Activated carbons (ACs) were developed from bio-waste materials like rice husk and peanut shell (PS) by various physicochemical activation methods. PS char digested in nitric acid followed by treatment at 673 K resulted in high surface area up to ∼585 m²/g. The novelty of the present study is the identification of oxygen functional groups formed on the surface of activated carbons by infrared and X-ray photoelectron spectroscopy and quantification by using temperature programmed decomposition (TPD). Typical TPD data indicated that each activation method may lead to varying amounts of acidic and basic functional groups on the surface of the adsorbent, which may be a crucial factor in determining the adsorption capacity. It was shown that ACs developed during the present study are good adsorbents, especially for the removal of a model textile dye methylene blue (MB) from aqueous solution. As MB is a basic dye, H₂O₂-treated rice husk showed the best adsorption capacity, which is in agreement with the acidic groups present on the surface. Removal of the dye followed Langmuir isotherm model, whereas MB adsorption on ACs followed pseudo-second-order kinetics.

Soil contamination with heavy metals and organic pollutants has increasingly become a serious global environmental issue in recent years. Considerable efforts have been made to remediate contaminated soils. Biochar has a large surface area, and high capacity to adsorb heavy metals and organic pollutants. Biochar can potentially be used to reduce the bioavailability and leachability of heavy metals and organic pollutants in soils through adsorption and other physicochemical reactions. Biochar is typically an alkaline material which can increase soil pH and contribute to stabilization of heavy metals. Application of biochar for remediation of contaminated soils may provide a new solution to the soil pollution problem. This paper provides an overview on the impact of biochar on the environmental fate and mobility of heavy metals and organic pollutants in contaminated soils and its implication for remediation of contaminated soils. Further research directions are identified to ensure a safe and sustainable use of biochar as a soil amendment for remediation of contaminated soils.

A large-scale groundwater contamination characterises the Pleistocene groundwater system of the former industrial and abandoned mining region Bitterfeld/Wolfen, Eastern Germany. For more than a century, local chemical production and extensive lignite mining caused a complex contaminant release from local production areas and related dump sites. Today, organic pollutants (mainly organochlorines) are present in all compartments of the environment at high concentration levels. An integrated methodology for characterising the current situation of pollution as well as the future fate development of hazardous substances is highly required to decide on further management and remediation strategies. Data analyses have been performed on regional groundwater monitoring data from about 10 years, containing approximately 3,500 samples, and up to 180 individual organic parameters from almost 250 observation wells. Run-off measurements as well as water samples were taken biweekly from local creeks during a period of 18 months. A kriging interpolation procedure was applied on groundwater analytics to generate continuous distribution patterns of the nodal contaminant samples. High-resolution geological 3-D modelling serves as a database for a regional 3-D groundwater flow model. Simulation results support the future fate assessment of contaminants. A first conceptual model of the contamination has been developed to characterise the contamination in regional surface waters and groundwater. A reliable explanation of the variant hexachlorocyclohexane (HCH) occurrence within the two local aquifer systems has been derived from the regionalised distribution patterns. Simulation results from groundwater flow modelling provide a better understanding of the future pollutant migration paths and support the overall site characterisation. The presented case study indicates that an integrated assessment of large-scale groundwater contaminations often needs more data than only from local groundwater monitoring. The developed methodology is appropriate to assess POP-contaminated mega-sites including, e.g. HCH deposits. Although HCH isomers are relevant groundwater pollutants at this site, further organochlorine pollutants are present at considerably higher levels. The study demonstrates that an effective evaluation of the current situation of contamination as well as of the related future fate development requires detailed information of the entire observed system.

The aims of this paper were to quantify the heavy metal concentrations in street dust of small towns in Shanghai suburban area compared with those in urban area, and examine their seasonal and spatial variations, and to assess their risks to water environment and local populations. Street dust samples were collected from three small towns and urban area in Shanghai in different seasons. Levels of heavy metals were determined by atomic adsorption spectrophotometer analyzer. The method of potential ecological risk index and the health risk assessment model were used to evaluate the potential risks to water bodies and local residents, respectively. The mean metal concentrations in street dust of small towns were far above soil background values but still lower than those in the urban area. No significant seasonal change was observed except for Cr, Ni, and Zn concentrations. Higher metal concentrations tended to be located in central area of towns and township roads. The integrated metal contamination was high and posed a strong potential ecological risk. Children had greater health risk than adults. The carcinogenic risk probabilities were under the acceptable level. The hazard index values to children were close to the safe level. Street dust from the studied area has been contaminated by heavy metals. The contamination of these elements is related more to the pollution source than seasonal change. The combination of the six metals may threaten the water environment and has non-cancer health risk to children, but not to adults.

The aim of the present investigation was to exploit the high specific surface area of activated carbons in immobilizing the manganese and iron oxides as to obtain a suitable, efficient and cost effective and environment benign wastewater treatment process in the remediation of cadmium-contaminated waters. The manganese and iron oxides were impregnated in situ onto the surface and pores of the activated carbons precursors to the rice hulls and areca nut wastes. The solids were characterized with the help of Fourier transform infrared spectroscopy and X-ray diffraction analytical data, and the BET specific surface area as obtained. The surface morphology of these solids was discussed with the help of scanning electron microscopic images. The activated carbon samples along with the manganese and iron immobilized activated carbons were further employed in the batch and column reactor operations in the remediation of cadmium-contaminated waters. The batch data showed that an increase in sorptive pH from 2.0 to 10.0 and concentration from 1.0 to 20 mg/L favoured the uptake of cadmium by these solids. Moreover, the 1,000 times increase in background electrolyte concentrations NaNO3 caused an insignificant decrease in cadmium uptake by these solids, which inferred that sorbing ions/species were sorbed specifically and forming 'inner-sphere' complexes onto the solid surface. The concentration dependence data were utilized to model various adsorption isotherms and indicated that Freundlich adsorption isotherm was reasonably fitted well. The kinetic data was fitted well to the pseudo-second-order rate equations; hence, the equilibrium sorption capacity was estimated. Furthermore, the dynamic experiments carried out by the column experiments and the breakthrough data were fitted well to the non-linear Thomas equations; accordingly, the loading capacity of the column was estimated. Iron or manganese immobilized activated carbons showed relatively higher loading capacity compared to its precursor activated carbons hence showing its possible implication in the remediation processes. Moreover, among these modified ACs, IIAC showed higher removal capacity than the MIAC solid.

This paper describes an in-depth analysis to investigate the huge variation in the measured roadside air-pollutant concentrations of carbon monoxide and nitrogen dioxide in terms of the traffic flow levels, the orientation of the street to the prevailing wind, the wind speed, temperature and barometric pressure. The work has attempted to develop generic parameters that can be applied to other urban areas. However, in the absence of a measure of congestion at the site in Palermo (Italy), the methodological approach proposed used the simultaneous noise measurements, in units of decibels (B), to help parameterise a generic congestion indicator in terms of the traffic flow. The potential transferability of the approach was demonstrated for a site in Marylebone Road, London (UK), given the similarity of the two study sites, canyon shape, traffic characteristics and road orientation. The results showed that, within the range of data available, noise levels could be used as a proxy for flow change on the shoulders of the peak hour and hence congestion and a generic relationship with factors statistically significant at 99 % confidence allows roadside concentrations due to traffic to be estimated with a regression coefficient of R (2) = 0.73 (R = 0.85). The research demonstrates that whilst there are indeed underlying relationships that can explain the roadside concentrations based on traffic and meteorological conditions, evidence is presented that confirms the complexity of the physical and chemical processes that govern roadside concentrations.

With the rapid urbanization, the southeast coastal cities of China are facing increasing air pollution in the past decades. Large emissions of VOCs from vehicles and petrochemical factories have contributed greatly to the local air quality deterioration. Investigating the pollution characteristics of VOCs is of great significance to the environmental risk assessment and air quality improvement. Ambient VOC samples were collected simultaneously from nine coastal cities of southeast China using the Tedlar bags, and were subsequently preprocessed and analyzed using a cryogenic preconcentrator and a gas chromatography–mass spectrometry system, respectively. VOC compositions, spatial distributions, seasonal variations and ozone formation potentials (OPFs) were discussed. Results showed that methylene chloride, toluene, isopropyl alcohol and n-hexane were most abundant species, and oxygenated compounds, aromatics and halogenated hydrocarbons were most abundant chemical classes (62.5–95.6 % of TVOCs). Both industrial and vehicular exhausts might contribute greatly to the VOC emissions. The VOC levels in the southeast coastal cities of China were sufficiently high (e.g., 6.5 μg m⁻³ for benzene) to pose a health risk to local people. A more serious pollution state was found in the southern cities of the study region, while higher VOC levels were usually observed in winter. The B/T ratio (0.26 ± 0.09) was lower than the typical ratio (ca. 0.6) for roadside samples, while the B/E (1.6–7.6) and T/E (7.2–26.8) ratios were higher than other cities around the world, which indicated a unique emission profile in the study region. Besides, analysis on ozone formation potentials (OFPs) indicated that toluene was the most important species in ozone production with the accountabilities for total OFPs of 22.6 to 59.6 %.

PURPOSE: Heavy metals are toxic pollutants released into the environment as a result of different industrial activities. Biosorption of heavy metals from aqueous solutions is a new technology for the treatment of industrial wastewater. The aim of the present research is to highlight the basic biosorption theory to heavy metal removal. MATERIALS AND METHODS: Heterogeneous cultures mostly dried anaerobic bacteria, yeast (fungi), and protozoa were used as low-cost material to remove metallic cations Pb(II), Cr(III), and Cd(II) from synthetic wastewater. Competitive biosorption of these metals was studied. RESULTS: The main biosorption mechanisms were complexation and physical adsorption onto natural active functional groups. It is observed that biosorption of these metals was a surface process. The main functional groups involved in these processes were hydroxyl (–OH) and carboxylic groups (C=O) with 37, 52, and 31 and 21, 14, and 34 % removal of Pb(II), Cr(III), and Cd(II), respectively. Langmuir was the best model for a single system. While extended Langmuir was the best model for binary and ternary metal systems. The maximum uptake capacities were 54.92, 34.78, and 29.99 mg/g and pore diffusion coefficients were 7.23, 3.15, and 2.76 × 10⁻¹¹ m²/s for Pb(II), Cr(III), and Cd(II), respectively. Optimum pH was found to be 4. Pseudo-second-order was the best model to predict the kinetic process. Biosorption process was exothermic and physical in nature. CONCLUSIONS: Pb(II) offers the strongest component that is able to displace Cr(III) and Cd(II) from their sites, while Cd(II) ions are the weakest adsorbed component.

The science parks have helped shape Taiwan as a high-tech island with a good reputation worldwide. But some complaints on air pollution from the science parks have recently risen. To better understand the environmental effects of volatile organic compounds (VOCs) emitted from various high-tech factories in a science park, this study uses a source–receptor approach to characterize the environmental effects of VOCs from control device exhaust in Taichung Science Park. The chemical mass balance model (CMB8.2) of field measurements of 30 stacks and ambient air at nine sites was used to identify the source and relative contribution of ambient VOCs. The exhaust gas of various pollution control devices was also sampled by drawing a stream of the gases from the exhaust duct at its sampling port. The VOC source profile of each control device exhaust was determined using a database of noncharacteristic compounds. Monthly ambient concentrations of 167 VOCs were divided into monsoon datasets to investigate the effect of monsoon conditions on the emission of VOCs in the science park. This study also suggests a method for determining the optimum source profile in source–receptor modeling, and identifies and analyzes the sources of ambient VOCs at nine sites during southwest and northeast monsoons. Results show a direct relationship between the relative contribution of each source and its control device efficiency. The proposed source–receptor approach can characterize the environmental effect of air pollutants from various factories and successfully assess the efficiency of various control devices.

Malaria continues to be a public health problem in Bangladesh, despite efforts in the 1960s to eradicate the vectors through the use of DDT. At one point, eradication of malaria was acclaimed but later on it reappeared. The use of DDT is no more legally allowed in Bangladesh, which has been officially replaced by a number organophosphates and/or synthetic pyrethroids and their combinations in addition to the integrated vector management (IVM) package. IVM being a community approach is still to go a long way to be mass popular. Adulticides, larvicides, residual sprays, mosquito coil, insecticide-impregnated curtain, aerosol, etc. still serve as the major weapons of mosquito control. Thus, mosquito control still mostly depends on chemical insecticides. Although the use of DDT is banned in Bangladesh, there are reports on its illegal use in different forms. Moreover, there is tons of leftover DDT in Bangladesh, which is likely to cause several diseases. As per one report, about 500 MTs of DDT stockpiles are lying in the Medical Sub-Depots at Chittagong for over a period of 26 years. DDT is a persistent organic pollutant pesticide, which can cause diseases like cancer, endocrine disorder, disruption of immune system, embryonic abnormality, reproductive disorder, etc. Other chemical insecticides, which are replacing DDT, are also not free of hazardous impacts. IVM thus appears to be a wise approach requiring concerted efforts for the management of mosquito to control malaria. Such an IVM comprises use of Bacillus thuringiensis Berliner var. israelensis, methoprene, biocontrol agents, cleaning of breeding sites, pyrethroid-impregnated curtain, etc. Therefore, a wise effort should be adopted to completely stop the use of DDT, eliminate its stockpiles wherever they are in Bangladesh and to popularise the IVM, not the chemicals-based alternatives throughout the country.