Design and Development of Onsite Biofilter Unit for Effective Remediation of Contaminants from Wastewater

Agricultural biomass is proven ecofriendly and effective adsorbent for the remediation of contaminants from wastewater. Here, rice husk biochar (600 °C) prepared by a one-step pyrolysis method is used for the remediation of different contaminants in real samples. An onsite biofilter unit is fabricated with parallel trenches of different layers of coconut coir and biochar and is used as a biofiltration unit. The efficiency of the designed unit is assessed for the removal of different contaminants in pilot-scale experiments. Results show that removal efficiency varies from metal to metal and ranges from 5.52% to 90.76% using the biofilter unit. Fourier-transform infrared spectroscopy, scanning electron microscopy with energy dispersive X-ray analysis, carbon, hydrogen, nitrogen, and Brunauer–Emmett–Teller analysis before and after the adsorption represent the changes in the morphology and surface functionalization of the biochar. Results indicate that the designed biofilter unit could also be used as a promising agent for the remediation of pharmaceutical and other emerging contaminants from wastewater.     

A Comparative Evaluation of the Geotechnical Index Properties of Clayey Sediments along the West Coast of India

Sediment core samples collected during geotechnical surveys along the West Coast of India in the near shore areas of Arabian Sea have generated data on the geotechnical index properties of clayey sediments up to nearly 5 m depth below seafloor. A comparative study of three sectors within themselves is attempted before carrying out a final evaluation between the sectors. Cohesive clayey sediments of Gujarat sector are comparable though widely variant in a few aspects; in the Maharashtra-Goa-Karnataka sector though, plasticity levels and clay type vary, and activity and consistency levels are quite similar. Though broadly comparable, the clayey sediments of Kerala-Tamilnadu sector have quite diverse characteristics that fail to conform to any particular pattern as each area has an exclusive set of geotechnical properties.     

A study on the spatial variations in stable isotopic composition of precipitation in a semiarid region of Southern India

The stable isotope analysis of all major rain events from Moinabad (MB), Rajendranagar (RN) and Osmanasagar (OS) reservoir, three closely placed locations in Hyderabad, India, were carried out during the 2005 to 2008 period. The OS station recorded the highest amount of rainfall with an average value of 1000 mm, whereas the MB station recorded the lowest average rainfall of 790 mm. The stable isotope (δ¹⁸O) values of the precipitation samples during these period varied from ?11.43‰ to ?0.03‰ for the MB station, ?8.21‰ to 0.54‰ for the RN station and ?11.47‰ to 0.72‰ for the OS station. The d‐excess of precipitation at the three stations also showed considerable variations and revealed that the precipitation in the region undergoes significant modification through secondary evaporation during its fall. The possible causes for these observed spatial and temporal variations in amount and the isotopic composition of precipitation in a small geographical area within the city were studied. The observed variations may be attributed to the regional scale differences in water budget induced by rapid urbanisation activities in the city coupled with the differences in secondary effects undergone by the falling drops. This study elucidating changes in precipitation patterns in the city and its possible causes may largely help in its water balance calculation. Copyright © 2011 John Wiley & Sons, Ltd.     

Estimation of structural vulnerability for flooding using geospatial tools in the rural area of Orissa,India

Vulnerability assessment of natural disasters is a crucial input for risk assessment and management. In the light of increasing frequency of disasters, societies must become more disaster resilient. This research tries to contribute to this aim. For risk assessment, insight is needed into the hazard, the elements at risk and their vulnerabilities. This study focused on the estimation of structural vulnerability due to flood for a number of structural elements at risk in the rural area of Orissa, India (Kendrapara), using a community-based approach together with geospatial analysis tools. Sixty-three households were interviewed about the 2003 floods in 11 villages and 166 elements at risk (buildings) were identified. Two main structural types were identified in the study area, and their vulnerability curves were made by plotting the relationships between flood depth and vulnerability for each structural type. The vulnerability ranges from 0 (no damage) to 1 (collapse/total damage). Structural type-1 is characterized by mud wall/floor material and a roof of paddy straw, and structural type-2 is characterized by reinforced cement concrete (RCC) walls/floor and a RCC roof. The results indicate that structural type-1 is most vulnerable for flooding. Besides flood depth, flood duration is also of major importance. Houses from structural type-1 were totally collapsed after 3 days of inundation. Damage of the houses of structural type-2 began after 10 days of inundation.     

Two-dimensional meshfree modelling of contaminant transport through saturated porous media using RPIM

This paper presents a new numerical tool to model the two-dimensional contaminant transport through saturated porous media using a meshfree method, called radial point interpolation method (RPIM) with polynomial reproduction. In RPIM, an approximate solution is constructed entirely in terms of a set of nodes and no characterisation of the interrelationship of the nodes is needed. The advection–dispersion equation with sorption is considered to illustrate the applicability of the RPIM. The Galerkin weak form of the governing equation is formulated using 2D meshfree shape functions constructed using thin plate spline radial basis functions. MATLAB code is developed to obtain the numerical solution. Three numerical examples are presented and the results are compared with those obtained from the finite element method and analytical solutions. In order to test the practical applicability and performance of the RPIM, two case studies of contaminant transport through landfill liners are presented. A good agreement is obtained between the results of the RPIM and the field investigation data.     

Study of simultaneous presence of DD and PP electric fields during the geomagnetic storm of November 7–8, 2004 and resultant TEC variation over the Indian Region

During very intense geomagnetic storm of November 7–8, 2004 simultaneous presence of storm time disturbance dynamo and eastward and westward directed prompt penetration electric fields inferred from the ground based magnetometer data in the 75^° E sector is presented. Magnetometer observations show that, on the whole, average ΔH variation on 8 November remains below the night time level compared to its quiet day variation. A number of upward and downward excursions have been observed between 0130 UT and 0800 UT in the ΔH variation on 8 November. These excursions in ΔH have been attributed to the episodes of eastward and westward prompt penetrating electric fields. Ionospheric response in the equatorial ionization anomaly region along 75^° E has also been studied using the total electron content data recorded at five GPS stations, namely Udaipur, Bengaluru (IISC), Hyderabad (HYDE), Maldives (MALD) and Diego Garcia (DGAR). Observation of markedly suppressed EIA, in conjunction with ΔH variation which was m negative during the daytime on 8 November, indicates the presence of an external field of opposite polarity (the disturbance dynamo electric field) that either undermined, or overshadowed the daytime ambient (eastward) electric field to the extent that the equatorial plasma fountain could not become effective.     

Processes controlling the surface temperature signature of the Madden�CJulian Oscillation in the thermocline ridge of the Indian Ocean

During boreal winter, there is a prominent maximum of intraseasonal sea-surface temperature (SST) variability associated with the Madden?CJulian Oscillation (MJO) along a Thermocline Ridge located in the southwestern Indian Ocean (5°S?C10°S, 60°E?C90°E; TRIO region). There is an ongoing debate about the relative importance of air-sea heat fluxes and oceanic processes in driving this intraseasonal SST variability. Furthermore, various studies have suggested that interannual variability of the oceanic structure in the TRIO region could modulate the amplitude of the MJO-driven SST response. In this study, we use observations and ocean general circulation model (OGCM) experiments to quantify these two effects over the 1997?C2006 period. Observational analysis indicates that Ekman pumping does not contribute significantly (on average) to intraseasonal SST variability. It is, however, difficult to quantify the relative contribution of net heat fluxes and entrainment to SST intraseasonal variability from observations alone. We therefore use a suite of OGCM experiments to isolate the impacts of each process. During 1997?C2006, wind stress contributed on average only about 20% of the intraseasonal SST variability (averaged over the TRIO region), while heat fluxes contributed about 70%, with forcing by shortwave radiation (75%) dominating the other flux components (25%). This estimate is consistent with an independent air-sea flux product, which indicates that shortwave radiation contributes 68% of intraseasonal heat flux variability. The time scale of the heat-flux perturbation, in addition to its amplitude, is also important in controlling the intraseasonal SST signature, with longer periods favouring a larger response. There are also strong year-to-year variations in the respective role of heat fluxes and wind stress. Of the five strong cooling events identified in both observations and the model (two in 1999 and one in 2000, 2001 and 2002), intraseasonal-wind stress dominates the SST signature during 2001 and contributes significantly during 2000. Interannual variations of the subsurface thermal structure associated with the Indian Ocean Dipole or El Ni?o/La Ni?a events modulate the MJO-driven SST signature only moderately (by up to 30%), mainly by changing the temperature of water entrained into the mixed layer. The primary factor that controls year-to-year changes in the amplitude of TRIO, intraseasonal SST anomalies is hence the characteristics of intraseasonal surface flux perturbations, rather than changes in the underlying oceanic state.     

A Comparative Evaluation of the Geotechnical Index Properties of Clayey Sediments along the West Coast of India

Sediment core samples collected during geotechnical surveys along the West Coast of India in the near shore areas of Arabian Sea have generated data on the geotechnical index properties of clayey sediments up to nearly 5 m depth below seafloor. A comparative study of three sectors within themselves is attempted before carrying out a final evaluation between the sectors. Cohesive clayey sediments of Gujarat sector are comparable though widely variant in a few aspects; in the Maharashtra-Goa-Karnataka sector though, plasticity levels and clay type vary, and activity and consistency levels are quite similar. Though broadly comparable, the clayey sediments of Kerala-Tamilnadu sector have quite diverse characteristics that fail to conform to any particular pattern as each area has an exclusive set of geotechnical properties.     

Tsunami Inundation Modelling for the Coast of Kerala,India

The disastrous tsunami of December 26, 2004, exposed the urgent need for implementing a tsunami warning system. One of the essential requirements of a tsunami warning system is the set up of tsunami inundation models which can predict inundation and run-up along a coastline for a given set of seismic parameters. The Tsunami Warning Centre and the State/District level Disaster Management Centres should have tsunami inundations maps for different scenarios of tsunami generation. In the event of a tsunamigenic earthquake, appropriate decisions on issue of warnings and/or evacuation of coastal population are made by referring to such maps. The nature of tsunami inundation and run-up along the Kerala coast for the 2004 Sumatra and 1945 Makran, and a hypothetical worst-case scenario are simulated using the TUNAMI N2 model and the results are presented in this paper. Further, scenarios of tsunami inundation arising out of possible rise in sea level as projected by the Intergovernmental Panel on Climate Change (IPCC 2001) are also simulated and analysed in the paper. For the study, three representative sectors of the Kerala coast including the Neendakara-Kayamkulam coast, which was the worst hit by the 2004 tsunami, are chosen. The results show that the southern locations and certain locations of central Kerala coast are more vulnerable for Sumatra when compared to Makran 1945 tsunami. From the results of numerical modelling for future scenarios it can be concluded that sea level rise can definitely make pronounced increase in inundation in some of the stretches where the backshore elevation is comparatively low.