Judul: Peningkatan Kualitas Air Baku Perusahaan Air Minum dengan Proses Biofiltrasi Menggunakan Media Plastik Tipe Sarang Tawon:
Abstrak: In big cities, quality of raw water (source: river water) are decreased, as result of industrial and domestic waste water are discharged to river, without any treatment. Existing concentrations of organic, ammonia and detergent of raw water of PDAM TKR Tangerang respectively are 19.2 mg/l, 3.8 mg/l, and 0.9 mg/l, which are above threshold limit value of raw water for drinking water. A biofiltration process is use as one alternative to reduce concentrations of organic, ammonia, detergent and total suspended solid (TSS) in raw water. In this treatment, biofilter reactor is use with plastic of Honeycomb tube type as media. Operational condition of treatment is variation of HRT (Hidrolisis Retention Time) between 1–4 hours and air supply between 0–30 l/min. The selected operational condition of treatment found at HRT of 2 hours and air supply of 20 l/min, with removal efficiency of concentration of organic, ammonia, detergent and TSS are 68%, 65%, 64% and 74% respectively. From this experiment, it was found that linear regression equations between removal efficiency and organic loading as yo = -5.98xo + 81.16, between removal efficiency and ammonia loading as ya = -91.19xa + 77,12, linear regression equation between removal efficiency and detergent loading as yd = -301.25xd + 71.53, linear regression equation between removal efficiency and TSS loading as yt= -0.84xt + 83.26.
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Judul: Penurunan Bahan Polutan Air Baku Biofiltrasi dengan Media Pengisi Pasir dan Plastik Sarang Tawon
Abstrak: Biofiltration is a biological treatment process utilizing the biofilm activity of certain microorganisms. The microorganism is utilized to degrade contaminants in the raw water. River water is widely used for drinking water supply, although it sometimes does not meet the standard of raw water. This research was aimed to determine the effectivity of biofiltration to pre-treat raw water and to evaluate the capability of biofiltration in equalizing a quality fluctuation. Honeycomb plastic and sand were used as media in this study. Continuous air supply was done so that an aerobic condition was created. This study was conducted to determine the effectiveness of biofilters for the treatment of raw water and to determine the capability of the biofilters in equalizing of a quality fluctuations. The research consisted of three stages, namely characterization of the raw water, the acclimatization for 4 weeks and loading test. The biofiltration with sand as media could reduce organic pollutants (COD) approx. 80%, that was higher than the COD reduction approx. 69% by biofiltration using honeycomb plastic has. Sand media biofiltration with detergent loading rate of 0.1-32 mg/L resulted in detergent reduction of approx. 55%, whereas the biofilter with honeycomb plastic resulted in detergent reduction of approx. 45%. Generally, increased loading rate would resulted in reducing of pollutant, both media. The absolut pollutants removal increased with increasing of load.
Keyword: contaminated raw water, biofilm, Biofiltration

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