Gangadhar Andaluri

Evaluation of relative importance of ultrasound reactor parameters for the removal of estrogen hormones in water

The growing interest in sonochemistry as a tool for environmental remediation leads to the need for process optimization. Sonochemistry is a complex process, which depends on physical parameters and also on the process conditions. Physical parameters are interrelated and therefore a systematic approach has to be taken to optimize the process. The effect of physical parameters on the destruction of seven estrogen hormones (17α-estradiol, 17β-estradiol, estriol, 17α-ethinylestradiol, 17α-dihydroequilin, estrone and equilin) is reported in this study. Artificial neural networks (ANN) was used as a tool to identify the correlations between these process parameters. ANN enabled the establishment of relationship between sonication parameters such as power density, power intensity, ultrasound amplitude, as well as the reactor design parameters. The major significance was attributed to the area-specific power density and the volume-specific power intensity. The results of this work provide a sound basis to design pilot and full-scale ultrasound treatment systems. Process optimization lead to a 5-fold decrease in energy consumption as compared to the commercially available reactors, thereby making the process attractive for field applications.

Ultrasound assisted removal of estrogen hormones.

Estrogen compounds are being detected in significant concentrations in surface water, wastewater, soil, sediments and groundwater. These estrogenic compounds influence the growth and performance of the reproductive system. Several reports indicate that the major source of these contaminants to the ecosystem is the effluents from wastewater treatment plants. These contaminants are found at significant concentrations in the effluent and the water bodies into which they are discharged. Reports also indicate that these estrogens are found in trace level concentrations in drinking water. Conventional treatment technologies are not designed to completely remove these pharmaceutically active chemicals (PhACs). Therefore there is a need to develop new treatment technologies in addition to the existing technologies. Ultrasound is an advanced oxidation process that effectively destroys many toxic organic chemicals. Ultrasound involves the process of passing high frequency sound waves into the liquid media. These sound waves create acoustic cavitations in the liquid media. The removal of these chemicals occurs through three different mechanisms, which are thermal degradation in the cavitation region, supercritical oxidation and hydroxyl radical oxidation in the interfacial or the bulk region. In the current work, ultrasound technology is employed as a mechanism of removal of several estrogen hormones. The estrogens targeted in this study were 17α-estradiol, 17βestradiol, estrone, estriol, 17α-dihydroequilin, 17α-ethinyl-estradiol and equilin. Also included in the results are the effect of various process conditions such as variation of pH and presence of oxidizing agents on the removal of estrogens. The degradation rates for each of the estrogen compound have been investigated in clean water. The effect of ionic strength of the system and the system alkalinity are also presented.

Occurrence of Estrogen Hormones in Environmental Systems

Occurrence of pharmaceutically active compounds (PACs), such as estrogen hormones in environmental systems, has gained widespread attention due to their adverse effects on the ecology and possibly humans. In our study, surface water was sampled from 21 water streams located in Eastern Pennsylvania. The presence of several estrogen hormones compounds was examined. All streams sampled showed the presence of at least one hormone compound. Estrone and estriol were detected in more than 80% of the sampling sites. The most frequently detected hormone was estrone, with concentrations ranging from 0.6 to 2.6 ng/L. Estriol was the hormone with the highest recorded concentration of 19.7 ng/L. The concentration of ethinyl estradiol detected in this study was about 30 times greater than the 0.1 ng/L reported to cause feminization of fish. One important pollution source of these pharmaceutical compounds is the effluent and sludge from wastewater treatment plants. Wastewater was collected from different points at two municipal wastewater treatment plants (WWTPs) and analyzed for estrogens. The effluent of the wastewater is directly discharged into the surface water. 17�-estradiol, 17�-dihydroequilin, 17�-ethinyl estradiol, estriol and estrone were found in the sampled effluent wastewaters. The concentration of the detected estrogen hormones ranged from 0.5 to 50 ng/L. Estrone was detected in the effluent of all two WWTPs. The occurrence of estrogens in the final dewatered sludge from municipal WWTP was also investigated. After being disposed or land applied as agricultural fertilizer, the sludge could represent a pollution source due to the leaching of pharmaceutical compounds into the water systems. The leaching process was simulated in the laboratory by mixing the sludge with clean water. The concentrations of leached hormones in the aqueous phase were then examined. Another important pollution pathway of these pharmaceutical compounds is from the agricultural animal wastes, which are typically land applied. In this study, cow manure and chicken manure were sampled for analysis of estrogen hormones. 17�estradiol, 17�-estradiol, 17�-dihydroequilin and estrone were detected in the cow manure with concentrations ranging from 6.2 to 27.4 ng/g dry solid. After mixing with water, about 18% to 48% of estrogens entered the aqueous phase. 17�-estradiol, 17�-estradiol and estrone were detected in chicken manure with concentrations ranging from 44 to 150 ng/g dry solid. About 10 to 100 % leaching was observed. Used compost was also

Kinetic model for sonolytic degradation of non-volatile surfactants: Perfluoroalkyl substances

Sonolytic degradation kinetics of non-volatile surfactant perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) were investigated over a range of concentration, considering active cavity as a catalyst. The Michaelis-Menten type kinetic model was developed to empirically estimate the concentration of active cavity sites during reactions. Sonolytic degradation of PFOA and PFOS, as well as the formation of its inorganic constituents, fluoride, and sulfate, follows saturation kinetics of pseudo-first order at lower concentration (<2.34 µM) and zero order at higher concentration (>23.60 µM). Nitrate and hydrogen peroxide formations were 0.53 ± 0.14 µM/min and 0.95 ± 0.11 µM/min, respectively. At a power density of 77 W/L and frequency of 575 kHz, the empirically estimated maximum number of active cavity sites that could lead to the sonolytic reaction were 89.25 and 8.8 mM for PFOA and PFOS, respectively. This study suggests that a lower number of active cavity sites with higher temperature needed to degrade PFOS might be the reason for lower degradation rate of PFOS compared to that of PFOA. Diffusion of non-volatile surfactants at the cavity-water interface is found to be the rate-limiting step for the mineralization of perfluoroalkyl substances.

Removal of 1, 4-Dioxane and Volatile Organic Compounds from Groundwater Using Ozone-Based Advanced Oxidation Process

ABSTRACT Ozone and ozone/peroxide processes were evaluated for the removal of 1,4-dioxane from laboratory water and site groundwater. The effect of process parameters such as solution pH and dosage of peroxide was studied. Ozone alone was not very effective in removing 1,4-dioxane from water (≤ 20% removal). Enhanced oxidation of 1,4-dioxane was achieved by increasing the solution pH or by adding peroxide at neutral pH. Pseudo–first-order rate constants were calculated for the removal of 1,4-dioxane using ozone. Correlations were developed for the consumption of ozone per 1,4-dioxane removed. Acidic and neutral pH conditions resulted in higher consumption of ozone per dioxane removed. Basic solution pH and presence of hydrogen peroxide enhanced the dioxane removal, which resulted in lower consumption of ozone per dioxane removed. Following the lab study, ozonation was used for the remediation of site groundwater contaminated with 1,4-dioxane and chlorinated volatile organics. Presence of 5 mg/L of hydrogen peroxide during ozonation resulted in simultaneous removal of 1,4-dioxane and volatile organics from groundwater to target levels. For the AOP process, removal kinetics was approximately 50% slower in groundwater compared to the lab DI water.