Judul: Estimasi Harga Pupuk Olahan Sludge Instalasi Pengolahan Air Limbah Berdasarkan Pendekatan Harga Produksi dan Willingness to Pay (Studi Kasus: IPAL RSUP H Adam Malik Medan)
Abstrak: An increasing number of hospitals in Indonesia shows access to health nowadays easier and varied, both in cost and service. There are consequences to be taken that is the extra load for environmental. It is caused by the waste from healthcare activities. Haji Adam Malik Hospital manage the waste from medical and nonmedical activities by build a Waterwaste Treatment Plant (WWTP) with tricling filter method. This method produces water with a pH of 7-7.7 which decent discharged into ambient and sludge can be recycled into fertilizer by adding coagulant Fe2Cl3. The primary objective of this study is to estimate the price of fertilizer with production cost approach and Willingness to Pay (WTP) approach and compare the prices of both approaches. Fertilizer prices from the cost of production approach is IDR 910.05 per kg. This price is obtained by calculating the average cost of raw material costs, direct labor costs and the overhead. WTP price obtained is IDR 773.7 per household per kg. The difference between the cost of production methods with the WTP method is IDR 136,354. This difference indicates that the price financially is in undervalued conditions in the surrounding community in H Adam Malik Hospital. This condition can be improved in several ways, efficient use of grinding machine, do education and promotion to the public, and do research and development.
Keyword: WTP, wastewater treatment plant, tricling filter, production costs, hospital, fertilizer

Judul: Efektivitas Biaya Pengelolaan Limbah Rumah Sakit X di Jakarta Selatan
Abstrak: X Hospital started the liquid waste management by built the liquid waste management installation (IPAL) with system of aerobic - anaerobic biofilter in 2006. While for the solid waste management, X Hospital collaborated with cleanliness services of South Jakarta and PT WASTEC. This research was about waste management assessing of X Hospital which analyzed from characteristic of waste management, people preference, IPAL efficiency, determination of Unit Daily Cost (UDC) and cost effectiveness of waste water management. People preference showed that waste management has already been well. The liquid waste efficiency has scored more than 80 percent from all parameter and declared to be efficient. The efficiency examination with t-test showed that IPAL could reduce waste concentration significantly. UDC value received was Rp. 3.569,51. The most effective reducing cost was reducing cost from COD parameter. Meanwhile, the cost effectiveness ratio on waste treatment with activated sludge bioreactor system has more effective than cost effectiveness ratio on waste treatment with anaerob-aerob biofilter system.
Keyword: cost effectiveness, efficiency of waste treatment, hospital waste management

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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