OPTIMIZATION OF FLUSHING PRESSURE, TIME, ACID AND CHLORINE TREATMENT ON DRIP EMITTER RECOVERY USING TREATED EFFLUENT

Abstract

The competitive water uses and demand for freshwater increase the vulnerability of water sources. Due to the resulting water scarcity, reclamation of wastewater has been shown as an alternative and a viable water supply source for critical food security. The utilization of wastewater in agriculture is more compatible with drip irrigation but challenged with system clogging. Flushing pressure and chemical treatments were investigated with regards to the recovery of clogged emitters operated with treated blackwater effluent. A set of orthogonal experiments with flushing pressure, time, acid contact time and chlorine contact time were used to study the emitter recovery of in-line labyrinth drippers. Water discharge rates were measured and characterized at 72-hour intervals. Physicochemical and biological water analyses were carried out to determine parameters triggering clogging. The results showed that the flushing treatments had a significant effect on clog removal and recovered the discharge rates by 98% of the initial flow. Among the four factors, acid removed the built-ups the most. This was a clear indication that clogging in this study was mainly due to the chemical precipitation of Fe, Ca2+ and pH of the wastewater. Coarse particles could easily wear down, but not so much for biological growth induced by the biochemical water parameters. The analysis of variance indicated that the flushing pressure had a significant effect on the discharge of the precipitates that were dislodged by acid in contact, resuscitating the emitter discharge. The pressure provided a flushing velocity of 0.28 m/s and 0.49 m/s, removing the clogging particles. The flushing treatments implemented in the study improved the relative emitter discharge, uniformity coefficient (Uc) and the Emitter Discharge Variation (Dra). This study provides relevant information on emitter operational recovery for uniform water application and management of drip irrigation system (DIS) using wastewater.