The concentrations of chlorine dioxide (CI02), chlorine, chlorite (CIO2), and chlorate (CI03) were evaluated following pretreatment of raw water by CI02 at water treatment plants in New Castle, Pennsylvania; Charleston, West Virginia; Skagit, Washington; and Columbus, Georgia. Chlorite and chlorate concentrations were unaffected by any of the water treatment processes and did not vary as a function of time of travel in the distribution system. Chlorine dioxide, which was analyzed on-site at two water treatment plants, reformed in the clear well and in the distribution system following post chlorination. The chlorite-removal capability of powdered activated carbon (PAC) was evaluated in both laboratory- and pilot-scale studies. Chlorite removal by PAC in laboratory studies decreased with increasing pH over a range from pH 5.5 to 7.5 and varied with the type of PAC. Chlorite was reduced to chloride at pHs ranging from 5.5 to 7.5, but CI03- formed at the pH 5.5 through 6.0. The pilot plant study; which was conducted at Newport News, Virginia; evaluated CI02 removal by PAC enmeshed in a floc blanket in a pulsed-bed, solids-contact clarifier. An average of 27 percent of the CI02 was removed when the PAC dose was 10 mg/L PAC and 57 percent when it was 20 mg/L PAC. Chlorate was not removed by PAC, but the concentrations could be reduced if the CIOz generator was properly operated. / Master of Science

This research investigated the efficacy of chlorine dioxide (ClO₂), ultraviolet (UV) irradiation, UV in combination with chlorine dioxide (UV/ClO₂), and UV in combination with hydrogen peroxide (UV/H₂O₂) for decolorizing three reactive azo dyes (sultan red, indigo blue and cypress green) and treated textile-manufacturing wastewater. The objective was to determine the best treatment for reducing color to the Virginia Pollutant Discharge Elimination System (VPDES) permit level of 300 American Dye Manufacturers Institute (ADMI) units. The effects of the three chemical oxidation treatments provided color reduction for all three dyes. The results suggested UV/H₂O₂ and UV/ClO₂2 treatments provided maximum color reduction of the red and blue dyes, and UV/H₂O₂ was the most effective for maximum reduction of the green dye. A research goal was to provide predictive models of the wastewater effluent for the treatment processes, including the UV exposure time required to reach the 300 ADMI permit value and the effective ClO₂ dose necessary to achieve the 300 units. The results of the investigations regarding the effluent indicated that UV/H₂O₂ and UV/ClO₂ (5 mg/L) provided reduction to 300 units in less than 10 minutes UV exposure when the initial effluent color was less than 500 ADMI units. Without the addition of oxidant, contact times longer than 10 minutes were required for UV to decolorize these effluents to 300 ADMI units. Chlorine dioxide dosages between 10 and 30 mg/L both with and without UV irradiation achieved the same results. / Master of Science

A number of advanced pre-treatment techniques and methods have been evaluated for the sole purpose of improving digestibility of waste activated sludge. The pre-treatment of waste activated sludge (WAS) offers the benefit of releasing solubilized substrates, making them readily available to be utilized in the anaerobic digestion process. Other potential benefits include: reducing shock loading to the digester, improving overall digestibility and potentially providing filament / foaming control. Chlorine dioxide, a well-known disinfectant and oxidizing agent has been utilized in many drinking water processes around the world. Its use in wastewater treatment processes however is limited; especially in Canada where legislation has prevented its use for final effluent disinfection. As an oxidizing agent, chlorine dioxide induces cell rupture resulting in the release of soluble material, which when fed into the digester, may serve as readily available substrate for active microorganisms. This mode of action creates the potential for chlorine dioxide to be used as a sludge pre-treatment agent to improve digester performance and in alleviating pre-existing filamentous sludge bulking. This study was conducted using waste activated sludge obtained from the City of Winnipeg’s South End Water Pollution Control Centre (SEWPCC), with the following objectives: 1. Determine the efficacy of chlorine dioxide in alleviating pre-existing filamentous sludge bulking; 2. Determine chlorine dioxide ability to increase WAS solubilization; and 3. Define impact of chlorine dioxide on anaerobic digester performance. WAS pre-treatment using chlorine dioxide was found to be effective in alleviating filamentous bulking. This is significant as filamentous bulking in the activated sludge may lead several problems downstream. Following pre-treatment, sludge bulking was determined to be alleviated as observed by photomicrographic evidence and as measured by a 57% decrease in the stirred sludge volume index (sSVI). Particulate COD solubilization increased by 60%, 76%, and 74% over the untreated sludge for WAS pre-treated with 25, 50, and 100 mg ClO2/L (v/v), respectively. The pre-treatment of sludge using chlorine dioxide did not have any negative impact on digester performance although it also did not lead to improved performance. The volatile solids destruction and COD removal remained unchanged for both untreated and pre-treated sludge. Chlorine dioxide pre-treatment did not affect anaerobic digestion even at the lowest SRT evaluated; it is possible to decrease the digester SRT to as low as 6 days while maintaining the solids destruction and COD removal capability. Biogas production did not improve with increasing chlorine dioxide dosage during pre-treatment but also was not hindered by the pre-treatment agent. Chlorine dioxide was shown to alleviate filamentous bulking and improve solubility and has the potential to improve digester performance without negative impacts to the digester. However, the full benefit of the pre-treatment method may only be realized for complex “difficult to disintegrate” sludge types. / October 2016

This thesis presents the potential of integrating chemical and biological treatment technologies for the removal of high concentrations of phenol in a bioremediation medium. High concentrations of phenol in wastewater are difficult to remove by purely biological methods. Chemical oxidation is one way to treat high concentrations of phenol but complete oxidation is not always possible or will make the treatment process uneconomical. An experimental design approach, based on central composite rotatable design (CCRD) was used to evaluate the effects of process parameters on phenol oxidation by Fentons reagent and chlorine dioxide. Performance of the chemical oxidation was evaluated by determining the percentage of phenol oxidized at equilibrium. The reaction mechanism for the oxidation of phenol by Fentons reagent was proposed based on identification of the intermediate compounds.<p> The effects of H₂O₂ concentration (2000 to 5000 mg L^-1) and FeSO₄.7H₂O concentration (500 to 2000 mg L^-1) were investigated on phenol oxidation and optimal concentrations of H₂O₂ and FeSO₄.7H₂O for complete oxidation of 2000 mg L^-1 phenol in medium were found to be 4340 mg L^-1 and 1616 mg L^-1, respectively, at 25°C and pH 3. The main oxidation products were identified as catechol, hydroquinone and maleic acid.<p> In the case of phenol oxidation by chlorine dioxide, the effects of chlorine dioxide concentration (500 to 2000 mg L^-1), temperature (10 to 40°C) and pH (3 to 7) on the oxidation of 2000 mg L^-1 of phenol were determined. The optimal concentration of chlorine dioxide to completely oxidize 2000 mg L^-1 of phenol was 2000 mg L^-1. The other parameters did not significantly affect the oxidation over the ranges studied. The main oxidation products were identified as 1,4-benzoquinone and 2-chloro-1,4-benzoquinone.<p> Finally, the biodegradation of 1,4-benzoquinone, the main oxidation product of phenol oxidation by chlorine dioxide, was studied in batch and continuous systems using Pseudomonas putida 17484 in two dose McKinneys medium. The effects of 1,4-benzoquinone concentration and temperature were studied on biodegradation of 1,4-benzoquinone in batch reactors. Under optimal conditions, it was found that 150 mg L^-1 1,4-benzoquinone could be successfully biodegraded at 15°C. In a continuous reactor operating at 15°C the highest removal rate with 500 mg L^-1 of 1,4-benzoquinone was found to be 246 mg L^-1 h^-1. The values of µmax, Ks and yield were also determined as 0.74±0.03 h^-1 and 14.17±3.21 mg L^-1 and 2x10¹³ cell mg^-1, respectively.

This thesis presents the potential of integrating chemical and biological treatment technologies for the removal of high concentrations of phenol in a bioremediation medium. High concentrations of phenol in wastewater are difficult to remove by purely biological methods. Chemical oxidation is one way to treat high concentrations of phenol but complete oxidation is not always possible or will make the treatment process uneconomical. An experimental design approach, based on central composite rotatable design (CCRD) was used to evaluate the effects of process parameters on phenol oxidation by Fentons reagent and chlorine dioxide. Performance of the chemical oxidation was evaluated by determining the percentage of phenol oxidized at equilibrium. The reaction mechanism for the oxidation of phenol by Fentons reagent was proposed based on identification of the intermediate compounds.<p> The effects of H₂O₂ concentration (2000 to 5000 mg L^-1) and FeSO₄.7H₂O concentration (500 to 2000 mg L^-1) were investigated on phenol oxidation and optimal concentrations of H₂O₂ and FeSO₄.7H₂O for complete oxidation of 2000 mg L^-1 phenol in medium were found to be 4340 mg L^-1 and 1616 mg L^-1, respectively, at 25°C and pH 3. The main oxidation products were identified as catechol, hydroquinone and maleic acid.<p> In the case of phenol oxidation by chlorine dioxide, the effects of chlorine dioxide concentration (500 to 2000 mg L^-1), temperature (10 to 40°C) and pH (3 to 7) on the oxidation of 2000 mg L^-1 of phenol were determined. The optimal concentration of chlorine dioxide to completely oxidize 2000 mg L^-1 of phenol was 2000 mg L^-1. The other parameters did not significantly affect the oxidation over the ranges studied. The main oxidation products were identified as 1,4-benzoquinone and 2-chloro-1,4-benzoquinone.<p> Finally, the biodegradation of 1,4-benzoquinone, the main oxidation product of phenol oxidation by chlorine dioxide, was studied in batch and continuous systems using Pseudomonas putida 17484 in two dose McKinneys medium. The effects of 1,4-benzoquinone concentration and temperature were studied on biodegradation of 1,4-benzoquinone in batch reactors. Under optimal conditions, it was found that 150 mg L^-1 1,4-benzoquinone could be successfully biodegraded at 15°C. In a continuous reactor operating at 15°C the highest removal rate with 500 mg L^-1 of 1,4-benzoquinone was found to be 246 mg L^-1 h^-1. The values of µmax, Ks and yield were also determined as 0.74±0.03 h^-1 and 14.17±3.21 mg L^-1 and 2x10¹³ cell mg^-1, respectively.

No description available.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 225-227). Also available on the Internet.

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 154-161).

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 225-227). Also available on the Internet.

Thesis(M.S.)--Auburn University, 2005. / Abstract. Vita. Includes bibliographic references.