Optimization and drying kinetics of the convective drying of microalgal biomat (lab-lab)

Abstract

Lab-lab, a periphyton that is composed of several microorganisms, is a potential commercial fish feed in the aquaculture industry due to its high protein content. However, the bottleneck in utilizing lab-lab as a fish feed is its cultivation process; it can only be mass produced during the dry season when the solar irradiation is high. To induce the availability of lab-lab all throughout the year, its moisture can be removed through drying, which will reduce its spoilage and will improve its product life. To effectively dry lab-lab with reduced operating costs and improved protein yield, its drying characteristics are investigated. In this study, lab-lab samples are dried in a convection oven dryer. A 3-factor, 2- level full-factorial design of experiment is used wherein the factors considered are drying temperature (60-100 °C) and the sample thickness (2-4 mm), and the responses that are observed are the drying time, drying rate and energy consumption. Mass data is instantaneously monitored using an Arduino-controlled load cell that is placed inside the convection oven dryer. A modified Aghbashlo model was used to represent the convective drying curve of lab-lab with low RMSE values (< 1.3196%) and high R2 values (>0.9988) at a significance level of 0.05. The effects of the factors on the drying time (p<.0152), drying rate (p<0.0174), and energy consumption (p<0.0393) are investigated, consisting only of one- degree effects with no interactions. Using the desirability function, the optimal temperature and thickness, where the drying time and drying rate are maximized while the energy consumption is minimized, is at 60°C and 3.45 mm with a desirability of 56.76%.