Land treatment of wastewater 413infiltration rate on N removal for a rapid infiltration site in Phoenix, Arizona, is
shown in Figure 8.8.
Application schedule
Treatment efficiency in rapid infiltration systems responds to variations in
application cycle. Short and frequent application schedules such as 0.5 to 3 days
on and 1 to 5 days drying, maximize nitrification probably because the soil is
exposed more to air and aerobic conditions, but minimize denitrification or
nitrogen removal. As the drying time during the cycle increases, the potential for
nitrogen removal increases. For example, the application schedule at Hollister,
California, is 1 to 2 days on and 14 to 21 days off. At Phoenix, Arizona,
maximum nitrogen removal occurred when 10 days on was followed by 10 to 20
days off.
Figure 8.8 Effect of infiltration rate on nitrogen removal for rapid infiltration, Phoenix, Arizona
(From Lance and Gerba 1977; reproduced by the permission of Pergamon Books Ltd)
NITROGEN REMOVAL, %INFILTRATION RATE, cm / day1 in / day = 2.54 cm / day