Answer:
28.57%
Explanation:
Given that:
= 10.0 mg/L
= 3.0 mg/L
We can calculate for the Original maximum deficit can be calculated which can be illustrated as follows:
where;
represents the maximum dissolved oxygen
represents the saturated dissolved oxygen
represents the minimum dissolved oxygen
= 10.0 mg/L - 3.0 mg/L
= 7.0 mg/L
We can also calculate the Desired maximum deficit by using the above expression:
In which ;
= 10.0 mg/L
= 5.0 mg/L
Now that we have all we need to replace the value; we have:
= 10.0 mg/L - 5.0 mg/L
= 5.0 mg/L
Finally, the percentage needed by the BOD for removing the waste can be determined using the following expression;
percentage = %
where;
Desired = 5.0 mg/L
Original = 7.0 mg/L
Then we have;
percentage = %
=71.43%
Required BOD = 100% - 71.43%
Required BOD = 28.57%
Hence, The percentage necessary for the BOD of the plant waste to be reduced to assure a healthy stream with at least 5.0 mg/L DO everywhere = 28.57%