Study on the use of geopolymer composites for nitrogen and phosphorus removal from poultry litter

Abstract

With the growing world population, animal agriculture demand in the following years will increase substantially to meet nutritional needs for humankind. An inevitable increase in demand is strongly interconnected with the meat production industry. Meeting the need creates a paradox for not bringing further stress on the environment where natural resources.

The poultry industry is one of the major meat production branches for the meat industry and Oklahoma is one of the biggest poultry contributors of the United States. Nonjudicious disposal of chicken litter or use as manure can result in leaching of nitrates and phosphates causing contamination in aquifers, a primary source of clean water. Current practices of waste management are not feasible in the long term while they majorly depend on disposal. Harvesting the waste through engineered materials and treatment on-site without additional costs is necessary to take this problem under control.

Adsorbent materials offer answers to this problem by their ion-selective structure. Their performance depends on environmental conditions and majorly on the exchangeable ions in their structure. Although most adsorbent materials are applicable for nutrient control, there are still limitations to full-scale waste management. Geopolymers, non-crystalline aluminosilicate materials on the other hand promise several advantages, including higher nutrient removal capacity, their low-cost requirements, and most importantly their high adaptation into diverse applications. Hence, their promise is considered valuable for waste management.

This study is a beginning effort on developing geopolymer composites for nutrient removal in complex environmental systems like poultry houses. Composites were processed using geopolymer as binder phase and natural zeolites and metal oxides powders as additives to increase nutrient removal capacity and nutrient uptake speed of the adsorbent products. Geopolymer composites are characterized by their microstructural and mechanical properties. Adsorbent performances are evaluated for their nutrient removal efficiencies from model solutions. In addition to their use in simultaneous nutrient removal was investigated to observe matrix effects created by the environment. This study provides a proof of concept on the development of novel geopolymer composites as adsorbents.