A Mini Review on Pyrolysis of Natural Algae for Bio-Fuel and Chemicals

The disposal and use of natural algae have recently been the subject of great interest, due to increasing concern for environmental protection and resource utilization. In this paper, a mini review of recent research on the pyrolysis of natural algae, especially the algae from water blooms, is presented. The chemical compositions of the natural algae are summarized, and the pyrolysis properties of different compositions are reviewed. Non-catalytic, catalytic, and integrated catalytic processes are reviewed. Different ideas and methods for the production of bio-fuel or chemicals are discussed. Apparently, deoxygenation and denitrogenation are highly necessary for algae-based bio-fuel and catalysts play an important role in these processes. In addition, the integrated catalytic process, which involves catalysis and other operation conditions aside from the thermal treatment under inert atmosphere, shows potential for the valorization of algae-based bio-oil. Based on the recent concept and progress, the research gaps are discussed, followed by the challenges and proposals to achieve high-value utilization of the natural algae.

Spatiotemporal Evolution of Chlorophyll-a Concentration From MODIS Data Inversion in the Middle and Lower Reaches of the Hanjiang River, China

The global construction of water projects has led to a clear trend of river and lake reservoir formation, spurring increasingly serious ecological environmental deterioration, especially that caused by the frequent occurrence of water blooms. Because of monitoring technology limitations, monitoring the algae content index in water has lagged behind the conventional water quality index, which makes sample monitoring too sparse in many rivers and the monitoring data incoherent, so it cannot truly reflect the evolution of water eutrophication. With moderate resolution imaging spectroradiometer (MODIS) remote sensing data monitoring, continuous chlorophyll-a observation data can be collected effectively. This method has important guiding significance for the early warning and control of water blooms. This study considers the middle and lower reaches of the Hanjiang River in China, based on the current remote sensing communication technology, MODIS remote sensing data, and statistical methods and measured chlorophyll-a concentration correlation analysis. Through the use of the trial and error method to establish the band ratio model and BP neural network model, two types of model errors were compared to determine the optimal algorithm settings for the middle and lower reaches of the Hanjiang River chlorophyll-a inversion. Subsequently, the algorithm model for 2000 to 2011 in the middle and lower reaches of the Hanjiang River chlorophyll-a concentration inversion and the results of the inversion analysis of spatiotemporal evolution characteristics we used to determine the influence of various environmental factors on the chlorophyll-a concentration change.

Spatiotemporal evolution of chlorophyll-a concentration from MODIS data inversion in the middle and lower reaches of the Hanjiang River, China

The global construction of water projects has led to a clear trend of river and lake reservoir formation, spurring increasingly serious ecological environmental deterioration, especially that caused by the frequent occurrence of water blooms. Because of monitoring technology limitations, monitoring the algae content index in water has lagged behind the conventional water quality index, which makes sample monitoring too sparse in many rivers and the monitoring data incoherent, so it cannot truly reflect the evolution of water eutrophication. With moderate resolution imaging spectroradiometer (MODIS) remote sensing data monitoring, continuous chlorophyll-a observation data can be collected effectively. This method has important guiding significance for the early warning and control of water blooms. This study considers the middle and lower reaches of the Hanjiang River in China, based on the current remote sensing communication technology, MODIS remote sensing data, and statistical methods and measured chlorophyll-a concentration correlation analysis. Through the use of the trial and error method to establish the band ratio model and BP neural network model, two types of model errors were compared to determine the optimal algorithm settings for the middle and lower reaches of the Hanjiang River chlorophyll-a inversion. Subsequently, the algorithm model for 2000 to 2011 in the middle and lower reaches of the Hanjiang River chlorophyll-a concentration inversion and the results of the inversion analysis of spatiotemporal evolution characteristics we used to determine the influence of various environmental factors on the chlorophyll-a concentration change.

THE FIRST INVESTIGATONS OF CYANOTOXINS PRESENCE IN WATERBODIES AND WATERCOURCES OF BELARUS

The estimation of species composition, abundance and biomass of cyanobacteria in “bloom” as well as the search for toxic species has been undertaken for the first time in 20 water bodies and water courses of Belarus mainly used for public recreation. There were identified 50 representatives of cyanobacteria assigned to 18 genera, among them three species were marked for the first time for the Belarus: Snowella atomus Komárek et Hindák., Anabaenopsis arnoldii Aptekar, Anabaenopsis kelifii Kog. By combining molecular-biological and analytical methods and by using genetic markers when studying toxic «water blooms» the search of genes responsible for synthesis of hepatotoxic microcystin, nodularin, cylindrospermosin and neurotoxic saxitoxin was undertaken. It has been shown that in all the investigated lakes and rivers there were cyanobacterium relating to Anabaena and Microcystis genera that can synthesize highly toxic microcystins – LR, RR, YR. Saxitoxin synthesis genes and close to it variants of paralytic toxins such as goniatoksins 5, 6, dekarbamoilgoniatoksin 2, dekarbamoilsaksitoksin and neosaksitoksin were found in 7 waterbodies.

Analysis and Diagnosis of Water Environment Pollution Sources of Tonggu Lake in Fuling District, Chongqing City

As an important urban lake in Fuling District, Chongqing City, there is water blooms in Tonggu Lake, which affect the ecological environment. This study analyzed and studied the external and internal status of water pollution through site survey, water quality testing and analysis, and laboratory data analysis, and diagnosed the water environment of Tonggu Lake, which is helpful for providing strong data support for the follow-up solution to the problem of water bloom in Tonggu Lake.

Characteristics of Fluorescence Spectra, UV Spectra, and Specific Growth Rates during the Outbreak of Toxic Microcystis Aeruginosa FACHB-905 and Non-Toxic FACHB-469 under Different Nutrient Conditions in a Eutrophic Microcosmic Simulation Device

Microcystis aeruginosa is the dominant alga forming cyanobacteria blooms, the growth of which is limited by available nutrients. Thus, it is necessary to study cyanobacteria blooms and explore the growth of Microcystis aeruginosa under different nutrient conditions. In this paper, we take Microcystis aeruginosa, including toxic Freshwater Algae Culture of Hydrobiology Collection (FACHB)-905 and non-toxic FACHB-469 strains, into account. The strains were cultured using a simulation device under different nutrient conditions. Ultraviolet spectra, three-dimensional fluorescence spectra, and kinetic parameter indicators of the two species are studied. Compared to FACHB-469, the results show that the specific growth rate of FACHB-905 is much higher, in particular, FACHB-905 is the dominant species under low nutrient conditions. Furthermore, the UV spectral characteristics indicate that the molecular weight of dissolved organic matter in the culture tank of toxic FACHB-905 is greater than that of FACHB-469. Additionally, the humification index of toxic FACHB-905 is slightly higher as well, which suggests that it is more stable in the presence of dissolved organic matter during blooms. Therefore, the toxic Microcystis strain is more likely to become the dominant species in water blooms under lower eutrophic conditions and water blooms formed by the toxic Microcystis strain may be more difficult to recover from.