Judul: Pemilihan Nutrisi pada Kolam Aerasi Unit pengolahan Limbah Cair Menggunakan Perhitungan C, N dan P (Studi Kasus di PT.XXX)
Abstrak: In accordance with ongoing development of PT. XXX, various problems in waste water management has been appeared. One of them is the selection of nutrient that is the most suitable for generated liquid waste. The previous research had analyzed the characterization and optimation of waste water treatment based on aeration system. This research was conducted to select the nutrients that were most suitable to decrease organic content. The optimum dose of nutrition is necessary to optimise process of organic content degradation. Research results showed that nutrient samples 2 with the dose 500 mg/L also urea and NPK as 107.99mg/L and 127.5 mg/L resulted in the highest value of COD decrease, namely 86.52 %. Nutrient samples 2 showed the highest TSS decrease namely 70.09 %
Keyword: nutrients., aeration, liquid waste

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: Invers Drazin dari Matriks Toeplitz Singular
Abstrak: Matriks Toeplitz adalah matriks yang setiap unsur pada diagonal utama bernilai sama dan setiap unsur pada subdiagonal yang bersesuaian dengan diagonal utama juga bernilai sama. Matriks singular adalah matriks yang tidak bisa ditentukan inversnya. Akan tetapi, dapat diupayakan untuk ditentukan inversnya menggunakan invers matriks yang diperumum. Invers Drazin merupakan salah satu jenis invers matriks yang diperumum. Pada karya ilmiah ini ditentukan invers Drazin dari matriks Toeplitz singular dengan menggunakan metode Leverrier Faddeev. Kemudian, ditentukan invers Drazin dari matriks Toeplitz singular yang direpresentasikan sebagai penjumlahan segitiga bawah dan segitiga atas matriks Toeplitz berdasar pada teorema Gohberg dan Semencul., Toeplitz matrix is a matrix in with element on the main diagonal has the same value and on the subdiagonal corresponding to the main diagonal also has the same value. Singular matrix is a matrix that has no inverse. However, it can be attempted to determine the inverse using a generalized inverse matrix. Inverse Drazin is a type of generalized matrix inverse. This paper discussed the inverse Drazin for a singular Toeplitz matrix using the Leverrier Faddeev method. Then, the Drazin inverse of the singular Toeplitz matrix which is represented as a sum of products of lower and upper triangular Toeplitz matrix based on Gohberg and Semencul theorem.
Keyword: inverse Drazine, singular Toeplitz matrix