title: Utilization of dehydrated sewage sludge as an alternative nutrient to stimulate lipid waste degradation by the thermophilic oxic process.
abstract: Dehydrated and dried powdered sewage sludge (SW) was examined for use as an alternative to yeast extract (YE) to promote the degradation of lipid materials by a thermophilic oxic process (TOP). Its stimulatory effect on lipid degradation was found to be superior to that of YE. When 1.5 g of SW was added in combination with urea and 60 ml of a trace-element solution, the degradation efficiency was 82.9% for a 120-h treatment of 15 g of salad oil while that attained with YE was 68.3%. Although the degradation efficiency attained for animal fat, lard, was 77.8% which was lower than for vegetable oil, salad oil, it was still comparable to that obtained with YE, 76.9%. The applicability of SW to lipid degradation was confirmed in tests on three kinds of highly concentrated lipid wastes. With a nutrient supplement consisting of SW, a constant degradation efficiency of around 75% in 120-h treatment was attained for all lipid wastes despite their different features. The results of an elemental analysis suggested that the effectiveness of SW as a nutrient to stimulate thermophilic microbial activity in TOP was attributable to both a sufficient quantity and variety of amino acids and mineral components.
authors.affiliation: Institute of Applied Biochemistry, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Nakano
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Matsumura