A meta-analysis and computational modelling of treated sewage as a bioorganic fertilizer

This study reviews the use of treated sewage as a bioorganic fertilizer to improve crop quality. It conducted a meta-analysis and descriptive statistics to synthesize findings from publications between 2000 and 2025, following the PRISMA framework. Pollutants are greater in summer than in winter, attributed to dilution and evaporation. Hybrid treatment is more effective than conventional and decentralized systems and achieves residual concentrations as low as 0.001 mg/l. The integration of contact oxidation with constructed wetlands improved the treatment effectiveness of BOD5 from 80.63 to 89.64%. It is treated more effectively in summer at 23.5 mg/l than in winter at 7.15 mg/l, due to denitrification. Anaerobic-anoxic-oxic treatment excels in achieving more than 90% removal of nitrogen and phosphorus. Bioorganic fertilization provides 82% organic nitrogen and increases soil organic matter by 65%, resulting in a 35.4% enhancement in clay soils. It reduces nitrate accumulation by 62%, enhances nitrogen and phosphorus availability by 74%, and reduces the reliance on synthetic fertilizer by 75%. Organic carbon improves soil microbial activity, but high levels in poorly aerated soil can cause root zone hypoxia. The concentration of lead in shallow soil exceeds that of cadmium because lead binds strongly to organic matter. Cadmium is more mobile than lead and can penetrate deeper, but not as deeply as zinc. Micronutrients improve edible crop quality, but mercury and arsenic require careful management. The long-term application of bioorganic fertilizer enhances soil pH, microbial diversity, and nutrient cycling, ultimately leading to better crop quality and increased agricultural production. Graphical abstract