Nitrogen and phosphorous removal from aerated lagoon effluent using horizontal roughing filter (HRF)

Traditionally, aerated lagoons are not reliable wastewater treatment systems to eliminate nutrient contents of municipal wastewater. This study aimed to enhance the aerated lagoon effluent quality by applying a simple filtration system. Removal of nitrogen and phosphorous from aerated lagoon effluent using horizontal roughing filter (HRF) was investigated. Also, the 1/3-2/3 theory was applied to predict the TSS concentration of HRF effluent. An experimental setup of HRF was used to receive the continuous effluent from wastewater treatment plant. HRF was operated at three consecutive filtration rates, including 0.5, 1 and 1.5m(3)m(-2)h(-1). At the first filtration rate (0.5m(3)m(-2)h(-1)), the removal efficiencies of total Kjeldahl nitrogen, total phosphorous, TSS, and COD were reported 50, 54, 63, and 68%, respectively. Decreasing the removal efficiency was occurred during raising the filtration rate (p<0.05). Applying the 1/3-2/3 theory revealed the significant correlation between predicted and measured TSS values. The capacity of HRF to retain nitrogen, phosphorous, and COD during the filtration runs was 24.3, 10.1, and 435.4gm(-3)d(-1), respectively. HRF can be applied as an appropriate alternative for tertiary treatment of the aerated lagoon effluent.