Fungal Biosorption of Ni (II) Ions

Abstract

Heavy metals are important pollutants released to the environment by human activities and natural processes. Industrial operations are the main source of dispersion of heavy metals into the environment. Nickel is one of these toxic heavy metals, which can affect human health and cause dermatitis, allergic sensitization, lung and nervous system damage. It is also a known carcinogen. According to the World Health Organization (WHO) guidelines for drinking water, the permissible level of Ni+2 is 5 ppm. Therefore, it is necessary to decrease the concentration of nickel to permissible limits before discharge. Biosorption using microbial biomass such as bacteria, fungi, yeast and algae, is regarded as a cost-effective biotechnology for the treatment of wastewaters containing heavy metals. This chapter includes experimental research on fungal biosorption of Ni (II) ions. Results indicate that it is possible to use dried Rhizopus oligosporus biomass to remove Ni (II) ions from their aqueous solutions. Food processing wastewater can be used as a substrate for cultivating the fungal biomass to reduce operational costs of biosorption process. The biosorption process was carried out in a batch process and the effects of contact time (1–48 h), initial pH (2.0–7.0), initial metal ion concentration (20–100 mg/L) and biosorbent dosage (0.5–5 g/L) on the biosorption were investigated. Experimental results showed that the biosorption onto dried fungal biomass could be well described by the Langmuir equations and the Langmuir monolayer capacity had a mean value of 116 mg/g. Pseudo-second-order reaction model provided the best description of the data with a correlation coefficient 0.99 for different initial metal concentrations. This result indicates that chemical sorption might be a basic mechanism in this system.