Treatment of oil sands process affected waters by constructed wetlands: Evaluation of designs and plant types

Monique C Simair; Joanne L Parrott; Mignon le Roux; Varun Gupta; Richard A Frank; Kerry M Peru; Chukwuemeka Ajaero; Dena W McMartin; John V Headley

doi:10.1016/j.scitotenv.2021.145508

Treatment of oil sands process affected waters by constructed wetlands: Evaluation of designs and plant types

Sci Total Environ. 2021 Jun 10:772:145508. doi: 10.1016/j.scitotenv.2021.145508. Epub 2021 Feb 1.

Authors

Monique C Simair¹, Joanne L Parrott², Mignon le Roux³, Varun Gupta⁴, Richard A Frank⁵, Kerry M Peru⁶, Chukwuemeka Ajaero⁷, Dena W McMartin⁸, John V Headley⁶

Affiliations

¹ Maven Water & Environment, 103-303 Wellman Crescent, Saskatoon, Saskatchewan S7T 0J1, Canada; Department of Civil, Geological and Environmental Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, Saskatchewan S7N 5A9, Canada. Electronic address: monique@mavenwe.com.
² Water Science and Technology Directorate, Environment and Climate Change Canada, Burlington, Ontario L7S 1A1, Canada. Electronic address: joanne.parrott@canada.ca.
³ Maven Water & Environment, 103-303 Wellman Crescent, Saskatoon, Saskatchewan S7T 0J1, Canada; Department of Civil, Geological and Environmental Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, Saskatchewan S7N 5A9, Canada.
⁴ Maven Water & Environment, 103-303 Wellman Crescent, Saskatoon, Saskatchewan S7T 0J1, Canada.
⁵ Water Science and Technology Directorate, Environment and Climate Change Canada, Burlington, Ontario L7S 1A1, Canada.
⁶ Watershed Hydrology & Ecology Research Division, Water Science & Technology Directorate, Environment & Climate Change Canada, 11 Innovation Boulevard, Saskatoon, Saskatchewan S7N 3H5, Canada.
⁷ Watershed Hydrology & Ecology Research Division, Water Science & Technology Directorate, Environment & Climate Change Canada, 11 Innovation Boulevard, Saskatoon, Saskatchewan S7N 3H5, Canada; Environmental Systems Engineering, University of Regina, 3737 Wascana Parkway, Regina, Saskatchewan S4S 0A2, Canada.
⁸ Department of Civil, Geological and Environmental Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, Saskatchewan S7N 5A9, Canada; Environmental Systems Engineering, University of Regina, 3737 Wascana Parkway, Regina, Saskatchewan S4S 0A2, Canada.

PMID: 33581517
DOI: 10.1016/j.scitotenv.2021.145508

Abstract

Constructed wetland treatment systems (CWTS)s can be used to treat various wastewaters. The main constituent in oil sands process-affected water (OSPW) with uncertain treatment by CWTS are naphthenic acid fraction compounds (NAFC)s. The NAFCs are also among the primary contributors of toxicity to aquatic organisms. While there is preliminary evidence that some CWTSs are capable of treating OSPW for future potential discharge, there is little information comparing the effectiveness and efficiencies of different CWTS designs. Obtaining large volumes of OSPW for testing can be difficult, and while it is known that synthetic NAFCs are simpler and have different toxicity than OSPW-NAFCs, it is unknown whether they could serve as a proxy for optimization of CWTS design and operation. This study presents a comprehensive comparison of CWTS performance operated with both synthetic OSPW and OSPW for four CWTS designs differing in plant type, aeration, flow path, water depth, and substrate type. This study evaluated the potential biodegradation of NAFCs including: (1) decrease in total NAFC concentration, (2) shifts in O_x-NAFC fractions from O₂- to O₃-, O₄-, and O₅-NAFC, (3) decrease in carbon number, (4) decrease of the double bond equivalencies (DBE), and (5) change in toxicity of the waters to test organisms. CWTS planted with Sedge achieved the greatest extent of NAFC treatment and detoxification regardless of design. Although CWTSs planted with Cattail and Bulrush also degraded NAFCs and decreased toxicity, a greater hydraulic retention time was required, and the total extent of treatment was less than the CWTSs planted with Sedge. While synthetic OSPW was more toxic and experienced faster degradation rates, it showed similar trends to OSPW in terms of CWTS design efficiencies and function. Although synthetic OSPW would not be appropriate for modelling or scaling of CWTSs, it can be useful for testing designs and operating conditions.

Keywords: Constructed wetland treatment systems (CWTS); Engineered wetlands; Naphthenic acids; Oil sands process-affected waters (OSPW); Passive water treatment; Toxicology; Water treatment.

MeSH terms

Biodegradation, Environmental
Carboxylic Acids
Oil and Gas Fields
Wastewater
Water Pollutants, Chemical* / analysis
Wetlands*

Substances

Carboxylic Acids
Waste Water
Water Pollutants, Chemical