Judul: Pengaruh Kadar Fosfor dalam Media Limbah Cair Sintetik terhadap Laju Pertumbuhan Spesifik Sel, Produktivitas Biomassa dan Produksi Minyak dari Konsorsium Mikroalga
Abstrak: Indonesia is famous as a rich country in natural resources, particularly which are found in the waters, one of them is microalgae. In nature, microalgae are usually found in microalgal consortium form which is a mixture of various types of microalgae and their contaminations (other microorganisms). Microalgae have an ability to synthesize food reserves such as carbohydrates, proteins and fats. Organic wastewater is generated from agriculture and domestic sources which contain organic matters, nitrogen and phosphorus in high concentrations. Agroindustrial wastewater is one of the organic wastewater and generally rich in nutrients N (nitrogen), P (phosphorus), C (carbon), and S (sulfur) which are the nutrients for microalgal cells growth. Microalgal growth will be optimum if the nutrients are in a certain concentration and a certain ratio. The aims of this research were to know the characteristric of microalgal consortium growth in the organic wastewater media, to know the effect of various phosphorus concentrations of synthetic wastewater media on cell specific growth rate, biomass productivity and oil content of microalgal consortium and also to determine the best phosphorus concentration for microalgal consortium growth. Before the main research, conducted the preliminary research with microalgal consortium cultivation in 4 litres cultures scale. The preliminary research was began by the characreizations of organic wastewater (slaughter house, livestock and sugar factory wastewater). These were showed that the nutrients and COD were relatively high (the highest nutrient content in 1,490 mg/L and the highest COD content in 32,000 mg/L) which might inhibit microalgal consortium growth, so before cultivated microalgal consortium, wastewater media were diluted before so that the highest nutrient concentrations were only in the range of hundreds and the highest COD concentrations were only in the range of thousands. For this preliminary research, the first was prepared the topless and then wastewater and microalgal consortium suspensions entered into the topless. The growth of microalgal consortium was observed until the cultures entered the death phase. Before organic wastewater cultivation stage 1, conducted the characterizations of microalgal consortium before. The composition of organic wastewater media stage 1 were 75% wastewater and 25% inoculums of microalgal consortium with the form of receptacles in fiberglass tanks, the cultures volume were in 180 litres and the cultures height were in 30 cm. Before proceed to organic wastewater cultivation stage 2, conducted the characterizations of organic wastewater 2 (slaughter house and livestock wastewater). In this organic media cultivation stage 2 had composition 75% organic wastewater and 25% inoculums of microalgal consortium with the receptacles in the form of aquariums, the cultures volume were in 20 litres and the cultures height were in around 16.7 cm. After organic wastewater cultivation stage 2, then cultivated in synthetic media with the characterization of fertilizers and synthetic media made before. The synthetic media were made by various phosphorus concentrations, i.e. 11 mg/L, 16.5 mg/L and 22 mg/L. In this synthetic media cultivations, the compositions were 75% synthetic wastewater and 25% inoculums of microalgal consortium with the receptacles of aquarium, the cultures volume in 28 litres and the cultures height in 23.3 cm. The results of the first
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Judul: Karakterisasi Pertumbuhan Mikroalga dan Penyisihan Nutrien dari Limbah Cair Rumah Pemotongan Hewan dengan Sistem Kultur Semi Kontinu
Abstrak: Organic wastewater with high nutrient content can stimulate uncontrolled microalgae growth. Whereas discipline control led growth can be very profitable. The research was performed to determine the characteristic of growth microalgae nutrient elimination from slaughterhouse wastewater in semi continuous culture system with 75% concentration of slaughterhouse wastewater : 25% consortium of microalgae. In addition, the separation and harvesting of microalgae for the known oil content was also investigated. Cultivation of microalgae has been done at a temperature and pH of the field approach, then temperature and pH dependent on state in the field daily. The light source is obtained directly from the sun. Circulation in a semi continuous culture media which have been made simply by aeration when sampling. Microalgae consortium cell density attained 640 000 cell/ml. During the cultivation for 18 days, the growth of Chlorella sp dominate the culture, that follow by growth of Euglena on day 20 after the death phase of Chlorella sp through. The best growth of Chlorella sp (on day-12) occurred with a concentration of nutrients containing: 1 mg/l for N-organic content, 1 mg/l for NNH3, 4 mg/l for N-NO3 - then total of nitrogen 6 mg/l, orthophosphate content of 10 mg/l, and potassium values of 87.5 mg/l with consortium cell density attained 3 130 000 cell/ml and TSS Filtration 1 930 mg/l. Convertion of biomass from TSS with amount of nitrogen or TKN (on day 2 until 12) is 180 mg TSS/ mg TKN and convertion of biomass from TSS with orthophosphate content in the same time is 4 200 mg TSS/ mg Orthophosphate. Maximum population of microalgae decrease due to lower nutrient content in culture media. Although the consortium of microalgae dominated by Chlorella sp, oil content (3.03%) and oil productivity is 3 000 liter/ha/year still low compared with a previous study, that have been in research by Hsieh and Wu (2009), Widjaja (2009) along with Danusubrata (2010). It was caused by nutrient treatment which have not yet optimum.
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Judul: Closed Knight’s Tour pada Papan Catur Berbentuk Persegi Panjang dengan Ukuran Maksimal 8 × 8
Abstrak: Closed Knight’s Tour merupakan langkah kuda yang mengunjungi setiap kotak pada papan catur tepat satu kali dengan langkah kuda berawal dan berakhir pada kotak yang sama. Graf yang terbentuk dari closed knight’s tour dinotasikan sebagai graf G(m,n), dengan m adalah banyaknya baris dan n adalah banyaknya kolom. Graf tersebut memuat Hamiltonian cycle. Sebuah graf terhubung G adalah graf bipartite jika dan hanya jika graf tersebut tidak memiliki cycle dengan panjang ganjil. Papan catur yang memenuhi syarat cukup untuk memiliki closed knight’s tour adalah papan catur berukuran 5 × 6, 5 × 8, 6 × 6, 6 × 7, 6 × 8, 7 × 8, dan 8 × 8.
Keyword: bipartite, closed knight’s tour, hamiltonian cycle, knight’s tour, teori graf