Kauser Jahan

Activated Sludge and other Aerobic Suspended Culture Processes.

This is a literature review for the year 2014 and contains information specifically associated with suspended growth processes including activated sludge and sequencing batch reactors. This review is a subsection of the treatment systems section of the annual literature review. The review encompasses modeling and kinetics, nutrient removal, system design and operation. Compared to past reviews, many topics show increase in activity in 2014. These include, nitrogen and phosphorus control, fate and effect of xenobiotics, industrial wastes treatment, and some new method for the determination of activated sludge. These topics are referred to the degradation of constituents in activated sludge. Other sections include population dynamics, process microbiology of activated sludge, modeling and kinetics. Many of the subsections in the industrial wastes: converting sewage sludge into fuel gases, thermos-alkali hydrolysis of Waste Activated Sludge (WAS), sludge used as H2 S adsorbents were also mentioned in this review.

Modeling the influence of nonionic surfactants on biodegradation of phenanthrene

Surfactant mediated solubilization and simultaneous microbial degradation of phenanthrene in a completely mixed batch system has been studied. A mathematical model is presented based on the rates of solids dissolution, substrate biodegradation and oxygen uptake in terms of five coupled differential equations. The model accounts for the concurrent utilization of surfactants for cell growth. The system of differential equations has been solved by numerical integration to calculate the oxygen utilization, cell mass production and substrate concentration as a function of time. Sensitivity analysis of the model indicates that the maximum specific growth rate, the oxygen consumption coefficient, cell yield coefficient and dissolution coefficient are the most significant parameters that control the process. Four commercial nonionic surfactants at a concentration of 25 mg/L were tested to evaluate their effect on biodegradation rates of phenanthrene. The model could adequately predict the oxygen uptake, cell growth and substrate disappearance data observed in the experimental studies. The presence of surfactants enhanced the biodegradation rate for phenanthrene. The results also indicated that the most significant effect of surfactant addition was the increase in the dissolution rate of phenanthrene to the aqueous phase.

Ultrasound inspection of wastewater concrete pipelines—signal processing and defect characterization

This paper focuses on the development of an innovative nondestructive test procedure (system+algorithm) for characterizing defects in concrete sewer pipelines, using ultrasonic inspection. A signal processing technique is being developed that is invariant to changes in both concrete material properties and composition of wastewater. Development of such an inspection procedure will be the first step in the design of a mobile autonomous vehicle for inspecting wastewater pipeline systems. Results demonstrating the validity of the proposed approach are presented.

Toxicity Of Nonionic Surfactants

Nonionic surfactants are amphilic chemicals that enhance desorption and bioavailability by increasing solubility and dispersion of poorly soluble hydrocarbons and oils. This study was conducted to determine the toxicity of commercial nonionic surfactants by using the Microtox Acute Toxicity test which is a rapid, simple test for toxicity. The test uses the luminescent bacterium V. fischeri as the test organism. Five common commercial nonionic surfactants Tergitol NP-10, Triton X-100, Igepal 630, Brij 35 and Tween 40 were used in the study. Light readings were taken initially as well as at 0 minutes, 5 minutes and 10 minutes to see how the toxicity of each surfactant changed with time. Experiments were conducted to determine the five-minute EC50 values. EC50 is the effective concentration that causes a 50% decrease in light output in a 5-minute exposure period. A higher effective concentration is interpreted as a lower toxicity. The critical toxic concentration (CTC) was also determined. Toxicity of the surfactants varied according to their difference in chemical structures and branching. EC50 values were less than the CTC and CMC values of all select surfactants. Higher toxicity was shown by surfactant solutions that contained a benzene ring in comparison to the others.

Phenanthrene mineralization in soil in the presence of nonionic surfactants

This research addresses the effect of surfactant addition on the microbial degradation of slightly soluble organic compounds in soil. Biodegradation of phenanthrene, coated on sand with a low f oc, was studied in the presence of nonionic surfactants. Phenanthrene coated sand was designed to simulate soil contaminated with excess phenanthrene which remains after evaporation of the lighter hydrocarbon solvents. A mixed culture acclimated to phenanthrene was used as the inoculum. Four nonionic surfactants were used in this study: Triton X‐114, Brij 35, Tween 40 and Corexit 0600. Continuous flow columns were employed to simulate groundwater flow through aquifers. The addition of Corexit 0600 and Tween 40 surfactants enhanced the biodegradation rate of phenanthrene while there was no enhancement by the other two surfactants. No appreciable lag period for mineralization was observed in these experiments. Additional tests are required to assess surfactant bacteria interactions to determine why certain surfactant...

Metal leaching from the bridge paint waste in the presence of steel grit

The disposal of paint waste from bridge rehabilitation is a significant issue because of the potential release of contaminants and the consequent impact to human health and the environment. In this study, leaching behavior of paint waste was evaluated for 24 bridges in New York State. Although elevated Pb (5-168,090 mg kg(-1)) and other metal concentrations were observed in the paint samples, leaching experiments that included the toxicity characteristic leaching procedure (TCLP) and the multiple extraction procedure (MEP) revealed toxicity characteristic (TC) limits were not exceeded. The relatively low concentrations observed are attributed to the use of iron-based abrasives (steel grit) in the paint removal process. In this research, trace metals are hypothesized to be sequestered through interactions with iron oxide coatings formed on the steel grit surface resulting in reduced leachable concentrations. Through sequential extraction iron oxides were observed at 11.03% by wt and X-ray diffraction (XRD) further corroborated the presence of iron oxide coatings on the steel grit surface. Sequential extraction demonstrated that less than 6.8% of Pb, Cr, and Ba were associated with the exchangeable and carbonate forms, while greater contributions were found with iron oxides. The largest fraction, however, greater than 80%, was associated with the residual phase comprised of minerals in the paint including SiO2 and TiO2.

SustainCity - An interactive virtual reality game system

This paper presents a working-in-progress project that designs a virtual reality (VR) game system to promote science and engineering design in the Project-Lead-The-Way curriculum. Using city infrastructure as the theme and engineers solving real-life problems as the scenes, the games of future sustainable city design engage students in science and engineering discovery through visualization, simulation, collaboration, and design.

Metal uptake by algae

Metal uptake by microorganisms has been studied for some years. Research indicates that algae have the ability to accumulate trace metals by biosorption and bioaccumulation. Biosorption is a term designated for all of the passive interactions with metals. In certain sites of the algae cell wall, adsorption reactions occur between the cell wall and the metal ion. Depending on the binding site (functional group on the binding site) and the type of metal, any of several various adsorption reactions can occur. Bioaccumulation reactions, on the other hand, are active reactions in which the metal ions are directly absorbed into the algal cell. The mechanism behind these reactions is generally a defensive one; meaning that the cell is absorbing the metal for the sole purpose of avoiding being poisoned. It is important to note that there is a striking difference in the time for each of these processes. The biosorption process has been shown to be rapid and frequently selective. Biosorption occurs in a matter of minutes while bioaccumulation occurs on a much longer time scale. Uptake of metals by algae may be a viable cost-effective biological pretreatment for the wastewater and water industries. Thus, a study was conducted to identify algae that can accumulate copper and arsenic via rapid biosorption. Common green algae Scenedesmus abundans and Chorella vulgaris were used for determining metal uptake (cupper and arsenic) in batch experiments. Results of the experiments indicated that the algae biosorption could be modeled by the conventional Freundlich and Langmuir isotherm models. Algae morphology studies indicated that the algae cells were impacted due to the presence of both metals as evidenced by clumping or loss of cell clusters. Results indicate that algae uptake of metals may be a viable method of pretreatment of metal contaminated wastewater.

Field methods for rapidly characterizing paint waste during bridge rehabilitation

For Department of Transportation (DOT) agencies, bridge rehabilitation involving paint removal results in waste that is often managed as hazardous. Hence, an approach that provides field characterization of the waste classification would be beneficial. In this study, an analysis of variables critical to the leaching process was conducted to develop a predictive tool for waste classification. This approach first involved identifying mechanistic processes that control leaching. Because steel grit is used to remove paint, elevated iron concentrations remain in the paint waste. As such, iron oxide coatings provide an important surface for metal adsorption. The diffuse layer model was invoked (logKMe=4.65 for Pb and logKMe=2.11 for Cr), where 90% of the data were captured within the 95% confidence level. Based on an understanding of mechanistic processes along with principal component analysis (PCA) of data obtained from field-portable X-ray fluorescence (FP-XRF), statistically-based models for leaching from paint waste were developed. Modeling resulted in 96% of the data falling within the 95% confidence level for Pb (R(2) 0.6-0.9, p ⩽ 0.04), Ba (R(2) 0.5-0.7, p ⩽ 0.1), and Zn (R(2) 0.6-0.7, p ⩽ 0.08). However, the regression model obtained for Cr leaching was not significant (R(2) 0.3-0.5, p ⩽ 0.75). The results of this work may assist DOT agencies with applying a predictive tool in the field that addresses the mobility of trace metals as well as disposal and management of paint waste during bridge rehabilitation.

Interactive and Collaborative Games Promoting Metacognition for Science and Engineering Design

The focus of this project is to design and implement a virtual reality game system that infuses cyberinfrastructure (CI) learning experiences into the engineering classrooms to promote metacognition for science and engineering design in context. Using city infrastructure as the theme and engineers solving real-life problems as the scenes, the games of future sustainable city design engage students, particularly beginning science and engineering students, in CI-enhanced and -enabled science and engineering discovery. The CI features, the metacognitive strategies, the context-oriented approaches as well as their seamless integration in the game are presented through a detailed game module.