Science Inventory

Scenario Analysis of the Impact on Drinking Water Intakes from Bromide in the Discharge of Treated Oil and Gas Wastewater

Citation:

Weaver, J., J. Xu, AND S. Mravik. Scenario Analysis of the Impact on Drinking Water Intakes from Bromide in the Discharge of Treated Oil and Gas Wastewater. JOURNAL OF ENVIRONMENTAL ENGINEERING. American Society of Civil Engineers (ASCE), Reston, VA, 142(1):04015050; 1-14, (2016). https://doi.org/10.1061/(ASCE)EE.1943-7870.0000968

Impact/Purpose:

The study discusses a model and various scenarios that illustrate the impacts on drinking water sources from bromide in the discharge of produced water, flowback water, and a mixture of both. Upon disinfection of drinking water, bromide can contribute to increased formation of disinfection byproducts (DBPs), regulated under the Safe Drinking Water Act. The simulations demonstrate that discharging treated produced water into rivers and creeks may create downstream conditions where bromide concentrations are above the EPA Information Collection Rule method reporting limit of 0.02 milligrams per liter (mg/L), based in part on health significance. The study does not address DBP formation upon treatment, which is caused by source water bromide concentrations and several other factors. The results suggest mitigation measures that can help meet the needs of drinking water plants: reducing effluent concentration or discharge rate/volume, pulsing discharges, or limiting otherwise acceptable discharges during low flow conditions in stream/river.

Description:

Elevated levels of bromide have been shown to contribute to increased formation of disinfection byproducts (DBPs). Hydraulic fracturing wastewaters can contain high levels of bromide. If these wastewaters are treated in conventional commercial waste water treatment plants, bromide may not be removed from the effluent and is discharged to receiving water bodies. Elevated bromide levels at drinking water plant intakes is a concern for public health reasons if elevated bromide levels cause elevated levels of DBPs. This study used data from commercial wastewater treatment plants and river flow data in western Pennsylvania to construct generic discharge scenarios that illustrate the impacts from disposal of produced water, flowback, or a mixture of both. Flows in the Allegheny River (PA) and Blacklick Creek (PA) were chosen for simulation, and treatment plant effluents were set at 100%, 50%, and 10% of the permitted value. For river flow, steady-state simulations showed that the disposal of mixed or flowback water generated median bromide concentrations below the EPA Information Collection Rule reporting limit of 0.020 mg/L only under high flow conditions. For creek flow, none of the simulated conditions resulted in median concentrations below 0.020 mg/L. Reduction in the effluent discharge reduced downstream impacts proportionally. Transient simulation showed that reduced mass loading from pulse inputs reduced the average downstream concentration by factors that exceeded the reduction in loading duration due to dispersion.