BG Max improved the efficiency of anaerobic wastewater basins at a large pork processing facility. The improvement in treatment efficiency led to improved biogas generation and reduced the demand for externally purchased natural gas for savings of $170,000 in savings per year.
- 37% increase in biogas generation
- 39% increase in biogas yield per swine slaughtered
- Increased stability in lagoon operation
A pork processing facility in the Midwestern U.S. processes between 15,000 and 17,000 swine per day. The facility generates approximately 8,700 m3/day (2.3 MGD) of organic-rich wastewater (up to 60,000 mg/L COD), which is treated in the on-site treatment plant. The heart of the wastewater treatment plant is two anaerobic basins, followed by an activated sludge system. Biogas generation occurs in the system and is utilized as a supplemental fuel source for the facility’s boilers. The customer contacted Novozymes Biologicals for a cost-effective solution to increase biogas generation and improve their anaerobic treatment system performance.
Following grit removal and a dissolved air flotation (DAF) unit, the wastewater enters two 19,000 m3 (5 million gallon) covered basins which provide approximately 4.4 days of anaerobic treatment and reduce the COD by 60%. After anaerobic treatment, wastewater flows to a fine-bubble activated sludge system for final COD reduction and nutrient removal.
The customer chose BG Max because of the potential return on investment from improved biogas generation. Additional goals of the program included meeting corporate sustainability directives, such as reducing their carbon footprint and trading carbon credits on the Chicago Climate Exchange (CCX).
In October, the customer began adding BG Max to the influent of the anaerobic basins following a prescribed dosing protocol. Prior to the addition of BG Max and during normal operating conditions, the biogas generation of the facility typically fell near 8,300 m3/day (295,000 ft3/day) of biogas on a yearly average basis.
At the time of year when temperatures drop and methane generation is typically inhibited, this customer was able to increase biogas generation to levels which exceeded the average biogas produced over the past two summers. With BG Max, the anaerobic system began generating on average 9,100 m3/day (325,000 ft3/day) of biogas. This marked a 39% increase in the amount of biogas being produced per swine slaughtered. This improvement was demonstrated without any reduction in biogas quality (methane content 60–70%).
Fig. 1. Biogas generation increased with the use of Novozymes BG Max™ 3000.
Fig. 2. Biogas generation per swine slaughtered increased with the use of BG Max™ 3000.
In this instance, BG Max delivered a significant return on investment based on the offset of natural gas purchases due to the generation of additional biogas. Furthermore, this rate of return was accomplished during a period where the price of natural gas was 27% lower than its 10-year average. As the cost of natural gas begins to rise, the benefits of improved anaerobic treatment will only increase. The customer also benefited from reduced loading to the aeration system which could potentially improve cost savings further, by lowering the energy requirements for aeration and reduce solids handling costs.
By using BG Max, the customer improved the productivity and efficiency of their anaerobic system. The use of BG Max led to:
- Increased biogas generation
- Improved stability of operation
- Reduced cost in wastewater treatment
- Decreased loading to the aerobic system
- Improved sustainability