Effects of phosphogypsum, superphosphate, and dicyandiamide on gaseous emission and compost quality during sewage sludge composting

Abstract

This study investigated the effects of phosphogypsum, superphosphate, and dicyandiamide on gaseous emission and compost quality during sewage sludge composting. Results showed that phosphogypsum reduced ammonia (NH₃) and methane (CH₄) emissions but increased nitrous oxide (N₂O) emission. Superphosphate simultaneously reduced NH₃, N₂O and CH₄ emissions. Dicyandiamide markedly reduced N₂O emission during composting. Combination of phosphogypsum and dicyandiamide reduced CH₄ and N₂O emissions by 75.6% and 86.4%, while NH₃ emission was increased by 22.0%. Combination of superphosphate and dicyandiamide reduced NH₃, CH₄ and N₂O emissions by 12.3%, 81.0% and 88.2%, respectively. More importantly, with the addition of 10% initial raw materials, phosphogypsum and superphosphate conserved nitrogen and improved compost quality by introducing additional nutrients.

Keywords: Compost quality; Composting; Dicyandiamide; Greenhouse gas emissions; Phosphogypsum; Superphosphate.