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Publications (147)
Minimizing the use of water for growing microalgae is crucial for lowering the energy and costs of animal feed, food, and biofuel production from microalgae. Dunaliella spp., a haloterant species that can accumulate high intracellular levels of lipids, carotenoids, or glycerol can be harvested effectively using low-cost and scalable high pH-induced...
Characterizing light in microalgal cultivation vessels is needed for modeling and optimizing microalgal growth for large-scale cultivation. Dynamic changes in light intensity over space due to geometry, refraction/reflection, and the interactive impacts of algal growth and their biocomponents with light make this characterization challenging. Under...
Temperatures as high as 100 °C have been reported at a few municipal solid waste (MSW) landfills in the U.S. A recently published model describing landfill heat accumulation identified reactions that contribute significant heat to landfills including the hydration and carbonation of Ca-containing wastes such as ash from MSW and coal combustion. The...
The marine microalgal species Dunaliella viridis is a promising source of biofuels because of its ability to accumulate neutral lipids without freshwater resources for growth. Less energy for biofuel production from D. viridis may also be required because of the possible extraction of lipids through osmotic lysis. However, there is a lack of experi...
Past research on AGS (aerobic granular sludge technology) has mainly focused on macro-environment factors, such as settling time, feeding pattern, OLR (organic loading rate), SRT (sludge retention time), among others, and their effects on the granulation process. The biomass granulation process, however, is significantly affected by the micro-envir...
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https://www.sciencedirect.com/science/article/pii/S0043135419309297?dgcid=author#ack0010
Enhancing biogas production, while avoiding inhibition of methanogenesis during co-digestion of grease interceptor waste (GIW), can help water resource recovery faciliti...
The iron deficiency response in plants is a complex biological process with a host of influencing factors. The ability to precisely modulate this process at the transcriptome level would enable genetic manipulations allowing plants to survive in nutritionally poor soils and accumulate increased iron content in edible tissues. Despite the collected...
The pathway of monolignol biosynthesis involves many components interacting in a metabolic grid to regulate the supply and ratios of monolignols for lignification. The complexity of the pathway challenges any intuitive prediction of the output without mathematical modeling. Several models have been presented to quantify the metabolic flux for monol...
Experimental bioreactors, such as those treating wastewater, contain particles whose size and shape are important parameters. For example, the size and shape of activated sludge flocs can indicate the conditions at the microscale, and also directly affect how well the sludge settles in a clarifier. Particle size and shape are both misleadingly 'sim...
Biological floc size is an important reactor microenvironment parameter that is often not experimentally controlled due to a lack of suitable methods. Here, we introduce the Couette-Taylor bioreactor (CTB) as an improved tool for controlling biological floc size, specifically as compared with bubble-column sequencing batch reactors (SBRs). A CTB co...
A multi-omics quantitative integrative analysis of lignin biosynthesis can advance the strategic engineering of wood for timber, pulp, and biofuels. Lignin is polymerized from three monomers (monolignols) produced by a grid-like pathway. The pathway in wood formation of Populus trichocarpa has at least 21 genes, encoding enzymes that mediate 37 rea...
Lignin is a polymer present in the secondary cell walls of all vascular plants. It is a known barrier to pulping and the extraction of high-energy sugars from cellulosic biomass. The challenge faced with predicting outcomes of transgenic plants with reduced lignin is due in part to the presence of unique protein-protein interactions that influence...
The steady state distribution of all the metabolic flux involved in the monolignol biosynthetic pathway.
(a) The steady state flux distribution in the absence of Ptr4CL3-Ptr4CL5 complex. The green box represents the median steady state flux and the red ‘+’ sign represents the mean steady state flux values, (b) The steady state flux distribution in...
Variation of S/G ratio as a function of Ptr4CL3 and Ptr4CL5 concentration in the absence of a complex.
The color bar shows the variation of S/G ratio in log scale, where S/G ratio of 2 corresponds to a value of 0.3 in log scale.
(TIF)
Description of flux equations for Ptr4CL enzyme related pathways with and without the complex.
(PDF)
The monolignol biosynthetic pathway in P. trichocarpa.
Thirty-five metabolic fluxes (V0 to V35, represented by the circled numbers) mediate the conversion of 24 metabolites (underlined numbers) for monolignol synthesis by the 21 pathway enzymes (Wang et al., 2014).
(TIF)
List of all the reactions involved in the monolignol biosynthesis pathway.
(DOCX)
Steady state flux (V7, V8 and V9) variation as a function of total Ptr4CL concentration for models without the Ptr4CL3-Ptr4CL5 complex.
(TIF)
Steady state flux (V7, V8 and V9) variation as a function of total Ptr4CL concentration for models with the Ptr4CL3-Ptr4CL5 complex.
(TIF)
Ptr4CL pathway inhibitory reactions.
(TIF)
Violin plot showing the steady state flux (V7, V8 and V9) variation as a function of total Ptr4CL concentration for models in the presence of the Ptr4CL3-Ptr4CL5 complex.
(TIF)
Variation in the distributions of P-coumaric (μM), caffeic (μM), and ferulic (μM) acid concentrations in the presence of the Ptr4CL3-Ptr4CL5 complex.
(TIF)
Variation of S/G ratio as a function of Ptr4CL3 and Ptr4CL5 concentration in the presence of a complex.
The color bar shows the variation of S/G ratio in log scale.
(TIF)
Variation of monolignol units resulting due to changes in levels of Ptr4CL3 and Ptr4CL5 concentrations in the presence of a complex: a) S and b) G.
(TIF)
List of all flux kinetic equations in the monolignol biosynthesis pathway.
(PDF)
Fat, oil and grease (FOG) released into the sewer collection system have resulted in the production of insoluble solids, leading to FOG blockages in sanitary sewer pipes and consequently sanitary sewer overflows (SSOs). FOG-related SSOs continue to be a global challenge for municipalities responsible for maintaining the conveyance of wastewater in...
There have been reports of North American landfills that are experiencing temperatures in excess of 80 − 100°C. However, the processes causing elevated temperatures are not well understood. The objectives of this study were to develop a model to describe the generation, consumption and release of heat from landfills, to predict landfill temperature...
The optimal design and operation of photosynthetic bioreactors (PBRs) for microalgal cultivation is essential for improving the environmental and economic performance of microalgae-based biofuel production. Models that estimate microalgal growth under different conditions can help to optimize PBR design and operation. To be effective, the growth pa...
Long chain free fatty acids (LCFFAs) from the hydrolysis of fat, oil and grease (FOG) are major components in the formation of insoluble saponified solids known as FOG deposits that accumulate in sewer pipes and lead to sanitary sewer overflows (SSOs). A Double Wavenumber Extrapolative Technique (DWET) was developed to simultaneously measure LCFFAs...
As part of a long-term project to develop a predictive model of lignin biosynthesis in the stem differentiating xylem of Populus trichocarpa, we explored the quantitative relationships of gene-specific monolignol pathway proteins and the amount of the lignin polymer. We determined the absolute abundance of monolignol pathway proteins in wild-type (...
Computationalfluid dynamics (CFD) is a rapid emerging field in wastewater treatment (WWT), with application to almost all unit processes. This paper provides an overview of CFD applied to a wide range of unit processes in water and WWT from hydraulic elements like flow splitting to physical,chemical and biological processes like suspended growth nu...
The mechanism which induces aerobic sludge granulation sludge is not fully understood. While many factors have been proposed and the ranges of values for some of those factors leading to granulation have been empirically determined, much of the work has been performed using either bubble column or airlift loop reactors. Hydraulic shear rates, which...
Computational fluid dynamics (CFD) modelling in the wastewater treatment (WWT) field is continuing to grow and be used to solve increasingly complex problems. However, the future of CFD models and their value to the wastewater field are a function of their proper application and knowledge of their limits. As has been established for other types of...
Fat, oil, and grease (FOG) deposits formed in sanitary sewers are calcium-based saponified solids that are responsible for a significant number of nationwide sanitary sewer overflows (SSOs) across United States. In the current study, the kinetics of lab-based saponified solids were determined to understand the kinetics of FOG deposit formation in s...
Time course transcriptome datasets are commonly used to predict key gene regulators associated with stress responses and to explore gene functionality. Techniques developed to extract causal relationships between genes from high throughput time course expression data are limited by low signal levels coupled with noise and sparseness in time points....
Insight into biological stress regulatory pathways can be derived from high-throughput transcriptomic data using computational algorithms. These algorithms can be integrated into a computational approach to provide specific testable predictions that answer biological questions of interest. This review conceptually organizes a wide variety of develo...
Alternative disinfection sources such as ultraviolet light (UV) are being pursued to inactivate pathogenic microorganisms such as Cryptosporidium and Giardia, while simultaneously reducing the risk of exposure to carcinogenic disinfection by-products (DBPs) in drinking water. UV-LEDs offer a UV disinfecting source that do not contain mercury, have...
Characterization of the complex pore structure which is often quantified by pore channel tortuosity has been challenging. In this work, two computational models were developed using computational fluid dynamics (CFD) to predict tortuosity of fibrous porous media. A novel experimental method of determination of tortuosity was also developed to valid...
Design and optimization of ultraviolet-initiated (UV-initiated) advanced oxidation processes (AOPs) using hydrogen peroxide (H2O2) must consider both system configuration and chemical kinetics. Alternative approaches to modeling AOP systems have been proposed in the literature; yet, due to the complex nature of the reactions involved, the literatur...
Modelling has been used frequently for both system understanding and optimization. However, the challenges put on the models are constantly growing. This entails new regulations for effluent, more accurate energy consumption predictions, predictions of greenhouse gas emissions, enlarging the scale towards urban water systems, to name but a few. Hen...
Population balance models (PBMs) represent a powerful modelling framework for the description of the dynamics of properties that are characterised by distributions. This distribution of properties under transient conditions has been demonstrated in many chemical engineering applications. Modelling efforts of several current and future unit processe...
The objective of this study was to characterize the microbial population dynamics during high strength anaerobic co-digestion of grease interceptor waste (GIW). GIW contains the entire contents of a grease interceptor including fat, oil, and grease (FOG), food residuals, and associated wastewater. Through step and pulse feeding strategies, two 8L l...
To date, computational fluid dynamics (CFD) models have been primarily used for evaluation of hydraulic problems at wastewater treatment plants (WWTPs). A potentially more powerful use, however, is to simulate integrated physical, chemical and/or biological processes involved in WWTP unit processes on a spatial scale and to use the gathered knowled...
Effective and low-cost dynamic membrane bioreactors (DMBR) can be a strong option for wastewater treatment in developing countries. The goal of this study was to investigate the effect of rice husk addition on the DMBR's nitrogen removal performance. Tests were performed at both lab-scale and pilot-scale facilities. Results showed that rice husk se...
Fat, oil, and grease (FOG) deposits are calcium-based saponified solids that can clog sewer systems and cause sanitary sewer overflows (SSOs) that pose a significant threat to public health. USEPA has set a requirement to public water treatment facilities to spend 15 billion dollars on new pipes and wastewater infrastructure to control sewer overfl...
The provision of safe water, sanitation and hygiene (WaSH) in schools has been established to improve health, boost educational achievement, and promote gender equity which has a positive impact on the society. However, in an earlier study conducted, with public secondary schools as the focus group, it was discovered that students knowledge and per...
We established a predictive kinetic metabolic-flux model for the 21 enzymes and 24 metabolites of the monolignol biosynthetic pathway using Populus trichocarpa secondary differentiating xylem. To establish this model, a comprehensive study was performed to obtain the reaction and inhibition kinetic parameters of all 21 enzymes based on functional r...
As a step toward predictive modeling of flux through the pathway of monolignol biosynthesis in stem differentiating xylem of Populus trichocarpa, we discovered that the two 4-coumaric acid:CoA ligase (4CL) isoforms, 4CL3 and 4CL5, interact in vivo and in vitro to form a heterotetrameric protein complex. This conclusion is based on laser microdissec...
Introduction
Fat, oil, and grease (FOG) deposits are calcium based saponified solids that can clog sewer systems and cause sanitary sewer overflows (SSOs) posing a significant threat to public health. Therefore, since 2007, USEPA has set a requirement to public water treatment facilities to spend 15 billion dollars on new pipes and wastewater infra...
Understanding the formation of Fat, Oil, and Grease (FOG) deposits in sewer systems is critical to the sustainability of sewer collection systems since they have been implicated in causing sewerage blockages that leads to sanitary sewer overflows (SSOs). Recently, FOG deposits in sewer systems displayed strong similarities with calcium-based fatty...
Understanding the formation mechanism of Fat, Oil, and Grease (FOG) deposits in sewer systems is important since they have been implicated in causing sewerage blockages, which eventually lead to sanitary sewer overflows (SSOs). Recently, FOG deposits in sewer systems were found to have strong similarities with calcium-based fatty acid salts, a prod...
Sanitary sewer overflows are caused by the accumulation of insoluble calcium salts of fatty acids, which are formed by the reaction between fats, oils and grease (FOG) and calcium found in wastewaters. Different sewer structural configurations (i.e., manholes, pipes, wet wells), which vary spatially, along with other obstructions (roots intrusion)...
FOG deposits in sewer systems have recently been shown to be metallic salts of fatty acids. However, the fate and transport of FOG deposit reactant constituents and the complex interactions during the FOG deposit formation process are still largely unknown. In this study, batch tests were performed to elucidate the mechanisms of FOG deposit formati...
4-Coumaric acid:coenzyme A ligase (4CL) is involved in monolignol biosynthesis for lignification in plant cell walls. It ligates coenzyme A (CoA) with hydroxycinnamic acids, such as 4-coumaric and caffeic acids, into hydroxycinnamoyl-CoA thioesters. The ligation ensures the activated state of the acid for reduction into monolignols. In Populus, it...
Anaerobic co-digestion of thickened waste activated sludge (TWAS) with grease interceptor waste (GIW) was conducted in two 8L lab scale semi-continuous digesters. GIW contains the entire contents of a grease interceptor (GI) including fat, oil, and grease (FOG), food residuals, and associated wastewater. The treated digester was spiked with periodi...
Anaerobic co-digestion of thickened waste activated sludge (TWAS) with grease interceptor waste (GIW) was conducted in two 8L lab scale semi-continuous digesters. GIW contains the entire contents of a grease interceptor (GI) including fat, oil, and grease (FOG), food residuals, and associated wastewater. The treated digester was spiked with periodi...
The Mass Action Law is a mathematical expression that relates reaction
rates and reactant concentrations. Michaelis-Menten kinetics, derived
from the mass action law, is frequently used in modeling biochemical
pathways. Michaelis-Menten kinetics requires knowledge on details of
the interaction between the substrates (and potential inhibitors) with...