Abstract
Alkaline solution was collected from alkali-treatment of steam-exploded rice straw and then reused as is or with addition of NaOH for the next pre-treatment batch. The as-is-reused solution (without addition of NaOH) showed a significant decrease of alkali-treatment efficiency because NaOH has already reacted with substrates from rice straw in the previous batch. Based on the comparison of alkali-treatment efficiencies between the first-used and as-is-reused alkaline solutions, corresponding reasonable amounts of supplementary NaOH were calculated. The results showed that reused alkaline solutions, with the addition of calculated amounts of NaOH, produce an alkali-treatment efficiency as that of the first-use, while the total amount of NaOH for both batches reduced to around 70 %, implying an impressive saving of chemicals, fresh water, and reduction of volume of waste water.
