Performance of basalt fiber-periphyton in deep-level nutrient removal: A study concerned periphyton cultivation, characterization and application.

Nutrients in centralized discharge area of treated sewage can cause high ecological risks to aquatic systems, thus a deep-level nutrient removal is necessary. Recently, periphyton has attracted increasing interests for its excellent performance in nutrient removal. In this study, the suitability and durability of basalt fiber (BF) as a new green carrier of periphyton was evaluated, and development process of basalt fiber-periphtyon (BFP) was tracked with bacterial community succession and physiological indicators. Then, well-developed BFP was applied to deeply purify water containing the same concentration of nutrient as the treated sewage. Results showed the periphyton could adapt to BF and formed in large quantities. In addition, the tensile strength of BF after being used as a carrier was still strong. Bacterial community and physiological indicators indicated that BFP was well developed in 40-50 days. LEfSE and random forest analysis revealed that Deinococcus-Deinococci, Spartobacteria and Chlamydiia at class-level, Rhizobiales and Rhodobacterales at order-level were the biomarkers for development of BFP. Moreover, application results showed BFP efficiently removed nitrogen and phosphorus from water and promoted the transformation of ammonia to nitrate. The concentration of ammonia and phosphorus severely decreased from 4.90 ± 0.11 mg/L to 0.51 ± 0.20 mg/L, from 0.66 ± 0.016 mg/L to 0.023 ± 0.013 mg/L, respectively. The efficient nutrient removal was attributed to accumulation of nitrogen and phosphorus metabolism related organisms in BFP as well as favorable water physic-chemical conditions created by BFP. These results suggest that BF is a suitable and durable green carrier of periphyton, and BFP could efficiently reduce ecological risk to aquatic systems receiving treated sewage.