By Michael Moore
Sustainability remains one of the most critical issues biosolids managers face today, but "Cost Effectiveness" of their management options has become even more important during these tough economic times. The changing regulatory climate, increased public scrutiny and reduction in the options available for disposal make biosolids management one of the more complex problems they face.
Issues facing biosolids management vary in different parts of the U.S. In California there are regulatory and legal drivers that reduce the available agricultural property for land application but in the central part of the U.S. the practice is actually increasing. Southern California delivers biosolids to welcoming farmers in western Arizona; Pittsburgh sends biosolids to Ohio and New York ships biosolids all the way to Colorado.
The farmers love to receive the inexpensive fertilizer, but municipalities are asked by biosolids opponents "If this stuff is so good why don't you use it in your own back yard?" which is not usually easy to answer. If a municipality tries to manage biosolids closer to their facility, permitting authorities or neighbors will typically put up significant hurdles.
Because of these siting issues there is a trend for municipalities to come together to form a coalition and site, build and operate one regional facility to manage their biosolids. The funding can sometimes be an issue so municipalities are now starting to allow the private sector to design, finance, build and operate these regional facilities.
There is a trend to want cleaner biosolids before distribution to the market place. Even though the scientific literature has not demonstrated problems with the current regulatory limits, the U.S. EPA is under a legal mandate to readdress their limits and if necessary reduce them.
Currently Pharmaceuticals and Personal Care Products (PPCPs) are not regulated in biosolids, but EPA is being pushed to develop limits even though the methods for analysis are not approved. Many municipalities have begun to monitor for PPCPs in their biosolids.
Municipalities are also being pushed to significantly reduce odors from the treatment processes that generate biosolids products, the transportation of those products and the final utilization of those products.
Biosolids, like wastewater treatment, has an odor and in order to be a good neighbor, there needs to be mitigation measures. On the municipal site with the pre-conditioning, digestion, dewatering, drying and truck loading there is a significant potential for odor release and neighbor reaction. During the transportation of unstable biosolids there is a great risk of angering neighbors near the site, along the roadways to a processing or utilization facility, and at that facility or agricultural site.
It has been said that "You smell with your eyes!" so even though a biosolids material has minimal odor, if the processing/utilization site has poor house keeping or if there is a pile of ugly material likely someone will complain about the odor.
For biosolids sustainability to occur, biosolids management warrants considerable attention. Water utilities should:
- Maximize use of methane from anaerobic digestion of solids & the thermal value of the solids for energy production, where applicable.
- Understand the greenhouse gas implications for the various management options.
- Understand sustainable return on investment (SROI).
- Implement biosolids management diversification.
- Implement cost containment strategies.
- Implement "Systems Thinking" including a "Stakeholder Involvement" Program.
About the Author: Michael Moore is HDR National Biosolids Lead. He may be contacted at email@example.com.