CO2 Control Strategies for Sustainable Cultivation of King Oyster Mushrooms and Romaine Lettuces in a Closed Production System

Abstract

Although the research of life support systems is getting active, it is difficult to perform actual experiments because various internal components in the system react complicatedly. Therefore modeling and simulation approaches have increased in the research of the life support system. A concept of supplying the CO2 generated by mushrooms to lettuces by simultaneous cultivation is important in both of the life support system and crop production. The objectives of this study were to establish a CO2 emission rate model for mushroom respiration, a photosynthetic rate model for lettuce photosynthesis, and to develop a simultaneous cultivation system of lettuce and mushroom. The CO2 emission rate of mushrooms and photosynthetic rate of lettuces were measured using closed acrylic chambers. The coefficients of the models were statistically determined. By using the established models, the simultaneous cultivation system was constructed for lettuce and mushroom, and the CO2 concentration in each chamber was predicted by simulation. And the difference between measured and estimated values was verified. R2 values of the CO2 emission and photosynthetic rate models were 0.64 and 0.94, respectively. The CO2 concentrations in the simultaneous cultivation system were controlled within allowable ranges. With the simultaneous cultivation system, CO2 emission into the atmosphere could be reduced to 80.6% of the total CO2 emitted from mushrooms by respiration. Based on this study, it is possible to control the CO2 concentration for optimum cultivation, and to reduce the CO2 emitted into the atmosphere during mushroom cultivation. Finally, it will help us to find out the appropriate gas circulation strategies in the life support system researches.