Trace Organics Removal by Advanced Waste Treatment

The performance of an advanced waste treatment plant, Water Factory 21, located in Orange County, Calif., was investigated with respect to organics removal. The processes for treating trickling-filter effluent were lime treatment for suspended solids and heavy-metal removal, ammonia stripping and breakpoint chlorination for nitrogen removal, recarbonation and filtration, activated-carbon adsorption for organics removal, reverse osmosis for demineralization, and final chlorination for disinfection. The COD and a broad range of volatile and gaschromatographable substances were measured in the plant influent and effluent and in the effluents of individual processes. Lime treatment was effective in removing COD and polychlorinated biphenyls, while both ammonia stripping and activated-carbon contacting removed a broad range of volatile compounds. Chlorination led to the formation of a variety of halogenated compounds, mainly trihalomethanes.