Judul: Utilization of Oil Palm Empty Fruit Bunch Fibers as Adsorbents for Palm Oil Mill Effluent Treatment
Abstrak: Oil Palm Empty Fruit Bunches (OPEFB) and Palm Oil Mill Effluent (POME) are two major byproducts of Crude Palm Oil (CPO) production. Both compounds include considerable amounts of pollutants, posing a harm to the environment. This study combines biological (modified RBC) and physical processes (adsorption using OPEFB as sorbent) for treating POME. Experiments using different parts of OPEFB as sorbent (stalk and spikelet) and conducted on various HRTs of modified RBC units. The results show that adsorption with spikelet fiber over a 24-hour HRT obtained the best O&G elimination effectiveness of 93%. Varying the HRT in the modified RBC unit had no significant effect on the adsorption process. Two well-known sorbent adsorption kinetic models were used to explain how O&G adsorbs onto the OPEFB fiber. The predicted result exemplified that the pseudo-second-order model from the kinetic model was well represented to remove O&G from POME onto the OPEFB fiber regarding the highest correlation coefficient (R2) and lowest normalized standard deviation (∆qt), indicating close of O&G adsorption value in the calculation (qt. cal) and experimental (qt. exp)., Tandan Buah Kosong Kelapa Sawit (TKKS) dan Limbah Pabrik Kelapa Sawit (LCKS) adalah dua produk sampingan utama dari produksi minyak sawit mentah (CPO). Kedua limbah tersebut mengandung polutan dalam jumlah besar sehingga membahayakan lingkungan. Penelitian ini menggabungkan proses biologis (RBC yang dimodifikasi) dan proses fisik (adsorpsi menggunakan TKKS sebagai sorben) untuk mengolah LCKS. Penelitian dilakukan dengan memvariasikan jenis TKKS yang digunakan (stalk dan spikelet) dan berbagai HRT pada unit RBC yang disesuaikan. Hasil penelitian menunjukkan bahwa adsorpsi dengan serat spikelet melalui HRT 24 jam memperoleh efektivitas eliminasi minyak dan lemak terbaik sebesar 93%. Memvariasikan HRT pada unit RBC yang dimodifikasi tidak memberikan pengaruh berarti pada proses adsorpsi. Dua model kinetika adsorpsi sorben digunakan untuk menjelaskan bagaimana minyak dan lemak teradsorpsi ke dalam serat TKKS. Hasil prediksi menunjukkan bahwa model pseudo orde kedua dari model kinetik terwakili dengan baik untuk proses adsorpsi minyak dan lemak ke serat TKKS dengan koefisien korelasi tertinggi (R2) dan standar deviasi ternormalisasi terendah (∆qt), yang mengindikasikan nilai minyak dan lemak yang terserap secara perhitungan (qt.cal) dan eksperimental (qt.exp) tidak jauh berbeda.
Keyword: Oil and Grease, Pseudo-First Order Model, Pseudo-Second Order Model, Spikelet, Stalk

Judul: Performance of Modification Hybrid Attached Growth Biofilm on Suspended Media on Anaerobic-Aerobic Unit in Treating Palm Oil Mill Effluent
Abstrak: Produksi minyak sawit mentah (CPO) di Indonesia hingga tahun 2022 telah mencapai 48,3 juta ton dari total produksi dunia sebanyak 75,45 juta ton dan tingginya produksi CPO menyebabkan peningkatan Limbah Cair Kelapa Sawit (LCKS) atau Palm Oil Mill Effluent (POME). Penelitian ini bertujuan untuk efektifitas pengolahan LCKS dengan variasi waktu detensi (HRT) yang berbeda pada Reaktor Anaerobic Contact-Stabilization (ACSt). Penelitian ini juga berfokus pada kajian mengenai parameter biokinetika pada unit Integrated Fixed-Film Contact Stabikization (IFCS) untuk estimasi nilai substrat di efluen. Penelitian terdiri atas tahap persiapan reaktor, aklimasasi, konfigurasi reaktor, dan pengoperasian reaktor, dan analisis data. Berdasarkan penelitian diketahui bahwa perubahan variabel operasional HRT berpengaruh terhadap persen penyisihan substrat sCOD pada pegolahan menggunakan Reaktor ACSt (Variasi 1 = 99,41%, Variasi 2 = 99,17%, Variasi 3 = 99,65%, Variasi 4 = 98,633% dan Variasi 5 = 96,47%). Selain itu, perhitungan parameter biokinetika untuk pengolahan LCKS menggunakan Reaktor ACSt pada unit IFCS memperoleh hasil nilai Kec, Kea, Yc, Ya, μmax-c, μmax-a, Ks-c, Ks-a dengan nilai berturut-turut sebesar 0,04 hari-1, 0,0018 hari-1, 3,51 mgMLVSS/mgCOD, 1,95 mgMLVSS/mgCOD, 2,33 hari-1, 2,09 hari-1, 75,55 mg/L, dan 49,57 mg/L, Production of crude palm oil (CPO) in Indonesia until 2022 has reached 48.3 million tons of the world's total production of 75.45 million tons and the high production of CPO can increase Palm Oil Mill Effluent (POME). This study aims to determine the effectiveness of POME processing with various detention time (HRT) in Anaerobic Contact-Stabilization (ACSt) Reactor. This research also focuses on the study of biokinetic parameters in the Integrated Fixed-Film Contact Stabikization (IFCS) unit to predict the value of the substrate concentration in the effluent. This research starts with reactor preparation, acclimation, reactor configuration, reactor operation, and data analysis. Based on the research, it is known that changes in HRT operational variables affect the percentage of sCOD substrate removal in processing using the ACSt Reactor (Variation 1 = 99.41%, Variation 2 = 99.17%, Variation 3 = 99.65%, Variation 4 = 98.633% and Variation 5 = 96.47%). In addition, the calculation of biokinetic parameters for LCKS processing using the ACSt Reactor in the IFCS unit yielded the values of Kec, Kea, Yc, Ya, μmax-c, μmax-a, K_s-c, K_s-a with consecutive values of 0.04 day-1, 0.0018 day-1, 3.51 mgMLVSS/mgCOD, 1.95 mgMLVSS/mgCOD, 2,33 day-1, 2.09 day-1, 75.55 mg/L, and 49.57 mg/L.
Keyword: Anaerobic Contact Stabilization, bioball, biokinetic, Hydraulic Retention Time, Palm Oil Mill Effluent

Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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