X-ray absorption spectroscopic analysis of raw and processed hog manure

Abstract

Anaerobic digestion technology is a process that allows livestock producers to generate electricity and heat by digesting manure. Clear-Green Environmental Inc. uses this process to make biogas from hog manure. Raw manure is pumped into a digester where it is digested anaerobically by mesophyllic bacteria. The digested manure is transferred to a dual purpose tank (DPT) which serves as a secondary digester from which the biogas is collected. Carbon is the only nutrient consumed in the digester and the by-product of this process is used in fertilizers. It has not been shown if there is a change in speciation of key elements like nitrogen and phosphorus upon digestion. X-ray Absorption Near Edge Structure spectroscopy (XANES) was used to characterize the nitrogen, phosphorous and iron found in raw and digested hog manure. Two detection modes, Total Electron Yield (TEY) and Fluorescence Yield (FY) were used for data collection. Raw hog manure contained organic nitrogen, phosphates and ferrous iron. Digested hog manure contained organic and inorganic nitrogen, phosphates as well as a mix of ferrous and ferric iron.