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Dr. Wendong Tao
Department of Environmental Resources Engineering, SUNY College of Environmental Science and Forestry, United States

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Research Keywords & Expertise

0 Anaerobic Digestion
0 Constructed wetland
0 Ammonia recovery
0 Struvite recovery
0 Autotrophic nitrogen removal

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Ammonia recovery
Anaerobic Digestion
Struvite recovery
Constructed wetland
Low-oxygen activated sludge process

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Journal article
Published: 25 August 2021 in Sustainability
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The microalgal strain Chlorella sorokiniana isolated from a waste stabilization pond was used for tertiary treatment of municipal wastewater. Three light:dark (L:D) regimes of 12:12, 16:8, and 24:0 were used for treating wastewater in microalga (A), microalga + sludge (A + S), and sludge (S) reactors. The removal of nutrients (N and P) was found to be the highest in the microalga-based reactor, with more than 80% removal of biochemical oxygen demand (BOD) and 1.2–5.6 log unit removal of pathogens. The addition of sludge improved chemical oxygen demand (COD) removal. Nitrifiers were found to be predominant in the A + S reactor. Algal biomass productivity was more than 280 mg/L/d in all the L:D regimes. The increase in light regime improved nutrient removal and biomass productivity in the algal reactor. Results of the kinetic study showed that (i) nitrifiers had more affinity for ammonium than microalga, and hence, most of the ammonia was oxidized to nitrate, (ii) microalga assimilated nitrate as the primary nitrogen source in the A + S reactor, and (iii) solubilization of particulate organic nitrogen originated from dead cells reduced the nitrogen removal efficiency. However, in the microalga-based reactor, the ammonium uptake was higher than nitrate uptake. Among pathogens, the removal of Salmonella and Shigella was better in the A + S reactor than in the other two reactors (microalga and sludge reactor). Additionally, the heterotrophic plate count was drastically reduced in the presence of microalga. No such drastic reduction was observed in the stand-alone sludge reactor. Kinetic modeling revealed that microalga–pathogen competition and pH-induced die-off were the two predominant factors for pathogen inactivation.

ACS Style

Swati Rani; Raja Chowdhury; Wendong Tao; Linda Nedbalova. Microalga-Mediated Tertiary Treatment of Municipal Wastewater: Removal of Nutrients and Pathogens. Sustainability 2021, 13, 9554 .

AMA Style

Swati Rani, Raja Chowdhury, Wendong Tao, Linda Nedbalova. Microalga-Mediated Tertiary Treatment of Municipal Wastewater: Removal of Nutrients and Pathogens. Sustainability. 2021; 13 (17):9554.

Chicago/Turabian Style

Swati Rani; Raja Chowdhury; Wendong Tao; Linda Nedbalova. 2021. "Microalga-Mediated Tertiary Treatment of Municipal Wastewater: Removal of Nutrients and Pathogens." Sustainability 13, no. 17: 9554.

Journal article
Published: 04 March 2021 in Energies
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Hydrolysate prepared from the chemical hydrolysis of water hyacinth biomass contains a high amount of solubilised carbohydrate and nutrients. This hydrolysate was utilised as a medium for the cultivation of two strains of Chlorella sorokiniana, isolated from a municipal wastewater treatment plant using two different media, i.e., BG-11 and Knop’s medium. Different light intensities, light–dark cycles, and various concentrations of external carbon sources (monosaccharides and inorganic carbon) were used to optimise the microalgal growth. For the accumulation of lipids and carbohydrates, the microalgal strains were transferred to nutrient amended medium (N-amended and P-amended). It was observed that the combined effect of glucose, inorganic carbon, and a 12:12 h light–dark cycle proved to be the optimum parameters for high biomass productivity (~200 mg/L/day). For Chlorella sorokiniana 1 (isolated from BG-11 medium), the maximum carbohydrate content (22%) was found in P-amended medium (N = 0 mg/L, P: 3 mg/L), whereas, high lipid content (17.3%) was recorded in N-amended medium (N = 5 mg/L, P = 0 mg/L). However, for Chlorella sorokiniana 2 (isolated from the Knop’s medium), both lipid (17%) and carbohydrate accumulation (12.3%) were found to be maximum in the N-amended medium. Chlorella sorokiniana 2 showed a high saturated lipid accumulation compared to other strains. Kinetic modelling of the lipid profile revealed that the production rate of fatty acids and their various constituents were species dependent under identical conditions.

ACS Style

Swati Dahiya; Raja Chowdhury; Wendong Tao; Pradeep Kumar. Biomass and Lipid Productivity by Two Algal Strains of Chlorella sorokiniana Grown in Hydrolysate of Water Hyacinth. Energies 2021, 14, 1411 .

AMA Style

Swati Dahiya, Raja Chowdhury, Wendong Tao, Pradeep Kumar. Biomass and Lipid Productivity by Two Algal Strains of Chlorella sorokiniana Grown in Hydrolysate of Water Hyacinth. Energies. 2021; 14 (5):1411.

Chicago/Turabian Style

Swati Dahiya; Raja Chowdhury; Wendong Tao; Pradeep Kumar. 2021. "Biomass and Lipid Productivity by Two Algal Strains of Chlorella sorokiniana Grown in Hydrolysate of Water Hyacinth." Energies 14, no. 5: 1411.

Preprint
Published: 21 January 2021
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Hydrolysate prepared from water hyacinth biomass, containing a considerable amount of solubilised carbohydrate and nutrients, was utilised as a medium for the cultivation of two strains of Chlorella sorokiniana. These strains were isolated from an oxidation pond using two different media, i.e., BG-11 and Knop's media maintained at pH-9. Different light intensities, light-dark cycles, and various concentrations of external carbon sources (monosaccharides and inorganic carbon) were used to optimise the microalgal growth. It was observed that in the presence of organic carbon (glucose), biomass productivity increased significantly (~300 mgL-1day-1) as compared to that in the presence of only inorganic carbon (~100 mgL-1day-1). For the accumulation of stress products (lipids and carbohydrates), the microalgal strains were transferred to nutrient-amended media (N-amended and P-amended). The combined effects of glucose, inorganic carbon, and a 12h:12h light-dark cycle proved to be optimum for biomass productivity. For Chlorella sp. isolated from BG-11, maximum carbohydrate content (22%) was found in the P-amended medium, whereas high lipid content (17.3%) was estimated in the N-amended medium. However, for Chlorella sp. isolated from Knop's medium, both the lipid (17%) and carbohydrate accumulation (12.3%) were found maximum in the N- amended medium. Kinetic modelling of the lipid profile revealed that kinetic coefficients obtained for strain isolated from BG-11 media were statistically significant from each other.

ACS Style

Swati Dahiya; Raja Chowdhury; Wendong Tao; Pradeep Kumar. Biomass and Lipid Productivity by Two Algal Strains of Chlorella Sorokiniana Grown in Hydrolysate of Water Hyacinth. 2021, 1 .

AMA Style

Swati Dahiya, Raja Chowdhury, Wendong Tao, Pradeep Kumar. Biomass and Lipid Productivity by Two Algal Strains of Chlorella Sorokiniana Grown in Hydrolysate of Water Hyacinth. . 2021; ():1.

Chicago/Turabian Style

Swati Dahiya; Raja Chowdhury; Wendong Tao; Pradeep Kumar. 2021. "Biomass and Lipid Productivity by Two Algal Strains of Chlorella Sorokiniana Grown in Hydrolysate of Water Hyacinth." , no. : 1.

Journal article
Published: 23 September 2020 in Journal of Water Process Engineering
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Low dissolved oxygen operation has been adopted by water resource recovery facilities to reduce operating costs of activated sludge processes. However, the effects of low dissolved oxygen setpoint in aeration tanks on nitrous oxide emission and microbial community have rarely been addressed at full-scale activated sludge systems. This study for the first time monitored nitrous oxide emission as an anoxic/aerobic membrane bioreactor facility decreased dissolved oxygen setpoint gradually from 3.5 to 0.5 mg/L. Low dissolved oxygen operation retained efficient ammonia removal and increased total nitrogen removal efficiency from 21.4% to 50.1%. Nitrous oxide emission decreased from 0.65% to 0.15% of total nitrogen removal due to uninhibited last stage of heterotrophic denitrification and one-step nitrification. Low dissolved oxygen operation is hence an energy-saving strategy that promotes climate-friendly, efficient biological nitrogen removal. Moreover, this study diagnosed microbial communities in anoxic/aerobic membrane bioreactors of another full-scale plant which had been operated efficiently for years at an ultra-low dissolved oxygen level (0.2 mg/L). Microbial community was similar in all the bioreactors and simultaneous nitrification and denitrification was the main mechanism of nitrogen removal. Nitrospira, which may include complete ammonia oxidizing bacteria, was the only genus of autotrophic nitrifying bacteria. Simultaneous nitrification and denitrification and one-step nitrification by comammox bacteria in low dissolved oxygen operation led to low nitrite concentration and less nitrous oxide emissions from both anoxic and aeration tanks.

ACS Style

Jianfeng Wen; Mark W. LeChevallier; Wendong Tao; Yanjin Liu. Nitrous oxide emission and microbial community of full-scale anoxic/aerobic membrane bioreactors at low dissolved oxygen setpoints. Journal of Water Process Engineering 2020, 38, 101654 .

AMA Style

Jianfeng Wen, Mark W. LeChevallier, Wendong Tao, Yanjin Liu. Nitrous oxide emission and microbial community of full-scale anoxic/aerobic membrane bioreactors at low dissolved oxygen setpoints. Journal of Water Process Engineering. 2020; 38 ():101654.

Chicago/Turabian Style

Jianfeng Wen; Mark W. LeChevallier; Wendong Tao; Yanjin Liu. 2020. "Nitrous oxide emission and microbial community of full-scale anoxic/aerobic membrane bioreactors at low dissolved oxygen setpoints." Journal of Water Process Engineering 38, no. : 101654.

Journal article
Published: 23 September 2020 in Journal of Environmental Chemical Engineering
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Nitrification is often the main mechanism to remove ammonium in constructed wetlands. An important factor hindering this biochemical process in constructed wetlands is the availability of dissolved oxygen. This study introduced hydrogen peroxide-based chemical oxygenation to saturated vertical flow constructed wetlands for removal of nitrogen. Hydrogen peroxide is decomposed into water and oxygen in the presence of catalase. Three hydrogen peroxide concentrations, 0.6%, 1% and 2% (w/v), were applied over three operating periods at the same dosage to test the effects of hydrogen peroxide concentration on nitrogen removal and growth of wetland plants in secondary effluent. More than 92% ammonia was removed in all the three periods. Ammonia removal via nitrification was not adversely affected by hydrogen peroxide at the tested concentrations. As hydrogen peroxide dosing concentration was increased, concentration of nitrate in the effluent decreased substantially due to stimulated plant growth and plant uptake of nitrate instead of ammonia. Dosing hydrogen peroxide to constructed wetlands extended ammonia removal via nitrification to total inorganic nitrogen removal by nitrification and stimulated plant uptake of nitrate. The optimum dosing solution appeared to be 1–2% hydrogen peroxide.

ACS Style

Madhuri Dinakar; Wendong Tao; Douglas Daley. Using hydrogen peroxide to supplement oxygen for nitrogen removal in constructed wetlands. Journal of Environmental Chemical Engineering 2020, 8, 104517 .

AMA Style

Madhuri Dinakar, Wendong Tao, Douglas Daley. Using hydrogen peroxide to supplement oxygen for nitrogen removal in constructed wetlands. Journal of Environmental Chemical Engineering. 2020; 8 (6):104517.

Chicago/Turabian Style

Madhuri Dinakar; Wendong Tao; Douglas Daley. 2020. "Using hydrogen peroxide to supplement oxygen for nitrogen removal in constructed wetlands." Journal of Environmental Chemical Engineering 8, no. 6: 104517.

Journal article
Published: 02 April 2020 in Ecological Indicators
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This study analyzed hierarchical change patterns of regional ecological vulnerability by coupling GIS data and fuzzy analytic hierarchy process. It identified the spatiotemporal features of eco-environment and major environmental problems in Weihe Plain, a typical urban agglomeration in China. Previous studies on regional ecological vulnerability have been focusing on evaluating ecological vulnerability status and developing assessment methods, while ignoring the mechanisms of vulnerability transformation from one to another level. This study further proposed a subjective evaluation model for ecological vulnerability classification and transformation analysis in a multi-index hierarchical evaluation system. The results indicated that ecological vulnerability index was higher in the urban areas than the surrounding counties from 2000 to 2012, which had a great relationship with the impacts of urbanization on ecological vulnerability. The light ecological vulnerability level was found to be relatively variable over the years and have the greatest impact on the change of regional ecological environment. Analysis with the transformation matrix model found that the degree of regional ecological environment stability was regulated by two mechanisms: 1) The proportion of the constant ecological vulnerability level is essential for maintaining the stability of ecological environment; and 2) the difference between the area percentages of decreased and increased vulnerability determines the trend of ecological vulnerability changes. As verified by applications to two nearby regions, this ecological vulnerability transformation model can be used to monitor the dynamics of ecological vulnerability and identify the leading ecological vulnerability level in other large geographical areas.

ACS Style

Kang Hou; Wendong Tao; Liming Wang; Xuxiang Li. Study on hierarchical transformation mechanisms of regional ecological vulnerability and its applicability. Ecological Indicators 2020, 114, 106343 .

AMA Style

Kang Hou, Wendong Tao, Liming Wang, Xuxiang Li. Study on hierarchical transformation mechanisms of regional ecological vulnerability and its applicability. Ecological Indicators. 2020; 114 ():106343.

Chicago/Turabian Style

Kang Hou; Wendong Tao; Liming Wang; Xuxiang Li. 2020. "Study on hierarchical transformation mechanisms of regional ecological vulnerability and its applicability." Ecological Indicators 114, no. : 106343.

Journal article
Published: 15 January 2020 in Water Science and Technology
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Simultaneous nitrification and denitrification under low dissolved oxygen conditions is an energy-saving modification of the activated sludge process to achieve efficient nitrogen removal. Geographically distinct full-scale treatment plants are excellent platforms to address the links of microbial community with operating parameters. Mixed liquor samples were collected from a sequencing batch reactor plant, oxidation ditch plant, and step-feed activated sludge plant. Next-Generation Sequencing of the samples showed that the microbial communities were similar at the phylum level among the plants, being dominated by Proteobacteria. Microbial composition of functional groups was similar between the react fill and react phases of the sequencing batch reactors, among four sequencing batch reactors, and among four oxidation ditches. Nitrospira was the only identified genus of autotropic nitrifying bacteria with a relative abundance of 2.2–2.5% in the oxidation ditches and 0.4–0.7% at the other plants. Heterotrophic nitrifying–aerobic denitrifying bacteria were dominated by Dechloromonas with a relative abundance of 0.4–1.0%. Microbial community composition and nitrogen removal mechanisms were related to overall level and local zonation of dissolved oxygen, mixed liquor suspended solids concentration, nitrogen and organic loadings, and solids retention time. Low dissolved oxygen and low organic and nitrogen loadings favored growth of Nitrospira.

ACS Style

Jianfeng Wen; Mark W. Lechevallier; Wendong Tao. Microbial community similarity and dissimilarity inside and across full-scale activated sludge processes for simultaneous nitrification and denitrification. Water Science and Technology 2020, 81, 333 -344.

AMA Style

Jianfeng Wen, Mark W. Lechevallier, Wendong Tao. Microbial community similarity and dissimilarity inside and across full-scale activated sludge processes for simultaneous nitrification and denitrification. Water Science and Technology. 2020; 81 (2):333-344.

Chicago/Turabian Style

Jianfeng Wen; Mark W. Lechevallier; Wendong Tao. 2020. "Microbial community similarity and dissimilarity inside and across full-scale activated sludge processes for simultaneous nitrification and denitrification." Water Science and Technology 81, no. 2: 333-344.

Journal article
Published: 25 December 2019 in Journal of Cleaner Production
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With population growth, water scarcity, and strict regulations, there is an increasing need for the water industry to search for advanced treatment technologies to reuse effluent from wastewater treatment plants. To accomplish an energy efficient and environment friendly facility for producing reclaimed water, a Water Recycling Plant successfully transitioned its aeration tank dissolved oxygen from moderate (0.8 mg/L) to low (<0.5 mg/L) level. Compared with the moderate dissolved oxygen operation, the low oxygen operation decreased aeration energy consumption by 11.2% while treatment performance was improved. Microbial response to dissolved oxygen change in activated sludge for simultaneous nitrification and denitrification has been studied by operating bench-scale bioreactors in parallel rather than at a full-scale treatment plant with a gradual change of dissolved oxygen set point over time. This study tracked nitrification kinetics and microbial community evolution at this Plant for understanding the low dissolved oxygen activated sludge process. Oxygen half saturation coefficient decreased from 0.23 to 0.19 mg/L for ammonia-oxidizing organisms and 0.19 to 0.08 mg/L for nitrite-oxidizing organisms, indicating a shift to nitrifiers with a high oxygen affinity. In the low dissolved oxygen operation, all the aerobic, anoxic and membrane tanks had similar microbial communities for simultaneous nitrification and denitrification. Nitrospira that has a high oxygen affinity was the only known genus of autotrophic nitrifiers, having a relative abundance of 0.6–1.7%. Denitrifying bacteria were detected in 15 genera at a total relative abundance of 0.8–1.2% in individual tanks. The kinetic results are key to aeration control and process optimization. This study also provides insights into design and operation of wastewater treatment plants to produce reclaimed water in an energy efficient and environment friendly manner.

ACS Style

Jianfeng Wen; Mark W. LeChevallier; Wendong Tao. Nitrification kinetics and microbial communities of activated sludge as a full-scale membrane bioreactor plant transitioned to low dissolved oxygen operation. Journal of Cleaner Production 2019, 252, 119872 .

AMA Style

Jianfeng Wen, Mark W. LeChevallier, Wendong Tao. Nitrification kinetics and microbial communities of activated sludge as a full-scale membrane bioreactor plant transitioned to low dissolved oxygen operation. Journal of Cleaner Production. 2019; 252 ():119872.

Chicago/Turabian Style

Jianfeng Wen; Mark W. LeChevallier; Wendong Tao. 2019. "Nitrification kinetics and microbial communities of activated sludge as a full-scale membrane bioreactor plant transitioned to low dissolved oxygen operation." Journal of Cleaner Production 252, no. : 119872.

Journal article
Published: 30 October 2019 in Chemosphere
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PM2.5 and PM10 samples were collected in the semi-arid city of Xi’an in Northwest China from November 2016 to November 2017 and analyzed to assess pollution characteristics, sources, health risks, and influencing factors of 6 priority phthalate esters (PAEs). The results showed that the sum of the 6 PAEs (Σ6PAEs) was 85.5 ng m−3 in PM2.5 and 94.5 ng m−3 in PM10, being higher at the suburban site than the urban site and winter > spring > summer > autumn. The most abundant PAE was bis(2-ethylhexyl phthalate) (DEHP). PM2.5- and PM10-bound PAEs were associated mainly with the use of plasticizers plus the uses of cosmetics and personal care products, construction materials, and home furnishings. Temperature, relative humidity, and visibility had stronger influences on the concentrations of PM and PM-bound PAEs than pressure and wind speed. Pressure and relative humidity were positively correlated with the concentrations of PM and most of the PM-bound PAEs, while temperature, visibility and wind speed had negative correlations with the concentrations of PM and PM-bound PAEs. The non-carcinogenic risks of human inhalation exposure to PM-bound PAEs were in the range of 10−7 to 10−3, suggesting low non-cancer risks, which were higher at the suburban site than the urban site and higher to children than adults. The cancer risks of human inhalation exposure to PM-bound DEHP and butyl benzyl phthalate (BBP) were in the range of 10−12 to 10−10, suggesting low carcinogenic risks, being in the order of the suburban site > the urban site and DEHP > BBP. Special attention should be paid to long-term low dose exposure to PAEs in the suburb, especially in winter and spring.

ACS Style

Bianbian Ma; Lijun Wang; Wendong Tao; Mengmei Liu; Panqing Zhang; Shengwei Zhang; Xiaoping Li; Xinwei Lu. Phthalate esters in atmospheric PM2.5 and PM10 in the semi-arid city of Xi’an, Northwest China: Pollution characteristics, sources, health risks, and relationships with meteorological factors. Chemosphere 2019, 242, 125226 .

AMA Style

Bianbian Ma, Lijun Wang, Wendong Tao, Mengmei Liu, Panqing Zhang, Shengwei Zhang, Xiaoping Li, Xinwei Lu. Phthalate esters in atmospheric PM2.5 and PM10 in the semi-arid city of Xi’an, Northwest China: Pollution characteristics, sources, health risks, and relationships with meteorological factors. Chemosphere. 2019; 242 ():125226.

Chicago/Turabian Style

Bianbian Ma; Lijun Wang; Wendong Tao; Mengmei Liu; Panqing Zhang; Shengwei Zhang; Xiaoping Li; Xinwei Lu. 2019. "Phthalate esters in atmospheric PM2.5 and PM10 in the semi-arid city of Xi’an, Northwest China: Pollution characteristics, sources, health risks, and relationships with meteorological factors." Chemosphere 242, no. : 125226.

Journal article
Published: 23 August 2019 in Journal of Environmental Management
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Source separation of human urine has not been widely adopted because of scaling on urine collecting fixtures and lack of verified technologies for on-site utilization of waterless urine. This study investigated the effects of flushing liquid, temperature and urease amendment on hydrolysis of urea to ammonia, explored ammonia recovery via vacuum stripping in connection with phosphorus recovery via struvite precipitation in different sequences, and performed economic analysis of a proposed nutrient recovery strategy. It was found that acetic acid could be dosed at 0.05–0.07 N to flush urine-diverting toilets and urinals for hygiene and prevention of scaling. However, a high dosage of 0.56 N completely inhibited urea hydrolysis. Source-separated urine could be stored at 25 °C with ample urease for complete urea hydrolysis within approximately 20 h. Fully hydrolyzed waterless urine contained 9.0–11.6 g/L ammonia-N, 0.53–0.95 g/L phosphate-P and only 2.3–9.1 mg/L magnesium. When magnesium was supplemented to attain the optimum Mg2+: PO43− molar concentration ratio of 1.0 in hydrolyzed urine, batch operation of a pilot-scale air-lift crystallizer removed 93–95% of phosphate and produced 3.65–4.93 g/L struvite in 1–5 h. Batch operation of a pilot-scale vacuum stripping – acid absorption system for 12 h stripped 72–77% of ammonia and produced 37.6–39.7 g/L (NH4)2SO4. Compared with the ammonia → phosphorus recovery sequence, the struvite precipitation → vacuum stripping sequence produced more struvite and ammonium sulfate. The strategy of urea hydrolysis → struvite precipitation → vacuum stripping of ammonia is a sustainable alternative to the conventional phosphorus fertilizer production and ammonia synthesis processes.

ACS Style

Wendong Tao; Alper Bayrakdar; Yanru Wang; Fred Agyeman. Three-stage treatment for nitrogen and phosphorus recovery from human urine: Hydrolysis, precipitation and vacuum stripping. Journal of Environmental Management 2019, 249, 109435 .

AMA Style

Wendong Tao, Alper Bayrakdar, Yanru Wang, Fred Agyeman. Three-stage treatment for nitrogen and phosphorus recovery from human urine: Hydrolysis, precipitation and vacuum stripping. Journal of Environmental Management. 2019; 249 ():109435.

Chicago/Turabian Style

Wendong Tao; Alper Bayrakdar; Yanru Wang; Fred Agyeman. 2019. "Three-stage treatment for nitrogen and phosphorus recovery from human urine: Hydrolysis, precipitation and vacuum stripping." Journal of Environmental Management 249, no. : 109435.

Journal article
Published: 15 March 2019 in Bioresource Technology Reports
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In order to gain insight into biodiesel production, suitability of an alkaliphilic green algae (Chlorellla vulgaris) was evaluated experimentally and by conducting an energy analysis. Biomass productivity was 28–31 mg-L−1- d−1 and lipid production reached the maximum of 38% of the algal biomass. At a low light intensity (60–90 μmol/m2/s), the specific growth rate showed a cyclic behavior. At a higher light intensity (240–280 μmol/m2/s), the growth rate was almost constant and more biomass was produced as compared to the low light intensity. Lipid analyses after transesterification showed that the major fractions of fatty acids were C16:0, C 18:1 and C18:2. A minute amount of trans isomer (which is very rare in the eukaryotic cells) was also detected during initial lipid accumulation phase. From the energy analysis, it was found that biodiesel production using this strain algae could be energy efficient, if biomass drying was facilitated by waste heat.

ACS Style

Raja Chowdhury; Patricia L. Keen; Wendong Tao. Fatty acid profile and energy efficiency of biodiesel production from an alkaliphilic algae grown in the photobioreactor. Bioresource Technology Reports 2019, 6, 229 -236.

AMA Style

Raja Chowdhury, Patricia L. Keen, Wendong Tao. Fatty acid profile and energy efficiency of biodiesel production from an alkaliphilic algae grown in the photobioreactor. Bioresource Technology Reports. 2019; 6 ():229-236.

Chicago/Turabian Style

Raja Chowdhury; Patricia L. Keen; Wendong Tao. 2019. "Fatty acid profile and energy efficiency of biodiesel production from an alkaliphilic algae grown in the photobioreactor." Bioresource Technology Reports 6, no. : 229-236.

Research article
Published: 28 October 2018 in Environmental Science and Pollution Research
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Macrophytes and bacteria are key drivers of nitrogen removal in constructed wetlands. Through mesocosm experiments with vegetated submerged beds and free water surface wetlands in various operational modes, wetland configurations, and system layouts, this study developed empirical models for non-destructive estimation of plant biomass growth and associated nitrogen assimilation and explored the combined effects of multiple factors that influence microbial nitrogen removal. The above-ground biomass of individual plants was a power function of plant height for both Cyperus alternifolius and Typha angustifolia. Below- to above-ground biomass ratio was 0.38 for C. alternifolius and 2.73 for T. angustifolia. Because of greater tolerance to ammonia stress, C. alternifolius and C. papyrus grew faster than T. angustifolia. There were no significant effects of wetland type, vegetation, and plant species on microbial nitrogen removal. Microbial nitrogen removal was inhibited by free ammonia at 13.3–16.2 mg N/L. Denitrification and anammox were suppressed at dissolved oxygen greater than 1.9 mg/L. Microbial removal of ammonia in vegetated submerged beds was sensitive mainly to dissolved oxygen, pH, and influent ammonia concentration, while in free water surface wetlands, it was sensitive to influent ammonia concentration, pH, and temperature.

ACS Style

Wendong Tao. Microbial removal and plant uptake of nitrogen in constructed wetlands: mesocosm tests on influencing factors. Environmental Science and Pollution Research 2018, 25, 36425 -36437.

AMA Style

Wendong Tao. Microbial removal and plant uptake of nitrogen in constructed wetlands: mesocosm tests on influencing factors. Environmental Science and Pollution Research. 2018; 25 (36):36425-36437.

Chicago/Turabian Style

Wendong Tao. 2018. "Microbial removal and plant uptake of nitrogen in constructed wetlands: mesocosm tests on influencing factors." Environmental Science and Pollution Research 25, no. 36: 36425-36437.

Journal article
Published: 16 August 2018 in Water Science and Technology
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A vacuum thermal stripping process coupled with acid absorption has been developed at laboratory scale to recover ammonia in anaerobic digestate. To make this ammonia recovery process scalable, this study investigated the effects of feed depth on vacuum thermal stripping in a pilot system, developed sodium hydroxide dosages required to raise feed pH for stripping, and simulated the dynamics of ammonia reduction in batch stripping tests. As feed depth was increased from 8.5 to 34.0 cm, the ammonia mass transfer coefficient and ammonia stripping efficiency decreased while the mass of stripped ammonia increased. Digested municipal sludge had a greater ammonia mass transfer coefficient than digested dairy manure at each feed depth, which could be attributed to the difference in suspended and dissolved solids concentrations. The optimum feed depth was 18 cm of the digested sludge and 14 cm of the digested manure. Sodium hydroxide dosage for the digested manure was higher than that for the digested sludge and co-digested foodwaste. The dosages were correlated to concentrations of total dissolved solids and ammonia. Total ammonia concentration decreased exponentially in batch stripping of the digested sludge at 25.5 cm deep, with a first-order stripping rate coefficient of 0.087–0.144 h−1.

ACS Style

Wendong Tao; Anayo T. Ukwuani; Fred Agyeman. Recovery of ammonia in anaerobic digestate using vacuum thermal stripping – acid absorption process: scale-up considerations. Water Science and Technology 2018, 78, 878 -885.

AMA Style

Wendong Tao, Anayo T. Ukwuani, Fred Agyeman. Recovery of ammonia in anaerobic digestate using vacuum thermal stripping – acid absorption process: scale-up considerations. Water Science and Technology. 2018; 78 (4):878-885.

Chicago/Turabian Style

Wendong Tao; Anayo T. Ukwuani; Fred Agyeman. 2018. "Recovery of ammonia in anaerobic digestate using vacuum thermal stripping – acid absorption process: scale-up considerations." Water Science and Technology 78, no. 4: 878-885.

Journal article
Published: 10 July 2018 in Journal of Environmental Management
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Process instability has been a challenge to anaerobic digestion of foodwaste at higher organic loading rates. Co-digestion is one of the measures to improve stability. This study conducted batch experiments to compare liquid dairy manure and dairy manure digestate as a co-substrate for anaerobic digestion of foodwaste. The batch co-digestion experiments showed a two-stage biogas production process, which could be simulated with a modification of the Gompertz model. The specific biogas yields derived with the two-stage biogas production model was further simulated against the co-substrate ratios with substrate limitation – inhibition models for identifying the optimal co-substrate ratio. The Haldane model was the best to simulate co-substrate limitation – inhibition kinetics in anaerobic co-digestion of foodwaste. A higher ratio of dairy manure could result in co-substrate inhibition to biogas production due to recalcitrance of cellulose and toxicity of lignin and lignin derivatives. Kinetic modeling shows that the optimal volatile solids (VS) ratio of liquid dairy manure is 16.6%, at which the maximum specific methane yield is 0.54 L/g VS. Semi-continuous co-digestion of 88% foodwaste and 12% liquid dairy manure at a hydraulic retention time of 14 d attained 94% of the simulated maximum methane yield. Although co-digestion of foodwaste and manure digestate resulted in lower biogas yields than co-digestion with liquid dairy manure, manure digestate is still an attractive co-substrate that has several operational advantages compared with liquid dairy manure.

ACS Style

Jonathan Masih-Das; Wendong Tao. Anaerobic co-digestion of foodwaste with liquid dairy manure or manure digestate: Co-substrate limitation and inhibition. Journal of Environmental Management 2018, 223, 917 -924.

AMA Style

Jonathan Masih-Das, Wendong Tao. Anaerobic co-digestion of foodwaste with liquid dairy manure or manure digestate: Co-substrate limitation and inhibition. Journal of Environmental Management. 2018; 223 ():917-924.

Chicago/Turabian Style

Jonathan Masih-Das; Wendong Tao. 2018. "Anaerobic co-digestion of foodwaste with liquid dairy manure or manure digestate: Co-substrate limitation and inhibition." Journal of Environmental Management 223, no. : 917-924.

Journal article
Published: 01 January 2018 in Chemosphere
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A total of 62 urban soil samples were collected in the city of Xi'an in Northwest China, and analyzed for six U.S. Environmental Protection Agency priority phthalate esters (PAEs). Unlike earlier studies on PAEs in agricultural soil as well as urban soil in humid climates, this paper for the first time comprehensively assessed pollution characteristics and health risks of human exposure to PAEs in urban soil in a typical semi-arid climate. The total concentrations of the six PAEs (Σ6PAEs) in the urban soil varied between 193.0 and 19146.4 μg kg(-1) with a mean of 1369.3 μg kg(-1). The PAEs were dominated by di-n-butyl phthalate and di(2-ethylhexyl) phthalate. Magnetic susceptibility and soil texture were controlling factors influencing the concentrations of PAEs in the urban soil. The concentrations of benzyl butyl phthalate, di(2-ethylhexyl) phthalate, and Σ6PAEs increased from the first to third ring roads, while the concentrations of di-n-octyl phthalate decreased. Relatively higher levels of PAEs were observed in industrial, traffic, and residential areas. The PAEs in the urban soil originated mainly from the application of plasticizers or additives, use of cosmetics and personal care products, emissions of construction materials and home furnishings, industrial processes, and atmospheric deposition. The concentrations of some PAEs in the urban soil exceeded soil allowable concentrations and environmental risk levels. The non-cancer and carcinogenic risks of human exposure to the PAEs were relatively low.

ACS Style

Lijun Wang; Mengmei Liu; Wendong Tao; Wenjuan Zhang; Li Wang; Xingmin Shi; Xinwei Lu; Xiaoping Li. Pollution characteristics and health risk assessment of phthalate esters in urban soil in the typical semi-arid city of Xi'an, Northwest China. Chemosphere 2018, 191, 467 -476.

AMA Style

Lijun Wang, Mengmei Liu, Wendong Tao, Wenjuan Zhang, Li Wang, Xingmin Shi, Xinwei Lu, Xiaoping Li. Pollution characteristics and health risk assessment of phthalate esters in urban soil in the typical semi-arid city of Xi'an, Northwest China. Chemosphere. 2018; 191 ():467-476.

Chicago/Turabian Style

Lijun Wang; Mengmei Liu; Wendong Tao; Wenjuan Zhang; Li Wang; Xingmin Shi; Xinwei Lu; Xiaoping Li. 2018. "Pollution characteristics and health risk assessment of phthalate esters in urban soil in the typical semi-arid city of Xi'an, Northwest China." Chemosphere 191, no. : 467-476.

Research article
Published: 13 July 2017 in Frontiers of Earth Science
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Intensive anthropogenic activities can lead to soil heavy metal contamination resulting in potential risks to the environment and to human health. To reveal the concentrations, speciation, sources, pollution level, and ecological risk of heavy metals in vegetable garden soil, a total of 136 soil samples were collected from three vegetable production fields in the suburbs of Xianyang City, Northwest China. These samples were analyzed by inductively coupled plasma- atomic emission spectrometry and atomic fluorescence spectrometry. The results showed that the mean concentrations of Cd, Co, Cu, Mn, Pb, Zn, and Hg in vegetable garden soil were higher than the corresponding soil element background values of Shaanxi Province. The heavy metals studied in vegetable garden soil were primarily found in the residual fraction, averaging from 31.26% (Pb) to 90.23% (Cr). Considering the non-residual fractions, the mobility or potential risk was in the order of Pb (68.74%)>Co (60.54%)>Mn (59.28%) >Cd (53.54%) ≫Ni (23.36%) >Zn (22.73%)>Cu (14.93%)>V (11.81%)>Cr (9.78%). Cr, Mn, Ni, V, and As in the studied soil were related to soilforming parent materials, while Cu, Hg, Zn, Cd, Co, and Pb were associated with the application of plastic films, fertilizers, and pesticides, as well as traffic emissions and industrial fumes. Cr, Ni, V, and As presented low contamination levels, whereas Co, Cu, Mn, Pb, and Zn levels were moderate, and Cd and Hg were high. Ecological risk was low for Co, Cr, Cu, Mn, Pb, Zn, and As, with high risk observed for Cd and Hg. The overall pollution level and ecological risk of these heavy metals were high.

ACS Style

Lijun Wang; Wendong Tao; Richard C. Smardon; Xue Xu; Xinwei Lu. Speciation, sources, and risk assessment of heavy metals in suburban vegetable garden soil in Xianyang City, Northwest China. Frontiers of Earth Science 2017, 12, 397 -407.

AMA Style

Lijun Wang, Wendong Tao, Richard C. Smardon, Xue Xu, Xinwei Lu. Speciation, sources, and risk assessment of heavy metals in suburban vegetable garden soil in Xianyang City, Northwest China. Frontiers of Earth Science. 2017; 12 (2):397-407.

Chicago/Turabian Style

Lijun Wang; Wendong Tao; Richard C. Smardon; Xue Xu; Xinwei Lu. 2017. "Speciation, sources, and risk assessment of heavy metals in suburban vegetable garden soil in Xianyang City, Northwest China." Frontiers of Earth Science 12, no. 2: 397-407.

Journal article
Published: 01 June 2017 in Chemical Engineering Journal
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ACS Style

Hanyan Li; Wendong Tao. Efficient ammonia removal in recirculating vertical flow constructed wetlands: Complementary roles of anammox and denitrification in simultaneous nitritation, anammox and denitrification process. Chemical Engineering Journal 2017, 317, 972 -979.

AMA Style

Hanyan Li, Wendong Tao. Efficient ammonia removal in recirculating vertical flow constructed wetlands: Complementary roles of anammox and denitrification in simultaneous nitritation, anammox and denitrification process. Chemical Engineering Journal. 2017; 317 ():972-979.

Chicago/Turabian Style

Hanyan Li; Wendong Tao. 2017. "Efficient ammonia removal in recirculating vertical flow constructed wetlands: Complementary roles of anammox and denitrification in simultaneous nitritation, anammox and denitrification process." Chemical Engineering Journal 317, no. : 972-979.

Journal article
Published: 04 January 2017 in Reviews in Environmental Science and Bio/Technology
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Wendong Tao; Keshav Sauba; Kazi Fattah; John R. Smith. Designing constructed wetlands for reclamation of pretreated wastewater and stormwater. Reviews in Environmental Science and Bio/Technology 2017, 16, 37 -57.

AMA Style

Wendong Tao, Keshav Sauba, Kazi Fattah, John R. Smith. Designing constructed wetlands for reclamation of pretreated wastewater and stormwater. Reviews in Environmental Science and Bio/Technology. 2017; 16 (1):37-57.

Chicago/Turabian Style

Wendong Tao; Keshav Sauba; Kazi Fattah; John R. Smith. 2017. "Designing constructed wetlands for reclamation of pretreated wastewater and stormwater." Reviews in Environmental Science and Bio/Technology 16, no. 1: 37-57.

Journal article
Published: 01 December 2016 in Water Research
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To prevent acetoclastic methanogens from ammonia inhibition in anaerobic digestion of protein-rich substrates, ammonia needs to be removed or recovered from digestate. This paper presents an innovative ammonia recovery process that couples vacuum thermal stripping with acid absorption. Ammonia is stripped out of digestate boiling at a temperature below the normal boiling point due to vacuum. Stripped ammonia is absorbed to a sulfuric acid solution, forming ammonium sulfate crystals as a marketable product. Three common types of digestate were found to have boiling point temperature-vacuum curves similar to water. Seven combinations of boiling temperature and vacuum (50 °C 16.6 kPa, 58 °C 20.0 kPa, 65 °C 25.1 kPa, 70 °C 33.6 kPa, 80 °C 54.0 kPa, 90 °C 74.2 kPa, and 100 °C 101.3 kPa) were tested for batch stripping of ammonia in dairy manure digestate. 93.3-99.9% of ammonia was stripped in 3 h. The Lewis-Whitman model fitted ammonia stripping process well. Ammonia mass transfer coefficient was significantly higher at boiling temperature 65-100 °C and vacuum pressure 25.1-101.3 kPa than 50-58 °C and 16.6-20.0 kPa. The low ammonia saturation concentrations (0-24 mg N/L) suggested a large driving force to strip ammonia. The optimum boiling point temperature - vacuum pressure for ammonia recovery in a recirculation line of a mesophilic digester was 65 °C and 25.1 kPa, at which the ammonia mass transfer coefficient was as high as 37.3 mm/h. Installation of a demister and liquid trap could avoid negative effects of higher stripping temperature and stronger vacuum on formation of ammonium sulfate crystals. Pilot tests demonstrated that high-purity ammonium sulfate crystals could be produced by controlling sulfuric acid content and maintaining acid solution saturated with ammonium sulfate. Although volatile organic compounds such as cyclohexene were found in the final acid solutions, no volatile organic compounds were found in the recovered crystals.

ACS Style

Anayo T. Ukwuani; Wendong Tao. Developing a vacuum thermal stripping – acid absorption process for ammonia recovery from anaerobic digester effluent. Water Research 2016, 106, 108 -115.

AMA Style

Anayo T. Ukwuani, Wendong Tao. Developing a vacuum thermal stripping – acid absorption process for ammonia recovery from anaerobic digester effluent. Water Research. 2016; 106 ():108-115.

Chicago/Turabian Style

Anayo T. Ukwuani; Wendong Tao. 2016. "Developing a vacuum thermal stripping – acid absorption process for ammonia recovery from anaerobic digester effluent." Water Research 106, no. : 108-115.

Journal article
Published: 19 July 2016 in Environmental Geochemistry and Health
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Phthalic acid esters (PAEs) are widely used as plasticizers and in consumer products, which may enter the environment and present risks to human health. U.S. EPA classifies six PAEs as priority pollutants, which could be accumulated in street dust at the interface of atmosphere, biosphere and geosphere. This study collected a total of 58 street dust samples from Xi’an City in Northwest China and analyzed for concentrations of the priority PAEs. Composition, distribution, sources and health risk of the PAEs were further examined. All the priority PAEs were detected in the street dust. The concentrations of individual PAEs varied between not detected and 183.19 mg/kg. The sum of the 6 priority PAEs (∑6PAEs) ranged from 0.87 to 250.30 mg/kg with a mean of 40.48 mg/kg. The most abundant PAEs in the street dust were di-n-butyl phthalate and di (2-ethylhexyl) phthalate (DEHP). Higher concentrations of ∑6PAEs in the street dust were found in the south and west parts of Xi’an City as well as its urban center, which were possibly attributed to the prevailing northerly Asian winter monsoon. The PAEs in the street dust originated mainly from wide application of plasticizers as well as cosmetics and personal care products. The main pathways of human exposure to PAEs in the street dust were ingestion and dermal adsorption of dust particles. The non-cancer risk of human exposure to PAEs in the street dust was relatively low, while the risk to children was higher than that to adults. The cancer risk of human exposure to DEHP in the street dust was lower than the standard limit value of 10−6.

ACS Style

Lijun Wang; Wenjuan Zhang; Wendong Tao; Li Wang; Xingmin Shi; Xinwei Lu. Investigating into composition, distribution, sources and health risk of phthalic acid esters in street dust of Xi’an City, Northwest China. Environmental Geochemistry and Health 2016, 39, 865 -877.

AMA Style

Lijun Wang, Wenjuan Zhang, Wendong Tao, Li Wang, Xingmin Shi, Xinwei Lu. Investigating into composition, distribution, sources and health risk of phthalic acid esters in street dust of Xi’an City, Northwest China. Environmental Geochemistry and Health. 2016; 39 (4):865-877.

Chicago/Turabian Style

Lijun Wang; Wenjuan Zhang; Wendong Tao; Li Wang; Xingmin Shi; Xinwei Lu. 2016. "Investigating into composition, distribution, sources and health risk of phthalic acid esters in street dust of Xi’an City, Northwest China." Environmental Geochemistry and Health 39, no. 4: 865-877.