The design used the Completely Randomized Design (CRJD) with 4 treatments and 5 replications. The treatments were without sludge palm oil (control), 10 %, 20% and 30 % used sludge palm oil. The parameters observed gas production, microbial populations such as cellulolytic bacteria, amilolytic, proteolytic and methanogenesis, degredation of dry matter (BKT) and organic matter (BOT), VFA (Volatil…