Reclaiming Local Sources of Nitrogen and Phosphorus for Land Application Via Adsorption from Wastewater Streams

The increase in the global population has driven the intensification of agriculture and animal production, often resulting in an imbalance, mainly in the cycles of different nutrients. For example, such imbalances can be characterized by a localized excess of phosphorus (P) in wastewater from animal feed operations (AFO), which adds to the environmental impact of nitrogen (N) discharge from municipal wastewater systems. The fundamental challenge addressed in this compendium of research projects is the recovery of N from wastewater streams with high ammonium content, specifically from centrate obtained from a municipal wastewater treatment facility, additionally to the integrated management and remediation of excess P resulting from the long-term use of swine manure as fertilizer. To achieve the above, first, the adsorption capacity and efficiency of zeolite was analyzed in a system of comparative batch studies using calcium- and sodium-rich clinoptilolite under different pretreatments to selectively recover ammonium from municipal wastewater. Second, in a column study a novel nitrogen liquid fertilizer (NLF) produced by the desorption of ammonium in zeolites was tested and compared to a commercial fertilizer (ammonium chloride, NH4Cl) in two types of soils (Florida and Texas) to understand the impact of the product on the physicochemical characteristics of the soils under study. Finally, remediation with hydrotalcite of high concentrations of P due to swine waste discharge was integrated. These three main projects complement a text that addresses multiple crucial steps within the circular bioeconomy. The analysis confirmed that sodium-rich clinoptilolite offers greater N adsorption capacity compared to its calcium counterpart. Furthermore, pretreatments with sodium chloride increased the adsorption capacity in both zeolites. In addition, different applications rates of NLF can increase bioavailable N, but at the same time sodium concentrations, so fertilizer management must be meticulous. The intrinsic characteristics of soil type and its physicochemical properties also played a role in the effectiveness of the application and N retention. Finally, hydrotalcite effectively immobilized P and other minerals from a soil treated with swine manure, and the reduction was consistent with increased application rates.