Composite radial filter for removal of agrochemicals from agricultural runoff

A composite radial filter was designed, fabricated and developed for the removal of agrochemicals particularly N, P, K and bacteriological contaminant in runoff water from rice field for recharging aquifer. Zeolite (Z), activated charcoal (C), coarse sand (CS) and gravel (G) filter materials were placed in annular concentric rings of composite radial filter in different combination of thickness in the ratio of 1:2:4:4, 1:3:4:4, 1:2:2:4, 1:3:2:4 and 0:2:1:2 for five treatments (T1, T2, T3, T4 and T5) respectively. Sodium hypochlorite solution (5%) injected at the rate of 0.1 ml per unit discharge (lps) through chlorination unit at the outlet of the radial filter decreased bacteriological contamination to