Biological Treatment

Starch wastes respond to biological treatment using trickling filters, aerated lagoons, or activated sludge processes. Waste pH should be adjusted to between 6.0 and 9.0, suspended solids should be removed and, if necessary, nutrients should be added to maintain a BOD-nitrogen-phosphorous ratio of 100 to 5 to 1.

Starch is almost completely oxidized biologically, provided that the loading is maintained within the limits of the biological activity. If an activated sludge process is used, it is important to maintain an F to M (BOD to mixed liquor suspended solids) ratio of less than 0.3 (per day) to minimize propagation of filamentous organisms that interfere with solids separation.

FIG. 8.2.13 Granular carbon systems for phenol removal tion at pH 7.7, provided that the stoichiometric amount of chlorine is added. This is accomplished in water treatment plants by superchlorination. The major portion of the chlorine applied consumes other organic compounds and destroys ammonia. Approximately 42 parts of chlorine per part of phenol are required (Ohio River Valley Sanitation Commission 1951).

Ozonation effectively oxidizes phenol. However, the initial cost of producing ozone is high. Ammonia does not interfere in ozonation, and approximately 5.8 parts of ozone are required per part of phenol (Ohio River Valley Sanitation Commission 1951).

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