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UNDERSTANDING URBAN VEHICULAR POLLUTION PROBLEM VIS-A-VIS AMBIENT AIR QUALITY – CASE STUDY OF A MEGACITY (DELHI, INDIA)
No full textAir pollution has become a growing problem in megacities and large urban areas through
out the globe, and transportation is recognized as the major source of air pollution in many cities,
especially in developing countries. Contribution of automobiles is reported in the range of 40 to 80%
of the total air pollution. The challenge facing megacities is how to reduce the adverse environmental
impacts and other negative effects of transportation without giving up the benefits of mobility. The
dilemma becomes most pressing under conditions of rapid urban growth, which is likely to increase
travel demand significantly.
The paper is aimed at understanding the problem of vehicular pollution vis-a-vis ambient air
quality for a highly traffic affected megacity, Delhi, wherein, the contribution of transport sector was
estimated to be as high as 72%. An effort has been made to review and evaluate the benefits (in terms
of improved air quality) of the technological interventions/policies adopted for vehicular pollution
control in Delhi. It also highlights the outcome of the efforts and suggests further improvements
thereon. The importance of public participation and awareness are also discussed. The paper focuses
on deriving the benefits of the implementation of management strategies, supported by scientific
and technical data/ interpretation, so that the people can realize and participate in the government’s
endeavor for clean city drive in a more effective manner
Concentrations of volatile organic compounds (VOCs) at an oil refinery
No full textThis study measured and analysed individual volatile organic compounds (VOCs), total hydrocarbon
and total VOCs at an oil refinery. Measurements were taken at various workplace locations, of the
ambient air and at some off-site facilities such as its gantry terminals, ETP and tank farms. The study
also identified certain pollutants that are difficult to measure routinely but could give an indication of
their presence in a refinery. The VOCs were sampled using charcoal adsorption tubes and desorbed
using a thermal desorption technique. The samples were subsequently analysed by Varian 2200 GC/MS system. The 8-h average concentrations of benzene, toluene, ethylbenzene and xylenes ranged between 23.48–113.05, 18.70–72.54, 2.91–9.80 and 5.83–27.64 μg/m3, respectively. Alongside substituted benzenes, such as 135 and 124, trimethylbenzenes and naphthalene were also detected.
The total hydrocarbon ranged between 5.0–13.8 ppm and the NMHC was in the range of 2.2–9.0 ppm. The study indicates the concentration of fugitive emissions of VOCs in the refinery and its utilities
Surfactant-Modified Zeolite as a Slow Release Fertilizer for Phosphorus
No full textThe feasibility of using surfactant-modified zeolite(SMZ)as a carrier for fertilizer and for slow release of phosphorus (P)was investigated. Zeolite-A was modified by using hexadecytrimethylammonium bromide, a cationic surfactant, to modify its surface to increase its capacity to retainanion, namely, infrared, and scanning electron microscopy to study the effect of surfactant modification. Zeolite-A and SMZ were then subjected to P loading by treating them with fertilizer(KH2PO4). It was observed that the P loading on SMZ increased by a factor of 4.9 as compared to the unmodified Zeolite-A. A comparative study of the release of P from fertilizer-loaded unmodified zeolite-A and SMZ and from solid KH2PO4 was performed using the conatant flow percolation reactor. The result show that the P supply from fertilizer-loaded SMZ was available even after 1080 h of continuous percolation, whwreas P from KH2PO4 was exhausted within 264 h. The result indicate that SMZ is a good sorbent for PO4, and a slow release of P was achievable. These properties suggest that SMZ has a great potential as the fertilizer carrier for slow relese of P
Air quality forecasting using a hybrid autoregressive and nonlinear model
No full textThe usual practices of air quality time-series forecasting are based on applying the models that deal with either the linear or nonlinear patterns. As the linear or nonlinear behavior of the time series is not known in advance, one applies the number of models and finally selects the one, which provides the most accurate results. The air pollutant concentration time series contain patterns that are not purely linear or nonlinear and applying either technique may give inadequate results. This study aims to develop a hybrid methodology that can deal with both the linear and nonlinear structure of the time series. The hybrid model is developed using the combination of autoregressive integrated moving average model,which deals with linear patterns and nonlinear dynamical model. To demonstrate the utility of the proposed technique,nitrogen dioxide concentration observed at a site in Delhi during 1999 to 2003 was utilized. The individual linear and nonlinear models were also applied in order to examine the performance of the hybrid model. The performance is
compared for one-step and multi-step ahead forecasts using the error statistics such as mean absolute percentage error and relative error. It is observed that hybrid model outperforms the individual linear and nonlinear models. The exploitation of unique features of linear and nonlinear models makes it a powerful technique to predict the air pollutant concentrations
Nonlinear Analysis and Prediction of Coarse Particulate Matter Concentration in Ambient Air
No full textThis study attempts to characterize and predict coarse particulate matter(PM10) concentration in ambient air using the concepts of nonlinear dynamical theory.PM10 data, India, was used to study the applicability of the chaos theory. First, the autocorrelation function and fourier power spectrum were used to analyze the behavior of the time-series.The dynamics of the timr-series was additionally studied through correlation integral analysis and phase space reconstruction. The nonlibear predictions were then obtained using local polynominal approximation based on the reconstructed phase space. The results were then compared with the autoregressive model. The results of nonlinear analysis indicated the presence of chaotic character in the PM10 time-series. It was also obsered that the nonlinear local approximation outperforms the autoregressive model, because the observed relative error of prediction for the autoregessive model was greater then the local approximation model. The invariant measures of nonlinear dynamics computed for the predicted time-series using the two models also supported the same findings
Resource conservation through land treatment of municipal wastewater
No full textIndustrialization and urbanization have been causing
tremendous pressure on the water resources. In turn,
to maintain the pace of development, it has become
necessary to search for alternative sources of water.
Conventional wastewater-treatment technologies are
cost-intensive and often pose financial constraint in
developing countries. Therefore, considerable attention
has been directed towards design and development of
low-cost wastewater management technologies coupled
with recycle and reuse benefits. High Rate Transpiration
System (HRTS) is one such technology which can
be implemented for domestic effluent disposal and reuse.
This hypothesis was examined in field and laboratory
experiments conducted by the National Environmental
Engineering Research Institute (NEERI), Nagpur, India.
This communication highlights the use of HRTS
for the removal of pollutants like BOD, nitrogen and
phosphorus from primary treated wastewater. The
low-tech and low-cost wastewater treatment HRTS
shows good performance for reduction of pollutants
with minimal soil and plant contamination
Heat Transfer and Thermographic Analysis of Catalyst Surface during Multiphase Phenomena under Spray-Pulsed Conditions for Dehydrogenation of Cyclohexane over Pt Catalysts
No full textDehydrogenation of cyclohexane over Pt/alumite and Pt/activated carbon catalysts has been carried out for hydrogen storage and supply to fuel cell applications. An unsteady state has been created using spray pulsed injection of cyclohexane over the catalyst surface to facilitate the endothermic reaction to occur efficiently. Higher temperature of the catalyst surface is more favorable for the reaction, thus the heat transfer phenomena and temperature profile under alternate wet and dry conditions created using spray pulsed injection becomes important. IR thermography has been used for monitoring of temperature profile of the catalyst surface simultaneously with product analysis. The heat flux from the plate-type heater to the catalyst has been estimated using a rapid temperature recording and thermocouple arrangement. The estimated heat flux under transient conditions was in the range of 10-15 kW/m2, which equates the requirement for endothermic reactions to the injection frequency of 0.5 Hz, as used in this study. The analysis of temperature profiles, reaction products over two different supports namely activated carbon cloth and alumite, reveals that the more conductive support such as alumite is more suitable for dehydrogenation of cyclohexane
Catalytic Properties of Strontium Ruthenate Perovskite Prepared by Hot Isostatic Pressure Method
No full textHot Isostatic Pressure (HIP) process has been used for the first time to
synthesize SrRuO3 type perovskite. The syntheitc material shows the formation
of highly crystalline and pure phase, which is often difficult to achieve due to
Ru volatalization during synthesis, also leading to the formation of undesired
phases. The catalytic properties of this material have been studied for methane
combustion reaction which infer good catalytic activity of this catalyst. SrRuO3
appears to follow a suprafacial mechanism through dissociative adsorption of
oxygen, while strontium may also be contributing towards the weakening of
Ru-0 bond of the adsorbed oxygen, to facilitate the catalytic activity for this
reaction. The catalyst shows very high thermal stability, which otherwise is a
limitation with ruthenium based catalytic materials. HIP therefore, can be
especially useful to synthesize catalytic materials based on volatile component
like ruthenium, which can be thermally stabilized in perovskite type structur