2021 WATER & WASTEWATER AWARDS

The 2021 ACEC/Iowa Engineering Excellence Awards winning projects in the Water & Wastewater Category, in the order listed:

Water and Wastewater Grand Place Award along with the overall Grand Conceptor Award (1st Place in Category and Overall)

Firm: Stanley Consultants
Client/Owner: City of Muscatine
Project: Converting Organic Waste into "Liquid Gold"

The Muscatine Organic Recycling Center (MORC) is one of just three municipally owned food waste recycling facilities in the U.S. It’s the only one of its kind in the Midwest.

What makes it so unique is its ability to separate food waste from its packaging. This allows it to process packaged foods that would otherwise be destined for the landfill because the labor costs to separate food from its packaging are cost prohibitive. But those costs are not a factor for the T42 Turbo Separator. Packaged food waste is dumped into a hopper where twin-screw augers feed it into the T-42. Its spinning paddles can break open a wide assortment of packaging, including paper, plastic, glass and aluminum. In just a matter of minutes the materials are separated. The packaging is funneled into a hopper for recycling or disposal. The captured organic waste is pumped into a tanker and transported ½ mile to the City’s Water and Resource Recovery Facility (WRRF).

At the WRRF the “liquid gold” is transferred through the high strength waste station into a 35,000-gallon treatment tank where it is blended so that the material becomes homogenous. It is continuously fed, via metered injection, into the same anerobic digesters that operate to clean the city’s municipal wastewater.
The bacteria in the anaerobic digesters break down organic matter by co-digestion, which occurs when anaerobic digestion is used to break down multiple forms of organic waste in one anaerobic digester. In addition to human waste, the bacteria feeds on fats, oils and greases (FOG) from restaurants, and food waste food from homes, businesses and industries.
The digestion process generates biogas that is mostly methane, the primary component of natural gas. Co-digestion can increase biogas production from low-yielding or difficult-to-digest organic waste. It also produces biosolids, a nutrient rich fertilizer that is applied to farm ground to naturally replenish nitrogen and phosphorus to the soil.
This uncommon facility is the vision of Muscatine’s Water and Resource Recovery Facility (WRRF) Director Jon Koch, who has a long-term goal of increasing the volume of biogas produced by the digesters, converting it into compressed natural gas for pipeline injection and eventually using it as a carbon negative vehicle fuel. That is a few years down the road. His first step toward that goal has created a novel organic waste recycling facility that has piqued the interest of wastewater professionals around the country.

The City’s two existing anaerobic digesters provide 888,000 gallons of co-digestion capacity equivalent to 8,900 tons of organic waste. “The bacteria in our digesters love the organic waste product we are feeding them,” according to Koch. “We are producing a lot more methane gas that is currently being flared off. Eventually we will have the facilities in place to turn that methane gas into compressed natural gas.”
The facility opened in May 2020 and has already put Muscatine on the map as a regional hub for organics recycling. Thus far, the vast majority of waste being processed is trucked in from local food manufacturers such as Kraft/Heinz and Nestle Purina. During the manufacturing process of many food products, packaged human or pet food is not suitable for sale due to health concerns or food quality standards. These must be destroyed as they are not suitable for consumption. Typically, these rejects end up in a landfill, but the new recycling center gives the manufacturers the better option of deriving benefit from the wastes and reducing the organic waste volume landfilled.
“We are processing 25 to 50 tons of organic food waste each day. Our target is 90 tons per day,” said Koch. The City has received an overwhelming number of inquiries from waste haulers and industries and he estimates that the capacity of the existing digesters will be exceeded in short order.

 

 

 

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