Environmental and Industrial Bio Systems Technology
Environmental and Industrial Bio Systems Technology tests biological treatment, bioremediation, bioprocessing, and the measurement of environmental load.
Core rules
- BOD measures oxygen consumed by microorganisms degrading organic matter; COD measures oxygen demand from chemical oxidation and is usually higher.
- Activated sludge uses an aerated mixed community, sludge return, and wasting to control sludge age. Bulking and foaming indicate separation problems.
- Anaerobic digestion proceeds through hydrolysis, acidogenesis, acetogenesis, and methanogenesis; methanogens are sensitive to oxygen, pH, and temperature.
- Composting is thermophilic aerobic decomposition; turning or forced aeration controls temperature and oxygen.
- Bioremediation may be in situ or ex situ; bioavailability, electron acceptors, and nutrients often limit rate.
- Industrial bioprocesses need upstream sterilization, process control, and downstream recovery; life-cycle assessment avoids shifting burdens.
Worked example
A wastewater sample has initial dissolved oxygen 8.0 mg/L and final dissolved oxygen 2.0 mg/L after 5 days. Undiluted BOD5 = 8.0 - 2.0 = 6.0 mg/L. If the sample was diluted fivefold, BOD5 = 6.0 x 5 = 30 mg/L. The dilution factor restores the oxygen demand of the original sample. If the final DO were below 1 mg/L, the test would be invalid because oxygen became limiting.
Traps
Do not report COD as biodegradable organic matter. Do not ignore seed correction in BOD. Do not assume anaerobic digestion is odorless or stable without pH control. Do not treat all bioremediation as fast; sorption can slow release. Do not omit the dilution factor.