Method for harvesting microalgae by using polysaccharide

Abstract

The invention relates to a method for harvesting microalgae by using acid group-containing polysaccharide. The polysaccharide (including cellulose, alginate, bacterial cellulose, starch, chitosan, chitin and the like) with dissociable acid group (including carboxyl group, phosphate group, sulfate group or the like) is used as a flocculant; a proper amount of solution of polysaccharide polyelectrolyte is added into microalgae suspension; the pH value of the suspension is then adjusted so as to flocculate and settle the microalgae; and then static demixing, dehydration and drying are performed so as to obtain the microalgae solid. The electrical property of the polysaccharide with the carboxyl group, sulfate group or phosphate group can be adjusted through the pH value and the content of the acid group so as to adapt to the settlement of different kinds of microalgae. The polysaccharide has the advantages of high bioactivity, safety, no toxicity, similar chemical constituent to the microalgae and no adverse effect on the subsequent processing and application of the microalgae and can be used with the microalgae for production of biomedicinal chemistry, foods, animal feeds, biodiesel oil, fuel ethanol and the like.

Description

technical field [0001] The invention relates to a method for flocculating and settling microalgae by using polysaccharide, and then dehydrating and harvesting the microalgae. Background technique [0002] Microalgae are a type of autotrophic organisms widely distributed on land and in the ocean, rich in nutrients and high in photosynthetic utilization. The chemical composition of microalgae cell metabolism is complex, rich in protein, lipid, algal polysaccharide, β-carotene, and various inorganic substances. Elements (such as Cu, Fe, Se, Mn, Zn, etc.) are potential resources for the production of biomedicine and fine chemicals, and have good application prospects in the fields of pharmaceutical industry, food industry, cosmetics, and animal feed. Compared with other plants, algae contain higher lipids, soluble polysaccharides, etc., and can be used to produce biodiesel or ethanol. The average calorific value of biomass fuel obtained from pyrolysis is as high as 33MJ / kg, whic...

AI Technical Summary

Problems solved by technology

Because the microalgae are extremely small, it is easy to cause the filter to be blocked, and the collection efficiency of the microalgae by the filter filtration method is low; the centrifugal separation method can effectively separate the microalgae, but this method requires a lot of energy consumption, which affects the efficiency of the method. Large-scale application; air flotation method is a relatively potential microalgae enrichment method, but this method requires reasonable air flotation separation equipment and separation process, and the separation effect is affected by many factors such as equipment structure and process conditions

At present, the most reported methods for microalgae enrichment are the pH method or the chemical method. By adjusting the pH value of the microalgae culture medium, the microalgae can be settled within a specific pH range; the chemical method is to add inorganic or Organic compounds cause microalgae to flocculate and settle. Commonly used compounds include alum, polyferric compounds, polyaluminum compounds and other substances. These substances will settle together with microalgae, pollute microalgae, and affect the subsequent application and processing of microalgae. There are also studies Those who use polyacrylamide, chitin, alginate, etc. as flocculants, but the effect is not obvious, which may be related to the size of the ionic strength