Fungal Biomass for Water Softening via the Biosorption Process

Abstract

Hardness in water, primarily caused by calcium and magnesium ions, poses significant operational, environmental, and health-related challenges. This study evaluates the potential of Aspergillus niger biomass (AN) and coconut-based activated carbon (AC) as lowcost biosorbents for water softening. Batch experiments were conducted to investigate the effects of contact time, shaking speed, pH, and adsorbent dosage on hardness removal from artificial hard water. The results demonstrate that both sorbents exhibit relatively rapid initial ion uptake, reaching equilibrium after 7 hours for AN and 11 hours for AC. Shaking speed showed only minor influence beyond 150 rpm, indicating that external mass transfer limitations were minimized at moderate agitation. Within the pH range of 5–9, hardness removal remained nearly constant, whereas literature data indicate a sharp increase in removal efficiency at pH values above 10 due to enhanced surface negativity. Increasing adsorbent dose improved removal efficiency up to a saturation threshold, with optimal performance observed at 15–20 g of biosorbent. Overall, A. niger biomass demonstrated promising softening capabilities, suggesting its potential application as an economical and sustainable alternative to conventional water softening technologies.