Judul: Penentuan parameter kinetika proses biodegradasi limbah cair industri pulp dan kertas dalam sistem lumpur aktif
Abstrak: Industri kertas merupakan salah satu jenis industri terbesar di dunia dengan menghasilkan 178 juta ton pulp, 278 juta ton kertas, dan menghabiskan 670 juta ton kayu per tahun. Pertumbuhan industri ini diperkirakan akan mencapai 2%-3.5% per tahun dalam dekade berikutnya (Rini, 2002). Dalam proses produksinya industri pulp dan kertas membutuhkan air dalam jumlah yang sangat besar. Selain itu industri pulp dan kertas menghasilkan berbagai bahan pencemar yang berbahaya bagi lingkungan, baik udara maupun air. Bahan pencemar tersebut berasal bahan-bahan kimia yang digunakan dalam proses pembuatan pulp (pulping) maupun proses pembuatan kertas (Rini, 2002). Limbah industri pulp dan kertas tersebut apabila dibiarkan tanpa diberikan penanganan terlebih dahulu tentu akan sangat berbahaya bagi lingkungan. Oleh karena itu penanganan limbah pulp dan kertas merupakan hal yang sangat penting dan mendesak. Menurut Metcalf dan Eddy (1991), hampir semua jenis limbah cair dapat ditangani secara biologis dengan analisis dan kontrol lingkungan yang sesuai. Untuk menghasilkan efluen yang aman bagi lingkungan, diperlukan perancangan proses bioreaktor yang tepat. Untuk dapat merancang bioreaktor, perlu diketahui terlebih dahulu nilai beberapa parameter kinetik karena nilai parameter kinetika berlaku spesifik bagi suatu proses yang diterapkan. Penentuan nilai parameter kinetika dapat dilakukan secara curah maupun sinambung, sesuai dengan metode kultivasi lumpur aktif. Kelebihan metode curah adalah mudah dan waktu proses yang diperlukan relatif singkat dibandingkan cara sinambung (Cech et al., 1996). Penelitian ini bertujuan untuk menentukan parameter kinetik degradasi limbah industri pulp dan kertas dengan lumpur aktif menggunakan metode batch (curah) yang meliputi koefisien hasil maksimum (Y), konstanta laju pertumbuhan spesifik (4), konstanta laju kematian (b) dan konstanta paruh (K) secara aerobik....
Keyword: Pulp, Kertas

Judul: Estimation of Biokinetic Parameters of Activated Sludge Process for Paper Mill Industry Wastewater in Unsteady State Conditions
Abstrak: Industri kertas menghasilkan polusi air dalam kuantitas yang cukup besar sehingga membutuhkan unit pengolahan lumpur aktif untuk mereduksi kandungan pencemar pada air limbah. Penelitian ini bertujuan untuk memperoleh hubungan biokinetika terhadap kinerja unit lumpur aktif sehingga memperoleh nilai efisiensi terhadap peningkatan kualitas efluen. Penelitian ini diawali dengan tahap konfigurasi reaktor lalu menganalisis parameter kualitas air limbah sehingga dapat digunakan untuk mencari pemodelan biokinetika yang presisi. Berdasarkan penelitian ini, persentase nilai removal chemical oxygen demand (COD) pada waktu detensi (HRT) 6, 8, dan 12 jam berturut-turut sebesar 56,64%; 64,92%; dan 70,80%. Pengaruh biokinetika terhadap unit pengolahan lumpur aktif tidak hanya untuk memprediksi pengolahan air limbah, tetapi juga merancang, mengoperasikan, dan mengendalikan sistem pengolahan. Nilai biokinetika terpilih berdasarkan analisis statistika dalam kondisi unsteady state tanpa inhibitor yaitu Persamaan Ming pada HRT 12 Jam dengan nilai Ke¸Y, μmax, dan Ks masing-masing sebesar 0,084/hari; 1,39 mgMLVSS/mgCOD; 2,12/hari; dan 26.279 mg/L. Selain itu, biokinetika terpilih dengan mempertimbangkan inhibitor nitrit yaitu Persamaan Jerusalimski pada HRT 8 jam dengin nilai nilai Ke¸Y, μmax, dan Ks berturut-turut sebesar 0,896/hari; 2,488 mgMLVSS/mgCOD; 2,01/hari; dan 57,57 mg/L. Maka dari itu, modifikasi unit pengolahan lumpur aktif perlu mempertimbangkan kondisi lingkungan agar nilai parameter biokinetika yang diperoleh lebih baik., The paper mill industry produces water pollution in large quantities that it requires an activated sludge to reduce the pollutant content in wastewater. This study aims to obtain a biokinetic relationship to the performance of the activated sludge so as to obtain an efficiency value for improving effluent quality. This research begins with the reactor configuration and then analyzes the wastewater quality parameters so that it can be used to find precise biokinetic modeling. Based on this study, the percentage of chemical oxygen demand (COD) removal at 6, 8, and 12 hours detention time was 56,64%; 64,92%; and 70,80%. The effect of biokinetics on activated sludge is not only to predict wastewater treatment, but also to design, operate and control treatment systems. Selected biokinetic values based on statistical analysis in unsteady state conditions without inhibitors is the Ming Equation at 12 Hours HRT with Ke¸Y, µmax, and Ks values of 0,084/day; 1,39 mgMLVSS/mgCOD; 2,12/day; and 26.279 mg/L. In addition, biokinetics was selected taking into account the nitrite inhibitor, namely the Jerusalimski equation at 8 hours HRT with the values of Ke¸Y, µmax, and Ks respectively 0,896/day; 2,488 mgMLVSS/mgCOD; 2,01/day; and 57,57 mg/L. Therefore, Modification of activated sludge treatment needs to consider environmental conditions so that the obtained biokinetic parameter values are better
Keyword: Biokinetika, Lumpur aktif, Industri kertas

Judul: Characteristic of Overshooting Top (OT) Based on  Himawari  8  Satellite  as  a  Convective  Cloud  Feature  that  Generates  Extreme Weather in the Java Island Region
Abstrak: Overshooting Top (OT) is a feature at the top of a convective cloud that is associated with extreme weather. Research on OT in tropical Indonesia is still very limited. The existence of geostationary satellites with wide area coverage and fast frequency observations is useful for observing the fast dynamics of the OT life cycle. Therefore, this study intends to analyze the relationship between OT and extreme weather, updraft and thermodynamic conditions of OT when extreme weather occurs, the best objective method for detecting OT in the day time and night time, and the spatiotemporal distribution of OT in the tropical region of Java Island during the 2018-2021 period. Based on visual analysis using visible channel and Himawari 8 sandwich products, 87% of extreme weather events in Java were accompanied by the appearance of OT. It indicates that the presence of the OT pattern is a convection cloud pattern or feature that is closely related to extreme weather events for the Java Island region. The existence of a time lag between the appearance of OT and extreme weather events on Java Island indicates that the OT of convection cloud can be used as a precursor or nowcasting for the appearance of extreme weather. Most of the convective cloud OT features during extreme weather events on Java Island have altitude that were only able to exceed the altitude of the equilibrium level and few were able to exceed the tropopause level of 9 km – 16 km. The difference in atmospheric conditions during extreme weather events on Java Island, which is in the tropics and subtropics, is a strong and unstable convective energy condition characterized by a larger CAPE, as well as unstable KI, LI, SI and TTI values. It is offset by kinematic factors in the form of a weak vertical wind shear (bulk wind shear 0-6 km) and a higher freezing point height. The difference between extreme weather events in the Java Island region and other tropical regions compared to subtropical regions is the strong updraft speed of convection clouds. The IRW Texture COMB algorithm based on the IRW-Texture Gradient modification and the COMB algorithm shows a significant increase in quality for detecting OT and non-OT pixels in Java. Rainy days with rainfall > 50 mm/day are very common in areas with an altitude of > 500 m. On the other hand, the level of convection activity which is indicated by the presence of OT and lightning is significantly reduced in this area. OT of convective clouds appear more frequently during the DJF season and less frequently during the JJA season. OT often appears during the day time and rarely at night time. Most OTs appear in the central part, away from the south and north coasts of Java Island during the day, while OTs that appear near the south and north coasts of Java Island can appear in the morning or afternoon.
Keyword: convective clouds, extreme weather, Overshooting Tops, Himawari 8 Satellite