Compost age and sample storage effects on maturity indicators of biosolids compost

Area of Science:

• Environmental Science
• Soil Science
• Waste Management

Background:

• Compost quality and safety are vital for horticultural, agricultural, and silvicultural applications.
• Lack of standardized industry protocols for compost sampling and testing hinders production.
• Biosolids composting requires reliable maturity assessment methods.

Purpose of the Study:

• To evaluate three methods for determining compost maturity.
• To assess the impact of storage on compost maturity indicators.
• To develop predictive models for compost maturity during composting and storage.

Main Methods:

• Studied lime-stabilized biosolids compost over a 57-day period.
• Measured Dewar flask self-heating capacity, oxygen uptake rate, and cation exchange capacity (CEC).
• Investigated the effects of cold storage (up to 11 weeks at 4°C) on maturity indicators.

Main Results:

• The Dewar flask self-heating test was the most effective indicator of compost maturity.
• Oxygen uptake rate stabilized after 29 days, while the Dewar flask test showed changes throughout the 57-day period.
• Cation exchange capacity (CEC) increased with compost age and storage duration, and storage impacted test results, potentially indicating premature maturity.

Conclusions:

• The Dewar flask self-heating test is a reliable method for assessing compost maturity in biosolids.
• Cold storage can affect compost maturity indicators, potentially leading to inaccurate assessments.
• Standardized testing protocols are needed to ensure reliable compost quality assurance.