Showing papers in "Environmental Technology and Innovation in 2015"

SMART biochar technology—A shifting paradigm towards advanced materials and healthcare research

Abstract: Biochar, produced through pyrolysis of biomass under low or no oxygen conditions, has found a wide range of applications from soil fertility improvement to removal of contaminants. Initial interest in biochar is to use it as a means to capture carbon dioxide from the atmosphere; however, recent developments are seeing biochar being applied in engineering, and health care and life sciences, some of those applications have large potentials for rapid commercialization. We expect a paradigm shift towards the development of the next generation of biochar with applications in a range of new fields.

Extraction and characterization of chitin and chitosan from fishery waste by chemical method

Abstract: After cellulose, chitin is the most widespread biopolymer available in nature. Chitin has economic value because of its biological activities, industrial and biomedical applications. There are three sources of chitin, namely crustaceans, insects and microorganism. The commercial sources of chitin are shells of crustaceans such as shrimp, crabs, lobsters and krill. In the present study, chitin has been extracted from locally available fish in Rourkela. The obtained chitin was converted into the more useful chitosan. The obtained chitin and chitosan have been characterized by using different techniques like spectral analysis, X-ray diffraction, Elemental analysis, Fourier transforms infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and Differential scanning calorimetry (DSC). XRD analysis indicated the crystalline nature of the chitin and chitosan. The FTIR patterns displayed the bands corresponding to stretching and vibration of O-H, N-H and CO bonds and conformed the formation of α -chitin. Degree of deacetylation (DD) value was calculated using elemental analysis, potentiometric titration and FTIR. Using FTIR analysis DD value was found to be 61%.

Treatment technologies for aqueous perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA): A critical review with an emphasis on field testing

Abstract: Perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) are used in fire-fighting foams but this is now being questioned because concerns are growing about their toxicity and impacts on the environment. Past use has resulted in their widespread accumulation in water sources, sediments and biota. They may pose risks to human health and the environment. Several technologies have been tested for removing PFOS and PFOA from water but most have only been developed at laboratory scale. This paper provides a critical review of existing methods for removing PFOS and PFOA from wastewaters with an emphasis on identifying processes that show promise for the development of practical industrial-scale remediation technologies. It is concluded that among the remediation technologies cited in the literature, removal by activated carbon has been the most widely used, with several successful field tests being reported. However, a number of limitations to the use of activated carbon exist, such as being ineffective at removing PFOA and other PFCs. Other adsorbents that have the potential to treat aqueous PFOS and PFOA include organo-clays, clay minerals and carbon nanotubes.

Adsorption of cationic dye from aqueous solution onto activated carbon prepared from olive stones

Abstract: The use of agriculture solid waste as low-cost adsorbents is considered as an ecofriendly adsorbent due to their contribution in the reduction of costs for waste disposal. The present study investigates the adsorption efficiency of raw olive stone (OS) and activated carbon prepared from Egyptian olive stones (OSAC). Batch adsorption experiments were conducted under varying conditions of contact time, initial concentration of methylene blue dye (MB), adsorbent dosage, pH and temperature. The experimental equilibrium data were examined using Langmuir, Freundlich, Temkin, Dubinin–Radushkevich, and Harkins–Jura isotherms. The adsorption kinetic dye was analyzed using pseudo-first order, pseudo-second order and the intraparticle diffusion model. The results showed that the percentage of dye removal increased as the temperature increased but it decreased with the increase in initial dye concentration. The optimum pH required for maximum adsorption was found to be 5. Kinetic studies showed that the adsorption MB onto OS and OSAC followed pseudo-second order kinetic model. The results indicated that olive stone activated carbon could be used as a low-cost adsorbent for the removal of methylene blue from aqueous solution.

High solid anaerobic digestion: Operational challenges and possibilities

Abstract: The process of high solid anaerobic digestions (HSAD) was developed to reduce water usage, increase organic loading rate (OLR), reduce nutrient loss in digestate and avoid or decrease the dewatering of digestate. However, the operation of HSAD is currently constrained by low rates and extents of methane production high operational costs. Several published investigations have been conducted to study the effects of inhibition, temperature, moisture, and reactor design on the efficiency of HSAD. However, low moisture and poor mixing, which are required for the dilution and diffusion of metabolites, have been reported to be the major causes of low methane yield in HSAD. In order to optimize the operation of HSAD, technological integration has to be considered, especially thermo–mesophilic digestion, co-digestion, mixing and integration of two or more reactors. This paper provides a critical review of recent research on HSAD while focusing on how these studies can be integrated to improve HSAD.

Bioremediation potential of natural polyphenol rich green wastes: A review of current research and recommendations for future directions

Abstract: ‘Green waste’ (food, agro-industrial and forest residues) is a renowned valuable resource of polyphenols. Natural polyphenols are relatively efficient in the clean-up of environmental pollutants based on their unique traits of chelation, adsorption, reduction, complexation, nutrient cycling, antibacterial effects and plant growth promotion. These significant traits have found emerging applications in the removal of heavy metals, pathogenic bacteria and dyes from contaminated soil and water through existing bioremedial techniques such as biosorption, phytoextraction and coagulation. Increasingly, polyphenol-rich natural extracts harnessed for green nanoparticle synthesis (production of particles between 1 and 100 nm in size using biological entities such as microorganisms or plant biomass) have found promising use as a remedial agent in the detoxification of toxic pollutants. However, current bioremediation approaches do not sufficiently exploit natural polyphenols, which are abundantly available and are non-toxic. This review examines the extent of natural polyphenol availability in green waste, and provides a critical view on the existing remedial options, knowledge gaps and hence scope for future research. It highlights the use of natural polyphenol-rich green wastes as nanofertilizers, bioamendments, biofilters and bacteriostats. Field application strategies such as microbe-assisted phytoremediation, bioaugmention and biostimulation are also emphasized, showing the multifunctional biotechnological potentials offered by natural polyphenols.

Carpet recycling: A review of recycled carpets for structural composites

Abstract: Carpets are multilayer mixtures of different polymers and inorganic fillers that are difficult and costly to reprocess upon disposal. About 400 000 tonnes of carpets are sent to landfill in the UK annually, however, the landfill option is becoming increasingly impractical due to increasing landfill costs and the physical limitations on the number of landfill sites available in the UK. In addition, carpets are non-biodegradable and reduce the availability of landfill for other uses. Hence, this leads to a major drive to increase carpet recycling, which could potentially have a significant positive impact on the environment. This paper gives an overview of the composition of carpets, and the different classifications of carpet waste. In addition, the paper discusses the different end of use options for carpets in the UK. The paper also reviews the different manufacturing processes that utilise carpet waste as raw material in the fabrication of structural composites. The tensile and flexural properties of these composites are presented and discussed. These mechanical properties appear to support the use of carpet waste as potential composite materials for structural load-bearing applications.

Characterization of iron–polyphenol complex nanoparticles synthesized by Sage (Salvia officinalis) leaves

Abstract: In this paper iron–polyphenol complex nanoparticles (Fe–P NPs) were synthesized by Sage ( Salvia officinalis ) leaf extract, which have excellent adsorptive-flocculation capacity for water treatment. They were characterized using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared Spectroscopy (FTIR) and X-ray diffraction (XRD) so that their surface properties could be understood. It was found that synthesized Fe–P NPs were cross-linked in colloid with spherical particles ranged from 5 to 25 nm. Their surfaces were capped with O–H groups. Dried powder derived from Fe–P NPs colloid can remain stable after several hours and then be partially oxidized to iron oxide on exposure to air. Removal of cationic dye ethyl violet with Fe–P NPs was tested to confirm that the surface charge on Fe–P NPs is positive.

Dispersion of particulate matter generated at higher depths in opencast mines

Abstract: Dispersion studies of particulate matter generated during opencast mining until now have mostly been confined to estimation of emissions from individual mining activity as well as total emission from an opencast mine. No study is available on particulate matter dispersion inside the mine since its generation until it escapes the mine. However, this is important particularly for deep mines where mine workings are confined to bottom benches and emission from it passes across all benches before it reaches surface, thus affecting the exposure level of workers at higher benches. This paper presents the results of a study on the dispersion of particulate matter in Malanjkhand Copper Project, one of the deepest opencast mines in India. The study was conducted for 4–5 h daily for 10 days during the month of October 2013. Mining activities at 168–180 m depth were the source of particulate matter. Particulate matter concentrations were measured by portable aerosol spectrometer. Meteorological data were collected using portable weather station. There was no direct correlation between wind speed and particulate matter concentration. Correlation between wind direction and particulate matter concentration was somewhat better. While coarse particle (PM 2.5–10 ) constituted 6%–8% of the background concentration, it increased to 31%–61% during mining, primarily due to generation of more coarse particles during mining. At locations farther from and higher than the source location, continuous decrease of concentration of particles of all sizes was observed due to settling and dispersion of particles. From source locations to the surface, the average mining induced incremental concentration of PM 2.5–10 , PM 1–2.5 and PM 1 decreased from 127.02 to 3.98 μg m −3 , 5.39 to 1.95 μg m −3 and 20.26 to 2.74 μg m −3 respectively. An empirical relationship has been established between particulate matter concentration and depth.

Can electrokinetic removal of metals from contaminated paddy soils be powered by microbial fuel cells

Abstract: Soil electrokinetic remediation (ER) is an efficient technique to remove heavy metals from the complex soil matrix, however, this process needs a large amount of electricity input, which increases the cost and limits its application in remote agricultural fields. Microbial fuel cells (MFCs) are able to convert organic matter into electric current by using extracellular-respiring microbes. In this study, MFCs were designed and applied to electrokinetic removal of zinc (Zn) and cadmium (Cd) from a contaminated paddy soil. The current produced by three-chamber MFCs was ∼0.4Am−2 when loaded with the citric acid-amended soil. Replacement of the anion exchangeable membrane with nylon filter increased the transport rate of metal ions from the middle remediation chamber to the cathode chamber. After 78-day running, the systems with 300 Ω resistors removed 12 mg Zn and 0.7 mg Cd more than those without resistors, suggesting that the current produced by the MFCs could significantly facilitate metal removal. The BCR extraction methods were applied to characterize the metal fractionation after ER treatment. The results showed that most of the removed metals came from acid extractable and reducible fractions. This study provides evidences that MFCs could power the soil ER processes, but the removal efficiency needs to be improved before its application in contaminated fields.

Evaluating methods for spatial mapping: Applications for estimating ozone concentrations across the contiguous United States

Abstract: Understanding spatial variability of air pollutant concentrations is critical for public health assessments. Our goal is to examine ground-level ozone and comparatively evaluate method performance for predicting and mapping national concentrations across the United States, while assessing the importance of accounting for spatial variability. Cross-sectional US EPA ozone monitoring data was acquired for three days in 2006, plus environmental covariates of land use, traffic, temperature, elevation, and population. Evaluation of ozone variability was assessed with land use regression (LUR) and spatially explicit kriging models. Ozone concentration was predicted with four approaches, including LUR, inverse distance weighting (IDW), ordinary kriging, and universal kriging, and evaluated with a Monte Carlo cross-validation simulation. Results were mapped for the continental United States. Temperature, elevation, and distance to major roads were significantly related to ozone concentrations and examination of spatial dependence on LUR models revealed the presence of residual spatial variation. Cross-validation results found kriging outperformed both LUR and IDW in terms of root mean squared prediction error. We demonstrate that national-level ozone is best evaluated using the statistically optimal kriging models, which account for residual spatial variation. Universal kriging was preferred over ordinary kriging by allowing us to assess the significance of environmental covariates both for inference and prediction of ozone concentrations.

Fate and behaviour of nitrogen-containing polycyclic aromatic hydrocarbons in soil

Abstract: Nitrogen-containing polycyclic aromatic hydrocarbons (N-PAHs) are analogues of the homologous polycyclic aromatic hydrocarbons (PAHs) in which one or more carbon atom(s) is replaced with nitrogen atom(s). They do not only exist in conjunction with the homocyclic PAHs in polluted systems, but unlike PAHs, they are intentionally produced. It has also been reported that heterocyclic PAHs contribute to the toxic effects identified in many environmental samples, containing PAH/N-PAH mixtures. N-PAHs are toxic, often displaying greater biological effects than their homocyclic analogues. As these chemicals are suspected of being carcinogens in humans and other biota, there is a need to know their fate, behaviour, bioavailability, ecotoxicity, and biodegradation for risk assessments of contaminated soils. The aim of this review is to consider the presence and behaviour of N-PAHs, focusing on their bioavailability, ecotoxicity and biodegradation in the soil environment.

Adsorptive removal of uranium ions from liquid waste solutions by phosphorylated chitosan

Abstract: The purpose of this work is to take a closer look for the phosphorylation of chitosan and its potential applications for uranium removal from waste effluents. The synthesized P-chitosan has first been characterized using FTIR spectroscopy and scanning electron microscope before and after adsorption of uranium. From the former it is showed that the phosphate groups may be more responsible for the adsorption of uranium. The relevant factors that influence the uranium adsorption onto the phosphorylated chitosan namely solution pH, contact time, temperature, Co-ions, solid–liquid ratio and initial uranium concentration were studied in detail. The obtained results are fitted into the different adsorption isotherms and according to Langmuir adsorption model the uranium adsorption capacity of the synthesized P-chitosan is estimated as 54.6 mg/g. It was also observed from the obtained kinetic data that the pseudo-second order model is more suitable to explain the adsorption kinetics of uranium up on the P-chitosan. Finally the thermodynamic parameters show the adsorption reaction to be a spontaneous process and more favorable at room temperature.

Risk based land management requires focus beyond the target contaminants—A case study involving weathered hydrocarbon contaminated soils

Abstract: Irrespective of the nature of contamination, the use of total contaminant loading as a measure of risk together with conservative policy guidance is proving major stumbling block towards remediation of contaminated sites. The objective of this study was to investigate the use of risk based approach to manage contaminated sites at field scale. This study recognizes the presence of weathered hydrocarbon compounds in long-term total petroleum hydrocarbon (TPH) contaminated soils and that such compounds may not pose risk to local receptors. A multispecies ecotoxicological assessment was used to determine the potential risk from weathered hydrocarbons to the surrounding environment. The ecotoxicity of soil residual TPHs was evaluated using earthworm, water-flea, two native and two non-native Australian plants, and soil microbial activity. Plant germination was 100% in all soils but post germination, seedlings except Ryegrass failed to establish. Earthworm toxicity studies found that there was a negative impact on earthworm reproduction and mortality. Further investigation of the poor plant growth and earthworm mortality revealed that it was due to the elevated salinity that developed due to surface evaporation of the saturated calcium sulphate and not residual soil TPHs. Toxicity assessment of the soil leachate on the aquatic environment showed no effect on the survival of water-flea even though the TPH concentrations in the first year leachate were as high as 1.6 mg TPH L − 1 . The study concluded that the residual TPHs in soils had little impact on a range of environmental receptors. Assessment of the residual TPH ecotoxicity was complicated by the elevated salinity of stockpile soils which impacted on the earthworm and phytotoxicity assessments. Therefore results of this study suggest that it is paramount to focus beyond target contaminants while implementing risk-based management approach. Indicators for risk based assessment are considered critical for regulatory decision making. The results of this study provide a valuable input in to the risk based management of contaminated sites.

Study of molecular interactions between humic acid from Brazilian soil and the antibiotic oxytetracycline

Abstract: Tetracyclines (TC) are the major class of antibiotics used in global cattle industry for the treatment of diseases and to promote animal growth. The impact of their residues on tropical soils is not completely understood and Brazil, the major agro-industrial country in the tropical regions, has the commitment to study the environmental fate of these antibiotics due its large consumption. Sorption and interactions at molecular level of the antibiotic oxytetracycline (OTC) with Brazilian humic acid (HA) extracted from soil have been determined in this study. 13 C solid-state nuclear magnetic resonance ( 13 C NMR), elemental analysis, and electron paramagnetic resonance (EPR) were used for the characterization of HA. Fourier transformed infrared (FTIR) and ultraviolet–visible (UV–Vis) absorption spectroscopies were used to evaluate molecular interactions and mechanisms involved. OTC interacted in acid and alkaline medium (range of pH values from 3.1 to 8.3). Interaction mechanisms were pH dependent, and comprise hydrogen bonding, hydrophobic interactions, and proton transferring - weak interactions. These behaviors are different from HA of temperate regions and suggest that OTC residues could reach the groundwater.

Fermentative production of glycine betaine and trehalose from acid whey using Actinopolyspora halophila (MTCC 263)

Abstract: Acid whey has become a major concern especially in dairy industry manufacturing Greek yoghurt. Proper disposal of acid whey is essential as it not only increases the BOD of water but also increases the acidity when disposed of in landfill, rendering soil barren and unsuitable for cultivation. Effluent (acid-whey) treatment increases the cost of production. The vast quantities of acid whey that are produced by the dairy industry make the treatment and safe disposal of effluent very difficult. Hence an economical way to handle this problem is very important. Biogenic glycine betaine and trehalose have many applications in food and confectionery industry, medicine, bioprocess industry, agriculture, genetic engineering, and animal feeds (etc.), hence their production is of industrial importance. Here we used the extreme, obligate halophile Actinopolyspora halophila (MTCC 263) for fermentative production of glycine betaine and trehalose from acid whey. Maximum yields were obtained by implementation of a sequential media optimization process, identification and addition of rate-limiting enzyme cofactors via a bioinformatics approach, and manipulation of nitrogen substrate supply. The implications of using glycine as a precursor were also investigated. The core factors that affected production were identified and then optimized using orthogonal array design followed by response surface methodology. The maximum production achieved after complete optimization was 9.07 ± 0.25 g/L and 2.49 ± 0.14 g/L for glycine betaine and trehalose, respectively.

Assessment of Phoslock® application in a tropical eutrophic reservoir: An integrated evaluation from laboratory to field experiments

Abstract: The main objective of this study was to develop laboratory and in situ experiments to control reactive soluble phosphorus (RSP) concentration and to evaluate the possible changes and toxic effects caused by Phoslock ® application in the Ibirite reservoir (SE Brazil) Microcosm trials indicated that Phoslock ® is a promising treatment because it shows fast response and effective RSP immobilization (reductions of 82% in the water column and 69% in the sediment interstitial water) Acute toxicity test results suggested that the negative impacts of Phoslock ® addition to the water column were temporary In situ mesocosm trials did not suggest significant physicochemical alterations after Phoslock ® application Only turbidity was drastically altered by this treatment Mean reductions in RSP concentration of 81% and 90% in the water column and sediment interstitial water, respectively, were observed 600 h after treatment The mortality of Ceriodaphnia silvestrii and changes in prevalent algae taxa were observed in the water column In the sediment, no acute toxic effect was observed, although the richness of benthic groups decreased due to the treatment Overall, the results indicate that Phoslock ® is a good option for the control of eutrophication in the studied reservoir

The effect of substrate to inoculum ratios on the anaerobic digestion of human faecal material

Abstract: The anaerobic digestion (AD) of human faecal material (HFM) was investigated to consider the effect different substrate to inoculum ratios (SIR) from 0.5 to 4 on the rate and extent of methane production as well as impact on pathogen numbers. The AD process was monitored by measuring pH, total volatile fatty acid, bicarbonate alkalinity, ammonium and methane production. The results showed that the highest amounts of methane production with a value of 254.4 ±12.6 ml CH 4 g VS added − 1 and highest pathogen removal with a value of 2.7×10 4 ±40 and 2.5×10 3 ±0.5 CFU/ml, respectively, for E.coli and faecal coliform bacteria was achieved by the 0.5 SIR incubation. However, the highest organic loading found in the 4.0 SIR incubation showed the lowest methane yield with a value of 110 ±1.3 ml CH 4 g VS added − 1 and the lowest pathogen removal with a value of 3.2×10 5 ±19 and 3.2×10 4 ±3.5 CFU/ml, respectively for E.coli and faecal coliform bacteria. The empirical equation was used to calculate the theoretical methane and compare this with the actual values of methane production. The relatively high methane conversion efficiency between theoretical and actual values for 0.5 SIR, further suggest that this operational condition was the most effective.

Biosorption of cadmium from aqueous solution by shell dust of the freshwater snail Lymnaea luteola

Abstract: An assessment of the metal biosorption potential of shell dust of the freshwater snail ( Lymnaea luteola ) was made using cadmium as model metal. Artificial Neural Network (ANN) model was constructed for portraying the biosorption process under varied conditions. Under optimal conditions, the shell dust of L. luteola (LSD) exhibited a biosorption capacity of 20.00 mg g −1 at pH 6. The adsorption data at equilibrium fitted significantly more to Langmuir ( R 2 = 0.997 ) than Freundlich equation ( R 2 = 0.790 ). The kinetics for the biosorption process followed the pseudo-second order model ( R 2 = 0.998 ) better than the Lagergren model ( R 2 = 0.835 ). Confirmation of cadmium adsorption by LSD was further revealed through EDX studies, and the experimental results fitted well with the predicted pattern of biosorption based on ANN model ( R 2 = 0.924 ). It appears that shell dust of the snail L. luteola (LSD), a waste biomaterial, can be used as a low cost and environment friendly biosorbent for cadmium removal from aqueous solution.

Bioadsorption and membrane technology for reduction and recovery of chromium from tannery industry wastewater

Abstract: Chromium plays dual role for industry and environment, one side it is important to improve the quality and second side it damages the life. To come out from this problem substitution will be required to maintain both the faces. Keeping this point it was planned to carry out the experiment for reduction and then recovery of chromium from tannery wastewater. For the reduction purpose low cost and waste are used as adsorbent like saw dust, coffee husk and eucalyptus bark was used as adsorbent material. Among all adsorbents eucalyptus shows 99% of adsorption at pH 4, contact time 240 min and mass loading 3.5 g/l. Recovery of chromium was carried out with three different types of membrane among them AFC 99 reverse osmosis membrane shows 99.9% of recovery at optimum pH 6.8, inlet flow rate 0.72 m 3 / h , working pressure 40 bars.

Improving urban metabolism study for sustainable urban transformation

Abstract: It is important understanding urbanization where residents outside of the area come into the urbanized region. Urbanized area is the one facing more environmental problems because of intensive population density amplifying more damage to the environment. This paper targets China’s rapid urbanization and discusses research and policy needs in the field of sustainable urbanization. We discuss research needs for metabolism studies for sustainability of cities, major driving forces in the context of urbanization, and knowledge integration through stakeholder engagement.

Perspectives on environmental ethics in sustainability of membrane based technologies for water and energy production

Abstract: Securing a sustainable supply of water and energy is nowadays a key global issue In the current practice of water and energy supply, there is still some gap in meeting the value criteria for sustainable development mainly related to environmental pollution as well as ecosystem disturbances In this work, the sustainability of integrated membrane based processes for water and energy production is assessed with a special focus on environmental and ecosystem impacts Feasibility of bridging the available gaps through process performance improvements is presented Major environmental impacts from hybrid membrane based technologies for water and energy production are identified and considered for upstream balance of social benefits and burdens to the present and future generations Ethical considerations were pointed mainly in the aspect of intergenerational justice (IRG-J) and ecological justice (EC-J) while setting value criteria for sustainability The ethical significance of the identified impacts was predicted based on the associated difficulties to meet these criteria The overall outcome will be beneficial in designing strategies for development and implementation of sustainable hybrid processes for clean water and energy production

Buriti palm stem as a potential renewable source for activated carbon production

Abstract: The growth of industrial sector has increased the generation of harmful pollutants to the environment, along with the need of their appropriate treatment including proper disposal or reuse so that activated carbon (AC), which can be obtained from various sources, has proven to be such a material with great adsorptive capacity to remove those pollutants. In this study, ​buriti petiole was used as an alternative raw material for AC production, once buriti palm is largely found in the Cerrado region, which comprises a broad environmental ecosystem in Brazil. In order to obtain activated carbons (ACs) from buriti petiole, salt of iron (III) chloride was used as activating agent in the ratios of petiole/activating agent from 1:1 to 1:3 (m/m), i.e. keeping the petiole mass constant and varying the activating agent mass. In the carbon activated production process it was employed activating agent of relatively low commercial cost, as well as low activation temperature at 400 °C under nitrogen flow for 3 h. The material was obtained with predominance of mesoporous structure, adequate to wastewater treatment due to its large adsorption capacity and low cost of production of activated carbon from a renewable vegetal source.

A review of non-exhaustive chemical and bioavailability methods for the assessment of polycyclic aromatic hydrocarbons in soil

Abstract: Current environmental regulations relating to risk assessment for contaminated sites are often set assuming that the contaminant is 100% bioavailable. It is therefore not surprising that remediation of contaminated sites is very expensive and maybe it is unrealistic to achieve a “remediated state” under current regulatory guidelines using existing technologies. In fact the reality is that only a portion of the contaminant on site becomes available for absorption and goes into the systemic circulation. This article gives an overview of existing in vivo animal models that quantify oral bioavailability of polycyclic aromatic hydrocarbons (PAHs) in soil. It also provides a summary of in vitro gastrointestinal extraction methodologies and some of the key factors influencing absorption of PAHs in soil. For innovation, it highlights that bioaccessibility values derived from in vitro studies still require validation from in vivo animal models to gain regulatory acceptance. Additionally, this review highlights the use of non-exhaustive chemical methodologies as a valuable tool to understanding the bioavailability process and behaviour of PAHs in soil.

Dispersion of respirable particles from the workplace in opencast iron ore mines

Abstract: Earlier studies on dispersion of Particulate Matter (PM) in opencast mines primarily focused on estimation of source strength of each mining operation and dispersion of the pollutants away from mines. No study has focused on estimation of particle travel from the workplace with respect to time since its emission, enhanced concentration at workplace during as well as after mining and contribution of workplace emission to concentration rise in other parts of the mine. However, this is important because particle generated at workplace travels to other places in the mine and therefore influences the PM exposure level and duration of mine workers. The paper presents the outcome of a study that involved measurements of PM concentration and local meteorology for a period of 24 days in two opencast iron ore mines to address the above in terms of (i) particle travel time, (ii) retention time and fraction at workplace, (iii) mass balance of particle generated at workplace and (iv) downward movement of the particle in mine. Results show that mining activity generates more coarse particles (PM 2.5−10 ) than fines (PM 1−2.5 and PM 1 ). Wind speed was significantly correlated with PM concentration when wind speed was high. Up to 17 min travel time was recorded for 9–10 m vertical movement of PM. Travel time is significantly correlated with wind direction. No relationship could be found between wind speed and travel time. Particle retention time at the workplace varied from 10 to 13 min. Retention fraction varied from 7% to 40% of the PM generated during the mining, indicating significant exposure after the mining activity stops. Retention fraction and retention time are strongly related. In the mine within a short vertical distance (18–20 m) from the source, PM 2.5−10 , PM 1−2.5 , and PM 1 settle in the ranges of 72–73%, 53–63%, and 7–15% respectively. The proportion of PM 2.5−10 , PM 1−2.5 , and PM 1 that escaped from the work place varied 27–28%, 37–47% and 85–93% respectively. An empirical relationship developed for downward movement of particle from the source was able to predict the PM concentration 73%–88% and 15%–80% of the measured value for depths of 10 m and 40 m respectively. The findings of this study enhance the understanding of workers’ exposure to PM inside the mine.

Optimal combination of food waste and maize husk for enhancement of biogas production: Experimental and modelling study

Abstract: This study was focused on the optimization of biogas production from the co-digestion of food waste (FW) and maize husk (MH). The co-digestion of FW and MH at various mixture ratios was carried out in digesters A to E at 37±1 °C. Digesters A, B, C, D and E contained FW: MH of (100:0; 75:25; 50:50; 25:75; 0:100) respectively. Results obtained showed that average biogas yields of 0.50 ± 0.04, 0.71 ± 0.07, 0.54 ± 0.05, 0.30 ± 0.03, and 0.24 ± 0.02 L/gVS were obtained from digesters A, B, C, D, and E respectively. The modified Gompertz modelling of the experimental data showed that digesters A, B, C, D, and E had latency ( λ ) of 4.1, 4.9, 6.9, 7.4, and 10.6 days respectively. Digester B had the highest maximum specific biogas production R m , and maximum biogas production potential (A) of 0.50 L/gVS/day and 20.7 L/gVS respectively. The R 2 values between experimental and simulation data ranged from 0.9913 to 0.9989 in all digesters. The Post hoc Test in ANOVA using the Least Significant Difference (LSD) confirmed that there were significant differences in the mean biogas yield from the different digesters. The study therefore shows that the best combination of FW and MH for enhanced biogas production occurred in digester B.

Understanding and managing de-icer contamination of airport surface waters:a synthesis and future perspectives

Abstract: De-icers containing propylene glycol and potassium acetate are a major source of organic pollution in airport surface waters. Direct discharges of these pollutants into receiving waters, even at very low concentrations, can result in detrimental environmental impacts and may breech regulatory requirements. The airport operator is responsible for devising a de-icer management plan (DMP) which outlines the pollution prevention strategies adopted to manage contaminated runoff. This poses one of the most significant environmental management challenges in the aviation sector. Within this review article, we conceptualise the transport and fate of de-icing fluids in the environment and consider the implications for management of runoff from airports. We examine the treatment technologies that are currently incorporated into DMPs in the aviation industry. Finally, we review the current application of subsurface flow treatment wetlands, an eco-innovative technology for advanced treatment of industrial strength wastewaters, and consider priorities for future research related to this emerging technology.

Measurement and modelling of the ingestion bioaccessibility of polyaromatic hydrocarbons in soils

Abstract: Total and human ingestion bioaccessible polycyclic aromatic hydrocarbon fractions of individual polycyclic aromatic hydrocarbons were determined (representative of a combination of the saliva, gastric and upper intestine compartments) on 26 soil samples from 3 gasworks sites and from a domestic garden. A Random Forest model using the Infra-red spectra of the soils and the PAH properties successfully predicted the bioaccessibility of PAHs in the soils. The Near Infra-red and Mid Infra-red diffuse reflection spectra of the soils were subjected to a mixture resolution algorithm. Comparison with spectra of known minerals tentatively identified carbonate, silica, clay and iron oxide components in the Mid Infra-red spectra. Multiple linear regression analysis suggested that three Mid Infra-red components were associated with the organic carbon. Principal Component Analysis of polycyclic aromatic hydrocarbon properties identified three components associated with the hydrophobicity, the aliphatic nature and the vapour phase partition coefficient of the polycyclic aromatic hydrocarbons.

Spatial distribution of Pb in urban soil from Port Pirie, South Australia

Abstract: Exposure to Lead (Pb) from soil and dust in urban areas continues to threaten human health especially that of children, who are more likely to ingest a higher Pb fraction from contaminated soil. Geostatistical approaches were evaluated for the prediction of soil Pb concentrations. Ordinary kriging (OK) and co-kriging (CoK) were used to predict spatial distributions of both soil Pb concentrations and bioaccessibility. The relative accuracies of the developed predictive models were assessed using of coefficients of determination ( R 2 ) and the root mean square error (RMSE) based on the cross validation method. The accuracy of the final model was evaluated via comparison between predicted and traditional soil measurements. While OK models ( n = 73 ) were unreliable for predicting a Pb concentration surface, correlation between Pb and Zn was a useful mechanism for obtaining better predictions of soil Pb using CoK. The CoK model of log transformed Pb with Zn resulted in the best fitted model ( R 2 = 0.63 ). The percentage relative improvement (RI) for this model was 39% which suggested relatively reliable prediction accuracy. A probability kriging (PK) surface was used to describe the probability of bioaccessibility exceeding a threshold of 17% as an indicator for potential human risk. The areas with highest probability of exceeding the threshold were in agreement with previous risk area divisions related to blood Pb (BPb) levels for children under 5 years of age. The results of this research confirmed that geostatistical methods had the ability to rapidly estimate soil Pb distributions for environmental health risk assessment.

Chemical modification of rice husk by quaternized hexadecylpyridinium for removal of chromate oxyanions from aqueous solution

Abstract: Rice husk was chemically modified with synthesized hexadecylpyridinium bromide (HDPBr) to enhance Cr(VI) adsorption capacity of the obtained surfactant modified rice husk (HDP + /RH). The structure of as-synthesized HDPBr surfactant was confirmed with 1 H NMR spectroscopy. The interaction between the HDPBr molecules and the RH surface was investigated by X-ray diffraction (XRD), FTIR spectroscopy, scanning electron microscopy (SEM) and nitrogen adsorption at −196 °C. HDP + /RH brought about decrease in the values of specific surface area, pore radius, pore size and pore volume compared with those of pure RH, indicating pore narrowing through grafting of HDPBr on the RH surface. The IR spectrum of HDP + /RH exhibited new frequency peaks at 1614, 1490, 1115 and 1043 cm −1 due to vibration of pyridinium ion, fact that is indicative of the successfully anchoring of the surfactant molecules through hydrophobic bonding to the cellulose chains in RH. The adsorption of Cr(VI)-oxyanions onto RH and HDP + /RH was investigated by batch studies at 20 and 50 mg L −1 initial concentration. HDP + /RH was evaluated as an efficient adsorbent for the Cr(IV)-oxyanions than RH, which rapidly attained equilibrium after 45 min compared with the latter at 110 min. This allows evidence for the electrostatic interaction between the Cr(VI)-oxyanions and HDP + -promoted RH. The adsorption data fitted reasonably with the Langmuir and Freundlich models for HDP + /RH, similarly the pseudo-second-order model shows a better fitting. The intraparticle diffusion analysis suggests that adsorption of Cr(VI) ions by HDP + /RH involved intraparticle diffusion which contributed to the rate of the process.