KINETIC ASSESSMENT OF BIODEGRADABILITY IN GEL-FORMING SOIL CONDITIONERS BASED ON BOD ANALYSIS

Abstract

Biodegradation is one of the main factors limiting the efficiency and service life of gel-forming soil conditioners. The study quantifies this process using laboratory analysis of biological oxygen uptake (BOD) in innovative composite superabsorbents with an acrylic polymer matrix, amphiphilic agents (humates, peat) and silver ions as an inhibitor of biological activity. A simple kinetic model of BOD is proposed to standardize the analysis and calculation of the half-life of polymers after their incubation in precision VELP respirometers (Italy). The half-life of hydrogels swollen in distilled water (1:100) at a temperature of 30°C varied in the range from 0,8±0,2 to 2,4±1,6 years. The addition of an aqueous extract from compost sharply enhances biodegradation and reduces the half-life of hydrogels up to 40–60 days. Doses of 0,1–1% silver in a polymer matrix or 10-100 ppm in swollen hydrogels increase their half-life by 5–20 times. The new methodological approach makes it possible to fully automatically evaluate the biodegradation of gel–forming polymers in laboratory conditions, however, for stable materials with a half-life of more than 2,5–3 years, the accuracy of manometric BOD analyzers is insufficient for a statistically reliable assessment of the kinetics of biodegradation even in long (120 days) incubation experiments.