小球藻（Chlorella vulgaris）於模擬煙道氣環境下之最適生長條件探討

Optimal Growth Conditions of Chlorella vulgaris in a Simulated Flue Gas Environment

微藻對於CO2吸收有良好的轉換效率，但若讓小球藻在類似煙道氣的環境下（含高濃度CO2和SOx）是否仍可以存活？最適生長條件又為何？本研究將模擬在煙道氣的各種操作條件下，小球藻的培養試驗，了解小球藻可以忍受和最適生長條件範圍。本研究主要試驗項目為：CO2濃度、pH、溫度、光照比例，及不同pH值下之Na2SO3濃度變化試驗，分成批次和連續曝氣培養。早晚曝氣培養下，當CO2濃度為15％，小球藻有最佳平均生長速率，為25.5mg/L/day；早晚曝氣兩次的小球藻可以忍受到35％的CO2，pH6、25℃為小球藻最適合生長環境；高於或低於此pH及溫度生長量與速率會逐漸減少，pH4和9，生長溫度於15和35℃開始受到抑制。小球藻全天日照有最大產量和平均速率均為最佳，但就單位時間照光之小球藻產率（mg/L/day）照光時間）以12小時照光，有最高產率，也最符合經濟價值。當pH6時小球藻可以忍受50mmol Na2SO3，pH5時可以忍受20mmol Na2SO3，pH4時只能忍受10mmol Na2SO3。小球藻之連續曝氣培養，最適pH、溫度、光照比例結果都與批次相同，可以忍受到30％的CO2，較早晚兩次曝氣低；生長速率以CO2為15％時，小球藻有最佳平均生長速率，為31.4mg/L/day。當pH6時小球藻可以忍受40mmol Na2SO3，其忍受度稍低於早晚兩次曝氣試驗。小球藻操作條件迴歸式：x＝0.98∣24-a∣(5.88*S/(91.3+S+S2/7.16)×c∣pH-6∣×d∣T-25∣

Microalgae demonstrate effective conversion efficiency in absorption CO2. However, it is difficult to determine whether 'Chlorella vulgaris' can survive in a flue gas environment filled with high concentrations of CO2 and SOx. In this study, 'Chlorella vulgaris' were cultivated under various simulated operating conditions in a flue gas environment to determine a tolerable range and the optimal conditions for its growth. The main test items used in this study were CO2 concentration, pH, temperature, illumination proportion, and Na2SO3 concentration varied according to different pH values to simulate the conditions of flue gas. The tests were mainly divided into batch-type aeration and continuous aeration cultivation. During morning and evening batch aeration cultivation, a 15% CO2 concentration resulted in the highest growth rate of 25.5 mg/L/d. The 'Chlorella vulgaris' that experienced morning and evening batch aeration could endure an environment of up to 35% CO2, with pH 6 and a temperature of 25 ℃; these were the most suitable environments for the growth of 'Chlorella vulgaris'. The growth rate of 'Chlorella vulgaris' at a higher or lower pH and temperature was gradually decreased, and was inhibited when it reached pH 4, 9 and 15, 35℃. Full-day illuminated cultivation led to the most production and highest production rate of 'Chlorella vulgaris'. However, regarding the production rate per unit time of illumination (mg/L/day/illumination time), the test with an illumination ratio of 1:1 demonstrated the highest and most economic test. At pH 6, 'Chlorella vulgaris' could withstand 50 mM of Na2SO3. At pH 5, it could withstand 20 mM of Na2SO3, and at pH 4, it could withstand only 10 mM of Na2SO3. The continuous aeration cultivation of 'Chlorella vulgaris' showed identical results for pH, temperature, and an illumination ratio to the batch aeration cultivation, however it could withstand a CO2 concentration of only 30%, which was lower than that of the cultivation with morning and evening batch aeration cultivation. The highest growth rate of 'Chlorella vulgaris' was 31.4mg/L/d, with a CO2 concentration of 15%. In a pH 6 environment, it could withstand 40 mM of Na2SO3, which was lower than the cultivation test with morning and evening batch aeration cultivation. Operation conditions regression of 'Chlorella vulgaris':X=0.98∣24-a∣(5.88*S/(91.3+S+S2/7.16)g)×c∣pH-6∣×d∣T-25∣