Judul: Studi Proses Elektrokoagulasi untuk Meningkatkan Kualitas Air Sungai sebagai Air Baku
Abstrak: A river is one of the most important sources of raw water for clean water. The increase of population and the development of various industries resulted in reducing of river water quality that does not meet water quality standards while the human need for clean water is increasing. The low river water quality requires an effective and efficient treatment, such as by electrocoagulation. Electrocoagulation combines coagulation process with electricity without using chemicals. The purpose of this study was to determine the effect of variation of power supply voltage and electrode contact time with the water, and to determine the effect on parameters such as pH, color, turbidity, TSS, and phospate levels (PO4 3-) as an indicator of sewage pollution and get a combination of electrical voltage and contact time best on the electrocoagulation process wastewater pollutant reduction efficiency. Electrocoagulation run on 1 liter of water in a batch system and using stainless steel electrodes. The water taken from Cihideung river with two different times which water stream in sunny and rainy conditions. The results showed that a color reduction of 11% at a voltage of 15 and 5-minute, turbidity of 17% at a voltage of 18 and 5-minute, TSS of 29% at a voltage of 12 and 5–minute, and phospate of 20% at a voltage of 12 and 30-minute could be achieved. With the water in rainy conditions a color reduction of 74% at a voltage of 18 and 60-minute, turbidity of 90% at a voltage of 9 and 60-minute, TSS of 94% at a voltage of 15 and 60-minute, and 70% of phosphate at a voltage of 12 and 25-minute could be achieved. Combination treatment of 9 volts and 5 minutes can be considered as the best condition of treatment.
Keyword: electrocoagulation, river water, raw water, Bogor Agricultural University (IPB)

Judul: Pengolahan Limbah Cair Laboratorium dengan Proses Elektrokoagulasi
Abstrak: Liquid Laboratory waste contains dissolved heavy metals, such as mercury (Hg), silver (Ag), and chromium (Cr) in high concentrations and have potential to pollute the environment. The waste produced in small quantities, but the waste are toxic and until now there is no adequate treatment. Electrocoagulation is a liquid waste processing technique by agglomerate and precipitate fine particles in water using electrical energy. The purpose of this research was to determine of variations in power supply voltage and the contact time to find out the best combination of electrocoagulation process regarding the removal efficiency of the pollutants. Liquid waste as much as 500 mL was treated in batch mode using iron electrode. Samples were given a voltage of 6, 9, and 12 V for 1, 2, 3, and 4 hours. The best combination based on the reduction of color, turbidity, and TSS was 12 volts with a contact time of 2 hours. Total cost for the treatment was 85.74 rupiahs per L.
Keyword: Bogor Agricultural University, COD waste, electrocoagulation, iron electrode, laboratory waste

Judul: Grup dan Homomorfisma Grup pada Rubik Revenge
Abstrak: Rubik cube is a kind of puzzle game. A player must arrange rubik sides, which have been disordered, back to the position where every side has the same colour. This paper does not focus on the settlement solution, but instead on proving the existence of a group homomorphism between rubik movement group and S96 symmetric permutation group in rubik revenge. Firstly, it has been proved that rubik movement set is a group. Then, it also has been proved that the M set, which contains numeric labels of 1 until 96 in cubinos sides, is S96 symmetric permutation group.
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