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341.
342.
Bashar J. Alhajjar C. Linn Gould Gordon Chesters John M. Harkin 《Journal of contaminant hydrology》1990,6(4)
The effects of phosphate (P) and zeolite (Z) -built detergents on leaching of N and P through sand columns simulating septic system drainfields were examined in laboratory columns. To simulate mound septic system drainfields, paired sets of columns were dosed intermittently with septic tank effluent from households using P- or Z-built detergent. Two other paired sets of columns were flooded with P- or Z-effluent to simulate new conventional septic system drainfields; after clogging mats or “crusts” developed at infiltration surface, the subsurfaces of the columns were aerated to simulate mature (crusted) conventional septic system drainfields. NO3 loading in leachate was 1.1 times higher and ortho-P loading was 4.3 times lower when columns were dosed with Z- than with P-effluent. Dosed columns removed P poorly; total phosphorus (TP) loading in leachate was 81 and 19 g m−2 yr−1 with P- and Z-effluent, respectively. In flooded columns 1.3, 2.0 and 1.8 times more NH4, organic nitrogen (ON) and total nitrogen (TN) respectively, were leached with Z- than with P-effluent; NO3 leaching was similar. Flooded columns removed P efficiently; TP leached through flooded systems was 2.5 and 1.4 g m−2 yr−1 with P- and Z effluent, respectively. Crusted columns fed Z-effluent leached 1.2, 2.6, 1.4 and 2.1 times more NH4, NO3, ON and TN, respectively, than those with P-effluent but 1.8 times less TP. Crusted columns removed P satisfactorily: 8.2 and 4.6 g m−2 yr−1 TP with P- and Z-effluent, respectively. The P-built detergent substantially improves the efficiency of N removal with satisfactory P removal in columns simulating conventional septic system drainfield. Simultaneous removal of N and P under flooded conditions might be explained by precipitation of struvite-type minerals. Dosed system drainfields were less efficient in removing N and P compared to flooded and crusted system drainfelds. 相似文献