Willamette Water Treatment Plant Wilsonville Oregon WQT 131 Field Trip

Meet The Wilsonville Water Treatment Plant Lead Operator: Kevin Battridge Wilsonville is a city of ~16,000 inhabitants. Plant is available to treat 15 MGD presently WTP treats 2-6 MGD. This slide show is a virtual tour of how the plant looks today from the remodeled version that took place in 2002.

Water Treatment Steps Collection from the Willamette River. pH adjustment. Coagulation and Flocculation with Actiflo design. Sedimentation with Lamella Tubular Settlers. Ozone Dose. Filtration with Granular Activated Carbon (GAC) with a biologically active component (BAC) Clear Well 12.5% Sodium Hypochlorite Disinfection.

Water Treatment Steps

What is novel at this plant? Uses state of the art technology (Ozone & GAC) Has a low ecological footprint The final product is water that is far below EPA regulations

Source Intake Process Water is collected from the bottom of the Willamette River through intake screens that bring in water at a very low velocity. This avoids brining in unwanted sediment and oils that float along the surface. An opening in the screen is about the diameter of a toothpick. To clean the screens water is back flowed back into the Willamette R.

Source Intake Process Water is then transported through a 72 inch diameter pipe to a Caisson (measuring 80 feet deep and 35 feet wide). pH adjustment with 25% NaOH (sodium hydroxide) buffer is added to influent water. Caisson 35 feet wide Willamette River 80 feet deep 72 inch diameter pipe

Actiflo Sediment and Flocculation process. First rapid mixing of water with cationic polymer and microsand. Flocculation in mixing pool before lamella tubular settlers, flocculation is heavy and stable flocs. Provides phosphorous removal. Return tubes are designed to reuse microsand. Very inexpensive process.

Rapid mixing of polymer and Microsand

Lamella Tubular Settlers & Solids/Sand Return Pipe & Flocculation tank

Lamella Tubular Settlers

Facts about Lamella Tubular Settlers Tubes are in a 60o angle to each other. Tubular Settlers need a flow rate of 1.5 - 3 gpm. Made of lightweight PVC material, which is very inexpensive. 2 to 4 times better operation in settling out floc.

Ozone Treatment 1.8 ppm dose to water after Actiflo (at 3.0 NTU) Ozone is made at the WTP. Ozone is very unstable disinfection. The more particles present in water the less contact time that ozone stays as an O3 molecule. Expensive, but there are no carcinogenic side-effects. Evaporators Liquid Oxygen

Ozone Production Because of the short half-life of a few minutes to a half hour, ozone is always produced on-site with a ozone generator. Corona-discharge method is used at WTP. A 800 volt arc ruptures the O2 into two free oxygen radicals. The oxygen atoms want to be stable so the atoms recombine into a combination of oxygen gas (90%) and ozone or O3 (10%). Ozone production is very energy intensive. Ozone is a toxic gas! Ozone is also very corrosive and to breakdown the ozone before continuing in the treatment process calcium thiosulfate is added to the water. This is a catalyst to decrease the half life of the ozone.

Willamette River Water Treatment Plant Wilsonville, OR Ozonation Liquid Oxygen Converts O2 gas to O3 (ozone)

Willamette River Water Treatment Plant Wilsonville, OR Converts O2 gas to O3 (ozone)

Clarifier Basin of Washed material after Lamella Tubular Settlers

Washed Water Collected waste water from treatment plant and all sediment waste water All wash water is recycled throughout the treatment plant

Granular Activated Carbon GAC Granular Activated Carbon 6 foot bed of GAC The bottom is a 1 foot bed of silicia sand. This is a biological process. GAC and sand is cleaned on a 4-5 year cycle. Takes care of taste and odor.

Sand Used for Coagulation

Chemicals 25% NaOH- Caustic Soda- raise alkalinity for pretreatment and improve Alum use post treatment corrosion control ALUM, Cationic polymer – improve coagulation with microsand (ActiFlo) 12.5% sodium hypochlorite- Residual dose about 0.2 mg/L Polymer for sludge settling in backwash basin Calcium thiosulfate- remove off gas of ozone and minimize its corrosiveness

Pumps for taking water to the four reservoirs Three reservoirs are in the north end of Wilsonville, and the other is in the southeast.