ConAgra Foods processes many types of foods including salsas, canned vegetables, and popcorn at its processing plant in Irapuato, Mexico. Popular brand names include Hunt’s®, Del Monte®, and Act II®.

Challenge

The type and amount of production at ConAgra’s processing plant in Mexico varies greatly, depending on the season. Correspondingly, the plant generates variable wastewater flows and loads through the year. Fluctuations in the influent flow rate and variability of the raw wastewater characteristics considerably increase treatment difficulties. ConAgra Foods was faced with the decision of how best to implement an on-site wastewater treatment system.

Solution

ConAgra Foods chose ADI Systems' anaerobic technology to treat the wastewater at its production plant. Based on its many years of experience in the food processing industry, ADI Systems proposed its low-rate anaerobic ADI-BVF® reactor to treat ConAgra’s wastewater. ADI Systems knew it would be a reliable, robust wastewater treatment system for ConAgra. It achieves high removals of organic load and converts the majority of the chemical oxygen demand (COD), including total suspended solids (TSS) and fats, oils, and grease (FOG), into green energy in the form of biogas.

The BVF® reactor is the first step of treating the process wastewater, followed by aerobic polishing to meet final effluent discharge standards. The main components of the biological treatment train include a duplex influent pump station, a 12,500 m3 (3.3 MG) anaerobic BVF reactor, a gen-set system for biogas utilization, an aeration basin, a secondary clarifier, and a chlorine disinfection system.

The BVF reactor is complete with a flexible, insulated geomembrane cover to contain biogas, supernatant and anaerobic sludge recycle systems, and a duplex biogas blower and flare system.

Results

The BVF reactor for ConAgra Foods has been operating effectively for many years—even at lower-than-optimum temperatures (average temperature of about 86°F, 30°C​).

The anaerobic BVF reactor provides many advantages in the process of treating ConAgra’s raw wastewater. The reactor’s relatively large size and ability to maintain a large inventory of biomass result in a particularly robust system with built-in equalization capability and ability to accommodate shock organic and hydraulic loads. The ConAgra plant is achieving excellent COD, biochemical oxygen demand (BOD), and TSS removal rates of over 90% and meeting its limits for direct discharge.

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