In the last twenty or so years, the potato processing industry has experienced rapid growth globally, accompanied by an astounding increase in the amount of wastewater produced. Extensive volumes of wastewater and organic wastes are generated in the spud processing as a result of the water used in washing, peeling, and additional processing operations.

A reliable supply of sufficient processing water is a main concern for potato processors worldwide. In regions where there is a lot of pressure on the available water resources, processors are forced to invest in water use optimizations and water reclamation to secure production and/or an eventual increase in production.

At the moment, there is an increasing demand for quality improvement of water resources as well as the demand for better-finished products. These demands have driven the potato industry to develop methods for providing effective removal of flocculent and dissolved solids from the potato processing wastewater, to meet national water quality limits. In addition, extensive research has been dedicated to waste reduction and utilization of recovered wastes as byproducts.

“The waters resulted at potatoes washing for chips, snacks or fries production are valuable wastes, which contain organic compounds as proteins (around 0.7%) and starch (around 1.66%). Because these wastewaters are obtained from already washed potatoes, they have a low microbial charge, including a small number of coliforms, and no pathogens as Salmonella, Bacillus cereus or staphylococci,” Monica Mironescu wrote in her “Investigations on wastewaters at potato processing and starch recovery and characterization” research paper.

Water consumption for fluming (i.e. an economic way of transferring large volumes of low-medium pressure moving water) and washing varies considerably from plant to plant. Flow rates vary from 4,921 to 7,949 liters per ton of potatoes.

“Depending upon the amount of dirt on the incoming potatoes, wastewater may contain 45–181 kg of solids per ton of potatoes. For the most part, organic degradable substances are in dissolved or finely dispersed form, and amount to 0,9–2,7 kg of BOD5 (biological oxygen demand) per ton of potatoes,” Yung-Tse Hung and Howard H. Lo from Cleveland State University, USA, and Adel Awad and Hana Salman from Tishreen University, Syria also wrote in their “Potato Wastewater Treatment” paper.

A Key Challenge for Food Producers

Before they can be turned into foodstuffs, potatoes must be peeled, sliced, destoned, and washed, processes that require a significant amount of water. In recent years, hot washing systems and pulsed electric field (PEF) technology have largely replaced the traditional blanching process as the method of choice for removing excess starch before frying. As before stated, these techniques have helped make materials handling more efficient, but managing water usage while maintaining the quality of the final product remains a key challenge for food producers.

You can read the rest of this article in your complimentary e-copy of Issue 4 of Potato Business Dossier 2021, which you can access by clicking here.