Search

Graphical abstract Highlights • Chlorella was introduced into MFC for Cd(II) removal in the biocathode. • Simultaneous high power generation and metal removal efficiencies can be achieved. • NF-rGO enhanced power generation (36.4 mW m−2) and Cd(II) removal (115 g m−2). • NF-rGO improve the maximum tolerable concentrations of Cd(II) for algal biocathode. • Cadmium were removed mainly through hydroxide precipitation and biosorption. Abstract Microalgae ( Chlorella sp. QB-102) was introduced into microbial fuel cell (MFC) as the cathode for Cd(II) removal using nickel foam/graphene (NF/rGO) as electrodes. It was found that graphene enhanced the power generation and decreased the internal resistance in the algal-cathode MFC. The start-up time was shortened and the maximum power density obtained by using NF/rGO (36.4 mW m−2) was eight times higher against bare NF. Graphene further improve the maximum tolerable concentrations of Cd(II) in the algal-cathode, which estimated to be 50 ppm. Using NF/rGO electrode, the algal-cathode MFC achieved a high Cd(II) removal efficiency of almost 95% and a maximum adsorption amount of 115 g m−2. It was found that hydroxide precipitation and biosorption are the major mechanisms for the Cd removal in the biocathode self-sustained MFC. The results suggested that photoautographic MFC is feasible and effective for heavy metal removal in the algal-cathode and graphene modification in the electrodes is recommended. [ABSTRACT FROM AUTHOR]

Cultivation modes of autotrophic microalgae for biodiesel production utilizing open raceway pond were analyzed in this study. Five before screened good microalgae were tested their lipid productivity and biodiesel quality again in outdoor 1000 L ORP. Then, Chlorella sp. L1 and Monoraphidium dybowskii Y2 were selected due to their stronger environmental adaptability, higher lipid productivity and better biodiesel properties. Further scale up cultivation for two species with batch and semi-continuous culture was conducted. In 40,000 L ORP, higher lipid productivity (5.15 versus 4.06 g m −2 d −1 for Chlorella sp. L1, 5.35 versus 3.00 g m −2 d −1 for M . dybowskii Y2) was achieved in semi-continuous mode. Moreover, the financial costs of 14.18 $ gal −1 and 13.31 $ gal −1 for crude biodiesel in two microalgae with semi-continuous mode were more economically feasible for commercial production on large scale outdoors. [ABSTRACT FROM AUTHOR]

Chlorella sp. and Monoraphidium sp. were the potential microalgal species for lipid production. This study aimed to investigate different light intensities (40, 200, 400 μmol photon m −2 s −1 ) on physiological changes, photosynthetic carbon partitioning and neutral lipid accumulation in both microalgae. Results suggested that under high light (HL, 400 μmol photon m −2 s −1 ), chlorophyll degraded, protein and carbohydrate content decreased; more carbon allocated into lipid as well as most of intracellular space was occupied by lipid bodies. Moreover, with the lipid accumulation, Fv/Fm decreased and ROS scavenging enzyme increased. Membrane lipid reduced dramatic (29.73–37.97%) to format NL (71.66% of total lipid in Chlorella sp. L1 and 60.65% in Monoraphidium dybowskii Y2). The NL productivity under HL (51.36 and 49.71 mg L −1 d −1 ) were more than 3 times of those under LL. Additionally, FAME profiles proved that the useful fatty acid components for biodiesel production were enhanced under HL. [ABSTRACT FROM AUTHOR]