by CASA Director of Renewable Resource Programs, Greg Kester 

What is the most successful recycling program in America? I would argue that it’s the successful recycling of biosolids back to land – returning to the soil that from which it came. Biosolids are the highly beneficial product of wastewater treatment. Solids produced in the water cleansing process are themselves treated and called biosolids when they meet federal and state requirements which allow their recycling to land. Land application has been researched for decades at virtually every land grant university in the country and the benefits well documented through myriad programs. Biosolids improve soil health through the increase of soil organic carbon, increased crop yield and biomass production, decreased need to irrigate due to their high water holding capacity, and improved soil tilth. Land application also mitigates climate change by sequestering carbon long term in the soil and reducing the use of fossil fuel-intense chemical fertilizer (almost a quarter of a gallon of fossil fuel is required to produce every pound of inorganic nitrogen). Yet, this recycling practice is curtailed in various parts of California due to restrictive county ordinances. We hope to work with those counties to revise their ordinances to allow land application while still providing sufficient safeguards so as to ensure public and environmental health.

California has enacted several laws to mitigate climate change and improve environmental and public health by 2020. The wastewater sector can help achieve all of the goals of these statutes, which include: returning to 1990 levels of carbon dioxide equivalent emissions; producing 50 % of our energy from renewable sources (by 2030); recycling 75% of the solid waste generated in the state; reducing the carbon intensity of transportation fuel by 10%; reducing short lived climate pollutants (SLCP) (including methane); and ensuring healthy soils for future generations of California farmers.

How can the wastewater sector help achieve these goals? We can help through the receipt of more organic waste for co-digestion at our plants—waste which would otherwise be destined for landfills. Through co-digestion with organics, we produce more biomethane which can be used to generate more renewable energy, be converted to low carbon transportation fuel, or be injected into pipelines. Diversion of this organic waste stream from landfills also helps meet the strategy outlined in the short lived climate pollutant reduction plan. Finally we can recycle biosolids to land to help improve soil health and simultaneously mitigate climate change.

Biosolids production will increase but management options for biosolids will decrease as climate change mitigation efforts intensify. While more than 60% of biosolids are currently land applied, they have historically also been used for alternative daily cover at landfills. In order to achieve the SLCP goal, we expect a ban of all organics at landfills, including their use as alternative daily or final cover, by 2025. Incineration, already very limited in California, is not a viable option for expansion, given the cost of compliance and the difficulty of permitting new incinerators. Innovative technologies may emerge to allow extraction of energy from biosolids and reduce the output of biosolids, but none are in place at full scale in California or the nation to date.

This means recycling of biosolids to agricultural land and other soil will continue and expand as a prime alternative. Support for land application at the state and local levels is key to ensuring sustainably viable long term biosolids management. CASA has engaged in dialogue with regulators at the state and local level and is encouraged that the benefits of land application are beginning to be understood by all. This dialogue must continue and turn into action to reverse restrictive local ordinances and policies to ensure biosolids are recycled to the maximum extent feasible and that healthy soils are indeed available for future generations of Californians.

Which leads us back to the ultimate act of recycling via the land application of biosolids. It completes the circle and creates a holistic solution for waste management. We accept organics for co-digestion rather than landfilling them. We produce more renewable energy and then recycle the resultant biosolids to land so they can replenish the food chain once again!

So, how do you think we can best engage with local officials to convince them of the benefits of land application?