Effects of carbon dioxide deficiency and metal toxicity on biological oxygen demand

In this study, the effects of carbon dioxide (CO₂) deficiency on the biological growth under respirometric conditions, first‐ and second‐order biological oxygen demand (BOD) progressions using two different BOD measurement techniques and metal toxicity effects on the respirometric BOD are investigated. The effects of CO₂ deficiency in the growth of bacteria and related effects on the first‐ and second‐stage BOD progressions are investigated using various media with respirometers in comparison with the BOD dilution method. CO₂ deficiency causes significant retardations on the growth of bacteria and the second‐stage respirometric BOD values are suppressed. CO₂ seems to be an essential nutrient for the growth of microorganisms and for the oxygen uptake progressing rates. HgCl₂, HgSO₄, CuSO₄, K₂Cr₂O₇, ZnSO4 and Al₂(SO₄)₃ inorganic metal compounds cause significant retardations in the respirometric BOD values obtained from a synthetic autotrophic medium. Effects are found to be dependent on the applied concentrations of these chemicals in the medium.