Effects of sample storage on biosolids compost stability and maturity evaluation

Area of Science:

• Environmental Science
• Soil Science
• Waste Management

Background:

• Compost stability and maturity are key quality indicators.
• Sample storage can alter compost quality assessments.
• Limited data exists on storage effects on compost parameters.

Purpose of the Study:

• To investigate the impact of air-drying and freezing on compost stability and maturity.
• To evaluate changes in CO2 evolution, seed germination, and WSOC after storage.
• To determine the reliability of WSOC as a compost quality indicator post-storage.

Main Methods:

• Collected biosolids compost samples from four Florida facilities.
• Stored samples short-term (refrigerated), air-dried, or frozen for one year.
• Measured CO2 evolution, seed germination rates, and WSOC.

Main Results:

• Storage effects varied with compost stability, maturity, and source.
• Frozen storage reduced CO2 evolution; air-drying reduced WSOC; freezing increased WSOC.
• Phytotoxicity was unaffected by storage, except for one facility's samples.
• Water-soluble organic carbon (WSOC) consistently correlated with CO2 evolution and seed germination.

Conclusions:

• Storage methods significantly influence compost stability and maturity metrics.
• WSOC is a robust indicator for compost quality assessment, even after storage.
• Careful consideration of storage methods is crucial for accurate compost research.