Bioaccumulation And Biosorption Of Nitrogen, Phosphorus And Heavy Metal Ions Cu²⁺, Pb²⁺, Cd²⁺ And Cr⁶⁺

As more and more attention is paid to environment, it is important to remove pollutants in aqueous solution. Conventional wastewater treatment methods are either inefficient or expensive, and they may also generate secondary wastes, which are difficult to treat. Consequently, it is urgent to find new technologies or materials for removing pollutants from wastewater. Biosorption and bioaccumulation are two kinds of valuable biological processes for pollutants removal from industrial waste streams and natural water. The method using alga to adsorb, accumulate and degrade of N, P, heavy metals, and organic compounds is effective and economical. The biomass can be used in animal feeds, industry materials and potential food for human beings. It has wide foreground, especially in our development country.In this work, some kinds of algae were used to treat eutrophic underground seawater. The results proved that Cladophora sp could absorb and remove N and P efficiently. The sea cucumber and turbot was breed in the treated underground seawater by Cladophora sp. The mode of alga cleansing fishery seawater can decrease N and P evidently, lessen the environmental infection of fishery wastewater, and increase the economy export of the fishery system, then realize sustainable development of the fisheries resources and the environment in mariculture.Biosorption utilizes the ability of certain materials to accumulate heavy metals from aqueous solutions by either metabolically mediated or physico-chemical pathways of uptake. In this study, biosorption of Cu2+, Pb2+ and Cd2+ by Cladophora fascicularis were investigated as a function of environment effects, biosorption equilibriums, biosorption kinetics and biosorption mechanism. Adsorption equilibriums were well described by Langmuir and Freundlich isotherm models. The maximum adsorption capacities were1.61 mmol/g for Cu2+, 0.96 mmol/g for Pb2+ and 0.98 mmol/g for Cd2+,and adsorption processes were endothermic. The biosorption kinetics followed the pseudo-second order model. The removal rate was rapid in the first 30 min, and leveled off after 1 to 2 h. With high metal ions biosorption and desorption capacities, the biomass has the potential to be used as an effective and economic biosorbent for the removal and recovery of heavy metals Cu2+, Pb2+ and Cd2+ from wastewater.Bosorption of Cr6+ from aqueous solutions by nonliving green algae C. fascicularis was investigated as a function of pH, initial Cr6+ concentration, and temperature. The removal rate increased with decreasing pH, increasing Cr6+ concentration and temperature. The mechanism of Cr6+ removed by C. fascicularis was discussed by analyzing the Cr6+ and total Cr in the solution at different time. Actual industry wastewater was used to evaluate the practicality of the biomass. The result showed that C. fascicularis could be used for removal of Cr6+ from wastewater by the reduction of toxic Cr6+ to nontoxic Cr3+.The utilization of C. fascicularis in industry was discussed in this study. The resource of C. fascicularis is abundant and economic, and the nutrition is rich, so it can be used in the sea cucumber feeds. The results showed that C. fascicularis was a kind of invaluable resource.Bosorption of Cu2+, Pb2+, Cd2+ and Cr6+ from aqueous solutions by algae residues was investigated. The biosorption characteristics of algal residues were consistent with C. fascicularis. At pH 5, the maximum adsorption capacities were 4.20 mmol/g for Cu2+, 3.13 mmol/g for Pb2+ and 2.97 mmol/g for Cd2+. Algal residues have high reduction capacity for low and high initial concentration Cr6+. From a practical viewpoint, the abundant and economic biomass algal residues could be used for removal of heavy metals from wastewater.