IMPACTS OF HYDRAULIC FRACTURING WASTEWATER ON DISINFECTION BYPRODUCT FORMATION DURING WATER CHLORINATION
Open Access
- Author:
- Huang, Kuan
- Graduate Program:
- Environmental Pollution Control
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- April 02, 2018
- Committee Members:
- Yuefeng F Xie, Thesis Advisor/Co-Advisor
Shirley Elizabeth Clark, Committee Member - Keywords:
- Shale gas production wastewater
disinfection byproducts
bromide
metal complexation - Abstract:
- Shale gas extraction based on unconventional horizontal drilling and hydraulic fracturing for nature gas recovery from low-permeable gas formation has greatly increased oil and gas production around the country in the past ten years. However, it also triggered environmental and human health concerns due to its impact on water resources, especially on disinfection by-product (DBP) formation upon chlorination. Increased bromide levels have been reported in several surface waters in Pennsylvania that accounted for the increased formation of DBPs in downstream water utilities. However, the effects of non-bromide ions in production wastewater at extremely high levels are vaguely defined. In this study, we investigated the effects of production wastewater, with bromide and non-bromide species, on the formation of DBPs when spiked into surface waters at different percentages. Results showed that the spiking of production wastewater dramatically increased DBP formation and shifted its speciation towards brominated species. Brominated DBPs increased at the expenses of chlorinated species as more production wastewater was added, while mixed bromochloro-DBPs rose and then declined. However, the introduction of debrominated production wastewater led to increased formation of some chlorinated DBP species in selected surface water and wastewater. As the spiking percentage of debrominated production wastewater increased, the chlorinated DBP species increased. The study of individual cations suggested that their contributions to DBP formation followed a sequence of magnesium > calcium > barium at high spiking percentage due to the different catalytic effects of their chelates with organic precursors. The study of anions suggested that the discharge of treated production wastewater containing elevated sulfate may further enhance DBP formation. The significance of this study lies in the fact that while bromide concerns from production wastewater are important, non-bromide species also contributed to DBP formation. The gas production wastewater management decision should consider the negative impacts from both bromide and non-bromide species to better protect drinking water resources.