Temporal changes in the characteristics of algae in Dianchi Lake, Yunnan Province, China

Abstract

Algal blooms have become a worldwide environmental concern due to water eutrophication. Dianchi Lake in Yunnan Province, China is suffering from severe eutrophication and is listed in the Three Important Lakes Restoration Act of China. Hydrothermal liquefaction allows a promising and direct conversion of algal biomass into biocrude oil. In this study, algal samples were collected from Dianchi Lake after a separation procedure including dissolved air flotation with polyaluminum chloride and centrifugation during four months, April, June, August and October. The algal biochemical components varied over the period; lipids from 0.7% to 2.1% ash-free dry weight (afdw), protein from 20.9% to 33.4% afdw and ash from 36.6% to 45.2% dry weight. The algae in June had the highest lipid and protein concentrations, leading to a maximum biocrude oil yield of 24.3% afdw. Biodiversity analysis using pyrosequencing revealed different distributions of microbial communities, specifically Microcystis in April (89.0%), June (63.7%) and August (84.0%), and Synechococcus in April (2.2%), June (12.0%) and August (1.0%). This study demonstrated remarkable temporal changes in the biochemical composition and biodiversity of algae harvested from Dianchi Lake and changes in biocrude oil production potential.

Keywords

• algal blooms|temporal change|biochemical property|biodiversity|hydrothermal liquefaction