Ferrofluid-assisted rapid and directional harvesting of marine microalgal Chlorella sp. used for biodiesel production.

In this work, a novel harvesting strategy using ferrofluids coupled with flocculation as a magnetic directional harvesting system was developed, providing a fast and easy way to effectively collect microalgae with no further modifications made to the ferrofluids. With a ferrofluid dosage of 25mgL-1, a high harvesting efficiency of 95-100% was achieved within 1min. In addition, we successfully performed a wastewater recycling strategy coupled with a microalgal ferrofluid-harvesting dynamic flow-through system to harvest biomass of Chlorella sp. MTF-7 which could achieve over 80% of the maximum level after three repeated recycling cultivations. This work demonstrated the use of an integrated microalgal ferrofluid-harvesting dynamic flow-through system to develop a simple and effective strategy to enhance microalgal harvesting efficiency, along with wastewater recycling, in a marine microalgal Chlorella sp. MTF-7.

Simultaneous microalgal biomass production and CO2 fixation by cultivating Chlorella sp. GD with aquaculture wastewater and boiler flue gas.

A microalgal strain, Chlorella sp. GD, cultivated in aquaculture wastewater (AW) aerated with boiler flue gas, was investigated. When AW from a grouper fish farm was supplemented with additional nutrients, the microalgal biomass productivity after 7days of culture was 0.794gL-1d-1. CO2 fixation efficiencies of the microalgal strains aerated with 0.05, 0.1, 0.2, and 0.3vvm of boiler flue gas (containing approximately 8% CO2) were 53, 51, 38, and 30%, respectively. When the microalgal strain was cultured with boiler flue gas in nutrient-added AW, biomass productivity increased to 0.892gL-1d-1. In semi-continuous cultures, average biomass productivities of the microalgal strain in 2-day, 3-day, and 4-day replacement cultures were 1.296, 0.985, and 0.944gL-1d-1, respectively. These results demonstrate the potential of using Chlorella sp. GD cultivations in AW aerated with boiler flue gas for reusing water resources, reducing CO2 emission, and producing microalgal biomass.

Cultivation of microalgal Chlorella for biomass and lipid production using wastewater as nutrient resource.

Using wastewater for microalgal cultures is beneficial for minimizing the use of freshwater, reducing the cost of nutrient addition, removing nitrogen and phosphorus from wastewater and producing microalgal biomass as bioresources for biofuel or high-value by-products. There are three main sources of wastewater, municipal (domestic), agricultural and industrial wastewater, which contain a variety of ingredients. Some components in the wastewater, such as nitrogen and phosphorus, are useful ingredients for microalgal cultures. In this review, the effects on the biomass and lipid production of microalgal Chlorella cultures using different kinds of wastewater were summarized. The use of the nutrients resource in wastewater for microalgal cultures was also reviewed. The effect of ammonium in wastewater on microalgal Chlorella growth was intensively discussed. In the end, limitations of wastewater-based of microalgal culture were commented in this review article.

Utilization of carbon dioxide in industrial flue gases for the cultivation of microalga Chlorella sp.

The biomass and lipid productivity of Chlorella sp. MTF-15 cultivated using aeration with flue gases from a coke oven, hot stove or power plant in a steel plant of the China Steel Corporation in Taiwan were investigated. Using the flue gas from the coke oven, hot stove or power plant for cultivation, the microalgal strain obtained a maximum specific growth rate and lipid production of (0.827 d(-1), 0.688 g L(-1)), (0.762 d(-1), 0.961 g L(-1)), and (0.728 d(-1), 0.792 g L(-1)), respectively. This study demonstrated that Chlorella sp. MTF-15 could efficiently utilize the CO2, NOX and SO2 present in the different flue gases. The results also showed that the growth potential, lipid production and fatty acid composition of the microalgal strain were dependent on the composition of the flue gas and on the operating strategy deployed.

Characterization and biocompatibility of chitosan nanocomposites.

Chitosan nanocomposites were prepared from chitosan and gold nanoparticles (AuNPs) or silver nanoparticles (AgNPs) of ∼5 nm size. Transmission electron microscopy (TEM) showed the NPs in chitosan did not aggregate until higher concentrations (120-240 ppm). Atomic force microscopy (AFM) demonstrated that the nanocrystalline domains on chitosan surface were more evident upon addition of AuNPs (60 ppm) or AgNPs (120 ppm). Both nanocomposites showed greater elastic modulus, higher glass transition temperature (T(g)) and better cell proliferation than the pristine chitosan. Additionally, chitosan-Ag nanocomposites had antibacterial ability against Staphylococcus aureus. The potential of chitosan-Au nanocomposites as hemostatic wound dressings was evaluated in animal (rat) studies. Chitosan-Au was found to promote the repair of skin wound and hemostasis of severed hepatic portal vein. This study indicated that a small amount of NPs could induce significant changes in the physicochemical properties of chitosan, which may increase its biocompatibility and potential in wound management.