Catalytic CO2 gasification of rubber seed shell-derived hydrochar: reactivity and kinetic studies

In this study, hydrothermal carbonization (HTC) of a biomass was used as a means to improve the physicochemical properties of rubber seed shell (RSS) and enhance its reactivity in the char-CO₂ gasification reaction, known as the Boudouard reaction (C + CO₂ ? 2CO). Hydrochar samples were developed by hydrothermal treatment of RSS, without separating the solid residue from the liquid product, at 433, 473, 513, and 553 K under autogenous pressure. The CO₂ gasification reactivity of the developed hydrochars was then investigated at different heating rates (5, 10, 20, and 30 K/min) by the non-isothermal thermogravimetric method. The hydrochars revealed higher reactivity and improved gasification characteristics compared to the untreated biomass, while the hydrochar which was filtered from the liquid slurry showed lower reactivity compared to the untreated biomass. This was due to the chemical and structural evolutions of the biomass during hydrothermal treatment as indicated by various analyses. The gasification reactivity of the hydrochar was substantially enhanced by introduction of a catalyst (NaNO₃) during HTC. Kinetic analysis of the char-CO₂ gasification reaction was carried out by applying Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), and Starink isoconversional methods, and thermodynamic parameters were also determined. The activation energy of the Na-loaded RSS hydrochar in CO₂ gasification (120–154 kJ/mol) was considerably lower than that of the untreated biomass (153–172 kJ/mol). Thermodynamic studies also confirmed the promoting effect of hydrothermal treatment and catalyst impregnation on enhancement of reactivity of the virgin biomass and reduction of gasification temperature.

     

Adoption and diffusion of conservation agriculture technology in Zambia: the role of social and institutional networks

Environmental Economics and Policy Studies - This study utilizes recall data from smallholder farmers in selected provinces in Zambia to examine the role of social and institutional networks, as...     

Can clean biomass energy use lower CO2 emissions in African economies? Empirical evidence from dynamic long-run panel framework

Environmental Science and Pollution Research - This paper seeks to answer an empirical question of whether clean biomass energy consumption lowers CO2 emissions while controlling for technical...     

Ecotoxicological assessment of oil-based paint using three-dimensional multi-species bio-testing model: pre- and post-bioremediation analysis

The present study validates the oil-based paint bioremediation potential of Bacillus subtilis NAP1 for ecotoxicological assessment using a three-dimensional multi-species bio-testing model. The model included bioassays to determine phytotoxic effect, cytotoxic effect, and antimicrobial effect of oil-based paint. Additionally, the antioxidant activity of pre- and post-bioremediation samples was also detected to confirm its detoxification. Although, the pre-bioremediation samples of oil-based paint displayed significant toxicity against all the life forms. However, post-bioremediation, the cytotoxic effect against Artemia salina revealed substantial detoxification of oil-based paint with LD₅₀ of 121 μl ml^?1 (without glucose) and >?400 μl ml^?1 (with glucose). Similarly, the reduction in toxicity against Raphanus raphanistrum seeds germination (%FG?=?98 to 100%) was also evident of successful detoxification under experimental conditions. Moreover, the toxicity against test bacterial strains and fungal strains was completely removed after bioremediation. In addition, the post-bioremediation samples showed reduced antioxidant activities (% scavenging?=?23.5?±?0.35 and 28.9?±?2.7) without and with glucose, respectively. Convincingly, the present multi-species bio-testing model in addition to antioxidant studies could be suggested as a validation tool for bioremediation experiments, especially for middle and low-income countries.

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Performance of biotic indices in comparison to chemical-based Water Quality Index (WQI) in evaluating the water quality of urban river

In order to evaluate the water quality of one of the most polluted urban river in Malaysia, the Penchala River, performance of eight biotic indices, Biomonitoring Working Party (BMWP), BMWP^Thai, BMWP^Viet, Average Score Per Taxon (ASPT), ASPT^Thai, BMWP^Viet, Family Biotic Index (FBI), and Singapore Biotic Index (SingScore), was compared. The water quality categorization based on these biotic indices was then compared with the categorization of Malaysian Water Quality Index (WQI) derived from measurements of six water physicochemical parameters (pH, BOD, COD, NH₃-N, DO, and TSS). The river was divided into four sections: upstream section (recreational area), middle stream 1 (residential area), middle stream 2 (commercial area), and downstream. Abundance and diversity of the macroinvertebrates were the highest in the upstream section (407 individual and H′?=?1.56, respectively), followed by the middle stream 1 (356 individual and H′?=?0.82). The least abundance was recorded in the downstream section (214 individual). Among all biotic indices, BMWP was the most reliable in evaluating the water quality of this urban river as their classifications were comparable to the WQI. BMWPs in this study have strong relationships with dissolved oxygen (DO) content. Our results demonstrated that the biotic indices were more sensitive towards organic pollution than the WQI. BMWP indices especially BMWP^Viet were the most reliable and could be adopted along with the WQI for assessment of water quality in urban rivers.     

Characteristics of <Emphasis Type="Italic">Pelargonium radula</Emphasis> as a mercury bioindicator for safety assessment of drinking water

Identification of Pelargonium radula as bioindicator for mercury (Hg) detection confers a new hope for monitoring the safety of drinking water consumption. Hg, like other non-essential metals, inflicts the deterioration of biological functions in human and other creatures. In the present study, effects of Hg on the physiology and biochemical content of P. radula were undertaken to understand the occurrence of the morphological changes observed. Young leaves of P. radula were treated with different concentrations of Hg-containing solution (0.5, 1.0 and 2.0 ppb) along with controls for 4 h, prior to further analysis. Elevated Hg concentration in treatment solution significantly prompted an increased accumulation of Hg in the leaf tissues. Meanwhile, total protein, chlorophyll and low molecular mass thiol contents (cysteine, glutathione and oxidized glutathione) decreased as Hg accumulation increased. However, phytochelatin 2 productions were induced in the treated leaves, in comparison to the control. Based on these findings, it is postulated that as low as 0.5 ppb of Hg interferes with the metabolic processes of plant cells, which was reflected from the morphological changes exhibited on P. radula leaves—the colour of the Hg-treated leaves changed from green to yellowish-brown, became chlorosis and wilted. Changes in the tested characteristics of plant are closely related to the Hg-induced morphological changes on P. radula leaves, a potential bioindicator for detecting Hg in drinking water.     

Fluoride Concentration in Drinking Water of Karachi City (Pakistan)

The ground and municipal water supply samples of Karachi city were analyzed for their fluoride contents. The fluoride contents in water samples collected from the subsurface and river sources were found below the WHO recommended value for the general health of the people. However, in some industrial areas the groundwater sample showed higher level of fluoride concentration. Continuous monitoring of water resources and cautious fluoridation is suggested to maintain proper status of fluoride concentration in the drinking water.     

Environmental impacts of anthropogenic activities on the mineral uptake in Oreochromis mossambicus from Indus River in Pakistan

We examined the extent of mineral uptake in different tissues of Oreochromis mossambicus from Indus River which is claimed to be polluted by human activities. Samples of water and fish tissues were analysed from two sites (SK = upstream and CH = downstream) of Indus River. Whilst the water quality appeared to be suitable for aquatic life, significant differences between fish tissues and sampling sites were observed for different mineral concentrations. Fins generally had the highest metal load followed by muscles, gills, scales and skin. Na, Mg, Mn and Zn concentrations in different fish tissues were greater for CH than SK, whereas K, Ca, Pb, Cu, Fe, Hg and Cr were higher at SK than CH (P?<?0.001). This variation in metal profiles of different locations of the Indus River was a reflection of relevant mineral pollutions at these sites. It appeared that the pattern of metal uptake in fish tissues can be utilised as an indicator of environmental contamination of river water systems. These studies may help us plan strategies to alleviate the ecotoxicological impacts of heavy metals in freshwaters on fish and human populations.     

Seasonal variation of different microorganisms with nickel and cadmium in the industrial wastewater and agricultural soils

Wastewater and soil samples were collected from the industrial area of Ghaziabad City, India from January 2005 to December 2007 and were analyzed for the presence of heavy metals by atomic absorption spectrophotometry. Test samples revealed high levels of Fe, Cr, Cu, Ni, Zn, and Cd as 967.03, 34.63, 27.97, 19.7, 16.70, and 3.20 mg/L of wastewater, respectively. The concentrations of inorganic minerals were higher in the soil samples irrigated with wastewater. Total coliforms were found to be maximum (1,133 × 10⁴ most probable number per 100 mL) during spring and summer followed by winter and postmonsoon in the wastewater samples. The microbial count in soil as well as in wastewater decreases as the metal concentration increases. The concentration 200 μg/mL of nickel and cadmium inhibits majority of the population, while, at some points, it inhibits 100% of the population. The exponential decay model for microbial count at the increasing metal concentrations indicate that asymbiotic N₂ fixers were best fitted to the model. In all the seasons, the order of decline in terms of exponential decay of the population of different microbial groups in soil was asymbiotic N₂ fixers > actinomycetes > fungi > aerobic heterotrophic bacteria. The different microbial groups that have different values of slope in different seasons indicate that the resistant population of microorganisms was variable with seasons.     

Application of chemometrics in understanding the spatial distribution of human pharmaceuticals in surface water

The growing interest in the environmental occurrence of veterinary and human pharmaceuticals is essentially due to their possible health implications to humans and ecosystem. This study assesses the occurrence of human pharmaceuticals in a Malaysian tropical aquatic environment taking a chemometric approach using cluster analysis, discriminant analysis and principal component analysis. Water samples were collected from seven sampling stations along the heavily populated Langat River basin on the west coast of peninsular Malaysia and its main tributaries. Water samples were extracted using solid-phase extraction and analyzed using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) for 18 pharmaceuticals and one metabolite, which cover a range of six therapeutic classes widely consumed in Malaysia. Cluster analysis was applied to group both pharmaceutical pollutants and sampling stations. Cluster analysis successfully clustered sampling stations and pollutants into three major clusters. Discriminant analysis was applied to identify those pollutants which had a significant impact in the definition of clusters. Finally, principal component analysis using a three-component model determined the constitution and data variance explained by each of the three main principal components.