USE OF CHEMICAL OXYGEN DEMAND VALUES OF BACTERIAL CELLS IN WASTE-WATER PURIFICATION.

Area of Science:

• Environmental Science
• Biotechnology
• Chemical Engineering

Background:

• Accurate substrate recovery determination is vital for understanding microbial metabolism in wastewater treatment.
• Partitioning substrate between biomass synthesis and respiration is a key process in activated sludge systems.
• Existing methods for measuring substrate recovery may have limitations in accuracy and reproducibility.

Purpose of the Study:

• To investigate and compare four different methods for determining substrate recoveries in activated sludge processes.
• To identify the most accurate and reliable method for quantifying substrate utilization for biomass synthesis and respiration.
• To assess the reproducibility of the standard chemical oxygen demand (COD) test for activated sludge.

Main Methods:

• Investigated four distinct methods for substrate recovery determination.
• Utilized an energy balance approach comparing chemical oxygen demand (COD) removed with oxygen uptake and cell COD.
• Employed the standard COD test to measure the COD of activated sludge.
• Analyzed the protein and carbohydrate content of cells relative to cell age and COD.

Main Results:

• The energy balance method, comparing COD removed to oxygen uptake and cell COD, yielded average recoveries closest to 100%.
• The standard COD test demonstrated high reproducibility when applied to activated sludge.
• Cellular COD did not consistently vary with changes in protein and carbohydrate content due to cell age.

Conclusions:

• The energy balance method is recommended for accurate substrate recovery determination in activated sludge studies.
• The standard COD test is a reproducible method for assessing activated sludge.
• Cellular COD is a reliable parameter, independent of cell age-related variations in macromolecular composition.