Passive solar evaporation and emissions reduction of process-affected and produced water using buoyant photothermal beads

Process-affected water (PAW), including flowback and produced water, presents considerable challenges for oil and gas industries and wastewater treatment providers. The complex chemistry and large volume production of PAW means that innovative solutions are required to treat and dispose of PAW while reducing environmental burden. Buoyant photothermal beads (BPBs) can operate in conjunction with existing evaporation ponds (EPs) by forming a connective layer and using sunlight to enhance the rate of water evaporation while also reducing the total amount of volatile organic compounds (VOCs) emitted from a water body. In this work, BPBs are shown to enhance the evaporation rate of a simulated seawater brine by 80%, as well as 5 different real PAW samples by 25% to 73%. Further analysis suggests that BPB performance is affected by the absorbance and apparent vapor pressure of the water matrix. Solid phase microextraction (SPME) is used to show that BPBs can significantly reduce VOC emissions compared to a bare surface when treating a volatile water matrix. Techno-economic analysis of the technology estimates a levelized cost of water of 0.44 USD/m3, demonstrating that BPBs have the potential to be a competitive technology and highly economical retro-fit for EPs. Graphical abstract. • Buoyant photothermal beads passively accelerate evaporation using sunlight. • Beads dewater process-affected waters and block VOC emissions. • Composite is easily manufactured and deployed at scale in evaporation ponds. • Competitive LCOW compared to existing wastewater disposal technologies.