Judul: Kajian proses denitrifikasi limbah organik dengan sistem modified ludzak-Ettinger : Studi kasus pada instalasi pengolahan air limbah IPAJ PT Capsugel Indonesia-Cibinong
Abstrak: Industrial wastewater effluents discharged that contains high nitrate concentration can cause eutrophication, poisoned to baby and child, and also toxic to water biota. High nitrate concentration in drinking water can cause Methemoglobinemia (blue babies). Nitrate-nitrogen yielded from ammonium- nitrogen oxidation through aerobic pond on WWTP. The case study at WWTP of PT. Capsugel Indonesia (PTC) was aimed to optimalize denitrification process in order to achieve the nitrate effluent quality as according to Baku Mutu I. This research was initiated by identification of WWTP process, analysing process influencing denitrification and followed by various process such as: an internal recycle treatment, SRT and HRT treatment at clarifier, jar test and determination of methanol dosing (as additional substrat) that influenced denitrification. All analytical procedures followed a Standard Operation Procedure (SOP) from WWTP PTC and based on HACH manual book and APHA 1992. Modified Ludzak-Ettinger (MLE) is a model which is most commonly used at WWTP because of its simply process. MLE represent nitrification- denitrification system in a single sludge activated-sludge for nitrogen removal which combine carbon removal, amonia oxidation and nitrate reductation in the same process. Shock loading and fluctuation of ammonium-nitrogen in the influent reduced WWTP performance. Initially, nitrate concentration level has been controled by adjusting the rate of mixed liquor recicling. Mixed liquor from aerobic pond to anoxic pond wes expected can bring nitrate as much as possible for oxidizing carbon source where nitrates replace oxygen in denitrification. Increasing of the mixed liquor recirculation rate really did not bring nitrate degradation level to the effluent. This happened because all COD as carbon source in anoxic pond have been used so that anoxic pond reached the maximum capacity for denitrification. Another possibility is that WWTP depend on carbon source only from waste influent. Carbon source from influent pertained a slowly biodegradable COD so denitrification rate also became slow. One of MLE system purpose is to reduce the cost of additional carbon sources, but in this case, the system was actually require external carbon sources. This research used technical methanol 2% (v/v) with dosing rate was 4 L/h combined with internal return rate (IR) = 4Q, the return activated sludge (RAS) rate IQ and influen rates (Q) = 1.2 m³/h gave acceptable results for nitrate-nitrogen removal. This combination reduced the average effluent nitrate concentration from 46.07 mg/L NO3-N to 12.6 mg/L NO3-N. This value below the regulation of Baku Mutu 1. The methanol addition in WWTP increased alkalinity formed during denitrification. It reduced up to 80% of Na2CO3 consumption.
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Judul: Denitrifikasi air limbah industri amonium nitrat menggunakan reaktor berbahan isian batu belerang dan batu japur
Abstrak: Ammonium nitrate industry is one chemical industries that produce waste water with inorganic nitrogen compounds which has potency to pollute environment and threaten human’s health. Waste water treatment is needed to meet environmental quality standards in accordance with government regulations. The purpose of this study is to assess autotroph denitrification process by using a sulfur and limestone packed bed bioreactor in the wastewater with high concentrations of nitrate compounds as well as financial to asses feasibility. Data analysis is processed descriptively by using tables and graphs. The denitrification treatment was done in two stages of processing which is a high concentration (2000 mg-N/L) and low concentration (100 mg-N/L) of nitrate. The results showed that the concentration of nitrate in the outlet of bioreaktor decreased in rate the high and low nitrogen concentrations. For the highs concentration of nitrate, the concentration of nitrate in the outlet is 56,25 mg-N/L with removal efficiency 97,20% at four days hydraulic retention time (HRT). For the low concentration of nitrate, the concentration of nitrate in the outlet is 4,04 mg-N/L with a removal efficiency of 96,37% at one day hydraulic retention time (HRT). Each cost of sulfur materials for high and low concentrations, are Rp.1.100,-/m3 and Rp.200,-/m3 respectively.
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Judul: Kajian frieze groups untuk klasifikasi dan konstruksi desain berdasarkan simetri pada pola
Abstrak: Frieze groups adalah konsep matematika untuk mengklasifikasikan desain pada dua dimensi permukaan yang berulang-ulang dalam satu arah berdasarkan simetri pada pola. Frieze groups merupakan grup yang mempertahankan bentuk pola. Pergerakan bentuk pola terdiri dari translasi, refleksi dan rotasi 180o. Tujuan dari karya ilmiah ini adalah mengkaji sifat Frieze group, mengkaji penggunaan Frieze group dalam mengklasifikasikan simetri pada pola dan mengkonstruksi pola dengan menggunakan software tesselmania. Hasil yang telah diperoleh, bahwa jenis Frieze groups merupakan subgroup dari grup pergerakan pola. Selain itu dapat dilihat dari sifat isomorfik berbagai jenis Frieze groups. Untuk mengkonstruksi sebuah bentuk pola dapat menggunakan salah satu software untuk membentuk sebuah pola bidang datar (dua dimensi) yaitu tesselmania.
Keyword: Frieze groups, Simetri, Pola