Reducing phosphorus to lowest level in U.S.

Quick reference
— Technology
— Pilot study
— Future reductions

Although many people believe Onondaga Lake supports little life, one of its biggest problems is that it is sometimes “over-alive” with algae. The algae thrive because the lake has an overabundance of nutrients—such as phosphorus.

When algae die in the lake, they decompose and deplete oxygen. Large areas without oxygen are created, and no life can live without oxygen.

Onondaga County is reducing the phosphorus that reaches the Lake to extraordinarily low levels (0.12 mg/L as a 12-month rolling average). By reducing the amount of phosphorus that reaches Onondaga Lake, Onondaga County is fostering better water quality.

The new Plant Operations Center, attached to the new ammonia and phosphorus treatment facilities and the ultraviolet disinfection facility

The new Plant Operations Center, attached to the new ammonia and phosphorus treatment facilities and the ultraviolet disinfection facility

Onondaga County has met its first required 12-month rolling average (April 2006-April 2007) for Stage II phosphorus limits in its Metropolitan Syracuse Wastewater Treatment Plant effluent. The ACJ limit is 0.10 mg/L total phosphorus. Metro serves much of Syracuse and the surrounding area.

Technology

To meet the new levels, Onondaga County examined several different ways to reduce phosphorus from the treatment plant's effluent. The selected technology, which also is economical to implement, uses “high-rate flocculated settling.”

Phosphorus reduction from the wastewater at Metro will take place after the plant's conventional treatment and after the special ammonia removal treatment.
Steps in phosphorus treatment.

Pilot study

In 2000, Onondaga County conducted a pilot-scale demonstration project to evaluate the feasibility of the innovative technology for removal of phosphorus from the treatment plant's effluent. On that basis, it projected that the technology would operate to meet the new phosphorus limits.

Future reductions

In the future—by 2012—Onondaga County will reduce the phosphorus it discharges to Onondaga Lake to 0.02 mg/L. This is the most restrictive in the U.S. and perhaps in the world. The limit has been set low because Onondaga Lake is small and because it receives phosphorus from other sources (mostly with water that flows over the land into the lake—nonpoint source pollution). To meet such a low limit, Onondaga County is again testing technologies.

Reducing phosphorus levels will curtail unsightly algae, diminish odors in the lake, and improve the environment for the lake's fish communities. All of these benefits will make the lake more of an asset to the people who live near the lake or visit its nearby attractions.