- Reduction of Solids Handling
- Odor Free Environment
- Odor Free Flush Water
- Denitrification of Ammonia
Hoffland Environmental, Inc. has developed an efficient, economical covered anaerobic system that not only digests the waste animal solids but also produces sufficient electrical energy to provide a positive payback for the farmer. The waste animal solids are utilized as a renewable energy resource (certain tax credits are available for this type of equipment). The waste solids (reference following diagram) flushed from the production floors are concentrated and transferred to a covered mesophilic (temperature 90-100°F) anaerobic digestion basin. The waste solids in the absence of oxygen and cultured under controlled mesophilic conditions, will biologically decompose forming biogas -principally methane gas. The methane is collected, pressurized and used as fuel for an engine/generator to produce electricity. The electricity produced will be adequate to supply all of the electric requirements for the farm plus sell the excess to the power grid. The amount of electricity produced is proportional to the farm’s animal population and also
to the efficiency of the anaerobic digester. The HEI Bio ’Lec digester is far more efficient than conventional technology because Bio ’Lec biogas production (600 Btu/cubic foot) reaches 42% conversion vs only 20 - 26% with conventional technology. Typically:
| Animal Units (AU) | CONVENTIONAL | Bio ’Lec | |
|---|---|---|---|
| 5000 Head – Finishers | 650 | 50 kW | 100 kW |
| 1000 Head – Sow – Farrow to Finish | 1300 | 100 kW | 200 kW |
The waste heat produced by the engine is captured and utilized to heat the digester basin to maintain the desired mesophilic microbial growth. Rapid decomposition of the waste solids occurs in a mesophilic culture. The size of the anaerobic basin is minimal requiring only 10 days retention, usually sized at 20 days for redundancy.
The effluent from the mesophilic digester is transferred to an aerobic basin to remove the remaining organic components and biologically remove the ammonia. The ammonia is biologically nitrified and subsequently denitrified to non-toxic benign nitrogen gas (process patented by HEI).
The effluent from the aerobic basin is stored for reuse or distributed through spray fields without the characteristic anaerobic odor.
Benefits
- Anaerobic odor free operation
- Anaerobic odor free spray fields
- Excess nitrogen nutrients are removed
- No chemicals required
- Sufficient electricity is produced for net payback of equipment
Typical Operating Cost
Sow Operation - (Positive payback from electricity produced, zero electricity bill)
Finisher Operation - (Positive payback from electricity produced, zero electricity bill)
Typical Treatment
| Organic Matter | Treatment Influent | Treatment Effluent | Reduction |
|---|---|---|---|
| Nitrogen | 20,000 mg/l | 250 mg/l | 99% |
| 600 mg/l | 25 mg/l | 97% |
Synopsis
Hoffland Environmental, Inc. will supply either the Aerobic or the Anaerobic system. The following is a brief comparison of the two processes.
|
|
Aerobic |
Anaerobic |
|---|---|---|
|
Capital Cost Operating Cost |
Low Capital Cost |
Low Operating Cost Available |
|
Ammonia |
Nitrogen Concentration Reduced |
Nitrogen Concentration Reduced |
|
Electricity |
Consumes |
Produces |
|
Waste Solids |
Solids produced must be stored or distributed daily |
Solids flow directly to the digester, no daily labor required |
Approximate Cost Excluding Earthwork & Installation
5000 Head Finishing Facility
|
|
Aerobic |
Anaerobic |
|---|---|---|
|
Capital Cost |
$100,000 |
$200,000 |
|
Energy Cost |
$5,000/year |
Net pay back possible $20,000/year |
15000 Head Finisher or 5000 Sow Facility
|
|
Aerobic |
Anaerobic |
|---|---|---|
|
Capital Cost |
$150,000 |
$280,000 |
|
Energy Cost |
$15,000/year |
Net pay back possibly $60,000/year |