A mixture consisting of 30ml of waste and 270ml of seeded dilution water has an initial DO of 8.55mg/l; after 5 day, it has a final DO of 2.40 mg/l. Another bottle containing just the seeded dilution water has an initial DO of 8.75 mg/l, and a final DO of 8.53mg/l. Find the 5 day BOD.