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GrencOr Design SYSTEMS Table Bi:Sample Mass Balance Calculation Table Source' Design Flow',Q Constituent 1: Constituent 2: Constituent 3: (gal or imp.gal or L or m3) BOD5(mg/L) TSS(mg/L) TKN(mg/L) Source 1 Qs1 BOD5s1 TSSS1 TKNs1 Source 2 QS2 BOD5S2 TSSS2 TKNS2 Source 3 QS3 BOD5S3 TSSS3 TKNS3 Source 4 QS4 BOD5s4 TSSS4 TKNS4 Total Flow',QT BOD5111 TSSB TKNB 'The table can be built with as many contributing sources and constituents as needed;four sources and three constituents shown for simplicity. 'The actual unit of measure doesn't matter as long as the same unit of measure is used for all sources as they fall out in the equation. 'The total flow,Or is the sum of flow from all contributing sources. For Constituent 1 (BODS)the mass balance equation for blended waste strength concentration (BOD513) is: Equation 132 Blended BODSg,mg/L= IQSl *BOD5SJ + (QS2 *BOD5S2) + (QS3 *BOD5S3) + (QS4 *BODSS4) QT Example Determine the blended BOD5B given the following for a camp application and using Equation 132. Table B2: Sample Equation Table Source Design Flow(gpd) PTE BODS(mg/L) RV Dump Station 250 1800 Shower House w/Restrooms 4500 225 Restrooms 1800 300 Camp Host Living Quarters 150 150 Total Flow(QT) 6700 BOD513 (250 gpd*1800 mg/L) + (4500 gpd*225 mg/L) + (1800 gpd*300 mg/L) + (150 gpd*150 mg/L) — Blended BOD5B = 6700 gpd 302 mg/L Determining Alkalinity Demand and Need for Supplemental Alkalinity Addition Ensuring that the pH remains above 7(and preferably above 7.5)at all times is critical for ammonia sensitive applications.Supplemental alkalinity should be included if influent alkalinity is insufficient to buffer the process.During nitrification,7.14 mg/L alkalinity is used per mg/L TKN; during deni- trification with a pre-anoxic return loop(at 100%denitrification),half of that—or 3.57 mg/L—is returned.Without a denitrification component,there is no return.To be conservative in our calculation of alkalinity need,we assume a 60%denitrification efficiency and a return of 2.14 mg/L during deni- trification.To determine alkalinity need,multiply the primary treated effluent value for TKNi(in mg/L)by 5(7.14 mg/L—2.14 mg/L).Alkalinity demand can be calculated using the following equations and assuming complete nitrification of the denitrified effluent: Equation 133 Alkalinity Demand=TKNi mg/L x 5 mg/L Alkalinity1 mg/L TKN Equation 134 Alkalinity Need = Alk Demand + Target Residual Alk — Influent Alk As described in pH Effect on Nitrogen on page 19 of the Design Criteria,the target residual for alkalinity is 100 mg/L.If the result of Equation 134 is a positive number,the system will require supplemental alkalinity addition.If the result is a negative number,there is a likely surplus of alkalinity in the source water and the system should function without alkalinity addition. NDA-ATX-1 Orenco Systems®•800-348-9843•+1 541-459-4449•www.orenco.com Rev.8,©10/20 Page 24 of 38