Enhanced suspended solids removal from high-concentration biogas slurry using magnesium ammonium phosphate and cationic polyacrylamide

Effective treatment of chicken manure biogas slurry (CMBS) with high suspended solids (SS) concentrations is crucial for environmental sustainability and agricultural reuse. This study investigated the combined effects of magnesium ammonium phosphate (MAP) crystallization and the addition of cationic polyacrylamide (CPAM) on SS removal from CMBS. The results indicated that using a molar ratio of Mg2+:NH4+:PO43- at the value of 1.6:1:1, achieved 60.55% SS removal, decreasing the concentration from 15,160 to 5,980 mg/L. The MAP crystals served as nucleation sites, facilitating floc aggregation, while CPAM enhanced flocculation through bridging and net trapping mechanisms. The resulting precipitates, rich in NH4+ and PO43-, can be repurposed as controlled-release fertilizers, thereby integrating nutrient recycling with wastewater treatment. This study provided a novel and efficient method for CMBS treatment, addressing the challenges posed by high SS concentrations and promoting sustainable agricultural and environmental practices.