[Using UV-Vis Absorbance for Characterization of Maturity in Composting Process with Different Materials]

Area of Science:

• Environmental Science
• Soil Science
• Analytical Chemistry

Background:

• Compost maturity is crucial for effective soil amendment.
• Assessing humification in dissolved organic matter (DOM) aids in determining compost quality.
• Diverse raw materials influence the composting process and final compost maturity.

Purpose of the Study:

• To evaluate humification and maturity of composted materials using UV-Vis spectra.
• To identify reliable UV-Vis spectral parameters for compost maturity assessment.
• To differentiate compost maturity based on raw material composition.

Main Methods:

• Composting various raw materials: chicken manure, pig manure, kitchen waste, lawn waste, fruits/vegetables waste, straw waste, green waste, sludge, and municipal solid waste.
• Measuring UV-Vis spectra of DOM and calculating parameters like SUVA254, SUVA280, E250/E365, E4/E6, A226-400, S275-295, and S350-400.
• Employing chemometrics, including principal component analysis (PCA) and hierarchical cluster analysis (HCA), for data interpretation.

Main Results:

• Significant changes in UV-Vis spectral parameters during composting.
• SUVA254 and SUVA280 increased, while E250/E365 and E4/E6 decreased.
• A226-400, SUVA254, S350-400, SUVA280, and S275-295 were identified as key indicators of compost maturity.
• Hierarchical cluster analysis grouped composts into two categories: lower maturity (chicken manure, pig manure, lawn waste, etc.) and higher maturity (straw waste, kitchen waste).

Conclusions:

• UV-Vis spectra combined with chemometrics provide an accurate method for assessing compost maturity.
• Selected parameters (A226-400, SUVA254, S350-400, SUVA280, S275-295) are effective primary indicators for compost maturity evaluation.
• Raw material type significantly impacts compost maturity, as evidenced by distinct clustering of composted materials.