Recovering struvite from livestock wastewater by fluidized-bed homogeneous crystallization as a pre-treatment process to sludge co-digestion

Livestock wastewater can contain high levels of phosphates and trace amounts of various ionic species harming the environment and human health. These ions can be successfully removed from livestock effluent and recovered in a non-toxic crystal form via crystallization. The fluidized bed homogeneous crystallization (FBHC) technology is a cutting-edge pretreatment method that removes phosphate and ammonium by crystallizing struvite. The findings demonstrated a 37% removal for ammonium solutions alone, 38% with copper, 35% with zinc, and 33% when copper and zinc were present, while the crystallization efficiency was achieved at 35%, 33% with copper, 28% with zinc, and 26% with copper and zinc. For phosphate-containing solutions, 95% was removed, 81% with copper, 96% with zinc, and 88% with copper and zinc. Similarly, crystallization efficiency was attained at 87%, 60% with copper, 94% with zinc, and 81% when copper and zinc were combined with phosphates. For ammonium solutions, copper and zinc reduced the removal and crystallization efficiency at constant pH and increased at increasing pH. For phosphate solutions, the removal and crystallization efficiencies increased at increasing pH. However, zinc ions resulted in the highest removal, and crystallization efficiency for phosphate solutions was attained. Based on SEM, EDS, XRD, and XPS analyses, the peaks revealed the presence of struvite in the form of magnesium ammonium phosphate.

Automated summary

Livestock wastewater contains high levels of phosphates and trace amounts of various ionic species, which are harmful to the environment and human health. Crystallization can effectively remove and recover these ions in a non-toxic crystal form from livestock effluent. The fluidized bed homogeneous crystallization (FBHC) technology uses struvite crystallization to remove phosphate and ammonium. The experiments showed different removal and crystallization efficiencies for ammonium and phosphate solutions depending on the presence of copper and zinc.