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: Production Cost Analysis of Waste Sludge Composting House Design at PT Tanjung Enim Lestari Pulp and Paper (TeLPP) South Sumatra
Abstrak: Industri pulp and paper di Indonesia menghasilkan limbah berupa sludge yang berasal dari Instalasi Pengolahan Air Limbah (IPAL) dan abu sisa pembakaran boiler yang saat ini belum dimanfaatkan secara optimal. Salah satu alternatif penanganan dan pemanfaatan limbah tersebut yaitu dengan proses pengomposan. Tujuan penelitian ini adalah untuk melakukan analisis biaya dari pemanfaatan limbah sludge dan boiler ash dari PT. Tanjung Enim Lestari Pulp and Paper untuk diolah menjadi produk kompos. Metode penelitian dilakukan dengan menghitung biaya produksi menggunakan metode life cycle cost (LCC). Jumlah limbah sludge yang dihasilkan yaitu 30 ton/hari. Pengomposan dilakukan setiap hari dengan komposisi penumpukan yaitu 30,24 ton sludge dan 19,76 ton boiler ash dengan kapasitas produksi sebanyak 50 ton. Analisis biaya produksi menggunakan pendekatan life cycle cost (LCC) untuk metode aerated static pile dan metode windrow composting. Estimasi biaya produksi pengomposan selama 40 hari kerja dan jumlah produksi sebanyak 1.379 Ton kompos dengan metode windrow composting sebesar Rp2.067.254.126, sedangkan dengan metode aerated static pile sebesar Rp2.188.847.563. Analisis LCC digunakan untuk menghitung biaya produksi per unit fungsionalnya sehingga diperoleh nilai LCC produk kompos kemasan berukuran 25 kg menggunakan metode windrow composting adalah sebesar Rp37.490.
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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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