Exploring Pichia kluyveri K-1 biomass as a novel biosorbent for chromium removal from aqueous solution: Process optimization study

Increased presence of chromium in water resources represents a significant environmental and public health concern due to its high mobility, toxicity, and carcinogenic nature. Biosorption using microbial biomass has emerged as a sustainable alternative to conventional physicochemical treatment methods. In this study, the biosorptive potential of dead Pichia kluyveri K-1 biomass was investigated for the first time for chromium removal from aqueous solutions. Process optimization was performed using response surface methodology based on a Box-Behnken experimental design evaluating the effects of solution pH (2-7), initial chromium concentration (20-100 mg/L), and biosorbent dosage (2-10 g/L). Chromium removal efficiency ranged from 7.8% to 42.0%, while final chromium concentrations after biosorption varied between 11.6 and 88.5 mg/L depending on process conditions. Lower initial chromium concentrations and a strongly acidic environment resulted in substantially reduced residual chromium levels, indicating improved biosorption performance under conditions favoring protonation of biomass surface functional groups. Analysis of variance showed that the initial chromium concentration was the dominant factor governing final chromium concentration, whereas pH had the strongest influence on removal efficiency. Response surface analysis confirmed significant nonlinear effects and identified optimal operating conditions at pH 2, an initial chromium concentration of 20 mg/L, and a moderate biosorbent dosage. Under these conditions, predicted removal efficiency was 42.8%, which was also confirmed experimentally. These findings provide a foundation for further optimization and biomass modification for water treatment applications using novel, environmentally safe biosorbents.