Integrated National Assessment of Biosolids Reuse for Sustainable Agriculture in Jordan: Soil Fertility, Land Suitability, and Environmental Considerations

This secondary-data integrated assessment combines national wastewater treatment records, two national sludge reports, Jordanian regulatory criteria, published agronomic evidence, engineering scenarios, and a previously prepared spatial screen. The present national context includes 33 municipal wastewater treatment plants (WWTPs), but the analytical sources cover different historical plant sets. The 2020 GIZ report surveyed 29 operating WWTPs and reported sludge-quality data for 25 plants, comprising 28 plant-stage records. The 2014 USAID strategy covered 28 WWTPs, with metal data for 9 plants and six nutrient samples from 3 plants. In the GIZ records, mean concentrations were 3.44 mg Cd kg−1, 7.93 mg Pb kg−1, 603.79 mg Zn kg−1, and 111.86 mg Cu kg−1 dry solids. Maximum concentration-to-limit ratios were 1.00 for Cd, 0.103 for Pb, 0.525 for Zn, and 0.377 for Cu. USAID nutrient samples averaged 3.93% total N, 1.71% total P, and 0.71% total K. GIZ estimated 101,533–108,719 t dry solids yr−1 in 2020 and 128,540–149,332 t yr−1 in 2035. USAID produced lower estimates of 50,947 and 72,418 t yr−1 for the same years, showing major model uncertainty. The source spatial screen mapped 10,150.28 km2, including 745.62 km2 of protected rangeland reserves. Excluding those reserves leaves 9404.66 km2 for further regulatory and field screening. The results support controlled reuse based on batch testing, pathogen reduction, nitrogen and phosphorus budgets, and long-term soil monitoring.