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The invention discloses a microalgae harvesting and dewatering method and device. The method comprises the following steps: microalgae liquid is harvested and dewatered by adopting more than one inclined type rotary-drum filter in series connection; the microalgae liquid to be dewatered is conveyed to the high ends of the inclined type rotary-drum filters to enter rotary drums; according to the free falling body principle and the centrifugal principle, microalgae mud in the microalgae liquid is retained on filtering nets, and finally is discharged by the low ends of the rotary drums; and water is discharged by the filtering nets on the inclined type rotary drums; and a stirring barrel arranged between two adjacent inclined type rotary-drum filters is used for stirring the microalgae mud collected by the former-stage inclined type rotary-drum filter in a water adding manner, and then is conveyed to the next-stage inclined type rotary-drum filter for dewatering and collection. The microalgae harvesting and dewatering method and device disclosed by the invention have the advantages that the original harvesting and dewatering mainly carried manually is changed into mechanical harvesting and dewatering, and by controlling the rotating speed of the inclined type rotary-drum filters, the working efficiency can be effectively increased, the labor intensity of workers can be reduced and the quality of a product can be improved.

Background technique

Microalgae are a class of individual small algae, mostly water eukaryotic, unicellular or by a number of cells. Microalgae nutritious, rich in protein, high in unsaturated fatty acids, polysaccharides, minerals, vitamins and other substances, and fast growth, high yield per unit area. Microalgae has a very wide range of applications in biological food, health food products, pharmaceuticals, fuels, chemical products and other industrial fields. However, since the individual small microalgae (3 30 ym), biomass concentration is usually low (＜I g / L), cell density and considerable body of water, which determines the great difficulty of harvesting and dewatering. First at home and abroad are generally liquid pretreatment of algae for harvesting microalgae, and conduct enrichment and separation. Algae solution is pretreated by physical or chemical properties of the surface or during the chemical solution environment changes microalgae suspension. Commonly used methods of pre-oxidation, flocculation, and chemical field flocculation, precipitation separation method commonly used, flotation, centrifugation and filtration. Domestic several small water concentrate can be applied to microalgae patents, methods Chinese Patent No. 98110303.0 "unicellular algae concentration method" and Chinese Patent No. 98110301.4 "unicellular algae concentration method" used the following shortcomings: contains flocculants, the products have a certain degree of pollution; required temperatures, and large energy consumption; can not be completely harvested, there is a certain waste of algae; not mass production. Chinese Patent No. 88106827 inefficient "eco-harvest chlorella law" is not suitable for industrial production, practicality is not strong. For industrial-scale microalgae cultivation, income from Algae Water meters microalgae has been a bottleneck. Data show that the cost of its received microalgae rice farming costs (including the culture and harvest) 20% -30%. Therefore, to find a high-efficiency, low-cost harvesting method is needed to solve the current problem.
Spirulina is a kind of lower plants belonging to Cyanophyta, Oscillatoria branch, which grows in tropical natural alkaline lake. It is a good natural food raw material resources, about 60% protein content, rich in P - carotene, vitamin E, vitamin B12, which is the highest vitamin content in plants, and other vitamins and mineral content is also very rich, including vitamin B1, vitamin B2, vitamin B6, vitamin K, zinc, iron, potassium, Han, magnesium, phosphorus, selenium, iodine and other minerals. Spirulina phycocyanin is characteristic of functional components, content of up to 17%, but also plants the most, their effectiveness has been improved lymphocyte activity, enhance immunity and rehabilitation of special significance for patients with gastrointestinal diseases and liver disease. Further, Spirulina also contains a lot of Y - linolenic acid, is the regulation of blood pressure, cholesterol-reducing function component; Spirulina platensis polysaccharides, chlorophyll, also have immunomodulatory functions. Therefore, Spirulina is FAO and the UN World Food Association recommended as "the best food twenty-first century." Commonly used at home and abroad runway ponds Spirulina, Spirulina harvest, major domestic recovery is accomplished by a variety of methods mesh manually operated appliance, such as generally soft object made of 300-380 mesh the flat screen, mesh pocket, or the like unpowered inclined screen sifter, and with a liquid so as to achieve the purpose of solid-liquid gravity separation. In this manner there are two, one for the single-stage bevel filter bed, the other is a multi-stage (usually 5-6) ramp filter bed. This method requires a lot of labor, and greater labor intensity, poor working conditions, low efficiency harvest, harvesting of algae is difficult to guarantee quality, affect product quality.