plastic

One Use for Post-Consumer Plastic Film: Agricultural Irrigation

Unlike metals, flexible plastic pipes don’t corrode. And they come with cheaper startup costs.

By finding a use for 100 percent post-consumer plastic film (LDPE) in the form of irrigation piping, Drought Diet Products is making the most of a material that’s proven tough to process by traditional recyclers. 

The company’s Aquifer pipe creates a virtual water table near crops’ root zone for more efficient irrigation. Because of its flexibility, recycled LDPE can easily be formed into coiled pipes. The coil sits on the back of a tractor and is simply inserted in the ground. Using traditional materials entails digging trenches, moving soil to install hard-to-maneuver pipes, and reburying them.  

Drought Diet president and founder Joseph Gallegos feels the Hawaiian Gardens, Calif.-based startup could create a strong market within the agricultural niche, while taking problematic wasted film off of MRF’s hands and diverting it from landfill, where most of it ends up. 

Unlike metals, flexible plastic pipes also don’t corrode. And, Gallegos says, they come with cheaper startup costs.

“Equipment to insert metal pipes or rigid plastics inexpensively does not exist. But flexible plastic pipes can be inserted into farmland at about a dollar a linear foot,” says Gallegos.

The company is conducting demonstration projects at several private farms in California and is involved in a joint study with the University of California, Riverside, on design for maximum flow through pipes.

Drought Diet also has the attention of other organizations focused on sustainability who believe the product could potentially be scaled up and commercialized. Closed Loop Foundation has awarded the company a $140,000 grant to see the idea move forward, and hopes others will follow the entrepreneur’s lead.

“It is not easy to sort film plastics at MRFs today," says Bridget Croke, vice president of external affairs, Closed Loop Foundation. "Why would MRFs want to solve this problem if there is no value in the commodity? We need companies like Drought Diet to build profitable markets for dirty film plastic packaging if we have any hope of diverting it from our landfills at scale.” 

The grant is underwritten and funded by SC Johnson, whose Ziploc bags will be incorporated into Aquifer pipes. The corporation has a stated goal of achieving curbside recycling, specifically for these products. Drought Diet is testing the process to determine if it can help its backer  achieve that goal.

“That Drought Diet has an existing product line that might soon offer one possible solution to Ziploc curbside recycling was a big factor in our decision to support the company.... All of us in the [manufacturing] industry and waste/recycling need to discover ways to build strong end markets … to see innovation in how this material is collected and recycled,” says Kelly M. Semrau, senior vice president global corporate affairs, communication and sustainability at SC Johnson.

“We hope the … product innovation we’re seeing from Drought Diet and others will provide a big step toward building those strong end markets,” Semrau says.

In the pipe application, the film is shrunk into a ball to be densified. It goes on to extruders who create the pipes and is delivered in coils to Drought Diet.

There are issues to be worked out, such as the problem of debris-clogged filters and screens.

But the biggest barrier has been in recovery. MRFs don’t want wasted plastic film, with its multiple layers and often with food debris and labels affixed. So it’s been hard to come by.

“Extruders shy away from dirty plastics because it leaves a bumpy finish and has pits in it. We don’t care about those finishes because our consumers just put it in the ground. No one sees it for decades, and it does not affect functionality,” says Gallegos.

The process could be cheaper and less time intensive than delivering clean plastic film, which entails shredding, washing and pelletizing before shipping to extruders for processing.

As the company moves forward, it’s focused on determining how to maximize mixed non-plastic materials that can also be passed through. And Drought is not the first innovator working on developing products from dirty plastics, including those mixed with other materials. 

Says Gallegos, “We want to see how dirty [the film] can get and still perform well.  So the question is, how much contamination [of nonplastic materials] can we accept before it affects products’ durability?  

“We feel once we work this out, we can provide domestic farmers with a tool that helps them drain or irrigate their fields effectively.

“We also see this as a model others can use to produce more plastic items. We may even be able to give knowledge to developing countries so they too can accept and process dirty plastics.”

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