LANTASI, Ayudya Izzati Dyah and Syafrudin, Syafrudin and Budiyono, Budiyono (2026) OPTIMASI MODEL KINETIKA L-AD PRODUKSI BIOGAS DARI SEKAM PADI. Doctoral thesis, UNIVERSITAS DIPONEGORO.

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Abstract

Penelitian ini menganalisis pengaruh total solids (TS) dan pretreatment grinding terhadap produksi biogas sekam padi melalui liquid anaerobic digestion (L-AD), sekaligus mengevaluasi kinetika, kondisi optimum, dampak lingkungan, dan kelayakan ekonomi. Response Surface Methodology (RSM) berdesain Central Composite Design digunakan untuk menentukan kondisi optimum. Produksi biogas kumulatif tertinggi 533 mL diperoleh pada TS 10,5% dan ukuran partikel 2,13 mm, sedangkan terendah 236–276 mL pada TS rendah atau ukuran partikel ekstrem. Analisis ANOVA menunjukkan TS dan ukuran partikel berpengaruh signifikan (p<0,0001). Kondisi optimum tercapai pada TS sekitar 11% dan ukuran partikel 2,28 mm (desirability 0,98; prediksi 527 mL). Model Modified Gompertz menghasilkan potensi produksi maksimum (A) 5,36–12,39 mL/gTS, laju maksimum (Ue) 0,19–0,54 mL/gTS/hari, dan lag phase (λ) 0,87–4,19 hari. Life Cycle Assessment menunjukkan kondisi optimum berdampak lingkungan terendah dengan global warming potential 2,50 kg CO₂-eq, lebih rendah dari kondisi pretreatment minimum (5,01 kg CO₂-eq). Pada reaktor fixed dome 6 m3, system terbukti layak secara ekonomi (Net Present Value/NPV Rp211.463.741; Internal Rate of Return/IRR 55,32%; Benefit Cost Ratio/BCR 2,13; payback period 2 tahun pada umur proyek 15 tahun). Temuan utama: lebih dari 99% pendapatan sistem berasal dari pemanfaatan digestate sebagai pupuk organik cair, sedangkan energi biogas menyumbang kurang dari 1%; sehingga nilai utama sistem adalah sebagai model bioenergi terdesentralisasi berbasis ekonomi sirkular bagi sentra produksi padi di Jawa Tengah, bukan semata-mata sebagai pembangkit energi. Produksi biogas yang masih relatif rendah (6–16 mL/gVS) akibat sifat lignoselulosa sekam padi yang sulit terdegradasi menegaskan bahwa optimasi kondisi operasi penting untuk meningkatkan efisiensi produksi sekaligus menekan dampak lingkungan.
Kata kunci: Biogas, Sekam Padi, L-AD, LCA, Kelayakan Ekonomi

This study analyzes the effect of total solids (TS) and grinding pretreatment on biogas production from rice husk via liquid anaerobic digestion (L-AD), and evaluates production kinetics, optimum conditions, environmental impact, and economic feasibility. Response Surface Methodology (RSM) with Central Composite Design identified the influencing variables and optimum conditions. The highest cumulative biogas production (533 mL) occurred at TS 10.5% and particle size 2.13 mm, while the lowest (236–276 mL) occurred at low TS or extreme particle sizes. ANOVA showed that TS and particle size significantly affected production (p<0.0001). The optimum was TS around 11% and particle size 2.28 mm (desirability 0.98; predicted 527 mL). The Modified Gompertz model gave a maximum production potential (A) of 5.36–12.39 mL/gTS, maximum rate (Ue) of 0.19–0.54 mL/gTS/day, and lag phase (λ) of 0.87–4.19 days. Life Cycle Assessment showed the optimum condition had the lowest environmental impact, with a global warming potential of 2.50 kg CO₂ eq versus 5.01 kg CO₂-eq for minimum pretreatment. A 6 m³ community-scale fixed-dome reactor was economically viable (Net Present Value/NPV IDR 211,463,741; Internal Rate of Return/IRR 55.32%; Benefit Cost Ratio/BCR 2.13; payback 2 years over a 15-year life). Notably, over 99% of revenue came from digestate used as liquid organic fertilizer while biogas contributed under 1%, so the system's principal value lies as a decentralized, circular-economy bioenergy model for rice-producing regions in Central Java rather than as an energy generator. Biogas yield remained low (6–16 mL/gVS) due to rice husk's recalcitrant lignocellulose, underscoring that optimizing operating conditions improves efficiency while reducing environmental impact.
Keywords: Biogas, Rice Husk, L-AD, LCA, Economic Feasibility.

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