Converting wastes to resource: Utilization of dewatered municipal sludge for calcium-based biochar adsorbent preparation and land application as a fertilizer

• Published in: Chemosphere (Oxford) Vol. 298; p. 134302
• Main Authors: Qin, Jiafu, Zhang, Chuchu, Chen, Zhenguo, Wang, Xiaojun, Zhang, Yangzhong, Guo, Lu
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.07.2022
• Subjects: Dewatered sludge; Land application; Phosphorus recovery; Resource utilization; Resource utilization; Phosphorus recovery; Dewatered sludge; Land application
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2022.134302

Pyrolysis combined with land application for dewatered municipal sludge disposal revealed advantages in heavy metals solidification and resource utilization compared with other disposal technologies. In this study, utilizing dewatered municipal sludge for calcium-containing porous adsorbent preparation via pyrolysis was proposed and verified. After pyrolyzing at 900 ° C (Ca-900), the dewatered sludge obtained maximum adsorption capacity (83.95 mg P⋅ g−1) and the adsorption process conformed to the pseudo-second-order model and double layer model. Characteristic analysis showed the predominant adsorption mechanism was precipitation. Continuous column bed experiment indicated 2 g adsorbent could remove 4.27 mg phosphorus from tail wastewater with the initial phosphorus concentration of 1.03 mg ⋅ L−1. No heavy metals leaching was observed from Ca-900 adsorbent with pH value exceeding 1.0, and merely 1% addition of Ca-900 adsorbent (after actual water phosphorus adsorption) with soil could extremely promote the early growth of seedlings. Economic estimates demonstrated that this cost-effective modification could generate the most add-on value production. Based on these results, the strategy of ‘one treatment but two uses’ was proposed in this study, converting the wastes to resource and providing a native strategy for sludge disposal and resource recovery. [Display omitted] •Novel P adsorbent was obtained from dewatered municipal sludge by easy pyrolysis.•Adsorbent by pyrolysis at 900 °C showed a maximum adsorption capacity (83.95 mg P/g).•The adsorbent could achieve both removal and recovery of P from real tail wastewater.•Saturated adsorbent after wastewater treatment could be reused as fertilizer in soil.