Judul: Performance and Biokinetic Modeling of Moving Bed Biofilm Reactor Based on Detention Time Variations in Recirculating Aquaculture System Configurations.
Abstrak: Konfigurasi RAS dapat disusun dengan Moving Bed Biofilm Reactor (MBRR) karena fokus utama pada sistem resirkulasi akuakultur adalah menyisihkan kontaminan amonia. Penelitian ini meneliti kinerja dan pemodelan biokinetika MBBR dalam sistem resirkulasi akuakultur dengan variasi waktu detensi. Fokus utama adalah pengolahan limbah akuakultur yang mengandung amonia, menggunakan MBBR sebagai unit pengolahan utama. Media kaldnes K5 digunakan untuk mendukung pertumbuhan bakteri nitrifikasi yang mengubah amonia menjadi nitrit dan nitrat. Penelitian ini dilakukan dengan tiga variasi waktu detensi (4, 5, dan 6 menit) untuk menentukan efisiensi pengolahan MBBR. Parameter kualitas air seperti amonia, nitrit, pH, alkalinitas, suhu, DO, dan TSS diukur untuk menilai kinerja MBBR. Pemodelan biokinetika digunakan untuk memprediksi konsentrasi substrat efluen dan mengestimasi parameter biokinetika yang diperlukan dalam pengembangan model kinerja MBBR. Hasil penelitian menunjukkan bahwa variasi waktu detensi mempengaruhi kinerja MBBR dalam menghilangkan amonia dan memperbaiki kualitas air. Hasil estimasi konsentrasi amonia menggunakan pemodelan biokinetika dapat berguna dalam desain dan evaluasi sistem resirkulasi akuakultur untuk budidaya ikan hias., Configuration of Recirculating Aquaculture Systems (RAS) can be structured using a Moving Bed Biofilm Reactor (MBBR) since the primary focus of RAS is to remove ammonia contaminants. This study examines the performance and biokinetic modelling of MBBR in a recirculating aquaculture system with varying detention times. The main focus is the treatment of aquaculture wastewater containing ammonia, using MBBR as the primary treatment unit. Kaldnes K5 media supports the growth of nitrifying bacteria that convert ammonia into nitrite and nitrate. The study is conducted with three different detention times (4, 5, and 6 minutes) to determine the treatment efficiency of the MBBR. Water quality parameters such as ammonia, nitrite, pH, alkalinity, temperature, dissolved oxygen (DO), and total suspended solids (TSS) are measured to assess MBBR performance. Biokinetic modelling predicts the effluent substrate concentration and estimates the biokinetic parameters necessary for developing the MBBR performance model. The results indicate that variations in detention time affect the performance of the MBBR in removing ammonia and improving water quality. The estimated ammonia concentrations using biokinetic modelling can be helpful in the design a
Keyword: amonia, MBBR, akuakultur, biokinetika, RAS

Judul: Optimization of Effluent Water Quality in Recirculating Aquaculture System Based on Variations in Pre-Treatment Configurations of Nanofiltration Membrane Technology
Abstrak: Teknologi membran nanofiltrasi (NF) yang diterapkan pada sistem resirkulasi akuakultur (RAS) memiliki kekurangan berupa terjadinya fouling. Fouling dapat direduksi dengan adanya unit pra-pengolahan seperti unit filter multimedia (FMM) serta filter karbon aktif (FK). Oleh karena itu, penelitian ini dilakukan pengaturan konfigurasi pada RAS menggunakan FMM, FK, dan membran NF90-4040 agar diketahuinya pengaturan sistem pengolahan terbaik dalam mereduksi kontaminan pada air limbah akuakultur. V1 (FMM-FK-NF) merupakan konfigurasi dengan nilai total efisiensi tertinggi dalam menurunkan konsentrasi kontaminan amonia sebesar 97,5% dan nitrit sebesar 100%. Unit FMM pada V1 dapat mereduksi amonia 36,25% dan nitrit 35,48% serta unit FK dapat mereduksi amonia dan nitrit sebesar 86,27% dan 10%. Selain itu, unit NF dapat mereduksi amonia sebesar 71,43% dan nitrit sebesar 100%. Reaktor RAS optimal dalam bekerja mereduksi nitrat dan TSS pada V1 sebesar 100%. V1 memiliki fenomena penurunan nilai fluks dan peningkatan resistensi yang lebih kecil daripada kondisi V2 (FMM-NF) dan V3 (FK-NF). Pengembangan model konsentrasi permeate memiliki kemampuan yang sangat baik dalam menggambarkan dan memprediksi proses filtrasi menggunakan membran NF dengan nilai Aw, Bs, dan X berbeda-beda pada setiap variasi., The nanofiltration (NF) membrane technology implemented in the recirculating aquaculture system (RAS) suffers from fouling issues. Fouling can be reduction by incorporating pre-treatment units such as the multimedia filter unit (FMM) and activated carbon filter (FK). Therefore, this study aims to investigate the configuration optimization of the RAS using FMM, FK, and NF90-4040 membrane to determine the most effective treatment system for reducing contaminants in aquaculture wastewater. Configuration V1 (FMM-FK-NF) demonstrated the highest overall efficiency in reducing ammonia concentration by 97.5% and nitrite by 100%. The FMM unit in V1 reduced ammonia and nitrite levels by 36.25% and 35.48% respectively, while the FK unit reduced ammonia and nitrite levels by 86.27% and 10% respectively. Additionally, the NF unit reduced ammonia by 71.43% and nitrite by 100%. The optimized RAS reactor achieved 100% reduction in nitrate and TSS in V1. Furthermore, V1 exhibited a smaller decline in flux value and resistance increase compared to V2 (FMM-NF) and V3 (FK-NF) conditions. The developed permeate concentration model showed excellent ability to describe and predict the filtration process using NF membranes with varying values of Aw, Bs, and X for each variation.
Keyword: flux, pre-treatment configuration, nanofiltration membrane, RAS

Judul: Analisis dan Implementasi Certificate Authorities (CA) pada Public Switched Telephone Network (PSTN)
Abstrak: Secure Telephone Protocol has ability to authenticate involved party and keep the secrecy of the message sent over the protocol. The secrecy of the message archieved by using symmetric key cryptographic scheme, and authentication archieved using public key cryptographic scheme. One of several party involved in the protocol and hold an important function called Certificate Authorities or CA. CA responsible for generating public key pair for other party involved in the protocol. When CA generates public key pair, several primitive cryptographic scheme used for guarantee the security of the key. Two of them are hash function SHA-1 and El-Gamal public key scheme embedded in Digital Signature Algorithm scheme. The prototype implementing the scheme above developed using Java programming language with JCE addition from Bauncy Castle. The analysis towards implemented prototype indicates that the prototype still has some flaws to be implemented in real world.
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