A simple chemical free arsenic removal method for community water supply - A case study from West Bengal, India

This report describes a simple chemical free method that was successfully used by a team of European and Indian scientists (www.qub.ac.uk/tipot) to remove arsenic (As) from groundwater in a village in West Bengal, India. Six such plants are now in operation and are being used to supply water to the local population (www.insituarsenic.org). The study was conducted in Kasimpore, a village in North 24 Parganas District, approximately 25 km from Kolkata. In all cases, total As in treated water was less than the WHO guideline value of 10 μg L⁻¹. The plant produces no sludge and the operation cost is 1.0 US$ per day for producing 2000 L of potable water.     

Application of low-cost adsorbents for dye removal – A review

Dyes are an important class of pollutants, and can even be identified by the human eye. Disposal of dyes in precious water resources must be avoided, however, and for that various treatment technologies are in use. Among various methods adsorption occupies a prominent place in dye removal. The growing demand for efficient and low-cost treatment methods and the importance of adsorption has given rise to low-cost alternative adsorbents (LCAs). This review highlights and provides an overview of these LCAs comprising natural, industrial as well as synthetic materials/wastes and their application for dyes removal. In addition, various other methods used for dye removal from water and wastewater are also complied in brief. From a comprehensive literature review, it was found that some LCAs, in addition to having wide availability, have fast kinetics and appreciable adsorption capacities too. Advantages and disadvantages of adsorbents, favourable conditions for particular adsorbate–adsorbent systems, and adsorption capacities of various low-cost adsorbents and commercial activated carbons as available in the literature are presented. Conclusions have been drawn from the literature reviewed, and suggestions for future research are proposed.     

Antibiotic uptake by plants from soil fertilized with animal manure

Antibiotics are commonly added to animal feed as supplements to promote growth of food animals. However, absorption of antibiotics in the animal gut is not complete and as a result substantial amounts of antibiotics are excreted in urine and feces that end up in manure. Manure is used worldwide not only as a source of plant nutrients but also as a source of organic matter to improve soil quality especially in organic and sustainable agriculture. Greenhouse studies were conducted to determine whether or not plants grown in manure-applied soil absorb antibiotics present in manure. The test crops were corn (Zea mays L.), green onion (Allium cepa L.), and cabbage (Brassica oleracea L. Capitata group). All three crops absorbed chlortetracycline but not tylosin. The concentrations of chlortetracycline in plant tissues were small (2-17 ng g(-1) fresh weight), but these concentrations increased with increasing amount of antibiotics present in the manure. This study points out the potential human health risks associated with consumption of fresh vegetables grown in soil amended with antibiotic laden manures. The risks may be higher for people who are allergic to antibiotics and there is also the possibility of enhanced antimicrobial resistance as a result of human consumption of these vegetables.     

Uptake and translocation of metals in Spinacia oleracea L. grown on tannery sludge-amended and contaminated soils: effect on lipid peroxidation, morpho-anatomical changes and antioxidants

The plants of Spinacia oleracea L. grown on contaminated soil (CS) and different amendments of tannery sludge (TS) have shown high accumulation of metals in its edible part. The accumulation of toxic metal (Cr) in the leaves of the plants grown on CS was recorded as 40.67 microgg(-1)dw. However, the leaves of the plants grown on 100% TS have accumulated about two times (70.80 microgg(-1)dw) higher Cr than the 10% TS (31.21 microgg(-1)dw). Among growth parameters, the root length was more affected at 90 d than the shoot length, number of leaves and leaf area. The study of scanning electron micrographs showed 29.31% increase in stomatal length in the leaves of the plants grown on CS as compared to garden soil (GS), which served as control, however it decreased in the plants grown on higher amendments of TS. The decrease in MDA content at initial period of exposure and lower amendment was recorded in the leaves, whereas, significant increase (>10% TS onward) was observed with increase in tannery sludge ratio at 90 d as compared to GS. A coordinated increase in all the studied antioxidants (cysteine, non-protein thiol, ascorbic acid, carotenoid contents) was found up to 75 d of growth. At 90 d, most of the antioxidant decreased as compared to 75 d causing oxidative stress as evidenced by increased level of lipid peroxidation and decreased chlorophyll and protein contents. Maximum increase of 181.43% in MDA content and maximum decrease of 53.69% in total chlorophyll content was recorded in the leaves of the plants grown on 100% TS after 90 d of growth. The plants grown on CS have shown an increase in shoot length, number of leaves, leaf area, photosynthetic pigments and protein contents and in all the studied antioxidants. Thus, these plants are able to combat stress involving defense mechanism, resulting in healthy growth of the plants. The results are well coordinated as there is no change in the MDA content as compared to the plants grown on GS. In view of high Cr accumulation in edible part of S. oleracea grown on CS after irrigation with tap water, it is not advisable to use these plants for edible purposes. Summing up, it is recommended that the level of metals in the edible part should be checked instead of healthy growth as deciding parameter for consumption. It is demonstrated through this study that metal enriched plants have detoxification mechanism and grow well on organic matter enriched contaminated soil.     

Treatment of phenolic wastewater by horseradish peroxidase immobilized by bioaffinity layering

Horseradish peroxidase was immobilized by bioaffinity layering and used for the treatment of wastewater containing p-chlorophenol. For this purpose, lectin Concanavalin A was bound to Sephadex beads. The glycoenzyme peroxidase was layered upon this Con A layer. Subsequently, alternate layers of the enzyme and Con A were applied. The most efficient design consisted of three layers of Con A and peroxidase each. This immobilized enzyme preparation retained 80% of the activity of the free peroxidase used for immobilization. PEG at the concentration of 0.1 mg ml(-1) was found to prevent enzyme inactivation by the products, although it increased the process time. Thus 60 U ml(-1) of enzyme completely converted the p-chlorophenol (into products) in 4 min in the absence of PEG. On the other hand, only 0.05 U ml(-1) of enzyme was required for this purpose in the presence of PEG but the process required 60 min. Peroxidase converts phenol molecules into free radicals. These free radicals then polymerize and get precipitated. As a further means of minimizing exposure of the enzyme to free radicals and enhancing the reusability, it was decided to remove the enzyme from reaction medium after 10 min. With this strategy, the bioaffinity layered peroxidase preparation could be reused five times without any loss of activity.     

Controlled release of thiram fungicide from starch-based hydrogels

In order to make the judicious use of thiram fungicide and to exploit the potential of agri-polymers, we have developed the starch- poly(acrylamide) and starch-poly(acrylic acid) based agrichemical delivery system (hydrogels) for its controlled and sustained release. Polymeric networks have been prepared by using N,N'-methylenebisacrylamide (N,N-MBAAm) as crosslinker and ammonium persulfate (APS) as initiator and characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and swelling studies. Release dynamics of thiram fungicide from polymeric matrices has been studied for the evaluation of the diffusion mechanism and diffusion coefficients. It has been established that Non-Fickian diffusion mechanism has occurred for the release of thiram from these polymeric matrices. Furthermore, the initial rate of diffusion of thiram from these polymeric matrices is more as compared to the late stages of diffusion, which is analogous to the trends obtained for the diffusion of water molecules from these polymer matrices.     

Bio-control of waterborne pathogens using Lactobacillus spp

Bacteria play a significant role in water contamination. Chemicals are mostly used for the treatment of bacteriologically contaminated water. The use of bacterial interactions is a new approach to limit the pathogens' growth. Detection of antimicrobial substances produced by lactic acid bacteria against the waterborne pathogens is the objective of this work. Microbiological and biochemical methods were used to identify lactic acid bacteria having an antimicrobial activity. Evaluation of antimicrobial activity with growth kinetic measurements was performed. Four isolates of lactic acid bacteria obtained from whey and curd were identified. The predominant species belonging to the Lactobacillus genera are: Lactobacillus rhamnosus, Lactobacillus sakei, Lactobacillus paracasei, and Lactobacillus paraplantarum. The present study revealed that the Lactobacillus consortium is able to inhibit Staphylococcus aureus's growth along with Escherichia coli and Vibrio species. In mixed culture, after 24?h, the Lactobacillus consortium reduces the growth of S. aureus by 2.03 log; moreover, the growth of the latter bacteria totally ceased after 72?h of incubation. The protein produced by the Lactobacillus consortium was responsible for arresting the growth of S. aureus.     

Heavy metal accumulation in vegetables grown in a long-term wastewater-irrigated agricultural land of tropical India

In the present study, the magnitude of contamination of vegetables with heavy metals (Pb, Zn, Cd, Cr, Cu and Zn) was determined in a long-term wastewater-irrigated agricultural land. Heavy metal concentrations in vegetables were several folds higher in wastewater-irrigated site compared to clean water-irrigated area. The wastewater-irrigated crops analysed in this study are heavily contaminated with heavy metals. Concentrations of Pb, Zn, Cd and Cr in all the sewage-fed vegetables were beyond the safe limit of FAO/WHO and Indian standard. Contamination is at its highest level in radish and spinach. Daily intake values of Pb, Cd and Ni through consumption of sewage-fed vegetables exceeded the recommended oral dose of metal for both adult and children. The study concludes that wastewater irrigation led to accumulation of heavy metals in vegetables causing potential health risk to consumers.     

Development of Noise Simulation Model for Stationary and Mobile Sources: A GIS-Based Approach

In the rapidly urbanizing country like India, the transportation sector is growing rapidly, which lead to overcrowded roads producing air and noise pollution. Noise of a particular region is influenced by the volume of traffic on the highway, in addition to other causative factors like existing infrastructure and industrial setup etc. In the present paper, a geographical information system (GIS)-based noise simulation model has been developed to generate noise levels in Versova region of Mumbai, India. The study area comprises effect of infrastructure, road network, traffic volume, and various mechanical components like sewage pumping station and wastewater treatment facility. Various meteorological parameters and effect of land use and land cover on noise attenuation are also considered in the model. In this way, commutative noise prediction for point as well as mobile sources has been presented in the study. GIS-based noise simulation has been calibrated with observed noise levels during day and night time with correlation of 0.84 and 0.74, respectively.