Evaluation of Enhanced Ozone–Biologically Active Filtration Treatment for the Removal of 1,4-Dioxane and Disinfection Byproduct Precursors from Wastewater Effluent

Abstract

Ozonation followed by biologically active filtration (BAF) (O3–BAF) treatment has become an alternative to reverse osmosis in potable wastewater reuse applications because of the ability to produce a high-quality effluent while reducing brine production and disposal. In this study, effluent from a sequencing batch membrane bioreactor (SBMBR) was treated by O3–BAF at three specific ozone doses (0.5, 0.7, and 1.0 mg O3/mg DOC) and different empty bed contact times (EBCTs; 15–45 min). The reaction of O3 with granular activated carbon (GAC) (O3/GAC) to promote the formation of hydroxyl radicals (·OH) was evaluated at 1.0 mg O3/mg DOC followed by BAF at 15–45 min EBCT. The efficacy of these techniques was compared for the removal of O3 refractory 1,4-dioxane and the reduction in the formation of bromate, 35 regulated and unregulated halogenated disinfection byproducts (DBPs), and 8 N-nitrosamines after chloramination. Conventional ozonation (without the presence of GAC during ozonation) removed 6–11% of 1,4-dioxane, while BAF increased the removal to ∼25%. O3/GAC improved the removal of 1,4-dioxane to ∼40%, while BAF increased the removal to ∼50%. No bromate was detected during conventional ozonation. Although O3/GAC formed 12.5 μg/L bromate, this concentration was reduced during BAF treatment to <6.8 μg/L. Even though conventional ozonation was more effective than O3/GAC for the reduction in chloramine-reactive N-nitrosodimethylamine (NDMA) precursors, BAF treatment after either conventional or enhanced ozonation reduced NDMA formation during chloramination to <10 ng/L. O3/GAC was more effective at reducing halogenated DBP formation during postchloramination. Regardless, the reduction in halogenated DBP formation during postchloramination achieved by BAF treatment was ∼90% relative to the formation in the SBMBR effluent after either conventional or enhanced ozonation. The reduction of haloacetic acid (HAA) formation improved moderately with increasing BAF EBCT. Both O3–BAF and (O3/GAC)–BAF met regulatory levels for trihalomethanes, HAAs, NDMA, and bromate.

Enhanced Ozonation of Trace Organic Contaminants in Municipal Wastewater Plant Effluent by Adding a Preceding Filtration Step: Comparison and Prediction of Removal Efficiency

“…Even though ATZ abatement was observed during both GAF/O 3 with 0.1 g O 3 /g DOC and ozonation with 0.5 g O 3 /g DOC, the ATZ removal for GAF/ O 3 with an ozone dose of 0.1 g O 3 /g DOC (38%) was much higher than that for ozonation with an ozone dose of 0.5 g O 3 / g DOC (7.9%). This is also consistent with previous studies, 33 indicating the potential of enhanced ozonation on TrOCs abatement and improve the utilization of ozone. Therefore, enhanced ozone−filtration could be considered for degrading more ozone-refractory compounds and to reduce energy requirement.…”

“…12,30−32 Hooman et al reported that the removal of 1,4-dioxane (an ozone-refractory compound) in effluent was increased from less than 10% to 50% by means of combining ozonation with biological active carbon filtration. 33 The results of Reungoat et al showed more than 90% TrOCs degradation was achieved by combining biofiltration and ozonation. 32 Recently, (biological) granular activated carbon (GAC) or sand has been mostly used as an alternative to be combined with ozonation, while limited studies have investigated the combination of other filtration steps to enhance the removal efficiency of TrOCs.…”

“…Ozone combined with filtration is also put forward as a recommended technique. Filtration contributes to the removal of • OH scavengers (e.g., nitrate, nitrite, and dissolved organic carbon (DOC)); therefore, a higher TrOCs abatement efficiency can be achieved at the specific ozone dose. ,− Hooman et al reported that the removal of 1,4-dioxane (an ozone-refractory compound) in effluent was increased from less than 10% to 50% by means of combining ozonation with biological active carbon filtration . The results of Reungoat et al showed more than 90% TrOCs degradation was achieved by combining biofiltration and ozonation …”

Transformation of N-Methylamine Drugs during Wastewater Ozonation: Formation of Nitromethane, an Efficient Precursor to Halonitromethanes

“…Water samples A– C had DOC levels of 9, 16, and 11.6 mg L –1 , respectively. Based on this input, five different ozone-to-DOC ratios, ranging from 0.125 to 1.0 mg O 3 /mg DOC, were tested to cover a range of doses relevant to practice. − …”

Bioelectrochemical Treatment of 1,4-Dioxane in the Presence of Chlorinated Solvents: Design, Process, and Sustainability Considerations

“…In the environment, 1,4-dioxane has shown remarkable recalcitrance to natural biological and chemical attenuation processes, and its removal by traditional water treatment approaches has proven to be a challenge. Generally, strong oxidants are needed to activate the diether ring. − Several studies have demonstrated that advanced oxidation processes (AOPs) such as H 2 O 2 , plasma, UV, peroxymonosulfate, and ozone treatment are effective in generating reactive oxygen species (ROS) to degrade 1,4-dioxane. − Electrochemical oxidation has emerged as a promising technology to remove persistent organic pollutants − because it is cost-competitive with other AOPs and can be implemented for in situ groundwater treatment by using mesh electrodes. , Indirect oxidation through generated ROS such as ·OH and direct electron transfer were shown as the main degradation mechanism of this technology . However, in spite of the effectiveness of the electrochemical oxidation processes, high capital costs and considerable energy consumption have thus far deferred field-scale applications.…”