본 연구는 양돈슬러리의 혐기소화 효율 증진을 위하여 양돈슬러리를 고액분리 하고 이때 발생하는 슬러지케이크를 200, 220, 250, $270^{circ}C$에서 각각 열가수분해 전처리하여 열가수분해 온도별 유기물의 가용화 효율과 혐기적 메탄생산 퍼텐셜을 분석하였다. 최종메탄생산퍼텐셜 ($B_u$)은 서로 다른 S/I 비율 (1:9, 3:7, 5:5, 7:3의 부피비)에서 73일간 혐기배양하여 구하였다. 양돈슬러리의 유기물 가용화율 ($S_{COD}$)은 $200{sim}270^{circ}C$ 열가수분해 반응에서 98.4~98.9%를 보였으며, 열가수분해액의 이론적 메탄생산퍼텐셜 ($B_{th}$)은 반응온도의 증가와 함께 증가하여 $200^{circ}C$, $220^{circ}C$, $250^{circ}C$, $270^{circ}C$에서 각각 0.631, 0.634, 0.705, $0.748Nm^3;kg^{-1}-VS_{added}$로 나타났다. 열가수분해액의 최종메탄생산퍼텐셜 ($B_u$)은 $200^{circ}C$의 열가수분해액에서 S/I 비율이 1:9에서 7:3으로 증가할수록 $0.197Nm^3;kg^{-1}-VS_{added}$에서 $0.111Nm^3;kg^{-1}-VS_{added}$로 감소하는 경향이 나타났으며, 다른 열가수분해 반응 온도 ($220^{circ}C$, $250^{circ}C$, $270^{circ}C$)에서도 $200^{circ}C$의 열가수분해액과 동일한 경향의 최종메탄생산퍼텐셜을 나타내었다. 유기물의 혐기적 분해율 ($B_u/B_{th}$)을 보면, $200^{circ}C$ 열가수분해액은 S/I비율이 증가함에 따라 31.2%에서 17.6%까지 감소하였으며, $220^{circ}C$, $250^{circ}C$, $270^{circ}C$의 열가수분해액에서 각각 36.4%에서 9.6%, 31.3%에서 0.8%, 26.6%에서 0.8%로 감소하는 것으로 나타나, 열가수분해 온도의 상승에 따라 유기물의 혐기적 분해능이 낮아졌다. 이러한 결과는 98% 대의 유기물 가용화율 ($S_{COD}$)을 보인 것과는 반대로 $250{sim}270^{circ}C$의 열가수분해액은 혐기소화에 분해저항성을 지니는 것으로 나타났다.
The objective of this study was to investigate the organic solubilization (SCOD) and improvement of methane production for pig slurry by thermal hydrolysis. A sludge cake was pretreated by thermal hydrolysis at different reaction temperatures (200, 220, 250, $270^{circ}C$). Ultimate methane potential (Bu) was determined at several substrate and inoculum (S/I) ratios (1:9, 3:7, 5:5, 7:3 in volume ratio) by biochemical methane potential (BMP) assay for 73 days. Pig slurry SCOD were obtained with 98.4~98.9% at the reaction temperature of $200{sim}270^{circ}C$. Theoretical methane potentials ($B_{th}$) of thermal hydrolysates at the reaction temperature of $200^{circ}C$, $220^{circ}C$, $250^{circ}C$, $270^{circ}C$ were 0.631, 0.634, 0.705, $0.748Nm^3;kg^{-1}-VS_{added}$, respectively. $B_u$ of $200^{circ}C$ thermal hydrolysate were decreased from $0.197Nm^3;kg^{-1}-VS_{added}$ to $0.111Nm^3;kg^{-1}-VS_{added}$ with the changes of S/I ratio from 1:9 to 7:3, and also $B_u$ of different thermal hydrolysates ($220^{circ}C$, $250^{circ}C$, $270^{circ}C$) showed same tendency to $B_u$ of $200^{circ}C$ thermal hydrolysate according to the changes of S/I ratio. Anaerobic biodegradability ($B_u/B_{th}$) of $200^{circ}C$ thermal hydrolysate at different S/I ratios was decreased from 32.2% for S/I ratio of 1:9 to 17.6% for S/I ratio of 7:3. $B_u/B_{th}$ of $220^{circ}C$, $250^{circ}C$, and $270^{circ}C$ thermal hydrolysat were decreased from 36.4% to 9.6%, from 31.3% to 0.8%, and from 26.6% to 0.8%, respectively, with the S/I ratio change, respectively. In this study, the rise of thermal reaction temperature caused the decrease of anaerobic digestibility and methane production while organic materials of pig slurry were more solubilized.
