In my opinion, the anaerobic digester is not a feasible system to effectively improve farm wastewater for discharge to waterways. The reason is, it would require more than 500 digester tanks of 12 million gallons each to treat a volume of 200 million gallons per day, assuming a 30-day retention. This also assumes the wastewater is acceptable for anaerobic treatment.
The Anaerobic Digester Request for Proposal (RFP) is an assault upon the Focus on Energy program. Those funds are in short supply to promote awareness of renewable energy. Governor Walker scores points with industry by demoting alternatives that affect the petroleum industry. Focus on Energy has been a leader in Wisconsin that provides funding to projects such as wind and solar.
The RFP only requires treatment of wastewater discharged from the digesters. It does not stipulate treatment of the entire waste stream. Therefore, only five to 10 percent of the entire waste stream is expected for treatment. This would require approximately 30 digesters of 12 million gallons each. This system will be used to generate electricity or methane gas with a limited capacity that is dependent upon the efficiency of the digesters.
The RFP does not specify any values to regulate wastewater discharged to waterways except the WPDES [Wisconsin Pollutant Discharge Elimination System] permit. But remember, only wastewater discharged from the digesters is treated.
I am not against farming, but I believe the farmer is responsible to maintain those resources that include waterways and precious groundwater supplies. There is a limit of pollution to our water supply that is acceptable. I believe those limits have been exceeded.
As an alternative, aerobic treatment is a demonstrated method well suited to correct the current situation. The CAFO industry with existing equipment can build aerobic windrows that are safe and generate low amounts of odor. The end product is clean compost that could be sold or used as land treatments. This is a viable solution, that is lowest cost, clean, and odor free.
Copy of RFP: co.kewaunee.wi.gov/docview.asp?docid=22254