Phosphorus and nitrogen recovery from wastewater by ceramsite: Adsorption mechanism, plant cultivation and sustainability analysis

Recovery of the nitrogen (N) and phosphorus (P) in wastewater would help to minimize eutrophication and their reuse would lead to a more sustainable society. Sewage sludge and fly ash were used to fabricate ceramsite in the laboratory. After modified with alkali or lanthanum it was shown in benchtop experiments to effectively recover N and P from real wastewater treatment plant effluent. The N&P-adsorbed ceramsite was then applied as an eco-friendly, slow-release fertilizer to promote the germination, growth and blooming of Impatiens commelinoides, realizing the recycling of N and P from wastewater. Emergy analysis shows that such recycling is more sustainable than the current two approaches (i.e., landfill and incineration) for sludge disposal. This work thus demonstrates a sustainable solution combining the reuse of solid waste, effective wastewater purification and recovery of N and P nutrients. Applying the technologies demonstrated would help to minimize the environmental impact of wastewater and solid waste. • Sewage sludge and fly ash are used to fabricate ceramsite. • Modified ceramsite effectively recovers N and P from real wastewater effluent. • N&P-adsorbed ceramsite is applied as a fertilizer to promote plant growth. • Emergy analysis shows high sustainability of the technologies demonstrated.