Thermally Stable Pyrolytic Biocarbon as an Effective and Sustainable Reinforcing Filler for Polyamide Bio-composites Fabrication

Natural fibers are limited in their use as reinforcement to commodity polymers. They cannot be used to reinforce engineering polymers due to their low thermal stability at high processing temperatures. This study presents an approach to successfully reinforce polyamides using a derivative of natural fibers as reinforcement without the effects of thermal degradation during melt processing. Biocarbon from miscanthus fibers was used to reinforce polyamide 6 up to 40 wt%. At 40 wt% filler content, the tensile and flexural strengths increased by 19.6 and 47% respectively in comparison to the neat polyamide. The moduli were also increased by 31.5 and 63.7% respectively. A maximum increase in impact strength of 43.7% was achieved at 20 wt% biocarbon loading. The morphology of the tensile fractured samples showed stretched polyamide ligaments attached to the biocarbon particles, indicating the presence of interaction between filler and matrix. Interestingly, more bonded interfaces were observed between the polyamide and biocarbon particles with increasing biocarbon content possibly stemming from increased biocarbon surfaces with functional groups. These composites show great potential to substitute in part or whole, some particulate filled polyamides currently used in the automotive industry.     

Carbon and nitrogen mineralization in Vertisol as mediated by type and placement method of residue

Selection of appropriate residue application method is essential for better use of biomass for soil and environmental health improvement. A laboratory incubation experiment was conducted for 75 days to investigate C and N mineralization of residues of soybean (Glycine max L.), chickpea (Cicer arietinum L.), maize (Zea mays L.), and wheat (Triticum aestivum L.) placed on the soil surface and incorporated into the soil. The residue of soybean and chickpea had a greater decomposition rate than that of maize and wheat, despite of their placements. Higher rate of decomposition of the residue of soybean and chickpea was recorded when it was kept on the soil surface while soil incorporation of residue of wheat and maize resulted in faster decomposition. Therefore, these findings could be used as guidelines for management of crop residue application in farmland to improve soil and environmental quality.     

Effects of meteorology on ground-level ozone (GLO) concentrations and identifying the hot spots having significantly higher GLO concentration in a semi-urban area

The present study aims to analyse the influences of five meteorological parameters (temperature, wind speed, barometric pressure, rainfall, and solar radiations) on ground-level ozone (GLO) concentrations over the region of Ranchi Municipal Corporation (Jharkhand, India). The diurnal variation of GLO concentration and the meteorological parameters were analysed in each month to understand the associations. The results indicated that the correlation coefficients of GLO concentration with SR, AT, and DPT are found to be positive in each month and also statistically significant. But, the association between WS and GLO concentration was not uniform between the study days. Furthermore, the study also demonstrates an approach for identifying the hot spots that are having the higher level of GLO concentration. The hot spot maps were produced for each month to understand the shifting of the locations of hot spot locations. The results reveal that the hot spot locations are changes frequently in each case. Since the hot spot analysis was conducted with limited data, the presented hot spots are indicative and dependent on the meteorological conditions of the specific period and cannot be considered as a robust epidemiological study.     

Characterization and quantification of solid waste generation in the Niger Delta Region of Nigeria: a case study of Ogbe-Ijoh community in Delta State

Journal of Material Cycles and Waste Management - In this study, the composition, characteristics and generation rates of solid waste (SW) in Ogbe-Ijoh community were investigated to provide...     

2D brine sewage after impinging on a shallow sea free surface

We consider the problem of the vertically upwards disposal of heavy brine sewage from a two-dimensional diffuser in a lighter, homogeneous, motionless and shallow ambient sea. The rejected high salinity water of seawater desalination plants for urban and agricultural uses is such a case of a two dimensional fountain. The disposal of brine sewage produces a negative buoyant jet due to its initial momentum, which impinges on the free surface, spreads laterally on it and then sinks downwards, because of the negative buoyancy. Laboratory experiments and dimensional considerations are used in this paper in order to investigate the spreading behavior (width) of the vertical fountain which impinges on the free surface of the shallow ambient fluid. The experimental results have been used to derive an equation relating the width at the free surface with the initial parameters of the flow. In addition, the experimentally measured dilution of the heavier brine sewage on the recipient’s surface is compared with the dilution which was calculated by a numerical simulation of a well-known commercial software package, CORJET (a CORMIX sub model).     

Mechanism of the intermittent motion of two-phase debris flows

A typical two-phase debris flow exhibits a high and steep flow head consisting of rolling boulders and cobbles with intermittent or fluctuating velocity. The relative motion between the solid phase and the liquid phase is obvious. The motion of a two-phase debris flow depends not only on the rheological properties of the flow, but also on the energy transmission between the solid and liquid phases. Several models have been developed to study two-phase debris flows. An essential shortcoming of most of these models is the omission of the interaction between the two phases and identification of the different roles of the different materials in two-phase debris flows. The tracer particles were used for the velocity of solid phase and the velocity of liquid phase was calculated by the water velocity on the surface of the debris flow in the experiments. This paper analyzed the intermittent feature of two-phase debris flows based on videos of debris flows in the field and flume experiments. The experiments showed that the height of the head of the two-phase debris flow increased gradually in the initiation stage and reached equilibrium at a certain distance from the start of the debris flow. The height growth and the velocity of the flow head showed fluctuating characteristics. Model equations were established and the analyses proved that the average velocity of the two-phase debris flow head was proportional to the flood discharge and inversely proportional to the volume of the debris flow head.     

Froude scaling limitations in modeling of turbidity currents

The scaling problem associated with the modeling of turbidity currents has been recognized but is yet to be explored systematically. This paper presents an analysis of the dimensionless governing equations of turbidity currents to investigate the scale effect. Three types of flow conditions are considered: (i) conservative density current; (ii) purely depositional turbidity current; and (iii) mixed erosional/depositional turbidity current. Two controlling dimensionless numbers, the Froude number and the Reynolds number, appear in the non-dimensional governing equations. When densimetric Froude similarity is satisfied, the analysis shows that the results would be scale-invariant for conservative density current under the rough turbulent condition. In the case of purely depositional flows, truly scale-invariant results cannot be obtained, as the Reynolds-mediated scale effects appear in the bottom boundary conditions of the flow velocity and sediment fall velocity. However, the scale effect would be relatively modest. The Reynolds effect becomes more significant for erosional or mixed erosional/depositional turbidity currents as Reynolds-mediated scale effects also appear in the sediment entrainment relation. Numerical simulations have been conducted at three different scales by considering densimetric Froude scaling alone as well as combined densimetric Froude and Reynolds similarity. Simulation results confirm that although the scaling of densimetric Froude number alone can produce scale-invariable results for conservative density currents, variations occur in the case of turbidity currents. The results become scale invariant when densimetric Froude and Reynolds similarities are satisfied simultaneously.     

Development of the hybrid cells in series model to simulate ammonia nutrient pollutant transport along the Umgeni River

Discharge of organic waste results in high nutrient pollution of the water bodies which is a major menace to the environment. A high quantity of nutrients such as ammonia causes a reduction in the dissolved oxygen level and induces algal growth in the water bodies. Water quality models have been the tools to evaluate the rate at which streams can disperse the pollutants they receive. Many water quality models are flawed either because of their inadequacy to completely simulate the advection component of the pollutant transport, or because of the limited application of the models, due to inaccurate estimation of model parameters. The hybrid cell in series (HCIS) developed by Ghosh et al. (2004) has been able to overcome such difficulties associated with the mixing cell-based models. Thus, the current study focuses on developing an analytical solution for the pollutant transport of the ammonia concentration through the plug flow, the first and second well-mixed cells of the HCIS model. The HCIS model coupled with the first order kinetic equation for ammonia nutrient was developed to simulate the ammonia pollutant concentration in the water column. The ammonia concentration at various points along the river system was assessed by considering the effects of the transformation of ammonia to nitrite, the uptake of ammonia by the algae, the respiration rate of the algae and the input of benthic source to the ammonia concentration in the water column. The proposed model was tested using synthetic data, and the HCIS-NH₃ model simulations for spatial and temporal variation of ammonia pollutant transport were analysed. The simulated results of the HCIS-NH₃ model agreed with the Fickian-based advection-dispersion equation (ADE) for simulating ammonia concentration solved using an explicit finite difference scheme. The HCIS-NH₃ model also showed a good agreement with the observed data from the Umgeni River, except during rainy periods.     

Sustainable cooking energy options for rural poor people in India: an empirical study

Currently, energy consumption for cooking in rural households of India is mostly based on fuelwood used in traditional stoves. This paper presents results of a study carried out in a forest fringe area of India on cooking energy use. The concept of calculating levelized cost as cost per unit of useful energy is applied on source–device combinations of cooking and validated in Bargaon Community Development Block of Sundergarh District in Odisha, India. About 92 % of the households in the study area use fuelwood as the only energy source for cooking; the total use of fuelwood for only cooking, in the Block is nearly 1.8 times the total sustainable wood supply showing an urgent need for promoting alternative cooking energy options. This paper also presents an assessment of different cooking options in terms of cost per unit of useful cooking energy. LPG, biogas and gasifier stoves are found to be far too expensive for the local people. Briquette-fired improved stoves appear to be a promising cooking energy option in the study area. Government support and intervention are recommended for promoting this option.