Theoretical Chemical Oxygen Demand

Several methods have been developed to estimate the oxygen demand in waste water treatment systems. Commonly used laboratory methods are biochemical oxygen demand (BOD), chemical oxygen demand (COD), total oxygen demand (TOD), total organic carbon (TOC), and theoretical oxygen demand (ThOD). 

Potassium hydrogen phthalate has many uses in analytical chemistry. It is a primary standard for standardization of bases in aqueous solutions. Its equivalent weight is 204.2. It also is a primary standard for acids in anhydrous acetic acid. Other applications are as a buffer in pH determinations and as a reference standard for chemical oxygen demand (COD). The theoretical COD of a Img/L potassium hydrogen phthalate is 1.176mg O2. 

Also the traditional BOD5 tests (e.g. the EU C.5 test) may demonstrate whether a substance is readily biodegradable. In this test, the relative biochemical oxygen demand in a period of 5 days is compared to the theoretical oxygen demand (ThOD) or, when this is not available, the chemical oxygen demand (COD). The test is completed within five days and consequently, the pass level defined in the proposed hazard classification criteria at 50% is lower than in the ready biodegradability tests. 

Note ThOD = theoretical oxygen demand or the weight ratio of oxygen required per mg of compound for complete conversion of the compound to dioxide and water BOD = biochemical oxygen demand COD = chemical oxygen demand DOC = dissolved organic carbon. 

Biological oxygen demand, 5 days Chemical oxygen demand Theoretical oxygen demand Biodegradation probability Partition coefficient, log K USE PERFORMANCE Manufacturer... 

A theoretical model has been developed permitting prediction of the chemical oxygen demand (COD) and instantaneous current efficiency (ICE) during the electrochemical oxidation of organic... 

Since the publication of the third edition, additional data have been critically reviewed. New or additional data included in this edition are bioconcentration factors, aquatic mammalian toxicity values, degradation rates, corresponding half-lives in various environmental compartments, ionization potentials, aqueous solubility of miscellaneous compounds, Henry s law constants, biological, chemical, and theoretical oxygen demand values for various organic compounds. Five additional tables have been added Test Method Number Index, Dielectric Values of Earth Materials and Fluids, Lowest Odor Threshold Concentrations of Organic Compoimds in Water, and Lowest Threshold Concentrations of Organic Compounds in Water. 

Molecular connectivity indices are desirable as potential explanatory variables because they can be calculated for a nominal cost (fractions of a second by computer) and they describe fundamental relationships about chemical structure. That Is, they describe how non-hydrogen atoms of a molecule are "connected". Here we are most concerned with the statistical properties of molecular connectivity Indices for a large set of chemicals In TSCA and the presentation of the results of multivariate analyses using these Indices as explanatory variables to understand several properties important to environmental chemists. We will focus on two properties for which we have a relatively large data base (1) biodegradation as measured by the percentage of theoretical 5-day biochemical oxygen demand (B0D)( 11), and (2) n-octanol/water partition coefficient or hereafter termed log P (12). 

Theoretical Oxygen Demand (ThOD) — tire cumulative amount of oxygen needed to completely oxidize a given material. The ThOD is the upper limit for BOD, values, although it is seldom achieved. A comparison of the BOD, and ThOD values for a given chemical provides an indication of the biodegradability of that chemical. 

Baker, J.R., Milke, M.W. and Mihelcic, J.R. (1999) Relationship between chemical and theoretical oxygen demand for specific classes of organic chemicals. Water Res., 33 (2), 327-334. 

Baker JR, Milke MW, Mihelcic JR (1999) Relationship Between Chemical and Theoretical Oxygen Demand for Specific Classes of Organic Chemicals, Wat. Res. 

The theoretical chemical (or ultimate) oxygen demand, or ThCOD (BODU), can be calculated for a wastewater with relatively few oxidizable components. The procedure requires one to calculate the equivalent oxygen concentration necessary for the complete stoichiometric oxidation of each of the wastewater components to its corresponding highest oxidation state and sum them for the total wastewater ThCOD. Carbonaceous components of wastewater generally considered to be fully... 

Theoretical oxygen demand, ThOD The theoretical oxygen demand is the amount of oxygen required to completely oxidise a given chemical compound, calculated from its chemical formula. 

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