Biodegradability of electrostatic photocopier toners

Abstract

The biodegradability of two of the most popular brands of electrostatic photocopier toners (Minolta-Mt-Toner II and Sharp-Katun) in the Niger Delta and their reused forms was investigated. Heterotrophic soil microflora from the rain forest soil in the Niger Delta served as seed for biodegradation tests. The static shake flask method with toner as sole carbon source was used. Biodegradation was monitored over a 28-day period using changes total organic carbon (TOC), Dissolved organic carbon (DOC) ratio of DOC to TOC (Primary biodegradation) and Biochemical Oxygen Demand (BOD) measurements. At day 0 the BOD for Fresh Sharp, Reused Sharp, Fresh Minolta and Reused Minolta toners were 24.0, 22.4, 25.7 and 23.04 mg/l respectively. By day 28 BOD values were 7.4, 6.3, 6.0 and 8.0 mg/l respectively. At day 28 percentage loss of TOC for fresh Sharp, reused Sharp, fresh Minolta and reused Minolta were 85.0, 74.7, 86.7 and 75.8% respectively. During the same period percentage loss of DOC was 90.9, 77.3, 91.4 and 87.5% respectively. Primary biodegradation of toners was 52.4, 65.8, 100 and 63.0% during the same period. The pH and alkalinity increased from day 0 to day 14 and decreased by day 28. Nitrate, Sulphate and Phosphate levels decreased throughout the study. There was no significant difference at 95% confidence levels in these parameters between the two toner brands and their different states. However the reused toners showed slightly lower values of TOC and DOC than the fresh toners. The results showed that the toner brands and states were biodegradable. However the reuse of toners in photocopiers should be discouraged because of the production of modified products that are slightly more recalcitrant.

Keywords: photocopier, toner, biodegradability, toxicity, water quality

Tropical Freshwater Biology Vol. 14 2005: 95-107