Rehabilitation and upgrading wastewater treatment plant for safe irrigation reuse in remote area

Abstract

Abstract This study presents an extensive evaluation of a full-scale sewage treatment system in a remote area with a population of 9,000 equivalents in Egypt. The present achievement can be implemented in several arid and semi-arid areas. Previously, this treatment system was heavily destroyed during the turmoil and became completely out of operation. Presently, the capacity of the treatment system increased from 345.5 to 648 m3/d. The present rehabilitation, upgrading, and optimizing consisted of rebuilding the main construction system, addition of chemical coagulation/sedimentation, Gravel Bed Hydroponic Wetland (GBHW) followed by waste maturation pond at a surface area of 784 m2. Results indicated that the overall removal of the pollution parameters namely: turbidity, total suspended solids (TSS), chemical oxygen demand (COD), Biological oxygen demand (BOD5), and oil and grease were excellent (ranged between 96.9 to 99%). Further improvement was achieved by employing the maturation pond. In addition, successful removal of the nutrients elements in the final treated effluent reached 83.4% for total kjeldahl nitrogen (TKN), 99.3% for ammonia-nitrogen, 63.4% for organic nitrogen, and 59.8% for total phosphorous (TP). The pathogen removal was excellent, namely: faecal coliform and E.coli, where the overall removal reached 100% each (more than ten and six orders of magnitude). Meanwhile, the number of cells or eggs of Nimatoda (count/L) in the raw wastewater was also 100% removed in the final treated effluent.