It has been known for some time that petroproteins can be produced by certain microorganisms which have the ability to attack or metabolize hydrocarbons. For example, yeasts can grow and multiply on a relatively inexpensive material and the yeast cells are a good source of protein for food supplement. The hydrocarbons can vary from simple hydrocarbons such as isopentane of n-pentane to complex hydrocarbons as crude oil, kerosene and residual oils. Microorganisms such as Monilia Murmanica, Monilia Sitophile and Saccharomyces are all suitable. A variety of nutrient media can be used depending on the type of yeast and usually contain sodium nitrate, potassium chloride, ferrous sulfate, phosphoric acid, etc. U.S. Pat. Nos. 2,697,061 and 3,474,001 disclose production of proteins from hydrocarbons using the above-mentioned microorganism including the various compositions of the nutrient media, and the conditions of the fermentation. U.S. Pat. No. 3,121,634 teaches useful compositions of animal feed containing calcium phosphate.
It is to be noted that the nutrient medium after fermentation, though depleted in minerals, still contains enough phosphate to cause a pollution problem when discharged as a waste stream into local waters.
Since phosphates have been recognized as notorious pollutants which cause algae formation, they have been in some areas banned from use as ingredients in detergents. Prohibitions exist against discharging industrial waste containing phosphates into rivers or streams. Therefore, removal of phosphates from the purge stream is a necessity.