Renewable Diesel: Unique Wastewater Treatment Challenges

Renewable diesel (RD) is an emerging market that is expected to grow fourfold over the next five years. The associated wastewater is challenging to treat with chemical oxygen demand (COD) on the order of 40,000 to 60,000 mg/L. To put this in perspective, the addition of a 10,000 barrel per day (bpd) RD capacity to an existing petroleum refinery with 200,000 bpd capacity has the potential to quadruple the COD loading to the wastewater treatment plant (WWTP) while adding less than five percent to the hydraulic loading. This paper presents observations from several RD refineries that highlight potential wastewater treatment strategies. The findings can be used to inform the design and operation of wastewater treatment facilities handling RD wastewater. Failure to recognize the unique nature of RD wastewater is likely to have significant economic and environmental impacts.