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Eruption of blue-green algal blooms occurs frequently in eutrophic lakes and fish ponds, with associated unpleasant odor and horrid scums. In the present study, we conducted a pre-test experiment in 3 m outdoor concrete ponds to determine the optimum concentration of aluminum sulfate (alum) required for reduction of the cyanobacterial blooms without negative effect on fish growth. As a consequence, 10 mg L alum was named as the optimum concentration that was applied in 1000 m earthen fish ponds. Obtained results showed that Secchi disc values significantly increased from 10 to 24 cm after 14 days of alum application. Alum-treated ponds showed a reduction in total phytoplankton counts by 94 and 96 % compared to the corresponding controls after 10 and 14 days, respectively. Abundance of blue-green algae in the treated ponds was decreased by 98 % compared to the corresponding control after 14 days of alum application. Consequently, dissolved oxygen, pH, total phosphorus, orthophosphate, and chlorophyll ' a' content declined significantly. Our study revealed that using 10 mg L of alum is an effective way to control cyanobacterial blooms in eutrophic waters, especially in fish ponds, without negative effect in water quality. [ABSTRACT FROM AUTHOR]

Highlights: [•] Cyanobacteria and microalgae are promising for sustainable production of commodities. [•] Cyanobacteria promising for small molecules (e.g. ethanol) that can be secreted. [•] Microalgae promising for the accumulation of storage products (e.g. lipids). [ABSTRACT FROM AUTHOR]

Abstract: The use of microalgae and cyanobacteria for the production of biofuels and other raw materials is considered a very promising sustainable technology due to the high areal productivity, potential for CO2 fixation and use of non-arable land. The production of oil by microalgae in a large scale plant was studied using emergy analysis. The joint transformity calculated for the base scenario was 1.32E + 5 sej/J, the oil transformity was 3.51E + 5 sej/J, the emergy yield ratio (EYR) was 1.09 and environmental loading ratio was 11.10 and the emergy sustainability index (ESI) was 0.10, highlighting some of the key challenges for the technology such as high energy consumption during harvesting, raw material consumption and high capital and operation costs. Alternatives scenarios and the sensitivity to process improvements were also assessed, helping prioritize further research based on sustainability impact. [Copyright &y& Elsevier]

Genetically engineered (CE) microalgae are nearing commercial release for biofuels production without sufficient public information or ecological studies to investigate their possible risks. Blue-green algae (cyanobacteria) and eukaryotic green algae are likely to disperse widely from open ponds and, on a smaller scale with lower probability, from enclosed photobioreactors. With powerful molecular techniques, thousands of algal strains have been screened, hybridized, and redesigned to grow quickly and tolerate extreme conditions. Some biologists do not expect GE microalgae to survive in the wild. However, thorough ecological and evolutionary assessments are needed to test this assumption and, if the algae do survive, to confirm that their persistence is highly unlikely to cause environmental harm. Cyanobacteria are especially difficult to evaluate because of the chance of horizontal gene transfer with unrelated microbes. Before novel CE algae enter the environment, key biosafety and environmental risk issues should be formally addressed by teams of experts that include ecologists. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this research was to evaluate the nutritional characteristics of Aphanothece microscopica Nägeli microalgae developed in the effluent of parboiled rice. The biomass was biologically evaluated by rat growth, during 10days for nitrogen balance studies and 28days for blood analysis. The feeding of Aphanothece biomass diets resulted in a nitrogen balance of 1.42g/rat/day, an apparent biological value of 73.33%, an apparent digestibility of 82.12%, an apparent net protein utilization of 60.21% and a net protein retention of 2.40. Significant differences between the glycemic indices of rats fed with the Aphanothece and those fed with the control diet were not observed. However, the total cholesterol levels in the plasma of rats fed the test diet proved to be significantly lower. These results suggest the use of A. microscopica Nägeli developed in parboiled rice effluent as a potential source of single-cell protein. [Copyright &y& Elsevier]