Determination of Proteins in Waste Water
CALVIN WOODS, Associate Professor of Civil Engineering
Texas Western College
El Paso, Texas
INTRODUCTION
Biological treatment of industrial wastes utilizes complex biochemical reactions and processes that result in the conversion of the organic wastes into
gaseous end products, living cells, more stable organic compounds, and into a
form more easily separated from the water carrier.
The microorganisms that carry out these reactions require an energy supply,
special growth factors, and a supply of elements in a suitable form. In any biological waste treatment scheme, the waste material serves as the source of essential metabolites and energy.
Evaluation of the performance of a treatment plant and analysis of wastewaters involves the determinations of various physical and chemical parameters
such as pH, residue, COD, BOD and others. A parameter that is often of interest
is proteins. Proteins can serve as a supply of available nitrogen as well as a supply
of energy. Protein is of special interest in many industrial wastes because it is
lacking or is present in low concentrations. Where proteins are present in high
concentrations, they are of interest because they represent one of the major groups
of organic wastes.
ORGANIC WASTES AND PROTEINS
Organic wastes of animal and plant origin are usually classified into three
general groups: lipids, carbohydrates, and proteins. Lipids and carbohydrates
differ in physical and chemical characteristics; however, both lipids and carbohydrates contain only carbon, hydrogen, and oxygen. Proteins, on the other hand,
contain nitrogen, sulfur (with few exceptions), and sometimes phosphorous, in addition to carbon, hydrogen, and oxygen (1). The chemical composition (on a
weight basis) of all proteins are similar (see Table I).
TABLE I
CHEMICAL COMPOSITION OF PROTEINS (2)
Percentage, by weight
Carbon      51    - 55
Hydrogen   6.5-   7.3
Oxygen  20     - 24
Nitrogen  15     - 18
Sulfur   0     -   2.5
Phosphorus   0     -    1.0
At one time it was thought that there was only one universal protein (3)
shared by all forms of life.   The results of investigations have shown that there are
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