Chemical characterization of synthetic soil from composting coal combustion and pharmaceutical by-products

Land application of coal combustion by-products (CCBs) mixed with solid org anic wastes (SOWs), such as municipal sewage sludge, has become increasingl y popular as a means of productively using what were once considered waste products. Although bulk chemical and physical properties of several of thes e CCB-SOW materials have been reported, detailed information about their sy nthesis and mineralogy of the CCB-SOW materials has not been reported. In t his paper, chemical and mineralogical properties of a soil-like material ob tained from composting a mixture of CCBs with a pharmaceutical fermentation by-product (FB) were investigated at the laboratory and field scale. All s tarting materials and products were characterized by X-ray diffraction (XRD ), fourier transform infrared (FTIR) spectroscopy, and elemental analyses. The results showed that the FB was strongly bound to the CCBs and could not be removed by washing. Within 2 wit of the start of a composting study, th ere was a rapid drop in pH from 12 to 8, an increase in temperature to 70 d egreesC, and a reduction in the dissolved oxygen content. attributed to the rapid establishment of a highly active microbial population. Composting pr oduced a soil-like material with high levels of plant nutrients, a high nut rient retention capacity, and metal contents similar to median levels of th ose metals reported for soils. The levels of boron and soluble salts are su ch that sensitive plants may initially show toxicity symptoms. However, wit h adequate rainfall, leaching should rapidly remove most of the B and solub le salts. With care, the material produced is safe for use as a synthetic t opsoil.