Pollution Control in Fertilizer Manufacture 1

Most air pollution regulations can be met by existing technology available. However, technology has not yet been developed to cope with the particulate emission problems at ammonium nitrate and urea prilling towers. Considerable technical effort is being devoted to finding solutions to the prilling tower problems. One possible solution for new plants is to granulate ammonium nitrate and urea in equipment which is amenable to particulate emission abatement. There are some unsolved water pollution problems at fertilizer plants awaiting further development of abatement technology. Miscellaneous discharges comprise a significant proportion of the aqueous wastes, and much of this loss can be avoided by adherence to good engineering practices when fertilizer plants are designed and constructed. In some cases, nutrients collected as wastes can be returned to the manufacturing process. Dust scrubber effluents and plant washdown obtained at granular fertilizer plants can be converted into liquid fertilizers; however, the dust collecting system should be designed to avoid excessive dust pickup. Two waste materials—gypsum and fluorides—are not normally suited for reuse in the manufacturing process. These materials are potentially useful by-products, and greater emphasis is being placed on their recovery as by-products because of the environmental problems associated with their disposal as wastes. Much progress has been made toward recovery of by-product fluorine, but by-product gypsum recovery involves large capital investment and extensive market development.