Focus on Wastewater Treatment Early and Often
By Pam Buzzetta and Ryan Caulfield
With any bench scale testing for a new technology, it’s easy to overlook major obstacles in ancillary operations. Wastewater treatment (WWT) is a critical piece to many bioprocessing projects. Neglecting to properly design WWT units can go so far as to kill a fledgling technology.
Biomass systems typically have large volumes of wastewater since the biomass feedstock is composed primarily of water. Bioprocessing WWT systems are often expensive due to the high loading of biochemical oxygen demand (BOD) and chemical oxygen demand (COD) from biomass feedstocks. The WWT system can be 1/3 of the cost of the entire plant.
Additionally, there are preconceptions that a process can just use a “standard” wastewater treatment plant. No such “standard” exists in bioprocessing. The needs are highly variable based on the contaminants in dirty process water and regulatory requirements associated with the point of discharge.
Some fundamental steps can keep a technology on the right track to ensure WWT won’t be the death of the innovation:
- Collect representative water samples during each stage of the technology scale up. Have a lab with expertise in characterizing wastewater provide appropriate analyses of the samples.
- Identify where a plant will be located as early as possible. Each county, municipality, or authority having jurisdiction over water discharge permits has different requirements. If the location is uncertain, consider evaluating the cost at multiple sites that are probable locations for the project.
- Engage a wastewater treatment vendor early and often. Provide them with the characterization of the wastewater samples along the development path and water discharge requirements identified. These vendors provide vital input to the true cost and needs of the process.
- Ensure the vendor understands the objectives of the unique process; writing a clear performance specification is key to successful communication. If a vendor is willing to provide a proposal for a treatment unit without reviewing water characterizations or established parameters at the point of discharge, think twice about using their solution. Those proposals may contain vastly oversized and/or unnecessary treatment steps that may or may not work for this unique process.
- Engage an EPC firm as early as possible as well. They have expertise in the integration of WWT system to the overall process. They can perform a plant water balance early on, then look for places to integrate and recycle water. They will also ensure sufficient plot space is allocated for wastewater treatment. Biological treatment systems can be large, and may require as much or more plot space as the entire bioprocessing process.