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Xiaofan Xu
Dep. of Civil and Environmental EngineeringUniv. of South Florida 4202 E. Fowler Ave. Tampa FL 33620 USA

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Special section
Published: 13 December 2019 in Journal of Environmental Quality
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Water reuse is believed to be a sustainable solution to overcome the scarcity of freshwater. Aerobic and anaerobic membrane bioreactors are becoming an effective technology for wastewater treatment and reuse. Aerobic membrane bioreactors show good nutrient removal, whereas those that are anaerobic have nutrient-rich effluent, enabling the direct agricultural use of the effluent. As a result, the end use will dictate the potential environmental impacts of the bioreactor's application. Therefore, with the consideration of the end use (i.e., discharge or reuse) of the effluent, this study aimed to compare the environmental and economic impacts associated with full-scale aerobic and anaerobic membrane bioreactors for municipal wastewater treatment under different end use scenarios using life cycle assessment and cost analysis. The results of these analyses show that anaerobic bioreactors have greater environmental impacts and life cycle cost than aerobic bioreactors in the discharge scenario due to the incorporation of a biological nutrient removal system. In the reuse scenario, anaerobic membrane bioreactors have lower impacts that are attributable to the offset of the nutrients required for crops, and the potential benefits vary depending on the types of crops receiving the reclaimed water. Integrating anaerobic membrane bioreactors with agricultural fertigation resulted in effluent water nitrate concentrations (after crop uptake and soil treatment) of <2 mg L-1 in most U.S. states. This indicated that the use of the anaerobic membrane bioreactors effluent for fertigation could be a win-win solution to both irrigation water shortage and high environmental impact associated with nutrient removal.

ACS Style

Xiaofan Xu; Hang Dao; Robert Bair; Ahmet E. Uman; Daniel Yeh; Qiong Zhang. Discharge or reuse? Comparative sustainability assessment of anaerobic and aerobic membrane bioreactors. Journal of Environmental Quality 2019, 49, 545 -556.

AMA Style

Xiaofan Xu, Hang Dao, Robert Bair, Ahmet E. Uman, Daniel Yeh, Qiong Zhang. Discharge or reuse? Comparative sustainability assessment of anaerobic and aerobic membrane bioreactors. Journal of Environmental Quality. 2019; 49 (3):545-556.

Chicago/Turabian Style

Xiaofan Xu; Hang Dao; Robert Bair; Ahmet E. Uman; Daniel Yeh; Qiong Zhang. 2019. "Discharge or reuse? Comparative sustainability assessment of anaerobic and aerobic membrane bioreactors." Journal of Environmental Quality 49, no. 3: 545-556.

Original research
Published: 01 November 2019 in AWWA Water Science
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Tracer analysis is commonly used to evaluate the hydraulics of environmental and chemical engineering systems. The traditional tracer analysis is conducted through physical experiments that are usually complex, costly, time‐intensive, and may be impractical. Because of the continued advancement of computing technology, computational fluid dynamics (CFD) has demonstrated its applicability in simulating tracer transport. CFD can provide advantages, including no interruptions of existing water treatment process, no impacts of background concentration, and a relatively low cost. However, no reports have quantitatively studied the cost that CFD can save on tracer analysis. This study first proved the accuracy of CFD tracer analysis for an existing ozone disinfection tank and then compared the economic expenses and environmental impacts of CFD tracer analysis with those of a field tracer analysis. It was found that CFD‐based tracer analysis has accuracy on par with the physical‐based study but at relatively low economic cost and environmental impacts.

ACS Style

Jie Zhang; Xiaofan Xu; Andres Tejada‐Martinez; Qiong Zhang; Edward Wicklein. Evaluating reactor hydraulics in a cost‐effective and environment‐friendly way: Numerical tracer study. AWWA Water Science 2019, 1, 1 .

AMA Style

Jie Zhang, Xiaofan Xu, Andres Tejada‐Martinez, Qiong Zhang, Edward Wicklein. Evaluating reactor hydraulics in a cost‐effective and environment‐friendly way: Numerical tracer study. AWWA Water Science. 2019; 1 (6):1.

Chicago/Turabian Style

Jie Zhang; Xiaofan Xu; Andres Tejada‐Martinez; Qiong Zhang; Edward Wicklein. 2019. "Evaluating reactor hydraulics in a cost‐effective and environment‐friendly way: Numerical tracer study." AWWA Water Science 1, no. 6: 1.

Journal article
Published: 01 May 2019 in Journal of Environmental Engineering
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ACS Style

Xiaofan Xu; Qiong Zhang. Sustainable Configuration of Bioretention Systems for Nutrient Management through Life-Cycle Assessment and Cost Analysis. Journal of Environmental Engineering 2019, 145, 04019016 .

AMA Style

Xiaofan Xu, Qiong Zhang. Sustainable Configuration of Bioretention Systems for Nutrient Management through Life-Cycle Assessment and Cost Analysis. Journal of Environmental Engineering. 2019; 145 (5):04019016.

Chicago/Turabian Style

Xiaofan Xu; Qiong Zhang. 2019. "Sustainable Configuration of Bioretention Systems for Nutrient Management through Life-Cycle Assessment and Cost Analysis." Journal of Environmental Engineering 145, no. 5: 04019016.

Journal article
Published: 16 April 2019 in Journal of Cleaner Production
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With a Multi-Regional Input-Output analysis, this study for the first time quantifies China's final electricity demands' life-cycle impacts on water quality using the indicator Grey Water Footprint (GWF). China's Grey Water Footprint for Final Power Demands (GWFP) amounts to 37.54 billion m³ in 2010, which is the highest in the north, east and central regions. Regarding the upstream sectoral contributions on a national scale, Coal Mining and Dressing, whose GWF is decided mainly by Chemical Oxygen Demand (COD) and petroleum, and Agriculture sector, whose GWF is decided by total nitrogen discharged, contribute the largest shares of 32.40% and 23.24%, respectively. 22.28 billion m³ of GWFP is transferred across provincial boundaries as virtual grey water embodied in electricity transmissions and trades of the power sector's upstream supplies. Electric power demands in coastal provinces induce water pollution in inland provinces. For example, 1.38, 1.07 and 1.06 billion m³ of GWF in Shanxi, Inner Mongolia, and Henan, respectively, are generated to fulfill final power demands in Shandong, Jilin and Shandong. Findings in this study are significant in helping policymakers recognize and mitigate final power demands' life-cycle adverse impacts on water quality. Moreover, insights of the inter-provincial virtual grey water transfers induced by power demands enable further discussions on burden sharing and compensation in terms of power demand management and water pollution controls.

ACS Style

Xiawei Liao; Li Chai; Xiaofan Xu; Qiong Lu; Junping Ji. Grey water footprint and interprovincial virtual grey water transfers for China's final electricity demands. Journal of Cleaner Production 2019, 227, 111 -118.

AMA Style

Xiawei Liao, Li Chai, Xiaofan Xu, Qiong Lu, Junping Ji. Grey water footprint and interprovincial virtual grey water transfers for China's final electricity demands. Journal of Cleaner Production. 2019; 227 ():111-118.

Chicago/Turabian Style

Xiawei Liao; Li Chai; Xiaofan Xu; Qiong Lu; Junping Ji. 2019. "Grey water footprint and interprovincial virtual grey water transfers for China's final electricity demands." Journal of Cleaner Production 227, no. : 111-118.

Journal article
Published: 11 December 2018 in Sustainability
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The stormwater runoff that carries pollutants from the land adjacent to road transportation systems may impair the water environment and threaten the ecosystem and human health. A proper management approach like green stormwater infrastructure (GSI) can help control flooding and the runoff pollutants. One barrier for GSI analysis relevant to system-level surface transportation planning is the lack of the inventory of GSI in many U.S. cities. This study aims to develop a GIS-based framework for creating GSI inventory in a time and labor efficient way, different from the traditional survey-based method. The new proposed framework consists of three steps, including road categorization, GSI mapping, and GSI type identification using the GIS data, high-resolution land-cover image, and Google Earth street view pictures. The new approach was tested in Philadelphia, Pennsylvania and also applied in Tampa, Florida. The results showed that the new GIS-based framework can achieve similar accuracy to the survey-based method while saving time and labor. The GSI inventory created in the study demonstrated the usefulness of the proposed framework for analyzing the status of GSI implementation and identifying gaps for future planning in terms of potential locations and underrepresented GSI types.

ACS Style

Xiaofan Xu; Dylan S. P. Schreiber; Qing Lu; Qiong Zhang. A GIS-Based Framework Creating Green Stormwater Infrastructure Inventory Relevant to Surface Transportation Planning. Sustainability 2018, 10, 4710 .

AMA Style

Xiaofan Xu, Dylan S. P. Schreiber, Qing Lu, Qiong Zhang. A GIS-Based Framework Creating Green Stormwater Infrastructure Inventory Relevant to Surface Transportation Planning. Sustainability. 2018; 10 (12):4710.

Chicago/Turabian Style

Xiaofan Xu; Dylan S. P. Schreiber; Qing Lu; Qiong Zhang. 2018. "A GIS-Based Framework Creating Green Stormwater Infrastructure Inventory Relevant to Surface Transportation Planning." Sustainability 10, no. 12: 4710.

Journal article
Published: 01 January 2018 in Proceedings of the Water Environment Federation
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Onsite Wastewater Treatment Systems (OWTSs) play a significant role in nutrient removal to control the impact of nutrient pollution on human and aquatic health. However, studies assessing the sustainability of OWTSs are limited and the impact of the location of the OWTS on sustainability indicators such as greenhouse gas emissions and eutrophication have yet to be examined. This study evaluates the life-cycle environmental and economic impacts of OWTSs relative to their nutrient management capabilities and highlights the influence of locational variation. The results show that the location influences the OWTS’s nutrient removal, life-cycle environmental impacts and cost. The less permeable soil type and higher soil temperature both positively improved the TN removal efficiency, reduced nutrient-related impacts like eutrophication, and improved cost-effectiveness. Compared to the advanced OWTS, the locational variation of soil conditions had a higher impact on the conventional OWTS due to its strong reliance on the performance of the drainfield. On the other hand, locational variation of energy mix had a strong influence on environmental performance of the advanced OWTS in terms of greenhouse gas emissions and fossil fuel depletion.

ACS Style

Xiaofan Xu; Nancy Diaz-Elsayed; Qiong Zhang. The Role of Location in Sustainable Nitrogen Removal for Onsite Wastewater Treatment Systems. Proceedings of the Water Environment Federation 2018, 2018, 83 -92.

AMA Style

Xiaofan Xu, Nancy Diaz-Elsayed, Qiong Zhang. The Role of Location in Sustainable Nitrogen Removal for Onsite Wastewater Treatment Systems. Proceedings of the Water Environment Federation. 2018; 2018 (5):83-92.

Chicago/Turabian Style

Xiaofan Xu; Nancy Diaz-Elsayed; Qiong Zhang. 2018. "The Role of Location in Sustainable Nitrogen Removal for Onsite Wastewater Treatment Systems." Proceedings of the Water Environment Federation 2018, no. 5: 83-92.

Journal article
Published: 01 September 2017 in Water Research
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The impairment of water bodies from nutrient pollution is a challenging environmental problem that could lead to high eutrophic conditions, fish kills, and human illness, while negatively impacting industries that rely on thriving water bodies. Onsite wastewater treatment systems (OWTSs) are a major source of nutrients, however no prior studies have conducted a holistic sustainability assessment of OWTSs that considers their ability to manage nutrients at the household-level in the United States. The aim of this study is therefore to evaluate the environmental and economic impacts of conventional and advanced OWTSs with respect to their ability to remove total nitrogen (TN). Septic tank and drainfield materials were varied for conventional systems, and the advanced systems evaluated consisted of aerobic treatment units (ATUs) and passive nitrogen reduction systems (PNRSs) with nitrification and denitrification stages. Life cycle assessment and life cycle cost analysis were performed to evaluate OWTSs operating in different soil and temperature conditions. Nutrient management of the advanced OWTSs outperformed the conventional systems (96.7-100% vs. 61-65% TN removal), and resulted in less than 40% of the freshwater (0.06-0.14 vs. 0.37-0.40 kg P-eq/kg TN) and marine eutrophication (0.04-0.06 vs. 0.54-0.65 kg N-eq/kg TN). However, the tradeoff for nutrient management was higher life cycle costs ($101-$121 vs. $45-$58 USD 2015/kg TN) and environmental impacts for the remaining impact categories. Lastly, when the TN removed by the drainfield was <20%, the advanced system had lower impacts than conventional OWTSs across all impact categories except ecotoxicity.

ACS Style

Nancy Diaz-Elsayed; Xiaofan Xu; Maraida Balaguer-Barbosa; Qiong Zhang. An evaluation of the sustainability of onsite wastewater treatment systems for nutrient management. Water Research 2017, 121, 186 -196.

AMA Style

Nancy Diaz-Elsayed, Xiaofan Xu, Maraida Balaguer-Barbosa, Qiong Zhang. An evaluation of the sustainability of onsite wastewater treatment systems for nutrient management. Water Research. 2017; 121 ():186-196.

Chicago/Turabian Style

Nancy Diaz-Elsayed; Xiaofan Xu; Maraida Balaguer-Barbosa; Qiong Zhang. 2017. "An evaluation of the sustainability of onsite wastewater treatment systems for nutrient management." Water Research 121, no. : 186-196.

Articles
Published: 01 April 2015 in International Journal of Remote Sensing
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This study aimed to detect and understand remotely sensed urban wetland dynamics as a sensitive indicator of the combined effects of human disturbances and climate impacts in the course of global change. To address this objective, the study developed technical approaches to detect and interpret wetland changes across spatial scales in complex urban landscapes. Using a series of Satellite Pour l’Observation de la Terre (SPOT) images covering 1992–2010, the study was conducted in the Kansas City metropolitan area of the USA, which has experienced significant urban sprawl in recent decades. As a fine-tuning of the traditional supervised image classification, a knowledge-based classification algorithm was developed to identify fine-scale, hidden wetlands that cannot be appropriately detected based on their spectral differentiability. The analyses of wetland change were implemented at the metropolitan, watershed, and sub-watershed scales as well as being based on the size of surface water bodies in order to reveal real pictures of urban wetland change trends in relation to major driving factors. The results of the study indicated that the knowledge-based classification approach improved the detection capability and accuracy of urban wetlands by fine-tuning the traditional classification results. The cross-scale analysis of detected land covers revealed that wetland dynamics varied in trend and magnitude from metropolitan, watersheds, to sub-watershed scales. The study found that increased precipitation swelled wetlands, which inflated the findings of remotely sensed wetland cover and related trend interpretation. During an 18 year study period, human development activities in the study area resulted in a large increase in impervious surfaces, which was mainly at the expense of farmland/grassland areas and some small wetlands in all urban watersheds. In contrast, increased precipitation in the region swelled large wetlands in particular. This mixed picture of urban wetland dynamics, associated with the analysis of underlying driving factors, provides a new baseline for relevant urban planning, management, and research in a global change perspective.

ACS Style

Wei Ji; Xiaofan Xu; Dzingirai Murambadoro. Understanding urban wetland dynamics: cross-scale detection and analysis of remote sensing. International Journal of Remote Sensing 2015, 36, 1763 -1788.

AMA Style

Wei Ji, Xiaofan Xu, Dzingirai Murambadoro. Understanding urban wetland dynamics: cross-scale detection and analysis of remote sensing. International Journal of Remote Sensing. 2015; 36 (7):1763-1788.

Chicago/Turabian Style

Wei Ji; Xiaofan Xu; Dzingirai Murambadoro. 2015. "Understanding urban wetland dynamics: cross-scale detection and analysis of remote sensing." International Journal of Remote Sensing 36, no. 7: 1763-1788.

Conference paper
Published: 01 January 2014 in INTERNATIONAL CONFERENCE OF COMPUTATIONAL METHODS IN SCIENCES AND ENGINEERING 2014 (ICCMSE 2014)
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It has been a challenge to accurately detect urban wetlands with remotely sensed data by means of pixel-based image classification. This technical difficulty results mainly from inadequate spatial resolutions of satellite imagery, spectral similarities between urban wetlands and adjacent land covers, and spatial complexity of wetlands in human transformed, heterogeneous urban landscapes. To address this issue, an image classification approach has been developed to improve the mapping accuracy of urban wetlands by integrating the pixel-based classification with a knowledge-based algorithm. The algorithm includes a set of decision rules of identifying wetland cover in relation to their elevation, spatial adjacencies, habitat conditions, hydro-geomorphological characteristics, and relevant geo-statistics. ERDAS Imagine software was used to develop the knowledge base and implement the classification. The study area is the metropolitan region of Kansas City, USA. SPOT satellite images of 1992, 2008, and 2010 were classified into four classes - wetland, farmland, built-up land, and forestland. The results suggest that the knowledge-based image classification approach can enhance urban wetland detection capabilities and classification accuracies with remotely sensed satellite imagery.

ACS Style

Xiaofan Xu; Wei Ji. Knowledge-based algorithm for satellite image classification of urban wetlands. INTERNATIONAL CONFERENCE OF COMPUTATIONAL METHODS IN SCIENCES AND ENGINEERING 2014 (ICCMSE 2014) 2014, 1 .

AMA Style

Xiaofan Xu, Wei Ji. Knowledge-based algorithm for satellite image classification of urban wetlands. INTERNATIONAL CONFERENCE OF COMPUTATIONAL METHODS IN SCIENCES AND ENGINEERING 2014 (ICCMSE 2014). 2014; ():1.

Chicago/Turabian Style

Xiaofan Xu; Wei Ji. 2014. "Knowledge-based algorithm for satellite image classification of urban wetlands." INTERNATIONAL CONFERENCE OF COMPUTATIONAL METHODS IN SCIENCES AND ENGINEERING 2014 (ICCMSE 2014) , no. : 1.

Journal article
Published: 31 October 2013 in Bioresource Technology
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In order to investigate the anaerobic ammonium-oxidation (Anammox) nitrogen removal pathway of the aged refuse bioreactor treating landfill leachate, a lab-scale bioreactor was established and run for 35 weeks, the performance of the bioreactor and its bacterial community structure of Planctomycetes were analyzed. The results showed that the average TN removal rate of landfill leachate could be reached to 89%. 16S rRNA gene library of Planctomycetes revealed that Anammox sequences accounted for 28.3% of the total Planctomycetes sequences in the bioreactor, and previously recognized Anammox bacterium Candidatus Kuenenia stuttgartiensis was the only detected Anammox species in the reactor. It was also found that Anammox bacteria distributed at different sites of the bioreactor while mostly concentrated in the middle and low-middle part. Results above confirmed that Anammox process could happen in aged refuse bioreactor treating landfill leachate and provided an alternative nitrogen removal pathway in practical landfills.

ACS Style

Chao Wang; Bing Xie; Lu Han; Xiaofan Xu. Study of anaerobic ammonium oxidation bacterial community in the aged refuse bioreactor with 16S rRNA gene library technique. Bioresource Technology 2013, 145, 65 -70.

AMA Style

Chao Wang, Bing Xie, Lu Han, Xiaofan Xu. Study of anaerobic ammonium oxidation bacterial community in the aged refuse bioreactor with 16S rRNA gene library technique. Bioresource Technology. 2013; 145 ():65-70.

Chicago/Turabian Style

Chao Wang; Bing Xie; Lu Han; Xiaofan Xu. 2013. "Study of anaerobic ammonium oxidation bacterial community in the aged refuse bioreactor with 16S rRNA gene library technique." Bioresource Technology 145, no. : 65-70.