Green-house gas mitigation capacity of a small scale rural biogas plant calculations for Bangladesh through a general Life Cycle Assessment approach

Calculations towards determining the greenhouse gas mitigation capacity of a small-scale biogas plant (3.2 m3 plant) using cow dung in Bangladesh are presented. A general life cycle assessment was used, evaluating key parameters (biogas, methane, construction materials and feedstock demands) to determine the net environmental impact. The global warming potential saving through the use of biogas as a cooking fuel is reduced from 0.40 kg CO2 equivalent to 0.064 kg CO2 equivalent per kilogram of dung. Biomethane used for cooking can contribute towards mitigation of global warming. Prior to utilisation of the global warming potential of methane (from 3.2 m3 biogas plant), the global warming potential is 13 t of carbon dioxide equivalent. This reduced to 2 t as a result of complete combustion of methane. The global warming potential saving of a bioenergy plant across a 20-year life cycle is 217 t of carbon dioxide equivalent, which is 11 t per year. The global warming potential of the resultant digestate is zero and from construction materials is less than 1% of total global warming potential. When the biogas is used as a fuel for cooking, the global warming potential will reduce by 83% compare with the traditional wood biomass cooking system. The total 80 MJ of energy that can be produced from a 3.2 m3 anaerobic digestion plant would replace 1.9 t of fuel wood or 632 kg of kerosene currently used annually in Bangladesh. The digestate can also be used as a nutrient rich fertiliser substituting more costly inorganic fertilisers, with no global warming potential impact

A Mitigation Approach to Alleviate Arsenic Accumulation in Rice through Balanced Fertilization

Pot experiments with boro and aman season rice on the same soils treated with arsenic contaminated irrigation water and using balanced fertilizer or not revealed that balance fertilization could be a strategy to mitigate arsenic accumulation in rice grain. The study also revealed that there is a carryover effect of As applied through irrigation in the boro season to the subsequent aman season rice. This carryover effect too, could be minimized with balanced fertilization

Understanding bioenergy production and optimisation at the nanoscale - a review

Nanotechnology has an increasingly large impact on a wide range of biotechnological, pharmacological and pure technological applications. Its current use in bioenergy production from biomass is very limited. This paper examines the potential interrelationships between nanotechnology and bioenergy production through a comprehensive literature review and analysis of data from biomass characterisation studies. The aim of this review is to indicate how nanotechnology can be applied in biomass-to-bioenergy conversion. This study shows currently nanotechnology has been applied in the production of only two types of biomass, i.e. sludge and algae. Hence, interaction of nanomaterials with active sludge and algal cells were examined. Our extensive literature review indicates that anaerobic digestion process in sludge can potentially be enhanced by using magnetite nanoparticles, which gives higher methane yields. On the other hand, nanosilver reduces growth and causes adverse effects on the morphology of green algae. This process for bioenergy generation has already been successfully applied to sludge and algae biomass. Our study confirms that the process can also be used in the production of bioenergy from the other biomasses, such as agricultural wastes and industrial residues. Outcomes of this work will be an important tool for implementing nanotechnology in bioenergy research. © 2016 Taylor & Franci

Fertilizer effects on yield, nitrogen content and amino acid composition of maize grain

International audienc

Arsenic Mitigation Approach in Soil by Some Indigenous Sources of Biochar Made at Low Pyrolysis Temperature

Biochar is being reported now a-days to potentially reduce the bioavailability of arsenic (As). A pot culture and an in vitro incubation study was conducted to evaluate the efficacy of biochar produced from different sources (viz., cow dung, poultry manure and sewage sludge) at low temperature (250ºC) on the phytoavailability of As. An experimental setup containing two sets of treatments (As and no-As) were followed. Biochar was applied at the rate of 5t/ha to the soils that received As treatment at a rate of 1mg/L As (80% arsenite and 20% arsenate). After 45 days of growth of Kalmi (Ipomoea aquatica), plant and soil samples were analyzed. Biochar insignificantly increased plant growth.  Biochar was observed to be more effective in alleviating As accumulation in plant than the biomass. The incubation study was done for 0, 15, 30 and 45 days to diagnose the temporal sorption of water soluble As by biochars. All the biochar materials reduced As availability than their corresponding biomass materials. Measurement of different physical (e.g. surface area, morphology, elemental composition), chemical (CEC, nutrient content, As) and physicochemical (pH) properties of the biochar showed that through pyrolysis process nitrogen(N), sulfur (S), phosphorus (P) content and pH of the biomass decreased and on the other hand potassium (K), As content and CEC increased. Slow pyrolysis process and variation in biomass material influenced the properties and behavior of biochar. Among the biochars, sewage sludge biochar showed the maximum and cowdAsung showed the minimum sorption capacity for As. Due to the threat of As to health and environment, this topic requires more consideration.  Moreover, covering all the above issues, this study identifies research gaps in the use of biochar as an adsorbent for As and proposes potential areas for future application of biochar

Effect of Arsenic Concentration in Irrigation Water and Soil on the Arsenic Content of Vegetables in Bangladesh

Two pot experiments were conducted to examine the effect of arsenic (As) concentration both in irrigation water and in soil on the As content in vegetables grown in a glass greenhouse. In the first experiment, spinach (Spinacia oleracea), green amaranth (Amaranthus viridis) and gima kalmi (Ipomoea aquatica) were grown in soil containing 10 mgAskg-1, where the irrigation water contained two As levels (0.1 and 0.5 mg L-1). In the second experiment, gima kalmi (Ipomoea aquatica) was grown in As spiked soil at different levels [10 (control), 15, 20, 30, and 50 mgAskg-1 soil] and with irrigation water without As contamination. The As concentration (mg kg-1 DW) and As accumulation (µg plant-1) in the edible part of the plants increased significantly with increasing As concentrations in irrigation water and/or soil. When plants were irrigated with As contaminated water, the As concentration of the edible part exceeded its maximum limit (0.5 mg kg-1) in spinach and green amaranth at 0.5 mg L-1 of As, but gima kalmi had a smaller amount than the other vegetables. Gima kalmi had the characteristics of a lower As accumulation. Therefore, the risk level of As in irrigation water was suggested to be 0.1 mg L-1 for vegetables. When gima kalmi was grown in elevated levels of As contaminated soil, the As concentration of gima kalmi, even being a low As accumulator, exceeded the maximum limit at the level above 20 mgAskg-1 soil. The risk level of As in soil, therefore, was suggested to be 20 mg kg-1. The risk value of As concentration in irrigation water and/or in soil needs to be investigated in detail by using many vegetables and/or soils

Comparison of extractability of Cd, Cu, Pb and Zn with sequential extraction in contaminated and non-contaminated soils

Various extraction procedures were employed for measuring extractable concentrations of potential toxic elements in soil. The extractability of Cd, Cu, Pb and Zn in four contaminated and four non-contaminated soils of Japan, was compared by single extraction (CaCl2, DTPA, NH4Cl, 0.1 M HCl and 1 M HCl ) and sequential extraction procedures [(six operationally defined chemical phases, viz. water soluble (F1), exchangeable (F2), carbonate (F3), oxide (F4), organic (F5) and residual (F6) fractions)]. Extractability of metals from soils samples varied depending on metals and/or extractants used. Among the extractants, 1 M HCl extracted the largest proportion of Cd (79 to 96% of total), Cu (61 to 83%), Pb (51 to 99%) and Zn (23 to 52%) from soils followed by 0.1 M HCl, NH4Cl, DTPA and CaCl2. In all the extractants, the proportion of extractability of metals was higher in the contaminated soils than the non-contaminated soils. Regardless of soils and extractants, relative extractability was higher for Cd as compared to other three metals. The use of 1 M HCl may be recommended for first-level screening of soil contamination with heavy metals. The other four weak extractants are believed to provide a better assessment of bioavailable/mobile metals content in soils than 1 M HCl extractant. However, 0.1 M HCl mobilized all four metals irrespective of soil types, therefore, might be the best choice if only one extractant is to be used. The sequential extraction procedures showed 22 to 64% of total Cd was in the mobile fraction (sum of F1 to F3), while the corresponding values for Cu, Pb and Zn in this fractions were 2 to 23% suggesting higher mobility of Cd than other three metals. The single extraction procedures are simple and easy to perform and obtained results are comparable with sequential extraction procedure