1. CE 3231 - Introduction to Environmental Engineering and Science Readings for This Class: 5.5-5.6 O hio N orthern U niversity Introduction Chemistry, Microbiology & Material Balance Water & Air Pollution Env Risk Management Biological Oxygen Demand When microbes and organic carbon are plentiful in lakes and streams, the microbes take over. The result is an oxygen depleted system that is very microbially diverse, but is void of higher trophic level organisms. Understand BOD and changes in OD is critical to maintaining healthy water quality.

2. Lecture 24 BOD Exertion and BOD levels downstream (Water Quality IV)

3. Water Quality, Carbon and Nutrient Cycling

4. Measures of Water Quality Dissolved Oxygen (DO) and Oxygen Demand (OD) Total Dissolved Solids (TDS) Nutrients Metals Pathogens Organic compounds – Total organic compounds (TOC)

5. Oxygen Demand Measure of amount of oxygen demanding organic and inorganic matter in a water Measurement – ThOD – – COD – – BOD –

6. Theoretical Oxygen Demand (ThOD) The total amount of oxygen required to: Calculated using stoichiometric principles Calculate ThOD for 1 g/L of glucose

7. Biochemical Oxygen Demand (BOD) BOD = DO initial – DO final BOD = L o – L t – L = oxygen consumed L o = initial L t = @ time = t

8. Biochemical Oxygen Demand (BOD) BOD Definition: BOD is used: Slow analysis: Typical analysis: Dependent upon:

9. BOD Jar Test L

10. DO Sag Curves

11. Simple Plug Flow River Model Wastewater discharge (High BOD, Low DO) Objective: derive a mathematical model to predict DO downstream: DO(x,t) - take your shot at it! Assumptions: 1.completely and uniformly mixed in the cross flow and vertical direction 2.neglect pollutant dispersion