| Amendments to the U.S. Clean Air Act in 1990 mandated the establishment of standards for air emissions in various manufacturing industries. The U.S. Environmental Protection Agency (EPA) stipulates that the emission of hazardous air pollutants by brick manufacturing industries are reduced to meet baseline standards by using air pollution control devices such as dry lime scrubbers and filters. The objectives of this research were: (i) characterize the effects of a by-product produced by the scrubbing process (scrubber by-product) on the growth and physiological responses of corn (Zea mays) and hybrid poplar clone 15--29 and OP367 when directly applied to soil, (ii) assess the potential utilization of the scrubber by-product in the treatment of dairy lagoon sludge, and (iii) characterize the effects of the treated sludge on the growth and physiological responses of sunflower plants.; Tests were conducted to investigate the effects of scrubber by-product on seedling emergence, dry matter production, chlorophyll a fluorescence, cumulative leaf area, and nutrient accumulation in corn and hybrid poplar plants. Application rates of up to 12.5% weight by weight (w:w) to soil had no adverse effect on corn seedling emergence, growth, and chlorophyll a fluorescence. Tissue concentrations of Ca and S were higher than normal in treated corn plants. Biomass production of hybrid poplar plants were not affected by scrubber by-product applications of up to 5% w:w, however, the photosynthetic apparatus of clone OP367 plants were more sensitive to the scrubber by-product than clone 15--29 plants. Plant tissues of both clones showed an excess of S above the 5% treatment level.; Experiments were conducted to investigate the effect of adding scrubber by-products to dairy lagoon sludge on (i) pH adjustment for pathogen control, (ii) settling rates of solids in the sludge, and (iii) mass reduction of the constituents of dairy lagoon sludge. Tests were conducted using two scrubber by-products from different sources. Scrubber by-product obtained from General Shale Brick (Louisville, KY) is designated as By-product I in the text, while that obtained from Boral Bricks Inc., (Augusta, GA) is designated as By-product II. The optimal levels of scrubber products that elevated the pH of the sludge under consideration to a level required for pathogen control were 84.02 g/L and 21.90 g/L for By-product I and II, respectively. Scrubber by-product I did not affect the settling rates of the sludge when compared to untreated sludge but treatments using scrubber by-product II had lower settling rates than that of untreated sludge. Use of the scrubber by-products enhanced the separation efficiencies of total solids (TS), volatile solids (VS), Al, B, Cl, Cu, Fe, K, Mg, Mn, P2O5-P, organic-N, soluble-P, and Zn. (Abstract shortened by UMI.)... |
