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Case Study – Finding a Circular Solution for Caustic By-Product

The Challenge:

A WTS client (a specialty chemical manufacturer) produces a versatile chemical product with multiple applications that are essential in the production of several important chemicals, polymer foams as well as a precursor to polymerization catalysts, pharmaceuticals, and agrochemicals. The custom manufacturing of this versatile chemical product requires the addition of caustic to maintain alkalinity in the production reactions. A caustic by-product is generated with a soluble concentration of the versatile chemical product. The properties and composition of the by-product required the manufacturer to manage the by-product as a hazardous waste stream, subject to costly destruction/disposal technology.

The Solution:

In collaboration with the chemical producer, WTS examined the manufacturing operations to ascertain the feasibility of modifying the process to create a caustic co-product. The process modifications addressed the removal of the soluble content of the versatile chemical product contamination by chemical oxidation. The resulting caustic co-product was staged in bulk as a recovered raw material with an average composition of 40% caustic, 60% water.

In collaboration with the chemical producer and WTS’ network of customers, WTS examined viable circular chemical solutions for the caustic co-product. WTS’ systematic approach involved connecting the producer with end-use manufacturers who could accept and use the bulk quantities of recovered caustic as a raw material, supplementing end-user requirements for the purchase of virgin caustic formulations.  In addition to confirming quality of the caustic co-product, WTS collaborated with the end-user to address any requirements for off-loading the caustic co-product in alignment with procedures that were in-place for virgin caustic purchases. WTS also collaborated with facility engineers to ensure the caustic co-product achieved the required treatment performance with the facility’s process water and wastewater treatment operations.

The collaborative process factored in logistic service solutions ensuring responsible management of bulk caustic transactions and the safe handling of the caustic co-product by the producer as well as the end-user facility.

The Results:

The operational changes and the systematic approach to rethinking material inputs and outputs resulted in a circular solution for the caustic by-product. In 2020, the producer was able to ship out six bulk loads of recovered caustic to a manufacturer who directly reused the caustic formulation in the plant’s water and wastewater treatment operations to ensure water quality for production as well as to address requirements for pH adjustment of treated wastewaters requiring discharge and environmental reuse. In total, 239,145 pounds of the recovered caustic co-product were directly used by the plant. This quantity of caustic co-product provided the end-user with environmental and economic benefits by ensuring compliance with wastewater discharges and minimizing the need to purchase and use virgin caustic, thereby reducing the embedded emissions in their supply chain.

For the chemical producer, this circular solution, eliminated the generation of a RCRA hazardous waste along with all relevant operating expenditures associated with ensuring proper handling, transport and destruction. By modifying the production flow and reacting the caustic by-product to eliminate the soluble concentrations of the versatile chemical product, the plant eliminated a hazardous waste and minimized environmental and safety hazards associated with in-plant handling and storage. The changes in the process resulted in a salable co-product that can be directly reused as a supplemental raw material.

The circular chemical solution aligns with sustainability commitments of the producer and end-user, and furthers WTS’ goal of enhancing the sustainability of its stakeholders.