Question

A chemical plant produces wastewater containing (C3H10 N203) at a concentration of 50 mg/L. a) Determine the COD, TOC, BOD, NBODand ThOD values. Assume that the BOD first-order rate constant is 0.23 per day (base e). b) What are two criteria to be considered for the selection of sample dilution factor for the standard BOD5 test? Calculate the dilution factor based on these criteria.

Answer 1

GIVEN DATA - C₅H₁₀N₂O₃ concentration in wastewater = 50mg/L

a) Determine COD

Ans) 1. COD - chemical oxygen demand is used to determine the quantity of water pollution. It is an indicative measure of amount of oxygen that can be consumed by reactions in a measured solution. It is calculated by following formula -

COD = mg O₂ in final volume x 1000

volume of sample (mL)

2. TOC - Total organic carbon ia a measure od total amount of carbon in organic compounds in the wastewater. This a test done in organizations and labs to determine how suitable a solution is for their processes.

TOC = total carbon - total inorganic carbon

3. BOD₅ - Biological Oxygen Demand , it is a 5 -day BOD test of domestic wastewater .

BOD_{5 =} DO_{i -} DO_f

(V_b/V_s)

where, BOD_{5 =} biological oxygen demand at t days (mg/L)

DO_{i =} initial dissolved oxygen in the sample bottle(mg/L)

DO_f= final oxygen dissolved in the sample bottle (mg/L)

V_{b =} sample bottle volume

V_s= sample volume (mL)