Recycling Life to Plastic Bottles

The Problem

A new bottle recycling center in North Carolina needed to process 75 million lb of compressed polyethylene terephthalate (PET) bottles. The bottles are sorted, shredded and sent through a series of processes. Because PET is semi-porous and absorbs food and beverage molecules, the shredded plastic must be chopped into “flakes”, washed and dried. It is then bagged and distributed to other companies for use in manufacturing a wide range of goods.

They use two sumps – a primary and a secondary pit – for the rigorous cleaning process. Wash down water, plastic pieces, dirt, soap, scum, and collect residue in the primary wash down sump during the initial grinding and cleaning. It is then pumped through clarifiers and screens to separate the plastic from the wastewater. The plastic is dried while the wastewater diverts to the secondary pit. The pumps in the secondary sump are responsible for reliably transporting this liquid to the onsite wastewater treatment plant. The wastewater is treated on site to remove all plastic and sludge before sending to the municipal sewer system.

The Solution

The recycling company worked with Derrick Heard at Tencarva Machinery to determine the pumps they would need. This sump application required specific attributes of the pumps:

1. High temperature capabilities: The temperature of the wash down water reach temperatures between 131°F and 140°F, which is too hot for standard submersible pump motors. Temperatures higher than 104°F typically cause standard submersible motors to fail;
2. Corrosion-resistant: The wash down water includes caustic cleaning chemicals. The pump would need to withstand abrasion from the corrosive materials; and 
3. Ability to shred the plastic pieces: The application required a solids handling pump (a shredder pump in this case) to shred the plastic in the liquid and transport it to the next stage.

Heard immediately thought of Industrial Flow Solutions. “I knew Industrial Flow Solutions offered the BJM Pumps Fahrenheit Series submersible pumps that handle high temperatures and could shred too. The combination is unique in the industry,” said Heard.

Heard recommended the BJM Pumps SKG Fahrenheit Series submersible shredder pumps because of the following:

• Reliably handles very hot liquids up to 200°F (93°C);
• Features patented Rad-ax dual shredding technology, which employs both radial and axial shredding to handle the plastic;
• Resists wear and operates longer, with all the shredding components manufactured from hardened 440C Stainless Steel (Rockwell hardness of 55C plus);
• Protects the high-torque, 4-pole motor with an oil-lubricated, double mechanical seal design with separate lip seal; and
• Withstands caustic chemicals with a corrosion-resistant, stainless-steel motor housing.