Sains Malaysiana 41(10)(2012): 1211–1216

Optimum Conditions for the Production of Polyhydroxybutyrate from Cassava

Wastewater by the Newly Isolated Cupriavidus sp. KKU38

(Keadaan Optimum untuk Penghasilan Polihidroksibutrat daripada Air Buangan

Cassava menggunakan Isolat Baru Cupriavidus sp. KKU38)

S. Sangyoka*

Program in Environmental Science, Faculty of Science and Technology

Phibulsongkram Rajabhat University, Phitsanulok, 65000 Thailand

N. Poomipuk

Department of Biotechnology, Faculty of Technology, Khon Kaen University, Khon Kaen, 40000 Thailand

A. Reungsang

Fermentation Research Center for Value Added Agricultural Products

Faculty of Technology, Khon Kaen University, Khon Kaen, 40002 Thailand

Diserahkan: 30 September 2011 / Diterima: 18 Jun 2012

ABSTRACT

The Cassava starch manufacturing wastewater (CSW) was used as a substrate to produce polyhydroxybutyrate (PHB) by Cupriavidus sp. KKU38. The acidogenic fermentation process of CSW was first conducted to obtain volatile fatty acids (VFAs), which are more efficient in PHB production than raw CSW. The effect on substrate concentration and nutrients, i.e. nitrogen and phosphorus concentrations, by means of chemical oxygen demand: nitrogen: phosphorus ratio (COD:N:P ratio) variation was investigated. The results indicated that PHB production from fermented CSW by Cupriavidus sp. KKU38 was optimized at the soluble COD:N:P ratio of 100:0.5:11. This ratio gave the maximum PHB content and yield of 85.53% and 0.31 g PHB/g COD consumed, respectively. By using the proposed PHB production process, the potential to produce 0.19 kg of PHB from 1.0 kg of soluble chemical oxygen demand (sCOD) contained in CSW was exhibited. The relatively high COD removal efficiency of 73.82% at the optimal condition could be achieved, which demonstrated the concept of water quality improvements alongside the production of the value-added by-product, PHB.

Keywords: Cassava wastewater; Cupriavidus sp. KKU38; polyhydroxybutyrate (PHB)

ABSTRAK

Air buangan daripada penghasilan kanji Cassava (CSW) telah digunakan sebagai substrat untuk menghasilkan polihidroksibutrat (PHB) menggunakan Cupriavidus sp. KKU38. Proses fermentasi asidogenik CSW dijalankan pada peringkat awal untuk mendapatkan asid lemak meruap (VFAs) yang lebih efisien dalam penghasilan PHB berbanding CSW mentah. Kesan kepekatan substrat dan nutrien iaitu kepekatan nitrogen dan fosforus menggunakan permintaan oksigen kimia: nitrogen: nisbah fosforus (nisbah COD:N:P) telah dikaji. Hasil kajian menunjukkan bahawa penghasilan PHB daripada fermentasi CSW melalui Cupriavidus sp. KKU38 telah dioptimumkan pada nisbah COD:N:P, 100:0.5:11. Nisbah ini memberikan masing-masing kandungan dan hasilan PHB 85.53% dan 0.31 g PHB/g COD yang digunakan. Dengan menggunakan proses penghasilan PBH ini, potensi untuk menghasilkan 0.19 kg PHB daripada 1.0 kg permintaan oksigen kimia terlarut (sCOD) yang terkandung dalam CSW telah ditunjukkan. Kecekapan pembuangan COD yang tinggi iaitu 73.82% pada keadaan optimum telah dapat dicapai. Ini menunjukkan bahawa konsep peningkatan kualiti air bersama penghasilan PHB dengan nilai tambah telah dapat dicapai.

Kata kunci: Air buangan Cassava; Cupriavidus sp. KKU38; polihidroksibutrat (PHB)

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*Pengarang untuk surat-menyurat, e-mail: suksaman@hotmail.com