High-tech wastewater system for ice cream firm

Tony Germann checks a pump on the coagulant tank. Multicap T capacitance probes measure level.

Chapman's Ice Cream in Markdale, Ontario, is a family business. Since its beginnings as a small creamery in 1971, it has grown to a multi-million dollar business producing ice cream products under its own brand name and others, such as President's Choice.

Ice cream production uses a lot of water, most of it in cleaning, which is carried out on a regular basis in the production cycle. The waste stream consists mostly of water, milk solids, sugars, flavourings and cleaning chemicals. Last year the owner decided it was time for the company to be treating its own wastewater, rather than sending it to the municipal system. He contracted the design and engineering of the new wastewater treatment facility to Elmira Pump Company, and gave owner Jim Germann, instructions to build a first rate system. Jim decided to use Endress + Hauser instruments for all measuring points in the new plant.

From the main plant the wastewater is held in a collection pit before being piped to the new facility. Here it goes into a 16 foot, 12,000 gallon surge tank which acts as a holding system to even out the flow. The level in the surge tank is measured by Prosonic T ultrasonic level transmitters.

In the next stage, the wastewater is pumped by variable speed drives to a neutralization tank where coagulant and polymer are injected to start the precipitation process. Caustic soda and sulphuric acid are added to neutralize the wastewater. This 12 foot tank contains an aggressive mixer. E+H analysis instruments measure turbidity and pH and control the amount of chemical to be added. Level is again measured by Prosonic T. Levels in the coagulant and polymer tanks are measured with Multicap T capacitance probes.

Wastewater is then pumped to the DAF (dissolved air flotation clarifier) where air is injected under high pressure causing bubbles to be trapped in the flocculant which then rises to the surface. A scraper at the top of the DAF removes the foamy solids which are collected in a holding tank. The resulting effluent is pumped to a holding tank where pH and turbidity are again measured before release to the municipal sanitary sewer. If the effluent is not in compliance, an alarm causes the system to reject the final discharge and the effluent is recycled through the process.

All measurements are relayed to a PLC and control panel in the wastewater facility.

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