Pilot polymer reduces phosphorus; UV adjustments cut wastewater counts but raise budgeting questions
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Summary
Water department staff reported a phosphorus-removal pilot achieved average 87% removal but had challenges with iron and manganese removal; adjustments to the wastewater UV channel have reduced microbial counts and may be incorporated permanently, with chemical costs to be split across departments.
Ocean Shores water department staff reported progress on two operational items: a pilot polymer injection for phosphorus removal and changes to wastewater UV-channel hydraulics intended to improve effluent performance.
On the phosphorus pilot, staff said a high-basicity polymer injected into a pilot filter produced an average phosphorus removal of about 87% in limited runs, but it did not match the existing polymer’s performance for iron and manganese removal. Staff and engineering partners (SCJ Alliance and the Department of Health) are evaluating tap points and contact time to improve performance before broader implementation.
On wastewater performance, staff described adjustments to a UV-channel gate and re-routing some waste flow from the water treatment process that corresponded with marked reductions in reported counts: staff reported lowest equivalent counts dropping from 29 in June to 1 in August/September and maximums of 3 and 2 for those months. Staff said the temporary configuration appears to work and they are evaluating engineering options to make the change permanent; chemical cost increases would be shared between the water and wastewater budgets.
Staff said they have only two to three weeks of usable pilot data for the phosphorus trial because of material and operational interruptions and that additional runs are needed to simulate day-to-day performance. No formal policy or budget action was taken at the committee meeting.