Aeration, biodegradability tests

Soil is a highly variable entity in terms of its composition and biological activity, both varying with location, season, pretreatment, and storage. To date it is impossible to standardize soil as a biodegradation test medium. Most test protocols use these soils with different texture characteristics namely sandy, loam and clay textured soil, and under near optimal conditions of moisture, aeration, temperature and pH [115]. 

Anaerobic tests generally follow biodegradation by measuring the increase in pressure and/or volume due to gas evolution, usually in combination with gas chromatographic analysis of the gas phase [83, 84]. Most aerobic standard tests apply continuous aeration the exit stream of air can be directly analysed continuously using a carbon dioxide monitor (usually infrared detectors) or titrimetrically after sorption in dilute alkali. The cumulative amount of carbon dioxide generated, expressed as a percentage of the theoretically expected value for total conversion to CO2, is a measure for the extent of mineralisation achieved. 

Appropriate mineralisation procedures in a laboratory composting test with adequate aeration using matured compost or soil as inocula to provide assurance of ultimate biodegradability [34,49,67]. 

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