Treatment of simulated oil and gas production wastewater using Typha latifolia in a pilot-scale constructed Welland

During hydraulic fracturing (‘fracking’), large volumes of highpressure, chemically-treated water are pumped into subsurface strata to free trapped petroleum and natural gas. Chemicallyenriched water, along with brine and groundwater, collectively termed oil and gas production water (PW), are eventually recovered from the well. PW poses environmental and health risks; however, it can be reused if potentially hazardous constituents are removed. A two-stage pilot-scale constructed wetland containing cattail (Typha latifolia) was tested for treatment of synthetic PW. After 49 days, PW pH increased from 4.2 to 7.0, and electrical conductivity decreased from 22,100 to 3,300µS•cm-1. Typha shoots had bioconcentration factors for Pb ranging from 2.8 (Stage 1 of constructed wetland) to 8.0 (Stage 2). Transfer factors for Pb were 0.67 (Stage 1) and 1.37 (Stage 2). These results indicate that Typha may be effective for Pb removal from PWs. The present study may be of practical value to oil and gas production companies that plan to recycle or properly dispose of large quantities of oil and gas production wastewater.