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Church and Dwight uses a phosphate-containing soap in their latex condom manufacturing process in Chesterfield County, VA. The wastewater streams from this process contain a concentration of phosphate that is over the county limit, costing $100,000/yr for non-optimized disposal. C&D has a need for an in-house method of phosphate removal which does not interfere with current manufacturing or wastewater treatment processes. The focus of the project was precipitation methodology as it is the most economically feasible option for these high concentrations of phosphate; more advanced technologies were considered for a potential final polishing step to remove any residual phosphate. The chemistry for the proposed process was developed by Design of Experiment, utilizing multiple independent and dependent variables. Once optimized, pilot trials were performed in order to verify the lab-scale chemistry. The proposed method of phosphate treatment requires a pH adjustment of the wastewater via sulfuric acid, followed by chemical precipitation via PC-1101 (proprietary coagulant). This solid precipitate is then to be collected utilizing a filter press. Optimal laboratory trials consistently reduced the phosphate concentration by >95%, from 2000-3000 ppm (as Phosphorus) to a nominal 50 ppm (as P). This method will reduce the cost of phosphate treatment by about 40%, with room to further reduce cost via long-term optimization of the pH and coagulant ratio.
Chemical Engineering | Engineering
Dr. Bennett Ward
VCU Capstone Design Expo Posters
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