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Abstract

The research of two-stage anaerobic digestion process for biological wastewater sludge of paper industry with modification of enzyme application and temperature treatment (mesophilic-thermophilic) has been done at the stage of acidification. Batch experiments were conducted to determine their effectiveness by applying treatment of the retention time (2-12 days) and the amount of inoculum (150-450 mL/L). They were observed by the performance process of increasing levels of soluble protein, and the formation of volatile organic acids (VFA). The results showed that application of the addition of protease 0.25 units / g. TS sludge at thermophilic temperatures can increase the hydrolysis with an indication of increased levels of soluble protein in supernatant reaching 380%, whereas in acidification process can improve the formation of organic acids through increased levels of VFA. The best performance of acidification process was found in thermophilic temperature conditions, with retention time of 4 days treatment and the addition of microbial inoculum at 300 mL/L. Sludge digestion of acidification stage at the condition of 2.25 load g.VS sludge / g.VS microbes.day can produce increased levels of VFA by approximately 624%. The solid produced of 40% v/v contains organic and nutrient elements that can be used as organic fertilizer.

Key words : biological wastewater sludge, anaerobic digestion, acidification, protease , thermophilic

ABSTRAK

Penelitian digestasi anaerobik dua-tahap lumpur IPAL biologi industri kertas dengan modifikasi
aplikasi enzim dan perlakuan suhu (mesofilik-termofilik) telah dilakukan pada tahap asidifikasi.
Percobaan yang dilakukan secara batch ditentukan efektivitasnya melalui perlakuan waktu retensi
(2-12 hari) dan jumlah inokulum (150-450 mL/L.) dengan pengamatan kinerja proses terhadap
peningkatan kadar protein larut, dan pembentukan asam-asam organik volatile (VFA). Hasil penelitian
menunjukkan bahwa aplikasi protease pada penambahan 0,25 unit/g.TS lumpur, pada suhu termofilik
dapat meningkatkan hidrolisis, yang ditunjukkan dengan peningkatan kadar protein larut mencapai
380%, sedangkan dalam proses asidifikasi dapat meningkatkan pembentukan asam organik melalui
peningkatan kadar VFA. Kinerja proses asidifikasi yang terbaik dijumpai pada kondisi suhu termofilik,
dengan perlakuan waktu retensi 4 hari dan penambahan inokulum mikroba 300 mL/L. Digestasi lumpur tahap asidifikasi pada kondisi tersebut yang berlangsung pada beban 2,25 g.VS lumpur/g.VS mikroba. hari; dapat menghasilkan peningkatan kadar VFA sekitar 624%. Padatan yang dihasilkan sebanyak 40% v/v mengandung komponen organik dan unsur-unsur nutrisi yang dapat dimanfaatkan sebagai pupuk organik.

Kata kunci : lumpur IPAL biologi, digestasi anaerobik, asidifikasi, protease, termofilik