Occurrence and recalcitrance of polyethylene bag waste in Nigerian soils
Attempts to biodegrade polyethylene bag wastes (pure water sachets) weighing 25.2 g each were made by burying them in the soil and subjecting them to acid treatment (0.5 M HNO3) and alkaline treatment (0.5 M NaOH) over a 24 week study period. The experimental polyethylene bags (ED1) were inoculated with a strain of Pseudomonas spp. isolated from a refuse dump and by inorganic nutrient supplementation to facilitate biodegradation. Samples without inorganic nutrient supplementation and Pseudomonas spp. inoculation served as first control (CD1), while those placed on a slab on the surface of the soil served as second control (CD2) to evaluate the roles played by microorganisms and physical degradation, respectively. ED1 showed a slight reduction in weight to 24.9 g at week 16 after the acid treatment for 5 days and further reduced to 24.7 g at the end of the study after the alkaline treatment. CD1 reflected no variations in weight, while CD2 reduced to 25.1 g. The study showed that recycling of used pure water sachets which yielded useful products such as water seal, polyethylene bags and jerry can covers, appears to be the only option of checking environmental pollution caused by this product as microbial degradation proved ineffective.
Key words: Biodegradation, polyethylene, waste, recycling, recalcitrance.