Judul: Stabilisasi Sludge dari Instalasi Pengolahan Air Limbah (IPAL) Menggunakan Starter Bakteri Indigenous pada Aerobic Sludge Digester
Abstrak: Sludge stabilization is degradation process for the organic components into simpler compounds, and to eliminate toxic compounds and volatile compounds that cause the unpleasant smell by activities of some microorganisms. Proteolytic and cellulolytic bacteria are predominant and indigenous microorganisms play an important role in the degradation of organic components on activated sludge. The aim of this study was to stabilize sludge that can be used for fertilizer production by using various types of indigenous bacterial isolated from industrial biological wastewater as liquid starter, as well as determine the effect of aeration time (0, 5, 10, 15, 20, 25, and 30 days) on the characteristics of sludge stabilization. The research investigated the effect of starter addition, from indigenous bacteria isolates, as (1) proteolytic bacteria, (2) cellulolytic bacteria, and (3) no starter addition as control. The process degradation by indigenous microorganisms and capable to convert nitrogen compounds such as ammonium to nitrate. The result showed that all bacteria starters have high capability to accelerate the degradation of organic compound, but not significantly in the stabilization procced periode. The addition of proteolytic bacteria increased the breakdown of protein compound into ammonium, while cellulolytic bacteria increasing the formation of total suspended solids (TSS), volatile suspended solids (VSS), total COD, and soluble COD compared to the control. The addition of cellulolytic bacteria showed the higest value of C/N ratio (9.17) compared to the others (7.12 - 8.97).
Keyword: cellulolytic., proteolytic, indigenous bacteria starter, organic components, sludge stabilization

Judul: Isolasi dan karakterisasi mikroorganisme asal sampah organik pasar dan isi rumen serta aplikasinya sebagai starter dalam pengomposan sampah
Abstrak: Waste is a negative side of materials that can cause nuisance, putrid odor and can become a growth media for contagious desease. Waste is a problem for people and goverment, for example evironment polution. Organic waste handling by Bsing nature ability needs long time. Microorganisms addition as a starter in waste composting can be as alternative to solve time problem. Indigenous starter in pitrid wastes or rumen substance naturally have an ability to adapt with evironment and decompose wastes. Isolation microorganisms from wastes and rumen substance which have ability to decompose cellulose very interested to do, especially it's aplications in composting, to solve wastes problems in big city. Based on that reason, this research was done. Ability of microorganisms isolate as starter observed by observed parameter during composting are temperate, pH value, C/N ratio, Kation Exchange Capacity and total phosphor (P) and Potassium (K) contents. This research used Completely Randomized Design with three times repeatation. The treatment of this research is isolate addition which obtained from purification and the controls are EM4 activator addition as positive control and without starter addition (TS) as negative control. Thirteen isolates obtained from the isolation process, eight isolate from waste. and five isolate from rumen substance. Selection ability to decompose cellulose there are two isolates from organic wasting (ISK and ISB) and one from rumen substance (IRK). Test by Composting showed that IRK and ISK isolate caused higher temperate and it also happened in pH value. Isolate ISK and IRK has pH value that almost same as pH value of composting by adding EM4 which become as positive control. Composting result showed that compost reduction velocity at first and second week was significantly different (P<0.05), while at third week it was very significantly different (P<0.01). The obtained of compost production showed that adding EM4 was very significantly different (P<0,01) with compost production that obtained from ISK, IRK and ISB. Compost C/N ratio showed that value of compost kation exchange capacity was significantly different (P<0.05).
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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