Malaysian Journal of Analytical Sciences Vol 19 No 4 (2015): 808 - 814

 

 

 

OPTIMIZATION ON PRETREATMENT CONDITIONS OF SEAWEED LIQUID WASTE FOR BIOETHANOL PRODUCTION

 

(Pengoptimuman Kondisi Pra-Rawatan Sisa Cecair Rumpai Laut untuk Penghasilan Bioetanol)

 

Nur Zatul -‘Iffah Zakaria¹, Dachyar Arbain¹*, Mohd Noor Ahmad², Mohd. Irfan Hatim Mohamed Dzahir¹

 

¹School of Bioprocess Engineering,

Universiti Malaysia Perlis, Kompleks Pusat Pengajian Jejawi 3, 02600 Arau, Perlis Malaysia

²Centre of Excellence for Advanced Sensor Technology (CEASTech),

Universiti Malaysia Perlis, Pusat Pengajian Jejawi II, Taman Muhibah, 02600 Arau, Perlis, Malaysia

 

*Corresponding author: dachyar@unimap.edu.my

 

 

Received: 23 November 2014; Accepted: 27 June 2015

 

 

Abstract

Seaweed liquid waste (SLW) from a non-conventional seaweed (Gracilaria sp.) drying process where the seaweed is ruptured and filter-squeezed has been investigated. The liquid contains proteins and minerals which potentially pollute the environment if it is not been properly treated. For that reason, this paper deals with study on the feasibility of SLW utilization as a feedstock for bioethanol production. The fermentation of bioethanol production was carried out by Saccharomyces cerevisiae in which ethanol produced was measured by gas chromatography. In order to increase its fermentable sugar content, the SLW was treated with dilute acid. Center composite design of response surface methodology (RSM) had been used to optimize the sugar content by varying the parameters involved in the dilute acid pretreatment conditions. These are sulphuric acid concentration (M), temperature (^oC) and seaweed waste concentration (g/ml).  It was obtained that the R² value reached 0.97 indicating that the model is acceptable. The three parameters showed p-value less than 0.05 suggesting their significance interactions. The optimization resulted 25 times improvement of reducing sugar concentration. The reducing sugar resulting from the optimized pretreatment was later used as fermentation medium to produce ethanol up to 123.197mg/l.

 

Keywords: bioethanol, dilute acid pretreatment, Gracilaria sp., Saccharomyces cerevisiae, seaweed liquid waste

 

Abstrak

Sisa cecair rumpai laut (SLW) hasil daripada proses pengeringan konvensional rumpai laut ( Gracilaria sp.) di mana rumpai laut dipecah dan diperah-tapis telah di kaji. Cecair ini mengandungi protein dan mineral-mineral yang berpotensi mencemarkan alam sekitar sekiranya tidak dirawat dengan betul. Oleh hal yang demikian, kertas kerja ini berkaitan dengan kajian mengenai kemungkinan penggunaan SLW sebagai bahan mentah untuk penghasilan bioetanol. Penapaian penghasilan bioetanol dilakukan oleh Saccharomyces cerevisiae di mana etanol yang dihasilkan diukur dengan kromatografi gas. Dalam usaha untuk meningkatkan kandungan gula fermentasi, maka SLW dirawat dengan asid cair. Reka bentuk komposit berpusat dalam metodologi permukaan sambutan (RSM) digunakan untuk mengoptimumkan kandungan gula dengan mengubah parameter yang terlibat dalam keadaan pra-rawatan asid cair. Parameter tersebut adalah kepekatan asid sulfurik (M), suhu (^oC) dan kepekatan sisa rumpai laut (g/ml). Didapati bahawa nilai R² mencapai 0.97 yang menunjukkan bahawa model ini boleh diterima. Tiga parameter menunjukkan nilai-p kurang daripada 0.05 menunjukkan kepentingan interaksi. Pengoptimuman ini memberikan peningkatan 25 kali kepekatan gula penurun. Gula penurun hasil daripada pra-rawatan yang dioptimumkan kemudiannya digunakan sebagai medium fermentasi untuk menghasilkan etanol sehingga 123.197mg / l.

 

Kata kunci: bioetanol, pra-rawatan acid cair, Gracilaria sp., Saccharomyces cerevisiae, sisa cecair rumpai laut

 

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