ผลของกรดอินทรีย์ระเหยง่ายต่อจุลินทรีย์ที่เกี่ยวข้องกับการผลิตก๊าซชีวภาพ

Effect of Organic Acids on Microorganism Involed in Biogas Production

Name: จงกล พูนทวี

Organization : มหาวิทยาลัยเทคโนโลยีพระจอมเกล้าธนบุรี

keyword: Biogas

; Acetic acid

; Propionic acid

; Butyric acid

; ก๊าซชีวภาพ

; กรดอะซิติก

; กรดโพรพิออนิก

; กรดบิวทีริก

Abstract: During the anaerobic digestion of organic substances to methane, acetic, propionicand butyric acids are found to be the intermediate products. The accumulation of these acidslead to a decrease in pH and stability of the digester. In this work, we investigated thetoxicity of each acid on the microorganisms from an anaerobic digester fed with pineapplepeel. The work has been carried out in serum vial bottles using digestion fluid as a basalmedia supplemented with acetic, propionic and butyric acids as a sole carbon source.With single substrate, rate of utilization depended on the type and concentrationof organic acids. In general , the initial rate increased with increasing substrate concentration.However, the maximum rate for acetic acid was at 30 millimolar in which the rate declined at40 millimolar. For a comparison butyric and acetic acids at an initial concentration of 7millimolar were completely utilized in 13, 26 day. After 26 days, only 5.88 millimolar ofpropionic acid was utilized.The rate of utilization changed with time depended on the concentration ofremained substrate, amount of microorganism and the concentration of produced products. Inthe first phase of acetic acid utilization led to an increase in the number of acetic acid utilizingmicroorganism thus the utilization was faster after 7 - 10 days. The amount of acid consumedand the presence of growth factor such as yeast extract affected amount of growth.Acetic acid was produced from the degradation of butyric and propionic acids.From this work , acetic acid up to 30 millimolar showed no effect on the degradation ofbutyric acid. In contrast, acetic acid at 3.3 millimolar inhibited the propionic acid utilizingbacteria. The inhibition was temporary as propionic acid started to degrade further whenWith single substrate, rate of utilization depended on the type and concentrationof organic acids. In general , the initial rate increased with increasing substrate concentration.However, the maximum rate for acetic acid was at 30 millimolar in which the rate declined at40 millimolar. For a comparison butyric and acetic acids at an initial concentration of 7millimolar were completely utilized in 13, 26 day. After 26 days, only 5.88 millimolar ofpropionic acid was utilized.The rate of utilization changed with time depended on the concentration ofremained substrate, amount of microorganism and the concentration of produced products. Inthe first phase of acetic acid utilization led to an increase in the number of acetic acid utilizingmicroorganism thus the utilization was faster after 7 - 10 days. The amount of acid consumedand the presence of growth factor such as yeast extract affected amount of growth.Acetic acid was produced from the degradation of butyric and propionic acids.From this work , acetic acid up to 30 millimolar showed no effect on the degradation ofbutyric acid. In contrast, acetic acid at 3.3 millimolar inhibited the propionic acid utilizingbacteria. The inhibition was temporary as propionic acid started to degrade further whenacetic acid was consumed.When acetic acid was added with propionic acid as cosubstrates, the inhibitoryeffect of acetic acid on propionic was the same. In addition, increasing acetic acidconcentration affected the utilization of propionic acid more than on increase in propionic acidconcentration. With pure substrate, propionic acid at 7.2 millimolar was utilized 66% within22 day where as the utilization was only 44% in the presence of 21 millimolar acetic acid. Inanother case with constant amount of propionic acid (12 millimolar) and increasing acetic acidfrom 10.5 to 28 millimolar, propionic acid was utilized by 48% and 28%, respectively.Propionic acid was found to inhibit the butyric acid utilizing bacteria. Though ,acetic acid was not directly involve in the inhibition of butyric acid , but in the presence ofpropionic , acetic and butyric acids the utilization of butyric acid was slower.The result of organic acids on the groups of microorganism involved in biogasproduction suggested that acetic acid was the most toxic on propionic acid utilizing bacteria atconcentration as low as 3.3 millimolar. Due to the fact that , acetic acid is an intermediateproduct from the degradation of sugar as well as C3 and C4 organic acids and be the substratefor methane bacteria, in the last step of anaerobic reaction. The information could be used toincrease the efficiency of the process such as to increase the number of acetic acid utilizingbacteria. This could remove the inhibitory effect from the accumulation of acids and tostimulate the production of biogas.

มหาวิทยาลัยเทคโนโลยีพระจอมเกล้าธนบุรี

Address: กรุงเทพมหานคร (Bangkok)

Email: info.lib@mail.kmutt.ac.th

Name: รศ.ดร. มรกต ตันติเจริญ

Role: อาจารย์ที่ปรึกษา

Created: 2537

Issued: 2005-04-09

Modified: 2006-05-30

วิทยานิพนธ์/Thesis

ISBN: 9746211587

CallNumber: BIT19

tha

DegreeName: วิทยาศาสตรมหาบัณฑิต

Level: ปริญญาโท

Descipline: เทคโนโลยีชีวภาพ

Grantor: มหาวิทยาลัยเทคโนโลยีพระจอมเกล้าธนบุรี

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3	BIT19ab.smi	4.85 KB	140	2019-12-10 13:52:11

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