Judul: Cultivation of Microalgae Arthrospira  platensis in palm oil mill effluent Media with Different Concentrations
Abstrak: Tingginya kebutuhan nutrien bagi pertumbuhan A. platensis berakibat pada pemenuhan kebutuhan pupuk yang tinggi. Salah satu cara mengatasi hal tersebut adalah dengan pemanfaatan limbah tinggi nitrogen hasil olahan minyak kelapa sawit berupa limbah cair yang dikenal dengan nama palm oil mill effluent (POME) sebagai media pertumbuhan A. platensis. Penelitian ini bertujuan mengevaluasi konsentrasi POME yang efektif sebagai media pertumbuhan A. platensis. Inokulan A. platensis diinokulasi ke dalam 15 unit wadah berukuran 15 L dan ditambahkan POME dengan konsentrasi berbeda, yaitu 10% v/v (P10), 20% v/v (P20), dan 30% v/v (P30) dan tanpa penambahan POME sebagai kontrol (K). Kepadatan A. platensis diukur menggunakan spektrofotometer pada panjang gelombang 680 nm. Kepadatan awal yang digunakan pada awal pemeliharaan memiliki nilai absorbansi optical density (OD) berkisar 0,50–0,55. Parameter yang diukur adalah laju pertumbuhan spesifik (LPS), biomassa panen A. platensis, efisiensi penurunan chemical oxygen demand (COD) dan efisiensi penurunan biological oxygen demand (BOD). Hasil penelitian menunjukkan bahwa POME dapat digunakan sebagai media pertumbuhan A. platensis. Pada perlakuan konsentrasi POME 10% (v/v), mampu meningkatkan laju pertumbuhan spesifik sel, biomassa serta mampu memanfaatkan karbon organik untuk tumbuh dalam POME yang ditunjukan pada penurunan COD dan BOD., The high need for nutrients for the growth of A. platensis results in meeting the high need for fertilizer. One way to overcome this is by utilizing high- nitrogen waste resulting from processed palm oil in the form of liquid waste known as palm oil mill effluent (POME) as a growth medium for A. platensis. This study aims to evaluate the effective concentration of POME as a growth medium for A. platensis. The A. platensis inoculant was inoculated into 15 units of 15 L containers and POME was added with different concentrations, namely 10% v/v (P10), 20% v/v (P20), and 30% v/v (P30) and without the addition of POME as a control (K). The density of A. platensis was measured using a spectrophotometer at a wavelength of 680 nm. The initial density used at the beginning of maintenance has an optical density (OD) absorbance value ranging from 0.50–0.55. Parameters measured were specific growth rate (LPS), A. platensis harvested biomass, chemical oxygen demand (COD) reduction efficiency and biological oxygen demand (BOD) reduction efficiency. The results showed that POME could be used as a growth medium for A. platensis. In the treatment of 10% POME concentration, it was able to increase the specific growth rate of cells, biomass and was able to utilize organic carbon to grow in POME which was shown in the reduction of COD and BOD.
Keyword: Arthrospira platensis, biomass, BOD, COD, POME

Judul: Production of spirulina for decreasing pollution level of palm oil mill effluent in continous photobioreactor
Abstrak: Spirulina platensis could be grown on Palm Oil Mill Effluent (POME) to produce algal biomass and to reduce pollution level of the effluent. The objective of this research was to determine the growth rate of S. platensis and the reduction rate of pollution level of POME on semi-continuous photobioreactor. Preliminary research was conducted by growing S. platensis on POME media with various concentration, namely 25%, 50%, 75%, and 90% POME by batch system. Results of the preliminary research could be used to obtain the optimum growth period as a reference for the main research. The main research on the growth of S. platensis was conducted on photobioreactor that adjusted with their feeding rate of media containing a mixtime of POME and synthetic media at optimum concentration. Feeding rate was set up at 1 drop/ 5 sec. (dilution rate of 0.03 hr -1), 1 drop/ 10 sec. (dilution rate of 0.015 hr -1), and 1 drop/ 15 sec. (dilution rate of 0.01 hr -1). The main research was conducted with 1.2 liter-capacity photobioreactor with POME media at optimum concentration after optimum growth. For optimum dilution rate, the experiment was scaled up eight times using 10-liter-capacity photobioreactor. The parameter observed was Total Dissolved Solid (TDS), Fixed Dissolved Solid (FDS), Volatile Dissolved Solid as approximate value of Total Carbon (TC), Optical Density (OD) at λ 480 nm (OD 480 nm), Dissolved Oxygen (DO), Biological Oxygen Demand (BOD), and Chemical Oxygen Demand (COD).
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Judul: Construction of Strongly Optimal Binary Linear Code with Minimum Distance 9 and 11
Abstrak: A binary linear code of length n over q F is a subspace of n q F . A code has three parameters that attached to it, namely length, dimension, and minimum distance. A code with length n, dimension k and minimum distance d is often called [n, k, d ]-code. Usually, when two parameters are given, then we want to find a code that has the best value for the last parameter. Based on Gilbert- Varshamov bound, if a [n, k, d ]-code exists and can not be expanded, we call it a strongly optimal code. In this paper, we construct strongly optimal code with minimum distance 9 and 11. In constructing the code, we created a theorem and algorithm based on Gilbert-Varshamov bound before we implement the algorithm to MAPLE programming language. Because of computational limitations, the program can only construct up to k = 10 for d = 9 and k = 12 for d = 11.
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