Treatment of landfill leachates by nanofiltration

Landfill leachate contains high concentrations of organic matter, color, heavy metals and toxic substances. This study presents the feasibility of a commercial nanofiltration membrane (NF-300) in the removal of pollutants from a landfill leachate generated from the Treatment Stabilization and Disposal Facility in Gujarat state of India. Two different leachate samples (Leachates A and B) were collected from the downstream side of closed landfill cells A and B. The average quality of the leachate was 67 719 mg/L COD, 217 mg/L ammonical nitrogen, 22 418 mg/L BOD, 3847 mg/L chlorides and 909 mg/L sulphate. The operating variables studied were applied pressure (4–20 atm), feed flowrate (5–15 L/min) and pH (2, 4, 5.5 and 6.7). It was observed that the solute rejection (R_O) increased with increase in feed pressure and decreased with increase in feed concentration at constant feed flowrate. In the present study, the rejection of cations followed the sequence: R_O (Cr³⁺) > R_O (Ni²⁺) > R_O (Zn²⁺) > R_O (Cu²⁺) > R_O (Cd²⁺) for leachates A and B. The order of solute rejection sequence is inversely proportional to the diffusion coefficients. The rejection of sulphate ions by the NF-300 membrane was 83 and 85%, while the rejection of chlorides was 62 and 65% for leachates A and B, respectively. The NF-300 membrane was characterized by using the combined-film theory-Spiegler–Kedem (CFSK) model based on irreversible thermodynamics and the ion transport model based on the extended Nernst–Planck equation. The membrane transport parameters were estimated using the Levenberg–Marquadt method. The estimated parameters were used to predict the membrane performance and the predicted values are in good agreement with the experimental results.     

Indoor aerobiological pollution in certain indian domestic environments

The paper deals with bacterial and fungal populations and other pollutants in the indoors of slums, middle class, and upper class dwellings. Both allergenic and nonallergenic organisms have been observed to be higher in slums than in other dwellings. Further, females were more susceptible to various kinds of allergies than males.     

Methane emissions from a coastal lagoon: Vembanad Lake,West Coast,India

An attempt has been made to estimate methane fluxes from a tropical coastal wetland the Vembanad Lake, a lagoon along the West Coast of India. It has been found that Vembanad Lake contributes significant amount of methane to the atmosphere. Average emissions varied spatially within the lake. Methane emissions were 193.2 +/- 24.5 mg m(-2) h(-1) at Kumaragam (fresh water) as compared to 9.3 +/- 9.6 mgm(-2) h(-1) at Pullot (brackish water) site. Seasonal variation was significant between pre- and post-monsoons. Soil temperature, time of the day, salinity sediment organic carbon, all control the rate of methane emissions from the Vembanad Lake.     

GIS-based hazard and vulnerability assessment of a torrential watershed

Environment, Development and Sustainability - Torrents are ephemeral streams which usually carry heavy bedload and flash flows. The frequent changes in its course caused by meandering and migration...     

Effect of harvesting operations on fungal spore populations of air

Agricultural practices such as harvesting of crops cause the pathogens to disseminate in abundance and may cause diseases, like skin and respiratory allergies in an epidemic form. Also the farm workers were likely to be exposed repeatedly to high doses of fungal spore allergens from crop harvesting operations. At Srikakulam, located in North Coastal Andhra Pradesh, India, the major crops grown include rice and sugarcane. As part of a major study on the airspora of Srikakulam the effect of harvesting of these two crops on aerial spore concentrations was studied through rotorod trappings. The results showed an enormous increase in the spore load not only of the fungi pathogenic to the crop but also saprophytic fungi while the crop was harvested. The increase in the pathogenic fungal spores was large as evidenced by the increase of the rice crop pathogens as Trichoconis padwickii, Ustilaginoidea virens, Cochilobolus oryzae etc.     

Riverine pollution in some northern and north eastern states of india

Water samples from 30 rivers in northern and north-eastern hilly states of India were analysed for bacteriological and physicochemical parameters along with metals and pesticide residues. It was found that 34% of samples had >50 coliforms/100 ml, while 24% of samples demonstrated >50 thermotolerant (faecal) coliforms/100 ml. Among the metals, iron was found to be above maximum permissible limits in the rivers of all the states, while manganese was found to be above the maximum permissible limit in the rivers of Tripura and some northern states. Zinc, lead, nickel, chromium, copper, cobalt and cadmium plus physicochemical parameters and residual pesticides, however, were within their maximum permissible limits.