FT-IR as an alternative method for measuring chemical properties during composting

Area of Science:

• Environmental Science
• Analytical Chemistry
• Biogeochemistry

Background:

• Traditional chemical analysis of compost maturity is time-consuming and costly.
• Accurate monitoring of compost properties is crucial for process optimization and quality control.

Purpose of the Study:

• To investigate Fourier Transform mid-Infrared Spectroscopy (FT-IR) as a rapid method for predicting chemical properties during composting.
• To develop and validate predictive models for compost maturity using FT-IR data.

Main Methods:

• Collected FT-IR spectra and measured chemical properties (total C, total N, LOI, lignin, cellulose, available-P, NH(4)(+)-N, NO(3)(-), pH) from diverse compost mixtures.
• Utilized partial least-squares regression analysis to build calibration models correlating FT-IR spectra with measured chemical properties.
• Assessed model accuracy using r(2) values to determine the reliability of FT-IR predictions.

Main Results:

• FT-IR models demonstrated sufficient accuracy for tracking broad changes in compost maturation for most properties.
• High calibration accuracies (r(2) 56-77%) were achieved for total carbon, total nitrogen, loss on ignition (LOI), lignin, and cellulose.
• Moderate calibration accuracies (r(2) 40-57%) were obtained for available phosphorus and ammonium-nitrogen (NH(4)(+)-N).
• No useful calibration was achieved for nitrate (NO(3)(-)) or pH.

Conclusions:

• FT-IR spectroscopy is a promising rapid technique for monitoring key chemical properties related to compost maturity.
• The method offers significant potential for time and cost savings in compost analysis.
• Further refinement may be needed for accurate prediction of properties like nitrate and pH using FT-IR.