Learning how to curtail phosphorus

A pilot project pointed the way for full-scale treatment of phosphorus at Metro

A pilot project pointed the way for full-scale treatment of phosphorus at Metro

When the Amended Consent Judgment was drafted, the Metropolitan Syracuse Wastewater Treatment Plant (Metro) was considered to be a major source of phosphorus to Onondaga Lake.

The Onondaga County Department of Water Environment Protection (WEP) implemented a $1.9 million pilot project in 2000—completed 6 years ahead of schedule—to evaluate six different phosphorus treatment technologies in anticipation of building new facilities to reduce phosphorus in its effluent.

The pilot project concluded that high-rate flocculated settling (HRFS) could reduce phosphorus in Metro's discharge to extraordinarily low levels (0.12 mg/L as a 12-month rolling average). On the basis of this work, WEP decided to use HRFS to meet New York State effluent requirements.

The pilot project also provided a basis of design for the full-scale phosphorus treatment facility that WEP completed in 2004.

The HRFS technology probably can achieve lower limits than Onondaga County currently must meet. Moreover, because of the high efficiency of the HRFS system, WEP has projected significant savings over traditional filter technologies.

By 2012 Onondaga County must reduce the phosphorus discharges to 0.02 mg/L, the most restrictive in the U.S. and perhaps in the world. To meet such a low limit, the County is again testing technologies.