Denitrification with carbon addition--kinetic considerations

The Blue Plains Advanced Wastewater Treatment Plant (Washington, D.C.) uses methanol as an external carbon source in a postdenitrification process, to achieve low effluent total nitrogen concentrations. This becomes more difficult in winter, at lower mixed liquor temperatures and higher flows, as a consequence of the kinetic behavior of the methanol-utilizing heterotrophs. The paper reports on an experimental batch test study conducted on Blue Plains postdenitrification sludge to investigate (1) the maximum specific growth rate of methanol-utilizing heterotrophs (Mu(METH)); (2) the temperature dependency of the growth rate; and (3) the efficacy of alternate substrates (ethanol, acetate, and sugar). A limited number of tests were conducted on sludge from two other treatment plants with methanol addition.     

Assessment of organochlorine pesticide residues in Indian flue-cured tobacco with gas chromatography-single quadrupole mass spectrometer

Presence of pesticide residues in tobacco increases health risk of both active and passive smokers, apart from the imminent potential health problems associated with it. Thus, monitoring of pesticide residue is an important issue in terms of formulating stringent policies, enabling global trade and safeguarding the consumer’s safety. In this study, a gas chromatography-single quadrupole mass spectrometry (GC-MS) method based upon quantifier-qualifier ions (m/z) ratio was employed for detecting and assessing ten organochlorine pesticide residues (α-HCH, β-HCH, γ-HCH, δ-HCH, 2,4-DDT, 4,4-DDT, endrin, α-endosulfan, β-endosulfan and endosulfan sulphate) in 152 flue-cured (FC) tobacco leave samples from two major tobacco growing states, Karnataka and Andhra Pradesh, of India. In the majority of samples, pesticide residue levels were below the limit of quantification (LOQ). In few samples, pesticide residues were detected and they found to comply with the guidance residue levels (GRL) specifications of the Cooperation Center for Scientific Research Relative to Tobacco (CORESTA). Detection of the phase out pesticides like DDT/HCH might be due to transfer of persistent residues from the environmental components to the plant. This is the first report on these ten organochlorine pesticide residues in Indian FC tobacco.     

Monitoring conservation effectiveness in a global biodiversity hotspot: the contribution of land cover change assessment

Tropical forests, which play critical roles in global biogeochemical cycles, radiation budgets and biodiversity, have undergone rapid changes in land cover in the last few decades. This study examines the complex process of land cover change in the biodiversity hotspot of Western Ghats, India, specifically investigating the effects of conservation measures within the Indira Gandhi Wildlife Sanctuary. Current vegetation patterns were mapped using an IRS P6 LISS III image and this was used together with Landsat MSS data from 1973 to map land cover transitions. Two major and divergent trends were observed. A dominant degradational trend can be attributed to agricultural expansion and infrastructure development while a successional trend, resulting from protection of the area, showed the resilience of the system after prolonged disturbances. The sanctuary appears susceptible to continuing disturbances under the current management regime but at lower rates than in surrounding unprotected areas. The study demonstrates that remotely sensed land cover assessments can have important contributions to monitoring land management strategies, understanding processes underpinning land use changes and helping to inform future conservation strategies.     

Garcinia gummi-gutta (L.) Robs.: A promising feedstock for biodiesel production

In the present study crude Garcinia gummi-gutta seed oil was evaluated as a potential feedstock for biodiesel production. Due to the high acid value (29.73 mg KOH/g) the oil was converted to biodiesel by using acid catalyzed esterification process. Further, biodiesel properties of the sample were evaluated, which fulfilled the biodiesel specifications laid by ASTM D6751, EN 14214 and IS 15607. The biodiesel possessed excellent cetane number (66.09) and a high flash point (158°C). In addition, the calorific value (41.03 MJ/kg) was very close to diesel fuel. The results suggest that the G. gummi-gutta can be an alternative source for diesel and can be used as a potential feedstock for biodiesel in India.     

Studies on degradation of 14C-chlorpyrifos in the marine environment.

Degradation of 14C-chlorpyrifos was studied in a marine ecosystem for 60 days and in marine sediment under moist and flooded conditions using a continuous flow system allowing a total 14C-mass balance for a period of 40 days. In the marine ecosystem, 14C-chlorpyrifos underwent rapid degradation and very little (1-2%) 14C-residues of the applied activity were detected after two months in sediments. Clams were major component of the ecosystem and played a significant role in degradation of the insecticide. In the continuous flow system chlorpyrifos did not undergo substantial mineralization. Volatilization accounted for 0.8-1% loss during first ten days of application. The amounts of extractable 14C-activity were higher in flooded sediments than in moist sediment. More bound residues were formed under moist conditions. TCP (3,5,6-trichloro-2-pyridinol) was the major degradation product formed under both moist and flooded conditions, its formation being higher in the latter conditions. These studies underline the role of clams in degradation of chlorpyrifos and lack of microbial degradation. In absence of clams, chlorpyrifos underwent abiotic degradation in marine sediment with formation of bound residues.     

Early-season agricultural drought: detection, assessment and monitoring using Shortwave Angle and Slope Index (SASI) data

Early season or crop-planting-period (ES/CPP) drought conditions have become a recurrent phenomenon in tropical countries like India, due to fluctuations in the time of onset and progression of monsoon rains. ES/CPP agricultural drought assessment is a major challenge because of the difficulties in the generation of operational products on soil moisture at larger scales. The present study analyzed the Shortwave Angle Slope Index (SASI) derived from Near Infrared and Shortwave Infrared data of Moderate Resolution Imaging Spectroradiometer, for tracking surface moisture changes and assessing the agricultural drought conditions during ES/CPP, over Andhra Pradesh state, India. It was found that in-season progression of SASI was well correlated with rainfall and crop planting patterns in different districts of the study area state in both drought and normal years. Rainfall occurrence, increase in crop planted area, and decrease in SASI were in chronological synchronization in the season. Change in SASI from positive to negative values is a unique indication of dryness to wetness shift in the season. Duration of positive SASI values indicated the persistence of agricultural drought in the crop planting period. Mean SASI values were able to discriminate an area which was planted in normal year and unplanted in drought year. SASI thresholds provide an approximate and rapid estimate of the crop planting favorable area in a region which is useful to assess the impact of drought. Thus, SASI is a potential index to strengthen the existing operational drought monitoring systems. Further work needs to be on the integration of multiple parameters—SASI, soil texture, soil depth, rainfall and cropping pattern, to evolve a geospatial product on crop planting favorable areas. Such products pave the way for quantification of drought impact on agriculture in the early part of the season, which is a major inadequacy in the current drought monitoring system.     

Hydrochemistry of Wet Atmospheric Precipitation Over an Urban Area in Northern Indo-Gangetic Plains

Rain water samples were collected to study the chemical composition of wet atmospheric precipitation (first event) over the Lucknow city in the northern Indo-gangetic alluvial plains. The samples were collected in the month of July, 2005 from different sites. The wet precipitation samples were analyzed for pH, EC, major ions (, Cl⁻, , , , F⁻, Na⁺, K⁺, Ca²⁺, Mg²⁺, ) and heavy metals (As, Cd, Al, Co, Cr, Cu, Fe, Mn, Mo, Ni, Hg, Pb, Se, Sn, Ti, V, Zn). The pH values of wet precipitation samples ranged between 6.5 and 8.7. The analysis of linear regression applied to the set of studied variables and computation of neutralization factors showed that neutralization occurred in precipitation samples and Ca²⁺ had the maximum neutralization capacity. It was found that Cl⁻, , Ca²⁺, Mg²⁺, Na⁺ and K⁺ in the precipitation samples originated mainly from crustal/anthropogenic sources in the region. On an average Fe, and Al accounted for >72% of the total concentration of trace metals in the wet precipitation samples followed by Zn (>10%). Enrichment factors calculated for heavy metals over reference background level in seawater and Earth’s crust showed relatively higher enrichment of Zn. The principal component analysis (PCA) identified the possible sources of ionic species and heavy metals in the wet precipitation samples.     

Numerical studies on the thermal regimes of the horizontal tube falling film evaporation under varying feeder height

ABSTRACT

This paper discusses about the effect of feeder height and heat flux on the heat transfer characteristics of horizontal tube falling film evaporation in the thermal regimes. In order to investigate this, a two- dimensional CFD model was developed to perform simulation and results were compared and validated with published data available in the literature. Heat transfer co-efficients in the thermal regimes were determined from the CFD simulation and the results were recorded, analyzed and validated with the mathematical models available in the literature. The novelty of the current study is to predict the commencement of the fully developed thermal region over the tube from the simulation model under varying feeder height and heat flux. An effort was also made to measure the liquid film thickness around the tube from the CFD model in the thermal regimes. It is observed that angle of thermally developing region contracts and fully developed thermal region extends with the increase of the feeder height and heat flux. It is observed from the study that increase of heat flux by 10 kW/m² resulted in increase of heat transfer co-efficient value by 10–12% average in thermally developing region and 12–15% average in fully developed region. Thinnest liquid film thickness observed between 85 and 127°angle. Shifting of thinnest region of liquid film upward from the mid tube with the increase of the feeder height and heat flux is noted.