A high rate physical/chemical treatment system has been evaluated for the removal of suspended solids and the macronutrients, phosphorus and nitrogen, from combined sewer overflow. The system utilized a single unit process concept consisting of in-line chemical addition, coagulation, flocculation, high rate filtration and ion exchange. The results of this program have demonstrated that the simultaneous removal of suspended solids, phosphorus, and ammonia-nitrogen from a combined sewer overflow is feasible using the high rate unit process concept. Suspended solids removal ranged from 90-100% with alum and polymer dosages of 220 mg/l and 1 mg/l, respectively. Alum dosages resulting in Al/P molar ratios greater than 1.4 were effective in reducing the total inorganic phosphorus (TIP) concentrations from greater than 10 mg/l to less than 0.9 mg/l. The clinoptilolite was effective in reducing the ammonia level to below the detectable levels of 0.02 mg/l NH3-N. Influent NH3-N concentrations ranging from 0.2 to 16 mg/l were reduced below detectable levels during the initial period of contact. The effective exchange capacity of clinoptilolite was found to range from 0.20 to 0.64 meq NH3-N/g clinoptilolite as the influent NH3-N concentration ranged from 7.5 to 16 mg/l, respectively.

EPA Grant No. Contract Number: S-802400. "June 1978." Includes bibliographical references (pages 60-61).