Wastewater Reuse Using Micro Gas Dispersion Stripping

摘要

Investigation was made of micro gas dispersion (MGD) flotation of heavily-loaded complex wastewaters, a new flotation process, which focused on wastes from an industrial laundry since they represented the kinds of mixed contaminations found in wastes from the laundry's industrial clients. Wastewaters from some client plants and from nonlaundry clients which produce simpler but more heavily-laden wastewaters were also studied. The overall investigation sought to produce a recyclable effluent. All wastewaters were successfully clarified in two flotation steps. This process (tested in test-tube batteries, separating funnels, and in a two-column test stand) included automatic pH correction, flotation with an MGD, a second pH correction, and a second MGD flotation. Optimum compositions of the MGDs were sought. The successful MGDs contained 40-60% air by volume, water which became recycled, about 100 ppm of surfactants, and about 1000 ppm of a flocculant. For industrial laundry wastewaters, non-metallic contaminants were reduced from thousands of ppm at removal ratios of 3-275 (67-99.6% removal); metallic constituents were reduced from up to 25 ppm at ratios up to 10,000 (99.99% removal). Wastewaters from other sources were generally more easily clarified.