Biodegradation of non-calorific fat substitutes sucrose polyesters in sewage sludge amended soil

• Published in: Chemosphere (Oxford) 1997-08, Vol.35 (3), p.413-425
• Main Authors: Haigh-Baird, S.D., Bus, J., Engelen, C., Hill, R.N.
• Format: Article
• Language: English
• Subjects: Applied sciences; Biological and physicochemical properties of pollutants. Interaction in the soil; Exact sciences and technology; Pollution; Soil and sediments pollution
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/S0045-6535(97)00106-9

As part of an overall environmental assessment, a non-metabolisable synthetic fat, sucrose polyester (SPE), was evaluated in terms of biodegradability in sewage sludge amended soil. Three SPEs were investigated, each predominantly composed of octa-esters, but varying in the saturation and chain length distribution of the attached fatty acyl groups. When applied at 100 mg/kg soil, the mineralisation of SPEs was poor to moderate. The most extensively degraded SPE was the liquid type (experimental code D2), with 36% mineralisation in 151 days compared to 63–79% for two triglyceride controls, glycerol trioleate and HB307. The solid SPE types (codes X12 and Z24) gave 0.47 and 0.94% CO 2 respectively under the same conditions. Following incubation, up to 30% of the residual D2 remained non-extractable, probably due biological breakdown followed by incorporation into biomass and soil humic material.For X12 and Z24, less than 2% of the residue was non-extractable, but for X12 at 7.5 mg/kg, 9% of the residue was non-extractable.Thin layer chromatography (TLC) demonstrated that almost all the D2 extracted exhibited more polar behaviour than the parent material. For X12 and Z24 there was little or no change in behaviour. However, for X12 at 7.5 mg/kg there was a significant shift of the extractable residue to more polar characteristics as compared to the parent material. The data suggest that the liquid SPE type D2 has the potential to undergo significant degradation in sludge amended soil, including incorporation into biomass and soil humic material, and it would be unlikely to persist. However, for the solid SPE types there is little evidence for either complete or partial breakdown of the materials, although at low concentrations X12 residues appeared to undergo some form of degradation. Therefore, the possibility of accumulation of the solid SPE types in soil, following their annual application via sewage sludge, cannot be discounted.