LCA based comparative study of a microbial oil production starch wastewater treatment plant and its improvements with the combination of CHP system in Shandong, China

• ALCA analysis was used to evaluate environmental impacts of a starch WWTP in China.
• The ALCA results were compared against a conventional WWTP.
• CLCA analysis was used to evaluate the effects of renewable biomass energy usage.
• Global and regional normalization factors were used to interpret the LCA results.
• This LCA study also identified the potential of sustainable renewable energy usage.

A life cycle assessment (LCA) analysis was carried out to evaluate the environmental performance related to a corn starch wastewater treatment plant (WWTP) with simultaneous microbial oil production in Shandong, China, compared against a non-oil producing WWTP. The software GaBi 5.43 was employed for the LCA analysis. Applying an attributional modeling LCA the results showed that the WWTP, despite removing high concentrations of organic matter from the wastewater and being economically feasible by the production of crude bio-oil, has 2330% increased emissions related to energy consumption into the air compared to a non-oil production process. Taking in consideration an estimated activated sludge WWT and anaerobic digester process, the conventional process would have higher GHG emissions. With the LCA results, a consequential modeling LCA taking corn stover biomass as renewable energy source in a direct-fire system was proposed. It showed that corn stover biomass has the potential to mitigate the high emissions to the air due to the abundant available resources near the plant location. Global and regional normalization references were also used to represent the real impact of the LCA results. This study not only revealed an environmental evaluation of the current wastewater microbial oil production technology, but it also helped to identify process bottlenecks and the use of renewable energy opportunities which should receive specific research efforts to make this process environmentally sustainable.