Origin of talc, iron phosphates, and other minerals in biosolids

• Published in: Soil Science Society of America journal Vol. 69; no. 4; pp. 1047 - 1056
• Main Authors: Jaynes, W.F, Zartman, R.E
• Format: Journal Article
• Language: English
• Published: Madison Soil Science Society 01.07.2005; Soil Science Society of America; American Society of Agronomy
• Subjects: Aggregates; Agronomy. Soil science and plant productions; Anaerobic digestion; Applied sciences; Biological and medical sciences; Biological and physicochemical properties of pollutants. Interaction in the soil; Biosolids; chemistry; Clay; Cosmetics; Earth sciences; Earth, ocean, space; Electron microscopy; Engineering and environment geology. Geothermics; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; inorganic materials; Iron phosphates; Kaolinite; land application; Mineralogy; Minerals; New York City; Other nutrients. Amendments. Solid and liquid wastes. Sludges and slurries; Pollution; Pollution, environment geology; Quartz; Sewage sludge; Silicates; Silt; Soil and sediments pollution; Soil and water pollution; Soil science; Soil sciences; Soil surfaces; Soil testing; Soil-plant relationships. Soil fertility. Fertilization. Amendments; Soils; Storm drains; talc; X-ray diffraction; New York; Texas; Origin; Soil chemistry; Iron phosphate; Talc; Mineralogy; Mineralogical composition; Organic fertilizer; Phyllosilicate; Earth science; Minerals; Sewage sludge; Mineral matter; Inorganic compound; Environmental engineering; Engineering; Inorganic chemistry; Non silicate mineral; Soil science; Chemical composition; Silicate mineral; Organic amendment
• ISSN: 0361-5995; 1435-0661
• DOI: 10.2136/sssaj2004.0207

Biosolids (i.e., sewage sludge) contain as much inorganic as organic materials. The inorganic materials include local soils, sediments, and other materials washed down residential, industrial, and storm drains. In this study, the chemistry and mineralogy of the inorganic materials in New York, NY (NYC) biosolids applied to soil surfaces in western Texas from 1992 to 1999 were examined. Inorganic residues were 44 to 77% of whole biosolid weights after oxidation of the organics with H2O2. Inorganic residues consisted largely of silt- and clay-size particles with smaller amounts of fine and very fine sand. Selective dissolution and chemical analyses of the residues indicated >20% Fe phosphates, formed during anaerobic digestion, that contained Al, As, Cr, Cu, Hg, and Zn. X-ray diffraction, selective dissolution, and surface area analyses showed that the Fe phosphates were poorly crystalline. The mostly quartz and feldspar sands also contained glass shards, textile fibers, and zircon grains. New York City area biosolids contained quartz, feldspars, kaolinite, mica, and expandable layer silicates. Electron microscopy and x-ray spectra of the clay fractions revealed aggregates of layer silicates and Fe phosphates containing Al, Ca, and Ti. Pigment TiO2, commonly used in foods and cosmetics, contributed Ti to the layer silicate aggregates. Talc derived from cosmetic products was identified in silt and clay fractions by x-ray diffraction and electron microscopy. Less talc occurred in the 1999 and 1997 biosolids relative to 1992, 1993, and 1994 biosolids suggesting reduced use of talc products. Nationally, cosmetic talc use decreased during that time, probably due to health concerns.