Case study: Pumps provide effective wastewater handling at California winery
Ecolabs designed and manages the wastewater treatment process for a Northern Californian vineyard producing premium varietal wines for global markets. Learn about the challenges and solutions in developing the system.
The dilemma of what to do with the waste stream created by the winemaking process is faced by every domestic vintner. Solutions are different for every one of them depending on where they are situated and the local and federal regulations for that particular location. One premium Californian winery manages these important issues with keen environmental awareness. Treatment and release of wastewater had to meet their high corporate standards.
With an expanding market for its wide range of varietal wines, production at the winery had to be increased. As such, an effective treatment process, for the wastewater generated by the plant, had to be designed. The challenge of meeting the waste stream demands, as well as maintaining optimum production at peak efficiency, fell to Jason Simpson, a plant manager at EcoLabs.
Part of the Water, Energy and Waste Solutions division, Ecovation Inc., which specializes in water treatment and wastewater treatment solutions that lower operating costs and raise energy efficiency, was the Ecolabs subsidiary responsible for the design. Working in concert with an engineering firm and hydraulic experts from Corrosion Products & Equipment (CPE), Ecovation designed a system that would collect the maximum output of the plant into a wet well and then move the effluent to an equalization tank, through a wastewater reacter, and finally to aerobic holding ponds. The treated wastewater would be used to irrigate the vineyard thus completing a completely green wastewater process.
Jake Scherer, vice president of sales, CPE pump division, coordinated the pump selection. There were numerous considerations:
- Corrosion resistance: The pumps needed to be corrosion resistant due to the acidity of the waste media.
- Erosion resistance: Hard metallurgy would be needed to stand up to the course solids (stems, pits, etc.) encountered.
- Non-clog design: As solids settle-out they would tend to clog pumping action.
- Minimal footprint and self priming: Using dry mount pumps would take up too much floor space and need to have reliable priming. Submersible pumps are inherently self-priming and keep cooler being submerged in the liquid.
- Reliable: Positioned at the bottom of a deep sump, the pumps would cause operational delays if they needed to be continuously pulled for inspection or maintenance.
- Capacity: Another consideration was providing the capacity needed for year round volume fluctuation. Vintage volume could fluctuate dramatically through the year. Daily flow through the plant could vary as much as three-fold (for example from 100,000 gallons per day off season to 300,000 gallons a day during the crushing season). As with most systems, the plant and equipment had to be sized to meet the maximum output.
Submersible pumps, in triplex design
Scherer decided to specify three submersible pumps installed in a triplex arrangement. The triplex lift station is a unique arrangement of three pumps operating in parallel. Choosing three pumps for the sump (instead of one or two larger pumps) increases reliability in the system while also efficiently covering a wide range of operating conditions. The triplex control allows operation of one, two, or all three pumps at a time depending on the changing rate of inflow to the tank. The pumps alternate lead and lag position so they get regular exercise and wear more evenly. There is also a high level alarm.
These pumps, for handling the grape wastewater process, are:
- Non-clogging: The pumps produce a shredding action caused by a cutting impeller with a tungsten carbide tip against a suction plate. The suction plate has an irregular opening with engineered cutting slots to help grab debris and aid the impeller with its shredding action.
- Volume and lift: The non-clog, single vane impellers are designed for high volume and lift performance – perfect for the wet well application.
- Wear resistance: All wear and "wet" parts (parts exposed to the grape waste) such as impeller, wear-plate, oil housing, pump-housing, and inner pump top are made of cast 316 stainless steel material.
- Reliability: The submersible motor is protected by double mechanical seals. Lower seals are made of silicon carbide/silicon carbide and the upper seal is made of carbon/ceramic. An additional lip seal was installed above the impeller to help prevent abrasives from entering into the seal chamber. Winding protection and (NEMA) Class F motor insulation allows the motor temperature to rise to 230 F, superior to pumps with Class A and B insulation. An automatic switch turns the pump motor off if the temperature and/or amp draw rises too high.
The final system was installed in 2008. As designed all wastewater flows to the wet well containing three submersible pumps in a series; a lag pump, a lead pump, and a spare. They remain totally submerged for maximum cooling, even at the lowest liquid level.
Effluent flows from the wet well to the equalization tank and the reactor then into aerobic settling ponds. The wastewater is held there until required for irrigation. Based on content, the ponds are drained and dredged to remove any sludge build-up. Reliability has been good, Simpson said; in five years, he has only replaced one seal, a failure recognized early by the warning system. The system keeps the winemaking process going. And keeps our glasses full.
– Edited by Jordan M. Schultz, content manager, CFE Media, Control Engineering and Plant Engineering, email@example.com.