Characterization of clogging deposits in an irrigation pipeline and effect of post-aeration on clogging potential of tertiary-treated wastewater

In Agadir, a water-scarce Moroccan region, municipal and industrial wastewater is tertiary-treated to be reused in golf courses. Wastewater reuse has been constrained by severe emitter clogging that caused technical and financial problems. This study aimed to perform an in-depth characterization of the treated wastewater in relation to its susceptibility to cause clogging, and to assess the capacity of an aeration post-treatment to reduce the clogging potential. The post-treatment consisted in injecting different airflows (0-33 L/h/Lreactor) into the treated wastewater. The structural, morphological and elemental composition of the clogging matter collected in the irrigation pipeline was characterized using Scanning Electron Microscopy, Scanning Transmission Electron Microscopy, X-ray Diffraction and X-ray Energy Dispersive Spectroscopy. The 15-day aeration post-treatment at 16.5 L/h/Lreactor presented the best cost-benefit ratio. Organic matter was totally degraded. Calcium was reduced by 9%, bicarbonates by 54%. The analysis of the deposits induced by the aeration post-treatment revealed a relevant decrease of the major constituents of the clogging deposits found in the irrigation pipeline. The results show the effectiveness of post-aeration in biodegrading residual organic matter and precipitating several salts, thus reducing the clogging potential.