IMPROVEMENT OF PARTIALLY TREATED WASTEWATER QUALITY BY SOIL AQUIFER TREATMENT IN UPPER EGYPT

Egypt is a semi-arid country and needs other water sources to cover shortages. Soil aquifer treatment (SAT) system is a natural advanced treatment technology of partially treated wastewater with no chemical additives. The present study evaluates the SAT system in west of the Sohag region for wastewater treatment and reuse. The measurements were concerned with hydrogen ion (pH), dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), total dissolved solids (TDS), total suspended solids (TSS), boron (B), total coliform (TC), fecal coliform (FC), heavy metals (HM), and major cations (Ca2+, Mg2+, Na+). Results indicated that the pH values of the reclaimed water ranged from 7.53 to 7.71. DO concentration was exceeded 4 mg/l for the reclaimed water. The SAT system's efficiency in removing BOD, COD, TSS, TC, and FC was 98.3%, 91 %, 90.7%, 99.99%, and 99.99%, respectively. While TDS and B concentrations increased slightly after the SAT system as it moved through the aquifer's vadose zone. On the other hand, HM concentrations were completely removed with a removal efficiency of nearly 100%. According to the Food and Agriculture Organization (FAO) and the Egyptian Code of Practice (ECP), reclaimed water is suitable for irrigation. Moreover, reclaimed water suitability for irrigation was assessed based on sodium adsorption ratio (SAR), electrical conductivity (EC), magnesium hazard (MH), total hardness (TH), and Kelley ratio (KR). It was found that extracted water at 1500 m is suitable for irrigation when considering the SAR, EC, and MH values. On the other hand, the reclaimed water at the same distance is present under hard to very hard category, reflecting its unsuitability for irrigation purposes. Based on KR, samples are unsuitable for irrigation if KR is considered. The cost of the SAT system is less than 34% the tertiary treatment cost. The artificial aquifer recharge by partially treated wastewater presents an attractive tool applied in Egypt to be safely reused in unrestricted irrigation and reuse wastewater in safe ways while preserving the environment.

Automated summary

Egypt, a semi-arid country, can use the Soil Aquifer Treatment (SAT) system as an efficient and safe method to treat and reuse wastewater for unrestricted irrigation.