Problems from Chapter 1, textbook:1.12 The stream has an unknown BOD concentration Co=? (instead of 20 mg/L). The regulatory limit at the discharge of Pond 2 is 20 mg/L (C2 = 20 mg/I). Find the maximum BOD concentration leaving Pond 1 and in the stream (Co =? and C1 =?). (Materials Balance, CSTR, 2 system)

Fig: 1