Recycling banana pseudostem waste as a substrate for microalgae biofilm and their potential in arsenic removal

Arsenic (As) is the most toxic metalloid and class I carcinogen present in the drinking water affecting around 200 M people worldwide. Among various strategies microalgal biofilm based As removal is considered as most suitable option. However, sustainable technologies for As removal from water is scanty. In the present study, banana pseudostem waste was used as a substrate for growing microalgae biofilm (BSB) and its As removal capacity was compared with nylon mesh grown microalgae biofilm (NMB). Response surface methodology optimize initial As concentration as the most important parameter (p < 0.0001) for As removal as compared to substrate area and initial phosphate concentration in both BSB and NMB treatments. BSB treatment removed 97.6% of added arsenite [As(III)] and converted into less toxic forms like arsenate and dimethylarsenic acid within 5 d. The As removal efficiency of BSB treatment is 20% higher than NMB treatment due to the high As accumulation by the banana pseudostem. In both BSB and NMB treatments, As exposure led to change in microalgae community composition towards more tolerant species that produced more proteins and lipids facilitating binding of As and amelioration of induced stress, respectively. The present study signifies the use of banana pseudostem to grow tolerant microalgae for efficient removal of As from water. The study also paves way for proving the concept “waste into wealth” by utilizing the agri-wastes for the sustainable and more economical water treatment process.