Anaerobic Digester Enhancement: Improving Efficiency and Cost Savings
Kick up your methane and begin your path to a positive cash flow!
Benefits of Enhanced Methane Production
Even if you only use your methane to run your heat exchangers, reductions in sludge volumes and related disposal cost savings will provide you with a positive cash flow! Maintain summer operating temperatures even during cool winter months.
Case Study: Alabama Municipality
An Alabama municipality applied the technology to three anaerobic digesters. Results included an immediate increase in methane production from this system; it averaged a 73% increase during our trial. Methane can cogenerate electrical power. Through biological stimulation in this system, methane production is increased and stabilized.
With our applications for odor control, liquid sulfide values are biologically reduced and eliminated; in this application, hydrogen sulfide is a by-product of the biological breakdown of organics. If less sulfide is present, less hydrogen sulfide gas is produced; thus, the gas quality is improved.
As organics are converted to methane gas, there are fewer solids (sludge) to dispose of, in this case, 40.5%. These solids are processed and hauled away, with less solids and less cost. Another benefit realized by the staff was a 44% reduction of ammonia levels.
Applications in this area of targeting anaerobic digesters have also shown benefits, including increased ability to supernate digesters, stabilized volatile acid/alkalinity ratio (VA/A), less foaming, increased methane quality, and increased volatile destruction. The best part is that he has a positive cash flow based on solids reductions and related disposal expenses.
Case Study: Florida Municipality
Background
In a Florida municipality, an anaerobic digester was designated as the receiving point for septage and grease trap waste from hauling companies within the county. Pinellas County Utilities didn’t have a formalized grease handling plan, but their sewer ordinance prohibited grease disposal in the sewer system. They approved grease acceptance at the McKay Creek WWTF in 1994 as an interim solution to prevent illegal dumping.
This practice led to numerous odor complaints and increased labor costs. Grease was introduced into the existing anaerobic digester in September 1996, continuously impairing the process over the following year. Lab tests indicated that inefficient operation was a direct result of the varying influx of grease.
Pilot Test Results
A pilot test using the product at the McKay facility began on September 27, 1997, and proved beneficial to the digester’s operation. Since the product was applied, the digester has been operating at optimum performance. Benefits include:
- Increased ability to supernate digester
- Stabilized volatile acid/alkalinity ratio (VA/A)
- Increased methane production
Lab data shows that since the product’s application:
- The average pH is 6.8
- VA/A has stabilized around 28
- Volatile solids reduction increased from 10% to 15%
- Gas production became continuous, making it the sole fuel for the heat exchanger
Cost Savings
Before using the biostimulant, the heat exchanger unit operated on diesel, consuming 57 gallons daily for $61.14. Allocating the biostimulant at $79.00 per day resulted in a net savings of $22.14 per day in total operational costs, projecting annual savings of $8,081.10.
Financial Analysis for Clients
We recently completed a cash flow analysis for a client using the product in anaerobic digesters. Based solely on savings in solids disposal, the client saw a 41% return on investment. This excludes increased methane production, improved gas quality, and other related benefits.
An investment of $1365 per week gave a positive return of $576. Can you afford NOT to use this product?
Ideal Client Profile
An ideal client for us utilizes ALL of the produced methane, powering the heat exchangers and plant and selling the unused power back to the electrical grid.