Strong Modules to Meet Strict Standards

The City of Stockton, Calif., needed to upgrade its 55-mgd wastewater treatment plant (WWTP) in order to meet National Pollutant Discharge Elimination System (NPDES) regulations for tertiary treatment. The goal of this upgrade was to select a reliable yet economical technology that would achieve tertiary nitrification, especially during the winter months.

Small Town, Big Challenges

As a 3.4 mgd plant built in the 1920s, the Aqua America Tiffin, Ohio, drinking water treatment plant faced the challenge of producing high-quality drinking water. With a full measure of seasonal variety combined with the runoff from a thriving agricultural environment, the small-town facility constantly encountered adverse conditions. In a short time period, influent turbidity could fluctuate from 10 to 2,000 ntu. This “flashy” water source and the area’s stringent regulations posed frequent operational difficulties.

Feeling the Squeeze

When the Coldwater Board of Public Utilities in Coldwater, Mich., abruptly received new ammonia permit limits in August 2007, it hired consultants Fishbeck, Thompson, Carr & Huber, Inc. (FTC&H) to guide it to a solution. With a full measure of influent waste variety—residential, commercial, industrial and septage—and a new seasonal permit limit of 2 mg/L, Coldwater needed a budget-friendly solution to consistently perform through peak flows and industrial shock loading.