Power generation by high head water in a building using micro hydro turbine—a greener approach

Demand for green energy production is arising all over the world. A lot of emphasis is laid in making the buildings green. Even a small amount of energy savings made contribute to saving the environment. In this study, an idea is proposed and studied to extract power from the high head water in the pipelines of a building. A building of height 15 m is considered for this study. Water flowing in the pipe has sufficient energy to run a micro hydro turbine. The feasibility of producing electrical energy from the energy of pipe water is found. The motivation is to find the feasibility of generating power using a low-cost turbine. The experimental setup consists of micro turbine of 135 mm diameter coupled to a 12-V DC generator; LEDs and resistors are employed to validate the results. The theoretical calculations were presented using the fundamental equations of fluid mechanics. The theoretical results are validated using experimental and numerical results using CFD simulation. In addition, exergy analysis has been carried out to quantify the irreversibilities during the process in the system.     

Fluoride in weathered rock aquifers of southern India: Managed Aquifer Recharge for mitigation

Climatic condition, geology, and geochemical processes in an area play a major role on groundwater quality. Impact of these on the fluoride content of groundwater was studied in three regions—part of Nalgonda district in Telangana, Pambar River basin, and Vaniyar River basin in Tamil Nadu, southern India, which experience semi-arid climate and are predominantly made of Precambrian rocks. High concentration of fluoride in groundwater above 4 mg/l was recorded. Human exposure dose for fluoride through groundwater was higher in Nalgonda than the other areas. With evaporation and rainfall being one of the major contributors for high fluoride apart from the weathering of fluoride rich minerals from rocks, the effect of increase in groundwater level on fluoride concentration was studied. This study reveals that groundwater in shallow environment of all three regions shows dilution effect due to rainfall recharge. Suitable managed aquifer recharge (MAR) methods can be adopted to dilute the fluoride rich groundwater in such regions which is explained with two case studies. However, in deep groundwater, increase in fluoride concentration with increase in groundwater level due to leaching of fluoride rich salts from the unsaturated zone was observed. Occurrence of fluoride above 1.5 mg/l was more in areas with deeper groundwater environment. Hence, practicing MAR in these regions will increase the fluoride content in groundwater and so physical or chemical treatment has to be adopted. This study brought out the fact that MAR cannot be practiced in all regions for dilution of ions in groundwater and that it is essential to analyze the fluctuation in groundwater level and the fluoride content before suggesting it as a suitable solution. Also, this study emphasizes that long-term monitoring of these factors is an important criterion for choosing the recharge areas.     

Hydroponic root mats for wastewater treatment—a review

Hydroponic root mats (HRMs) are ecotechnological wastewater treatment systems where aquatic vegetation forms buoyant filters by their dense interwoven roots and rhizomes, sometimes supported by rafts or other floating materials. A preferential hydraulic flow is created in the water zone between the plant root mat and the bottom of the treatment system. When the mat touches the bottom of the water body, such systems can also function as HRM filter; i.e. the hydraulic flow passes directly through the root zone. HRMs have been used for the treatment of various types of polluted water, including domestic wastewater; agricultural effluents; and polluted river, lake, stormwater and groundwater and even acid mine drainage. This article provides an overview on the concept of applying floating HRM and non-floating HRM filters for wastewater treatment. Exemplary performance data are presented, and the advantages and disadvantages of this technology are discussed in comparison to those of ponds, free-floating plant and soil-based constructed wetlands. Finally, suggestions are provided on the preferred scope of application of HRMs.     

Adsorptive amputation of hazardous azo dye Congo red from wastewater: a critical review

Increasing amount of dyes in an ecosystem has propelled the search of various methods for dye removal. Amongst all the methods, adsorption occupies a prominent place in dye removal. Keeping this in mind, many adsorbents used for the removal of hazardous anionic azo dye Congo red (CR) from aqueous medium were reviewed by the authors. The main objectives behind this review article are to assemble the information on scattered adsorbents and enlighten the wide range of potentially effective adsorbents for CR removal. Thus, CR sorption by various adsorbents such as activated carbon, non-conventional low-cost materials, nanomaterials, composites and nanocomposites are surveyed and critically reviewed as well as their sorption capacities are also compared. This review also explores the grey areas of the adsorption performance of various adsorbents with reference to the effects of pH, contact time, initial dye concentration and adsorbent dosage. The equilibrium adsorption isotherm, kinetic and thermodynamic data of different adsorbents used for CR removal were also analysed. It is evident from a literature survey of more than 290 published papers that nanoparticle and nanocomposite adsorbents have demonstrated outstanding adsorption capabilities for CR.

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Review of receptor modeling methods for source apportionment

Efforts have been made to relate measured concentrations of airborne constituents to their origins for more than 50 years. During this time interval, there have been developments in the measurement technology to gather highly time-resolved, detailed chemical compositional data. Similarly, the improvements in computers have permitted a parallel development of data analysis tools that permit the extraction of information from these data. There is now a substantial capability to provide useful insights into the sources of pollutants and their atmospheric processing that can help inform air quality management options. Efforts have been made to combine receptor and chemical transport models to provide improved apportionments. Tools are available to utilize limited numbers of known profiles with the ambient data to obtain more accurate apportionments for targeted sources. In addition, tools are in place to allow more advanced models to be fitted to the data based on conceptual models of the nature of the sources and the sampling/analytical approach. Each of the approaches has its strengths and weaknesses. However, the field as a whole suffers from a lack of measurements of source emission compositions. There has not been an active effort to develop source profiles for stationary sources for a long time, and with many significant sources built in developing countries, the lack of local profiles is a serious problem in effective source apportionment. The field is now relatively mature in terms of its methods and its ability to adapt to new measurement technologies, so that we can be assured of a high likelihood of extracting the maximal information from the collected data.

Implications: Efforts have been made over the past 50 years to use air quality data to estimate the influence of air pollution sources. These methods are now relatively mature and many are readily accessible through publically available software. This review examines the development of receptor models and the current state of the art in extracting source identification and apportionments from ambient air quality data.     

Household preferences and willingness to pay (WTP) for freshwater quality improvement in Pakistan’s Swat River Valley

This two-part study investigates household preferences and willingness to pay (WTP) for water quality improvement of the Swat River in Pakistan. First, a four-point Likert scale was used to rank preferences for water quality benefits without using any financial metric. Results show that households have comparatively strong preferences for non-use benefits. Second, a contingent valuation question was designed to determine WTP for adopting a management plan developed exclusively for water quality improvement in the Swat River. The estimated annual mean WTP per household for water quality improvement is $2.40 when donating to an NGO. Generalizing this value to households living in Swat Valley would generate up to $544,000 per year. The present value aggregate benefit for 15 years would be sufficient to cover the present value of aggregate costs to adopt the management plan. A mandatory program that would require paying for the management plan generates half the WTP compared to the voluntary plan, but is still sufficient to cover costs and may be more feasible than a voluntary program because payment is assured.     

Adsorption studies on coir pith for heavy metal removal

Biosorption efficiency of coir pith, a waste product from coir industry, was investigated in this study for the removal of metallic pollutants such as Ni, Cu and Zn from aqueous solutions. The disposal of coir pith is a major problem associated with the coir industries, especially working in the small-scale sector. The present study explores the effectiveness of utilization of coir pith, an accumulating waste, as a biosorbent for heavy metal removal. Batch mode studies were done to evaluate the efficiency of removal of metals under varying adsorption conditions of pH, metal concentration and contact time. Characterization studies of the biosorbent and SEM analysis were done. Kinetic modelling studies were tried using Lagergren pseudo-first-order and second-order models. Equilibrium studies were done using well-known Freundlich, Langmuir and D–R isotherm models. It was found that all isotherms are fitting well indicating the efficiency of coir pith as an adsorbent of heavy metals. The applicability of all the three isotherms to the sorption processes shows that both monolayer adsorption and heterogeneous energetic distribution of active sites on the surface of the adsorbent are possible. Due to the abundance and low cost of these materials, adsorption technologies developed can act as good sustainable options for the future in heavy metal removal from industrial effluents.     

Two-echelon closed-loop supply chain deterministic inventory models in a batch production environment

This paper considers a two-echelon closed-loop supply chain consisting of a manufacturer and a remanufacturer at the upper echelon and a retailer at the lower echelon. The retailer faces a constant demand from customers, which is satisfied through recovered and new products received from the remanufacturer and the manufacturer, respectively. The manufacturer produces the product with finite rate, whereas the recovery of returned product is instantaneous at the remanufacturer. We develop three models to determine the optimal production-inventory policy of the players for minimizing the joint total cost of the system. In the first model, the retailer receives the product in batches from the manufacturer and the remanufacture simultaneously, whereas in the second and third models, the batches are received alternatively. In the third model, however, the procurement of raw material at the manufacturer is also considered. Numerical illustration is presented to examine the impact of certain key parameters.     

Climate change,multiple stressors and human vulnerability: a systematic review

We systematically reviewed current climate change literature in order to examine how multiple processes that affect human vulnerability have been studied. Of the 125 reviewed articles, 79 % were published after 2009. There are numerous concepts that point out to stressors other than climate change that were used in reviewed studies. These different concepts were used interchangeably, and they illustrate processes that act on different scales. Most widely used concepts included non-climatic (40 % of the articles), multiple stressors (38 %) and other factors (37 %). About 75 % of the studies either acknowledged or carefully analyzed the social and environmental context in which vulnerability is experienced. One-third of the studies recognized climate change-related stressors as the most important, one-third argued that stressors other than climate are more important, and the rest of the studies did not analyze the relative importance of the different processes. Interactions between different stressors were mentioned in 76 % and analyzed explicitly in 28 % of the articles. Our review shows that there are studies that analyze the social context of vulnerability within climate change-related literature and this literature is rapidly expanding. Reviewed studies point out that there are multiple interacting stressors, whose interlinkages need to be carefully analyzed and targeted by policies, which integrate adaptation to climate change and other stressors. In conclusion, we suggest that future studies should include analytical frameworks that reflect dissimilarities between different types of stressors, methodological triangulation to identify key stressors and analysis of interactions between multiple stressors across different scales.     

US exposure to multiple landscape stressors and climate change

Regional Environmental Change - We examined landscape exposure to wildfire potential, insects and disease risk, and urban and exurban development for the conterminous US (CONUS). Our analysis...