in maturation basins at the El-Zarabi oxidation pond system in Egypt. Additionally, the study explores barley straw as a sustainable pre-filtration method to enhance sand filtration performance. Laboratory-scale experiments evaluated three placements—surface, suspended, and bottom—using maturation pond effluent with initial concentrations of 182 mg/L COD, 138 mg/L BOD, 86 mg/L TSS, 54 mg/L TN, and 5.2 mg/L TP.Results monitored over 12 weeks demonstrated that a suspended configuration significantly inhibited algal biomass (p = 0.0166) and reduced TSS (p < 0.05). While numerical improvements were observed for COD and BOD, the differences were not statistically significant compared to the control (p > 0.05). Regarding nutrients, suspended barley straw achieved a statistically significant reduction in Total Nitrogen (TN) from 54 mg/L to <3.4 mg/L (p = 0.0359). However, Total Phosphorus (TP) reduction (from 5.2 mg/L to 2.1 mg/L) did not reach statistical significance across all groups. Molecular analyses identified four dominant microalgal species: Synechocystis PCC 6803, Cyanobacterium aponinum, Chlorella vulgaris, and Desmodesmus intermedius. The study concludes that barley straw is an effective, low-cost pretreatment that significantly reduces filter clogging and maintenance by managing algal biomass. These findings align with UN Sustainable Development Goals (SDGs 6, 11, 12, and 13). Field-scale validation is recommended to confirm efficacy under diverse operational conditions.