Arka Pandit

Selective removal of phosphorus from wastewater combined with its recovery as a solid-phase fertilizer

Influx of Phosphorus (P) into freshwater ecosystems is the primary cause of eutrophication which has many undesirable effects. Therefore, P discharge limits for effluents from WWTPs is becoming increasingly common, and may be as low as 10 μg/L as P. While precipitation, filtration, membrane processes, Enhanced Biological Phosphorus Removal (EBPR) and Physico-chemical (adsorption based) methods have been successfully used to effect P removal, only adsorption has the potential to recover the P as a usable fertilizer. This benefit will gain importance with time since P is a non-renewable resource and is mined from P-rich rocks. This article provides details of a process where a polymeric anion exchanger is impregnated with iron oxide nanoparticles to effectuate selective P removal from wastewater and its recovery as a solid-phase fertilizer. Three such hybrid materials were studied: HAIX, DOW-HFO, & DOW-HFO-Cu. Each of these materials combines the durability, robustness, and ease-of-use of a polymeric ion-exchanger resin with the high sorption affinity of Hydrated Ferric Oxide (HFO) toward phosphate. Laboratory experiments demonstrate that each of the three materials studies can selectively remove phosphate from the background of competing anions and phosphorus can be recovered as a solid-phase fertilizer upon efficient regeneration of the exchanger and addition of a calcium or magnesium salt in equimolar (Ca/P or Mg/P) ratio. Also, there is no leaching of Fe or Cu from any of these hybrid exchangers.

Performance of Nitrogen-Removing Bioretention Systems for Control of Agricultural Runoff

This research evaluated nitrogen-removing bioretention systems for control of nutrients, organics, and solids in agricultural runoff. Pilot-scale experiments were conducted with bioretention systems incorporating aerobic nitrification and anoxic denitrification zones with sulfur or wood chips as denitrification substrates. Varying hydraulic loading rates (HLRs), influent concentrations, and wetting and drying periods were applied to the units during laboratory and two seasons of field tests with dairy farm runoff. Total N removal efficiencies greater than 88% were observed in both units with synthetic storm water. In first-season field tests, moderate removal efficiencies were observed for chemical oxygen demand (46%), suspended solids (69%), total phosphorous (TP) (66%), and total N (65%). During the second season, operational changes in the farm resulted in lower organic, solids, and nutrient loadings resulting in improved effluent quality, especially for suspended solids (81% removal) and total N (82% ...

Progress and Recommendations for Advancing Performance-Based Sustainable and Resilient Infrastructure Design

AbstractIncreasing variability in climate and environmental degradation call for an infrastructure design paradigm that considers both sustainability and resilience using performance-based metrics. This paper discusses recent progress in this direction, including recent and emerging infrastructure rating systems, design technologies and tools, and examples of sustainable and resilience infrastructure projects. Recommendations are made for new research, development of new technologies and tools, and policy changes needed to further advance progress towards integrating performance-based approaches across the entire design cycle. These include a call for improved models and tools to better evaluate the full suite of infrastructure costs and benefits, both internally and externally; multicriteria design to assess tradeoffs among all costs and benefits at multiple scales; and an iterative design cycle based on measurable performance criteria.

Water, energy, land use, transportation and socioeconomic nexus: A blue print for more sustainable urban systems

Preparation for global movement to urban regions requires a holistic study of infrastructure interactions. The impact of water and energy on one another has been studied to show how they are dependent upon one another. Other infrastructure interactions also are vital to designing more sustainable cities. The primary infrastructures are: water, energy, land use, and transportation. Creating more sustainable cities may involve low-impact development techniques, opting for compact living, and studying alternatives for water, energy, and transportation provision. Every city is different, and infrastructure decisions should be tailored to fit each city. This group is primarily focused on the greater Atlanta region and the Phoenix area.

Index of network resilience for urban water distribution systems

A unique demographic shift towards urban centres has necessitated incorporation of sustainability principles in the tenets of urban infrastructure planning and design. Adopting resilience as the indicator of sustainability, this paper presents a novel index of network resilience (INR) for urban water distribution systems. The index developed in this paper incorporates six network attributes to develop a composite INR based on the topology of the water distribution systems. A multi-criteria analysis (MCA) using the weighted summation approach is employed to evaluate the alternative configurations which would satisfy the demand and other hydraulic requirements. Analytic hierarchy process (AHP) was assigned to assign weights to the attributes and was optimised for two scenarios: resilience and efficiency. Using the original configuration of Anytown network as the base case scenario, four alternative designs were developed. The results indicate that resilience of the system, in terms of increased robustness and redundancy, can be increased through a better topology without increasing material and energy investment. In addition, the results also indicate that there might be some potential trade-off between resilience and efficiency of flow for the network.

Sustainability: Multi-disciplinary perspectives

The sustainability concept is inherently multydisciplinary because it concerns the management of a complex system having economic, technological, ecological, political, and other perspectives. Consequently, any effort in the area of sustainability involves concept, principles, and methods from engineering, the social science including economics ans social psychology, the biological science including ecology, and physical sciences. In this context, the book Sustainability:Multi Disciplinary Perspectives edited by Heriberto Cabezas and Urmila Diwekar discusses, in a coherent and comprehensive manner, the salient concepts, principles and methods relevant to sustainability from the perspective of different disciplines. The book is a collection of fourteen papers, written by 23 authors drawn from fifteen distinct disciplinary backgrounds ranging from engineering to public policy, from ecology to thermodynamics, from organizational behavior to social psychology, and from industrial ecology to economics. Chapter 1, Introduction, by Heriberto Cabezas describes the general context, the aims and structure of the book. This chapter also provides the definition of sustainability: Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs . Chapter 2, Principles of Sustainability from Ecology, by Audrey L. Mayer, details what are the principles which support sustainability: resilience, desirability, temporal and spatial equity. Ecological theories and hypotheses have inspired new and creative ways to create more sustainable systems. In particular, the complex systems approach to understanding ecosystems have readily incorporated linked human systems into these models, and allowed for a greater understanding of the impacts of specific human activities on the entire socioecological system. ...

An infrastructure ecology approach for urban infrastructure sustainability and resiliency

The concept of ecology can be extended to the urban infrastructure as well when the infrastructure components are not analyzed individually but as an interlinked system, which then can be termed as ‘infrastructure ecology’. Urban infrastructure can be envisioned as an integrated network of four major infrastructure components, which are the water infrastructure, the energy infrastructure, the transportation infrastructure and the land-use pattern or the urban form. Two of the more prominent interactions are between water and energy and that between energy and transportation, but these inter-relations extend beyond the water-energy nexus to all individual infrastructure components. A system level integrative approach reveals many options which might be more sustainable but not apparent when approached on an individual basis. A holistic system level approach is required to attain sustainability as a comprehension of these interrelations lead to better design and assessment of the urban infrastructure system.

Energy and Water Interdependence, and Their Implications for Urban Areas

There are many definitions for sustainability. Mathis Wackernagel, creator of the ecological footprint concept, defined sustainability as “securing people’s quality of life within the means of nature”. The United Nations’ World Commission on Environment and Development (the Brundtland Commission) defined sustainable development as “development that meets the needs of the present without compromising the ability of future generations to meet their own needs” . Throughout this report, sustainability will be defined as the development of the anthroposphere within the means of nature.

Water, Air Emissions, and Cost Impacts of Air-Cooled Microturbines for Combined Cooling, Heating, and Power Systems: A Case Study in the Atlanta Region

Abstract The increasing pace of urbanization means that cities and global organizations are looking for ways to increase energy efficiency and reduce emissions. Combined cooling, heating, and power (CCHP) systems have the potential to improve the energy generation efficiency of a city or urban region by providing energy for heating, cooling, and electricity simultaneously. The purpose of this study is to estimate the water consumption for energy generation use, carbon dioxide (CO 2 ) and NO x emissions, and economic impact of implementing CCHP systems for five generic building types within the Atlanta metropolitan region, under various operational scenarios following the building thermal (heating and cooling) demands. Operating the CCHP system to follow the hourly thermal demand reduces CO 2 emissions for most building types both with and without net metering. The system can be economically beneficial for all building types depending on the price of natural gas, the implementation of net metering, and the cost structure assumed for the CCHP system. The greatest reduction in water consumption for energy production and NO x emissions occurs when there is net metering and when the system is operated to meet the maximum yearly thermal demand, although this scenario also results in an increase in greenhouse gas emissions and, in some cases, cost. CCHP systems are more economical for medium office, large office, and multifamily residential buildings.

A Framework to Identify the Sustainable and Resilient Zone of Urban Infrastructure System Planning and Design

To meet the global challenge of infrastructure provision for 6 billion urban residents by 2050, it is imperative to incorporate sustainability and resilience as key attributes for infrastructure development/rehabilitation. However, there is no robust approach available to decision makers to explore whether there are tradeoffs between sustainability and resilience or they are complementary. This paper presents an approach to identify the sustainable and resilient zone of urban infrastructure development. The authors demonstrate the efficacy of the approach through a case study on seismic retrofit of a potable water distribution system in California. The approach along with the case study provides us with a few key insights. First, while there is an apparent trade-off between sustainability and resilience, as increasing resilience increases capital investment; they are complementary when conceived from a life-cycle perspective. Second, there indeed exists a sustainable and resilient zone of planning and design, where both sustainability and resilience can be optimized together.