Design of 90-MGD Wastewater Reclamation Plant

Ninety MGD of municipal secondary effluent is to be reclaimed for use as cooling water in the Palo Verde Nuclear Generating Station in Arizona. The water reclamation plant design criteria are presented for nitrification, lime-soda softening, filtration, and sludge processing. In-pipe storage is used for flow equalization. Forced air down-draft trickling filters with computer-controlled recycle are used for nitrification. Effluent recirculation is used to maintain constant sludge blanket dept in the upflow solids contact clarifier softening units. An influent flow-splitting, gravity-backwash, dual-media filter is used for final suspended solids removal. Rheological data was used in the hydraulic design of sludge piping. Computerized automatic flushing also aids in preventing sludge pumping problems. Reclamation plant design and construction are integrated in one Engineering-Procurement-Construction project conducted by a single company.