Founded in 1950, Grupo LALA is the largest dairy company in Latin America, and the only dairy company that operates nationwide in Mexico. The company is made up of over 25 food and beverage brands, which make many different products including milk, cheese, yogurt, spreads, juice, desserts, and frozen treats.
Challenge
When Grupo LALA's plant in Torreón, Coahuila, Mexico, prepared to expand and introduce new product lines, the dairy processor knew its existing lagoons would not have enough capacity to handle the increase in plant production. Moreover, the open air lagoons were causing odor concerns. The plant is located in a busy, commercial area, so addressing the odors was important for community relations.
Water is extremely scarce in northern Mexico, and the hot sun can intensify odors. Grupo LALA, which prides itself on environmental sustainability, also had a keen interest in recycling water and recovering biogas for green energy. Based on the success of ADI-BVF® reactor systems at two other plants in Mexico, Grupo LALA expected the technology could be the solution for managing its complex dairy wastewater too.
Solution
ADI Systems designed, constructed, and commissioned an anaerobic treatment system at Grupo LALA's dairy plant in Torreón. The 22,000 m3 Type L BVF® reactor is able to treat dairy processing wastewater containing high chemical oxygen demand (COD), total suspended solids (TSS), as well as fat, oil, and grease (FOG) without the need for pre-treatment. As wastewater passes upward through the sludge blanket in the reactor, microorganisms digest the organic matter present in the wastewater (both soluble and non-soluble compounds), converting the majority of it into valuable biogas.
The low-rate BVF reactor is covered with a gastight, floating geomembrane cover system to capture all biogas from the anaerobic digestion process. ADI Systems' involvement in the project also included an accompanying biogas system that includes blowers and a flare. The headspace under the cover operates under a slight vacuum, which allows for odor control and temperature control.
Results
The BVF reactor at Grupo LALA's Torreón plant is designed to treat roughly 22,000 kg of COD per day, helping the dairy processor remain environmentally compliant. The expected COD and BOD removal rates are over 84% and 90%, respectively. The system eliminates primary treatment as raw suspended solids and FOG can be removed and digested in the reactor.
The long hydraulic retention time and large biomass inventory in the BVF®reactor work together to provide a high degree of stability and resiliency to changes in hydraulic and organic load. The treated anaerobic effluent exits the reactor through effluent piping and flows by gravity to the downstream aerobic system for polishing. Built-in equalization provides flow and load equalization for the remaining treatment, and the system can accept and digest waste activated sludge from the downstream aerobic process.
It is projected that the BVF reactor will produce approximately 420 Nm3/h of biogas with a composition of approximately 65% methane. The collected biogas has an estimated energy value of approximately 230 MMBtu/d. Biogas will be utilized in a process boiler at the production plant, helping the dairy processor reduce its carbon footprint. Excess biogas will be sent to a flare for safe disposal.
The BVF reactor contributes to the overall plan to reuse water at the Grupo LALA facility, helping address water scarcity. After further polishing, 1,000 m3 of industrial water per day can be reused in evaporative condensers and cooling towers. The wastewater treatment system will provide value and consistently high performance for many years.
