Calibration and Validation of Far Field Dilution Models for Outfall at Worli, Mumbai

The city of Mumbai, India with a population of 15 million discharges about 2225 MLD of domestic wastewater after partial treatment to adjoining marine water body. Under the Mumbai Sewage Disposal Project Scheme, sewage is being disposed to the west coast at Worli and Bandra through 3.4 kms long submarine outfalls. A field study was conducted at recently commissioned outfall diffuser location at Worli, at the onset of neap flood tide to study the dispersion patterns and measure the far field dilutions using radio and dye tracers. Estimated dilutions using different tracers were compared with outputs from an empirical model (Brooks) and a 2D numerical model (DIVAST). Validation using parameters such as BOD and FC, indicated a good match for BOD in near field compared to FC. The radiotracer ⁸²Br and Rhodamine WT generally gave good correlation with Brooks' and DIVAST models for nearfield, however at further distances predictions were not accurate.     

Effect of size variation of fibre-shaped waste tyre rubber as fine aggregate on the ductility of self-compacting concrete

Environmental Science and Pollution Research - Abandoning shredded waste tyre rubber (WTR) in cement-based mixes facilitates safe waste tyre disposal and conserves the natural resources used in...     

Metal Accumulation by Riverine and Lacustrine Populations of Angulyagra Oxytropis (Benson) (Gastropoda : Viviparidae)

Cadmium, chromium, iron, manganese, nickel, lead and zinc concentrations were determined in sediment and body tissues, viz. digestive gland, mantle and shell, of the freshwater snail, Angulyagra oxytropis (Benson) (Gastropoda : Viviparidae), from River Barak and one of its floodplain lakes in Cachar district, Assam State, Northeastern India. The concentrations of all the metals except iron are significantly higher in the lake sediment. When compared to their riverine counterparts, the lacustrine snails contain higher concentrations of cadmium, chromium and iron in their mantle; nickel and zinc in digestive gland; manganese in both digestive gland and mantle; and lead in all the three tissues examined. The accumulation patterns of most of the metals varied considerably between the two sites. The implications of these findings in storage, sequestration and detoxification of metals by this animal are discussed. The study also indicates that A. oxytropis may be a potential biological indicator of metal contamination in freshwater ecosystems.     

Indexing method for assessment of pollution potential of leachate from non-engineered landfill sites and its effect on ground water quality

Dumping of solid waste in a non-engineered landfill site often leads to contamination of ground water due to leachate percolation into ground water. The present paper assesses the pollution potential of leachate generated from three non-engineered landfill sites located in the Tricity region (one each in cities of Chandigarh, Mohali and Panchkula) of Northern India and its possible effects of contamination of groundwater. Analysis of physico-chemical properties of leachate from all the three landfill sites and the surrounding groundwater samples from five different downwind distances from each of the landfill sites were collected and tested to determine the leachate pollution index (LPI) and the water quality index (WQI). The Leachate Pollution Index values of 26.1, 27 and 27.8 respectively for landfill sites of Chandigarh (CHD), Mohali (MOH) and Panchkula (PKL) cities showed that the leachate generated are contaminated. The average pH values of the leachate samples over the sampling period (9.2 for CHD, 8.97 for MOH and 8.9 for PKL) show an alkaline nature indicating that all the three landfill sites could be classified as mature to old stage. The WQI calculated over the different downwind distances from the contamination sites showed that the quality of the groundwater improved with an increase in the downwind distance. Principal component analysis (PCA) carried out established major components mainly from natural and anthropogenic sources with cumulative variance of 88% for Chandigarh, 87.1% for Mohali and 87.8% for Panchkula. Hierarchical cluster analysis (HCA) identifies three distinct cluster types for the groundwater samples. These clusters corresponds to a relatively low pollution, moderate pollution and high pollution regions. It is suggested that all the three non-engineered landfill sites be converted to engineered landfill sites to prevent groundwater contamination and also new sites be considered for construction of these engineered landfill sites as the present dumpsites are nearing the end of their lifespan capacity.     

Interdimensional correlations in individual and dyadic performance ratings

Performance rating research about individual performance may not necessarily generalize to rating performance of dyads. Using data from the 1992 Winter Olympics, this study demonstrates that observed interdimensional correlations are higher when dyads rather than individuals are being rated, particularly when raters have the opportunity to form prior general impressions of ratees. Implications of these results are discussed. © 1998 John Wiley & Sons, Ltd.     

Biofilm mediated degradation of commercially available LDPE films by bacterial strains isolated from partially degraded plastic

Biodegradation is an attractive approach for the elimination of synthetic polymers, pervasively accumulated in natural environments and generating ecological problems. The present work investigated the degradation of low‐density polyethylene (PE) by three Bacillus sp., that is, ISJ36, ISJ38, and ISJ40. The degree of biodegradation was assessed by measuring hydrophobicity, viability, and total protein content of bacterial biofilm attached to the PE surface. Although all three bacterial strains were able to establish an active biofilm community on the PE surface, ISJ40 showed better affinity toward PE degradation than the other two. Bacterial colonization and physical changes on the PE surface were visualized by scanning electron microscopy. Fourier transform infrared spectroscopy analysis revealed alteration in the intensities of functional groups along with an increase in the carbonyl bond indexes. The study results suggest that the Bacillus strain ISJ40 can be used as a potential degrader for the eco‐friendly treatment of PE waste.     

Removal and recovery of toxic nanosized Cerium Oxide using eco-friendly Iron Oxide Nanoparticles

• Eco-friendly IONPs were synthesized through solvothermal method. • IONPs show very high removal efficiency for CeO₂ NPs i.e. 688 mg/g. • Removal was >90% in all synthetic and real water samples. • >80% recovery of CeO₂ NPs through sonication confirms reusability of IONPs. Increasing applications of metal oxide nanoparticles and their release in the natural environment is a serious concern due to their toxic nature. Therefore, it is essential to have eco-friendly solutions for the remediation of toxic metal oxides in an aqueous environment. In the present study, eco-friendly Iron Oxide Nanoparticles (IONPs) are synthesized using solvothermal technique and successfully characterized using scanning and transmission electron microscopy (SEM and TEM respectively) and powder X-Ray diffraction (PXRD). These IONPs were further utilized for the remediation of toxic metal oxide nanoparticle, i.e., CeO₂. Sorption experiments were also performed in complex aqueous solutions and real water samples to check its applicability in the natural environment. Reusability study was performed to show cost-effectiveness. Results show that these 200 nm-sized spherical IONPs, as revealed by SEM and TEM analysis, were magnetite (Fe₃O₄) and contained short-range crystallinity as confirmed from XRD spectra. Sorption experiments show that the composite follows the pseudo-second-order kinetic model. Further R²>0.99 for Langmuir sorption isotherm suggests chemisorption as probable removal mechanism with monolayer sorption of CeO₂ NPs on IONP. More than 80% recovery of adsorbed CeO₂ NPs through ultrasonication and magnetic separation of reaction precipitate confirms reusability of IONPs. Obtained removal % of CeO₂ in various synthetic and real water samples was>90% signifying that IONPs are candidate adsorbent for the removal and recovery of toxic metal oxide nanoparticles from contaminated environmental water samples.     

Biodiesel production from a free fatty acid containing Karanja oil by a single-step heterogeneously catalyzed process

Karanja oil, containing 6.2% free fatty acids (FFAs), was considered for biodiesel production using a single-step solid-phase acid catalyzed process. Different types of zeolites and Amberlyst15 catalysts were tested and biodiesel was produced. Under similar conditions, the highest biodiesel yield was achieved using an Amberlyst15 catalyst, which contained 3–5% of moisture. The effects of operating parameters of the reaction such as reaction temperature, catalyst amount, and methanol-to-oil ratio were studied. An increase of methanol:oil ratio revealed a non-monotonic increase in biodiesel yields. Similar non-monotonic behavior was observed when Jatropha oil was used. Leaching and catalyst reusability were also considered. No significant effects of leaching were observed and catalyst reusability appeared to be affected by methanol interactions. The presence of a co-solvent, Tetrahydrofuran (THF), increased the biodiesel yield. Furthermore, an optimum amount of THF (THF:methanol volume ratio of 1:2) gave rise to the highest biodiesel yield. A biodiesel yield of 93% was achieved at 120 °C using a single-step process with Amberlyst15 as a catalyst, THF as a co-solvent, and a methanol:oil ratio of 30:1.     

Experimental evaluation of the catalytic efficiency of calcium based natural and modified catalyst for biodiesel synthesis

Transesterification of a mixture of vegetable oils with methanol using metal oxide catalysts derived from snail shell (SS) for biodiesel production was investigated. The metal oxides obtained from calcined snail shells in the temperature range of 650°–950 °C and modified by loading different potassium salts were used as a catalyst in the process. The catalysts were characterized by FT-IR, XRD, SEM-EDS, XPS and TGA. Catalytic activities of developed catalysts were also tested by Hammet indicator method and ion exchange method. The best calcination conditions were observed at 850°C for 4 hours based on biodiesel yield. The KF loaded snail shell gave highest biodiesel yield of 98 ± 1% in a batch reactor with highest basicity (15.9 mmoles/g) and basic strength measured by Hammet method. The optimized reaction conditions were: reaction temperature 65°C, reaction time 3 hours, methanol to oil molar ratio 9:1 and catalyst concentration 3wt%. Leaching and reusability tests confirm the stability of the catalyst as it encounters only 3% of leaching and small changes in catalytic activity up to five runs in terms of biodiesel yield.