Use of Cost-Effective Untreated Biomasses as Potential Biosorbents for Formaldehyde Removal from Wastewater

Formaldehyde is a toxic and dangerous compound that is considered as one of the carcinogenic and mutagenic agents in organisms [۱]. Formaldehyde is used in many industrial activities such as the production of adhesives and resins, paper, and pharmaceuticals [۲-۴]. The toxicity of formaldehyde to microorganisms limited its removal by aerobic biological methods. In this study, the ability of the alga Chlorella Vulgaris in removal of formaldehyde was investigated. In this regard, Chlorella Vulgaris was grown in a sterile B.G.۱۱ medium. It was then centrifuged; the algae were separated from the culture medium and rinsed several times with distilled water. The amount of formaldehyde was measured by the spectrophotometry method. Parameters affecting the removal of formaldehyde such as contact time, temperature, and pH have been investigated and optimized. The sorption isotherms and analytic kinetics with biosorbent were investigated using linear and nonlinear regression. Under the optimized pH of ۶.۰, Chlorella Vulgaris Microalgae was able to remove ۹۸ % of formaldehyde within ۱۰ minutes. The equilibrium sorption experiments were evaluated by Langmuir, Freundlich, Tempkin, and Dubinin-Raduskovich isotherm models. The sorption kinetic were studied by pseudo-first-order, pseudo second order, Elovich, and intra-particle diffusion. The sorption isotherm followed Langmuir isotherm and the kinetics of the sorption followed the pseudo-second-order model. The maximum monolayer sorption capacity of Chlorella Vulgaris based on Langmuir model was found to be ۱۵۸ mg g-۱. Rapid and relatively high capacity of natural and untreated Chlorella Vulgaris Microalgae is the main advantage of this biosorbent for wastewater treatment.