Sorbent materials of biological origin are considered as an alternative to the use of traditional methods in order to remove heavy metals. Interest in using these materials has increased over the past years due to their low cost and friendliness to the environment. The objective of this study was to synthesize and characterize cross-linked beads made of chitosan, alginate, and mycelium of a copper-tolerant strain of Aspergillus australensis. The acute toxicity of the biocomposite beads was assessed using brine shrimp Artemia salina nauplii and the phytotoxicity was determined using lettuce (Lactuca sativa) and chili pepper ’Anaheim’ (Capsicum annuum) seeds. The biosorption capacity for copper removal in simulated wastewater was also evaluated. Results showed that the biosorbent obtained had a maximal adsorption of 26.1 mg of Cu²⁺ per g of biocomposite, and removal efficiency was around 79%. The toxicity of simulated residual water after treatment with the biocomposite showed low toxicity toward seeds, which was highly dependent on the residual copper concentration. The toxicity of the biocomposite beads to A. salina was considered medium depending on the amount of the biocomposite, which was attributed to low pH. Biocomposite shows promise as biosorbent for the removal process of heavy metals.

With the purpose of determining the copper biosorption mechanism, iron influence on the bioremoval, and methane production in a batch system using an anaerobic sludge a systematic study was carried out. In addition, sludge was characterized before and after biosorption treatment by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). According to results, Fe(III) has effect on copper biosorption. At neutral pH and concentrations from 50 to 300 mg/L, copper biosorption increases. However, at concentrations >300 mg/L a reduction in biosorption is observed. During biosorption, Fe(III) does not have an effect on both methane production and methanogenic activity; consequently, it is possible establishing that methanogenic bacteria are active under these conditions. Results of analysis by EDS reveal the copper presence into diatoms (2.66w%). In addition, biosorption of copper is by means diatoms-bacteria-polimeric matrix, and it is also bioaccumulated into diatoms.