Design and development of a continuous harvesting system using solid-liquid cyclone separator for harvesting of Dunaliella salina for mass production of biomass: Part-1: Performance in single-stage

Abstract

Microalgae is a viable alternative to depleting conventional fuel sources, a solution to the industrial requirement of organic consumables, and an option for a green and sustainable economy for biofuels, pigments, and nutrient production. Dunaliella salina is an efficient choice among various species due to its high lipid/carotenoid content and growth in extreme saline conditions. Existing batch-production harvesting methods, such as centrifugation and flocculation, are neither inexpensive nor environmentally benign. This paper presents the experimental studies on three different Rietema-type solid-liquid cyclone separators (RSLCS) for continuous harvesting of microalgae as a concentrated trap for mass biomass production to achieve an economy for biofuels and other desirable by-products if required. Two of these RSLCS were modified and had two inlets (orthogonal RSLCS and parallel RSLCS) when compared with conventional RSLCS. The experiments were performed to calculate the growth of microalgae culture on different days (Day-7, 14, 21, and 28), and concentrations of outflows on day-28 were used as feed for all the RSLCS. The recorded separation efficiency for conventional, orthogonal, and parallel RSLCS are 61.66 %, 67.95 %, and 60.14 % respectively. CFD simulations were also done to validate the results, and CellProfiler was used to measure the size of Dunaliella salina for hydrodynamic analysis. The CFD simulations showed separation efficiency of 60.72 %, 67.04 %, and 59.52 % for conventional, orthogonal, and parallel RSLCS. Thus, the use of orthogonal RSLCS is proposed as a simple, cheap, and eco-friendly solution to the industry-level requirement of continuous harvesting for microalgae in replacement of existing batch-production techniques.