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f <br /> 11-6 COMBINATION TREATMENT FOR NITROGEN REMOVAL 755 <br /> Four polyethylene modules <br /> containing biofibrous peat <br /> Distribution system <br /> Screened Soil cover <br /> effluent <br /> Influent <br /> - " Treated effluent percolates <br /> Screened pump vault into the soil under peat filter <br /> Septic tank <br /> FIGURE 11-30 r n <br /> Definition sketch for peat filter (adapted from Bord na-Mona Corp.). <br /> TABLE 11-18 <br /> Summary performance data for peat filters used to treat <br /> individual household wastewater` . <br /> influent Effluent % <br /> Constituent Unit cone. conc. reduction <br /> BODS mg/L 250-280 <10 96 <br /> TSS mg/L 190 <10 95 <br /> NH3 as N mg/L 50 c5 .90 <br /> Total N as N mg/L 60 <10 80 <br /> Total P as P mg/L 7.7 3.2 58 <br /> Total coliform NoJ100 mL 3.0 x 106 6.0 X103 99.9 <br /> 'Adapted from McKee and Brooks(1994)and Henry(1995). <br /> I <br /> I 11-6 COMBINATION TREATMENT FOR NITROGEN REMOVAL <br /> As discussed above,both intermittent and recirculating filters will nitrify septic tank <br /> effluent.The degree to which the nitrate will be denitrified depends on the availabil- <br /> ity of_a carbon source and the alkalinity of the wastewater. In the literature dealing <br /> with nitrogen removal in intermittent and recirculating filters, much of the reported <br /> information is confounded statistically because nonstandardized- sampling and <br /> analysis protocols are used and the alkalinity of the wastewater is not reported. <br /> To enhance the degree of denitrification or total nitrogen removal, a variety of flow f <br /> diagrams have been developed (see Chap. 13). <br /> Attempts have been made to recycle the effluent from IPBFs through the sep- <br /> tic tank to enhance denitrification. Denitrification is enhanced;however,ammonium . <br /> and organic nitrogen will remain in the septic tank effluent to limit the overall nitron' <br /> gen removal.:An alternative approach for the removal of nitrogen has been developed- <br /> by Orenco Systems, Inc. (1996). The approach involves the removal of nitrogen in <br />