PubMed · 2026-06-30
Researchers turned sewage sludge from a coral island treatment plant into two soil amendments - a water-absorbing hydrogel and a biochar - that together dramatically improved nutrient-poor, drought-prone coral sand soil, boosting vegetable growth and soil microbial health.
The sludge-derived hydrogel absorbed up to 815 g of water per gram in pure water and 148 g/g in saline solution, outperforming cellulose-only hydrogel by 19-24%.
Combined application of 0.2 wt% hydrogel and 0.5 wt% biochar promoted pak choi growth and reduced stress indicators under reclaimed-water irrigation.
Treatment significantly increased beneficial copiotrophic bacteria (Pseudomonadota) and decreased oligotrophic Cyanobacteriota, indicating a shift toward a more fertile, active soil microbiome.
