A comparative techno-economic analysis review of gas valorization in the transition from wastewater treatment plants to water resource recovery facilities

Wastewater treatment plants (WWTPs) are transitioning into water resource recovery facilities (WRRFs), where the recovery of resources from wastewater streams is increasingly prioritized. CH 4 , CO 2 , and volatile organic compounds (VOCs) represent a promising resource for generating value-added products. This study presents a comparative techno-economic review of gas valorization pathways in the transition from conventional WWTPs to WRRFs, synthesizing technical evidence and literature-reported production costs. While several biological, catalytic, electrochemical, and membrane-based routes demonstrate strong technical potential, their economic viability remains uncertain. Cost analysis shows that added-value products obtained from CH 4 and CO 2 have production costs broadly comparable to market prices, suggesting potential competitiveness, whereas those derived from VOC lack reliable cost data. The findings underscore the need for comprehensive economic evaluations that include non-market externalities and carbon benefits.