Pilot project at Hazira,India, for capture of carbon dioxide and its biofixation using microalgae

The objective of the present study was to set up a small-scale pilot reactor at ONGC Hazira, Surat, for capturing CO₂ from vent gas. The studies were carried out for CO₂ capture by either using microalgae Chlorella sp. or a consortium of microalgae (Scenedesmus quadricauda, Chlorella vulgaris and Chlorococcum humicola). The biomass harvested was used for anaerobic digestion to produce biogas. The carbonation column was able to decrease the average 34 vol.% of CO₂ in vent gas to 15 vol.% of CO₂ in the outlet gas of the carbonation column. The yield of Chlorella sp. was found to be 18 g/m²/day. The methane yield was 386 l CH₄/kg VS_fed of Chlorella sp. whereas 228 l CH₄/kg VS_fed of the consortium of algae.     

Plant biodiversity and ethnobotany inside the projected impact area of the Upper Seti Hydropower Project,Western Nepal

A survey of plant biodiversity and ethnobotany was conducted along the Seti river banks in the Tanahun district of Western Nepal. This area, home of the Magar ethnic group, will be impacted by a major hydropower project, currently under feasibility study. The objective of the study was to document plant biodiversity and ethnobotany in order to suggest appropriate conservation and management strategies. Botanical sampling was conducted inside quadrats and along transects. A total of 221 plant species were recorded in the study area, distributed as herbs (80 species), trees (68), shrubs (28), climbers (19), pteridophytes (18), lianas (5), and epiphytes (3). Twelve of the inventoried species figure in one or more conservation categories identified by various national or international agencies. Group discussions and personal interviews allowed to find out that 43% of the species were ethnobotanically important for the local people and that most were used as medicine, food, or timber. We propose specific species for sustainable use programs based on certain criteria. The area is very important in terms of plant biodiversity and ethnobotany, and hence, immediate implementation of conservation measures is recommended to maintain the high social, ecological and economic values of the area.     

Artificially roughened solar air heater: A comparative study

Artificially roughened solar air heater has been topic in research for the last 30 years. Prediction of heat transfer and fluid flow processes of an artificially roughened solar air heater can be obtained by three approaches: theoretical, experimental, and computational fluid dynamics (CFD). This article provides a comprehensive review of the published literature on the investigations of artificially roughened solar air heater. In the present article, an attempt has been made to present holistic view of various roughness geometries used for creating artificial roughness in solar air heater for heat transfer enhancement. This extensive review reveals that quite a lot of work has been reported on design of artificially roughened solar air heater by experimental approach but only a few studies have been done by theoretical and CFD approaches. Finally this article presents a comparative study of thermo-hydraulic performance of 21 different types of artificial roughness geometries attached on the absorber plate of solar air heater in terms of thermo-hydraulic performance parameter. Heat transfer and friction factor correlations developed by various investigators for different types of artificially roughened solar air heaters have also been reported in this article.     

Allometric models for the estimation of above- and below-ground biomass of Jatropha curcas L. in semi-arid regions of Southern India

Jatropha curcas L. (Jatropha) is an important multipurpose tree valued for oil. In India, plans are underway to bring substantial area under this crop for meeting the biofuel requirements of the country. A study was conducted to develop allometric relationships in Jatropha to predict various biomass-related components (above ground and below ground) using easily measurable attributes, viz. collar diameter, tree height, number of branches, crown diameter, and crown depth. Further, it was aimed to establish the reliability of these relationships using an independent dataset obtained from varied management situations. Destructive sampling was carried out during the rainy season of 2011, when Jatropha plants were eight years old. Highly significant allometric relationships (F-values significant at 1% level) were obtained while predicting various biomass components (above, below, and total) using easily measurable attributes with R² values ranging from 0.89 to 0.98. Of all the predictors, collar diameter exhibited a highly significant relationship with total dry biomass per plant (R² = 0.97). The allometric relationships developed were validated with an independent dataset. The allometric relationships developed would serve as valuable tools for estimating total dry biomass production and carbon sequestration with reasonable accuracy in Jatropha systems, as they are proposed to be taken up in substantial area in the years to come.     

A review on recent progress in observations,sources, classification and regulations of PM<Subscript>2.5</Subscript> in Asian environments

Natural and human activities generate a significant amount of PM_2.5 (particles ≤2.5 μm in aerodynamic diameter) into the surrounding atmospheric environments. Because of their small size, they can remain suspended for a relatively longer time in the air than coarse particles and thus can travel long distances in the atmosphere. PM_2.5 is one of the key indicators of pollution and known to cause numerous types of respiratory and lung-related diseases. Due to poor implementation of regulations and a time lag in introducing the vehicle technology, levels of PM_2.5 in most Asian cities are much worse than those in European environments. Dedicated reviews on understanding the characteristics of PM_2.5 in Asian urban environments are currently missing but much needed. In order to fill the existing gaps in the literature, the aim of this review article is to describe dominating sources and their classification, followed by current status and health impact of PM_2.5, in Asian countries. Further objectives include a critical synthesis of the topics such as secondary and tertiary aerosol formation, chemical composition, monitoring and modelling methods, source apportionment, emissions and exposure impacts. The review concludes with the synthesis of regulatory guidelines and future perspectives for PM_2.5 in Asian countries. A critical synthesis of literature suggests a lack of exposure and monitoring studies to inform personal exposure in the household and rural areas of Asian environments.     

Willingness to pay towards a public good: how does a refund option affect stated values?

Mandatory taxes and/or voluntary contributions are commonly adopted as the payment vehicle when eliciting willingness to pay (WTP) in environmental valuation studies. While mandatory taxes may arouse negative feelings, voluntary contributions may lead to strategic behaviour (over bidding) or free riding (under bidding). In this paper, we explore an alternative payment vehicle which avoids the draconian undertones associated with taxes and may be more incentive compatible than a voluntary contribution – a tax that incorporates a refund option. The template for such a payment vehicle is the value added tax charged to tourists in Ireland, but which can be reclaimed on exiting the country. In the context of raising public funds to support the conservation of rural countryside landscape, a comparison is made between the elicited WTP via a mandatory tax and that elicited via the alternative payment method incorporating a refund option. While we observe similar participation rates between the two payment methods, the refund option reveals a higher stated WTP.     

Status and Environmental Impact of Emissions from Thermal Power Plants in India

The main emissions from coal combustion at thermal power plants are carbon dioxide (CO₂), nitrogen oxides, sulfur oxides, chlorofluorocarbons (CFCs), and airborne inorganic particles such as fly ash and soot; CO₂, methane, and CFCs are greenhouse gases. These emissions are considered to be partially responsible for harmful global climate change. This review summarizes the status of thermal power plants in India and their various types of emissions that directly or indirectly produce harmful effects on the environment and human health. Moreover, it focuses on various types of preventive measures used to avoid/minimize emissions.     

Risk factors and prevalence of dental fluorosis and dental caries in school children of North India

The aim of the study was to assess the prevalence of dental fluorosis, dental caries, and associated risk factors in the school children of district Fatehgarh Sahib, Punjab, India, using a cross-sectional study design. Oral health status of children aged between 8 and 15 years was assessed using World Health Organization (WHO) 2013 criteria. Dental fluorosis was assessed using Dean’s index, and dental caries were recorded using decayed, missing, filled/decayed, extracted, filled (DMF/def) indices. Four hundred school children were examined, of which 207 were in the 8–11-year-old group and 193 were in the 12–15-year-old group. The overall prevalence of dental fluorosis was 4.1%, which might be linked to a high concentration of fluoride in drinking water at certain locations of rural Punjab. The prevalence of dental caries was 36.5% with a mean DMF score of 0.3 and def score of 0.6. Risk factors for dental caries include oral hygiene behavior and sugar consumption patterns. The study highlights the need to increase awareness about the oral health and hygiene among the school children in India.     

Effect of stocking density and food quality on the growth and fecundity of an epigeic earthworm (<Emphasis Type="Italic">Eisenia fetida</Emphasis>) during vermicomposting

Physico-chemical characteristics of the feed and optimum worm density are important parameters for the efficient working of a vermicomposting system. Overcrowding of worms can affect the efficiency of a vermicomposting system even if all other parameters have been optimized. This article reports the effect of stocking density and feed quality on the growth and fecundity of Eisenia fetida under laboratory conditions. The feed mixtures contained cow dung and textile mill wastewater sludge in different ratios. Three feed mixtures and five stocking rates (1, 2, 4, 8, and 12) were tested for 12 weeks. The results showed that E. fetida growth rate was faster at higher stocking densities; however, biomass gain per worm was faster at lower stocking densities. Sexual maturity was attained earlier at higher stocking densities. Growth rate was highest in 100% cow dung at all the stocking densities when compared to textile mill wastewater sludge containing feed mixtures. A worm population of 27–53 worms per kg of feed was found to be the most favorable stocking density.