Synthesis of nano-zeolite from coal fly ash and its potential for nutrient sequestration from anaerobically digested swine wastewater

The treatment of anaerobically digested swine wastewater (ADSW) is problematic due to its high nutrient concentration. This study investigated the simultaneous sequestration of ammonium (N) and phosphate (P) from ADSW using nano-zeolites synthesized from fly ash (ZFA). The nanometer-scale crystalline structures plentiful of zeolite-NaP1 coating on ZFA particle increased the levels of specific surface area and cation exchange capacity at times of 40 and 104, compared to raw fly ash. Kinetic N and P sorption experiments with ZFA were well described by both the Langmuir and Freundlich models, suggesting the co-existence of homogeneous and heterogeneous sorption mechanisms. N and P removal efficiencies ranged from 41% to 95% and 75% to 98%, respectively, across a range of ZFA doses (from 0.25 to 8 g/100 ml). Collectively, application of the laboratory-synthesized ZFA can alleviate the nutrient loads in ADSW and therefore modify the ratio of N:P in wastewater beneficial for subsequent biological treatment.