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The release of pharmaceuticals into the environment induces adverse effects on the metabolism of humans and other living species, calling for advanced remediation methods. Conventional removal methods are often non-selective and cause secondary contamination. These issues may be partly solved by the use of recently-developped adsorbents such as molecularly imprinted polymers. Here we review the synthesis and application of molecularly imprinted polymers for removing pharmaceuticals in water. Molecularly imprinted polymers are synthesized via several multiple-step polymerization methods. Molecularly imprinted polymers are potent adsorbents at the laboratory scale, yet their efficiency is limited by template leakage and polymer quality. Adsorption performance of multi-templated molecularly imprinted polymers depends on the design of wastewater treatment plants, pharmaceutical consumption patterns and the population serviced by these wastewater treatment plants.

Biohydrogen production from various organic wastes, wastewaters and biomass has been widely studied due to the higher production rates and fundamentals and technologies have also been well developed and heavily documented through diverse laboratory-scale bioreactors. Recently, research has been geared to the concomitant production of biohydrogen and methane which is so called “biohythane”. One-stage and two-stage (bio-H2 + bio-CH4) methods are the main biohythane production methods and this field of research for probing into green biofuels is gradually gaining ground. In this paper, the salient aspects of biohythane research at the present time are revisited and the research success and latent promise of biohythane are highlighted based on the findings of the relatively few publications in this area.

This review analyses the relevant studies which focused on hydrogen synthesis by dark fermentation of galactose from macroalgal biomass by discussing the inoculum-related pretreatments, batch fermentation and inhibition, continuous fermentation systems, bioreactor designs for continuous operation and ionic liquid-assisted catalysis. The potential for process development is also revisited and the challenges towards suppressing glucose dominance over a galactose-based hydrogen production system are presented. The key challenges in the pretreatment process aiming to achieve a maximum recovery of upgradable (fermentable) sugars from the hydrolysates and promoting the concomitant detoxification of the hydrolysates have also been highlighted. The research avenues for bioprocess intensification connected to enhance selective sugar recovery and effective detoxification constitute the critical steps to develop future red macroalgae-derived galactose-based robust biohydrogen production system.

Endosulfan is a highly polluting and toxic pesticide which has been used in many areas globally to control pests in view to improve productivity. Concomitantly, endosulfan has also been associated with many cases of environmental pollution and various types of irreversible metabolic dysfunctions in living organisms both on lands and in waters. Subsequently, since over the last three decades, several endosulfan remediation methods have been studied and many are gradually bringing hope towards efficient clean-up. This article specifically reviews endosulfan degradation and endosulfan removal by discussing the recent findings reported and the trends observed in studies reporting bacterial and fungal bioremediation, photocatalytic degradation, adsorption and membrane separation processes. The salient observations from this review are: there are many bacterial species which degrade endosulfan isomers with relatively high efficiencies; many studies indicate the merits of plants in phytoextracting and accumulating endosulfan but the identification of endosulfan hyperaccumulators remains; photocatalytic systems involving one or two metals also bring about significant endosulfan degradation but issues related with variations in rates of reactions, catalyst deactivation due to fouling, intricacy of metal-based nanocatalyst structures and their complex fabrication methods and lack of control of morphology of the nanosized structures have to be addressed; and membrane retention systems specifically treating endosulfan-contaminated aqueous media are scanty and more analysis is also needed to optimize the shear force-membrane structural integrity-membrane stability rapport of the membranes being developed. In the end, a number of research and development avenues which need further attention and probing towards the development of suitable endosulfan-remediation routes are pointed out. Post-print / Final draft

The green approach of the one-pot enzyme-assisted biomass deconstruction for the production of biofuels and high-value added chemicals in the presence of combined ionic liquids with metal nanoparticles (CILMNPs) process is receiving more interest in biomass-to-energy research. This paper gives a succinct overview of the recent applications of CILMNPs in the pretreatment of lignin-based biomass for macrocellular deconstruction at the one-pot scale and then holistically addresses the multifarious research hurdles, challenges and prospects which have to be addressed to achieve the green merits on a larger scale of processing. Once the one-pot green metrics will be matched by their corresponding process metrics, the potential for pilot-scale production and eventually industrial utilization of CILMNPS will take good shape. Furthermore, such process scale-up campaigns using CILMNPS for biomass depolymerization will have to be robustly designed for an effective and efficient application by selecting bioprocesses involving enzymatic hydrolysis, saccharification and deoxygenation/hydrodeoxygenation routes operated under continuous regimes. These tasks will demand considerable applied research efforts in the form of process intensification and optimization both at the one-pot scale and for prospective large-scale bioprocessing units.

Three abundant coffee residues (green coffee powder, parchment and defatted cake) and sugarcane vinasse were co-digested under thermophilic anaerobic conditions. A pilot plant was set-up and operated under optimized conditions using mesophilic sludge seed to produce biohydrogen. The initial conditions were acidogenic regimes (pH 5.0–6.5) followed by methanogenic conditions (pH 6.5–8.0). Results indicated the concomitant generation of biohydrogen and biomethane (termed biohythane) from the coffee residues. The green coffee powder bioreactor produced a hydrogen-rich biohythane for the first 15 days with a maximum yield on day four (31.45% hydrogen). Results also suggested that start-up of the biosystem reached the methanogenic stage in only 20–25 days and produced methane yields as high as 0.14mlCH4/gVSadded. For the co-digestion of defatted cake and vinasse, the only gas of interest produced was biohydrogen 32% vol./vol. between the 9th and 32nd day. Anaerobic co-digestion of parchment and vinasse produced biohythane at an average yield of 0.21mlCH4/gVSadded.

Biohydrogen production from lignocellulosic biomass (LCB) is an active research area. Several workers have tested a number of substrates under different operational conditions and brought forward the many positive process performance features and identified the main sources of inhibition. This review analyzes selected fermentative biohydrogen production processes by revisiting the core biohydrogen production performances in terms of gas production rates and yields and equally addresses the options for process enhancement by the application of through pretreatment methods and detoxification of process inhibitors. In addition, the issues related to continuous biohydrogen operation in different reactor configurations are highlighted. Lastly, future avenues of research which may be engendered and engineered to enhance the biohydrogen generation and process biokinetics are discussed. This review intends to provide the fundamental understanding of biohydrogen production and provides a perspective on future developments in this area of applied research.

The objective of this study was to evaluate the effects of sonication on the biogas production dynamics of sugarcane straw and vinasse in an anaerobic digestion. Two different ultrasound pretreatments were evaluated namely 180 W of ultrasonic power irradiated at 37 kHz for 30 min (PBU) and 800 W of ultrasonic power irradiated at 19 kHz for 15 min (PSU). Significant differences were observed in the biogas compositions of the PBU and PSU pretreatments and their respective controls. A continuous increase in methane concentration of the biohythane (biohydrogen and methane combined) was recorded in the PBU reactors (60–80% by volume). The main effect of ultrasound pretreatment was on the composition biohydrogen, methane and carbon dioxide (biohythane) produced.

Excess consumption of energy by humans is compounded by environmental pollution, the greenhouse effect and climate change impacts. Current developments in the use of algae for bioenergy production offer several advantages. Algal biomass is hence considered a new bio-material which holds the promise to fulfil the rising demand for energy. Microalgae are used in effluents treatment, bioenergy production, high value added products synthesis and CO2 capture. This review summarizes the potential applications of algae in bioelectrochemically mediated oxidation reactions in fully biotic microbial fuel cells for power generation and removal of unwanted nutrients. In addition, this review highlights the recent developments directed towards developing different types of microalgae MFCs. The different process factors affecting the performance of microalgae MFC system and some technological bottlenecks are also addressed.

Textile effluents in natural waters pose environmental health problems if not treated to safe limits. Various bacterial species have the potential to degrade dyes. Here we studied the ability of Bacillus algicola to decolourise red, blue and yellow azo dyes. B. algicola was isolated from soil samples taken from a sanitary landfill site. Isolation and screening were performed using mineral salt medium. Dye-decolourising isolates were assessed in their capacity to decolourise dyes. Experiments were conducted at pH 6, 7 and 8, and 25, 35 and 45 °C. Phytotoxicity of the dyes and biodegradation products was assessed by seed germination tests. Results show that B. algicola gave the highest decolourisation at pH 8.0 and 25 °C in the presence of yeast extract as media supplement. B. algicola degraded the red and blue azo dyes by over 95%. The phytotoxicity results indicated that biodegradation products of the red and blue azo dyes were not toxic. Biodegradation products of the yellow dye were, however, toxic and considerably hindered germination. From these results, we infer that B. algicola has good potential for degrading and decolourising the red and blue test azo dyes.

Hydrogen production from lignocellulosic biomass (LCB) using dark fermentation is an interesting research niche being developed over the last decade. This review analyses the relevant studies which focused on biohydrogen production from LCB using dark fermentation techniques in terms of substrate characterization, bottlenecks associated with the pretreatment and its subsequent utilization, possible remedies for the scale-up of the most adapted processes and finally the prospects and suggestions which may be envisaged. Studies dealing primarily with the utilization of raw and pretreated LCB have been assessed in terms of biohydrogen production performance for production rate and yield. Energy production analysis and prospecting of suitable cellulosic biomass and efficient cellulolytic microbes have been elucidated towards better cellulose hydrolysis and efficient conversion of LCB to H2 in addition to process economics.

The aim of the study was to investigate the effects of carton in the composting process of mixed vegetable wastes using an experimental composter of capacity 80L. Three different mixes were set-up (Mixes 1, 2 and 3) which consisted of vegetable wastes, 2.0kg paper and bulking agents, vegetable wastes, 1.5kg carton and bulking agents, vegetable wastes, 4.5kg carton and bulking agents, respectively. Temperature evolution, pH trends, moisture levels, respiration rates, percentage volatile solids and electrical conductivity were monitored for a period of 50days. The system remained under thermophilic conditions for a very short period due to the small size of the reactor. The three mixes did not exceed a temperature of 55°C, where sanitization takes place by the destruction of pathogens. The highest peak of CO2 evolution was observed in Mix 2 indicating that maximum microbial degradation took place in that mix.

Heavy metals released from industrial activities pose a significant threat to the environment and public health due to their reported toxicity even at trace levels. Although there are several available methods to treat or remove heavy metals from water and wastewater, the research focuses on development of technological solutions which sound environmental friendly and economically feasible, able to reduce the costs and maximize the efficiency. In this framework, the biosorption process, which uses cheap and non-pollutant materials, may be considered as an alternative, viable and promising, technology for heavy metal and metalloid ions sequestration and ultimately removal technology in the waste water treatment. However, there is as yet little data on full-scale applications for the design and testing of adsorption units using single biosorbents and their combinations to sequester heavy metal ions from multi-metal systems. Immediate research and development is hence earnestly required in this specific direction to further make progress this blooming technology and widen its scope of application to real situations needing heavy metal pollution remediation. This review provides a comprehensive appraisal of the equilibrium modeling of a number of biosorption processes as well as the structural, chemical and morphological modifications and activation of biosorbents. Further the relative merits of the methods used to recover sequestered heavy metal ions and regenerate biosorbents through desorption routes and their future applications are discussed.

The kinetics, adsorption isotherms, thermodynamics and spectroscopic analyses of the removal of the anthraquinone dye, Alizarin Red S by adsorption onto mustard husk were studied. Batch adsorption experiments were conducted using synthetic aqueous solutions and the effects of initial dye concentration, initial pH of solution, adsorbent dose and temperature were investigated. The mustard husk adsorbent was characterized using Fourier transform infrared spectroscopy, scanning electron microscopy and through the determination of pH zpc . The equilibrium adsorption data fitted very well to the Freundlich model and this provided evidence of multilayer adsorption of the dye molecules onto the active sites on the biosorbent. The kinetic studies showed that the process was quite rapid and 90% of equilibrium capacity was achieved within 80 min. The process followed the pseudo-second-order kinetic model with a k 2 value of 0.094 g/mg min for an Alizarin Red S concentration of 25 mg/L. Positive Δ H ° and negative Δ G ° were indicative of the endothermic and spontaneous nature, respectively, of Alizarin Red S removal by adsorption onto mustard husk biomass.

Due to the excellent chelating properties of aminopolycarboxylic acid (APCAs), they can be used for the removal of metals from contaminated waters. This paper reviews the research results obtained for both commercial and self-prepared adsorbents functionalized with four most common APCAs: iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), and diethylenetriaminepentaacetic acid (DTPA). The structural characteristics and unique metal binding properties of these chelating adsorbents are presented. The theory of the adsorption phenomena is discussed based on the kinetics of adsorption, equilibrium adsorption isotherm models, and thermodynamic models. The most important applications of APCA-functionalized adsorbents are also described. APCA-functionalized adsorbents are found to be highly promising materials for metal removal from contaminated waters.

This paper reports the potential of chemically treated wood chips to remove copper (II) ions from aqueous solution a function of pH, adsorbent dose, initial copper (II) concentration and contact time by batch technique. The wood chips were treated with (a) boiling, (b) formaldehyde and (c) concentrated sulphuric acid and characterized by Fourier transform infrared spectroscopy, scanning electron microscopy and energy dispersive analysis X-ray. pH 5.0 was optimum with 86.1, 88.5 and 93.9 % copper (II) removal by boiled, formaldehyde-treated and concentrated sulphuric acid-treated wood chips, respectively, for dilute solutions at 20 g L−1 adsorbent dose. The experimental data were analysed using Freundlich, Langmuir, Dubinin–Radushkevich and Temkin isotherm models. It was found that Freundlich and Langmuir models fitted better the equilibrium adsorption data and the adsorption process followed pseudo-second-order reaction kinetics. The results showed that the copper (II) is considerably adsorbed on wood chips and it could be an economical option for the removal of copper from aqueous systems.

Heavy metals affect the biochemical reactions that take place during anaerobic digestion processes of organic matter. In this review, the different effects observed in anaerobic digestion processes and during the production of biomethane and biohydrogen from several substrates contaminated with and/or inheriting heavy metals from the substrates themselves were discussed. It has been found that heavy metals exert important roles in biochemical reactions. Heavy metals like copper, nickel, zinc, cadmium, chromium and lead have been overwhelmingly reported to be inhibitory and under certain conditions toxic in biochemical reactions depending on their concentrations. Heavy metals like iron may also exhibit stimulatory effects, but these effects have been scantily observed. This review also concludes that the severity of heavy metal inhibition depends upon factors like metal concentration in a soluble, ionic form in the solution, type of metal species, and amount and distribution of biomass in the digester or chain of biochemical reactions which constitute the anaerobic digestion process. A majority of studies have demonstrated that the toxic effect of heavy metals like chromium, cadmium and nickel is attributable to a disruption of enzyme function and structure by binding of the metal ions with thiol and other groups on protein molecules or by replacing naturally occurring metals in enzyme prosthetic groups. This review has not found published data on the effects of heavy metals on the hydrolysis stage of anaerobic digestion process chemistry, and hence further studies are required to depict any changes.

The Port Louis Harbour is the sole port in Mauritius and handles 99% of cargo entering the island. The port area is subject to a wide range of port installations handling, processing and storing a wide range of cargo ranging from petroleum products, coal, cement, edible oil, heavy oil, molasses, wheat, bitumen to fertiliser manufacturing. This study integrated procedures of ISO14001 and was carried out in the context of the UNEP GEF WIO–Lab Solid Wastes Demo Project during the period April 2009 to May 2010. An inventory of the wastes generation and flow from ships and within the industrial port area was conducted, and on basis of the results obtained, an environmental pollution prevention and protection program was developed to eventually assist in the setting up of a Port Waste Management System (PWMS) at the Port Louis Harbour. The PWMS identified the significant environmental aspects and impacts, structure of the organisation, distribution of responsibilities, needs for training, objectives and targets as well as the operational control measures. At the end of the study, suggestions on how to improve the port’s environmental performance with regards to waste management were recommended.

In pursuit of a green and sustainable world, wastewater remediation and sludge treatment have equally become a growing global environmental concern. Several innovative treatment processes have been designed throughout the last few decades for treating wastewaters and sludges but many of them are very costly and operate at low efficiencies. In view to find novel treatment processes, active research is being conducted globally. Microwave irradiation technology is gradually making a modest but promising mark of its own in enhancing to significant extents the ease, fastness, and efficiency of certain treatment processes involved in wastewater and sludge management. The authors focus on and appraise the budding use and application of microwave irradiation in chemical research undertaken for sludge and wastewater treatment. The related aspects of microwave-assisted heavy metal stabilization, pathogen inactivation, wastewater parameter analysis, and wastewater treatment polymers synthesis are also discussed.

Arsenic is a toxic element and has been responsible for many accidental, occupational, deliberate, and therapeutic poisonings since its discovery in 1250. It occurs in natural waters as the arsenite (As3+) and arsenate (As5+) ions. The solubility of arsenite and arsenate compounds is relatively high so that these ions are readily transported through aqueous routes into the environment. Arsenic can be transferred from soils to crops and accumulates in various food crops and aquatic plants. The fascinating chemistry and toxicity potential make arsenic and its compounds of particular scientific interest and environmental concern. The conventional removal of heavy metals from wastewater, natural waters, and drinking water has only limited effects on arsenic removal. In this review, the main engineering and medical applications, salient health and environmental concerns, novel research on treatment for arsenic poisoning, and removal technologies for arsenic and their derivatives are discussed and enumerated wi...

Sustainable development requires the development and promotion of environmental management and a constant search for green technologies to treat a wide range of aquatic and terrestrial habitats contaminated by increasing anthropogenic activities. Bioremediation is an increasingly popular alternative to conventional methods for treating waste compounds and media with the possibility to degrade contaminants using natural microbial activity mediated by different consortia of microbial strains. Many studies about bioremediation have been reported and the scientific literature has revealed the progressive emergence of various bioremediation techniques. In this review, we discuss the various in situ and ex situ bioremediation techniques and elaborate on the anaerobic digestion technology, phytoremediation, hyperaccumulation, composting and biosorption for their effectiveness in the biotreatment, stabilization and eventually overall remediation of contaminated strata and environments. The review ends with a note on the recent advances genetic engineering and nanotechnology have had in improving bioremediation. Case studies have also been extensively revisited to support the discussions on biosorption of heavy metals, gene probes used in molecular diagnostics, bioremediation studies of contaminants in vadose soils, bioremediation of oil contaminated soils, bioremediation of contaminants from mining sites, air sparging, slurry phase bioremediation, phytoremediation studies for pollutants and heavy metal hyperaccumulators, and vermicomposting.

The corrosion inhibition of Neem (Azadirachta indica (AZI)) leaves extract as a green inhibitor of zinc corrosion in H2SO4 has been studied using the gravimetric method. The results of the study reveal that the different concentrations of the AZI extract inhibit zinc corrosion and that inhibition efficiency of the extract varies with concentration and temperature.

The overall heat-transfer coefficients ( U-values) developed during the self-heating composting of mixed vegetables and chicken manure were determined based on a combined fluid film theory and thermal boundary layer concept. The heat flow was modeled into four heat transfer components. The heat transfer mechanisms have been modeled as comprising two conductive heat fluxes across the compost matrix and compost reactor walls, one heat flux across the film of water condensing on the inner reactor surface and a convective heat flux due to free convection on the outside surface of the reactor walls. Individual film heat-transfer coefficients have been calculated using a series of dimensionless correlations grouping the outer reactor surface temperature, the Nusselt (Nu), Prandtl ( Pr), Grashof ( Gr) and Rayleigh ( Ra) numbers. Gr has varied between 5.11 × 10^6 and 3.71 × 10^9, Pr from 0.692 to 0.712, and Ra from 3.64 × 10^6 to 2.56 × 10^9. Four different equations have been used to evaluate the heat transfer coefficients characterizing the heat flow due to free convection. The maximum U-values have been found to vary between 0.368 and 0.387 W.m^-2·K^-1, and the minimum U-values have ranged from 0.255 to 0.288 W.m^-2·K^-1. A 4-parameter Weibull model was found to describe the variation of U-value with compost matrix temperature reliably with R^2 = 0.9999.

The overall heat-transfer coefficients for four self-heating composting experiments were determined and mathematically modeled based on an energy balance approach. Heat dissipation to the surroundings through combined conductive/convective/radiative heat transfer mechanisms has been considered. Energy balance parameters were mathematically modeled with time for the data collected for the composting of mixed yard/green vegetables wastes, broiler litter and bagasse in PVC drum composters. The rates of reaction for the mixes varied between 7.5 and 8.75 K/day for the first 4 days, after which the rate of temperature decrease varied from 1.32 to 3.01 K/day. The rate of temperature change for all mixes best fitted a first order intermediate with equilibrium variation in time with R2 values varying from 0.9809 to 0.9999 for day 3 to day 33. Variations of U-values for the composting experiments in this study were two-tiered. Initial U-values (before day 3) were much larger than the values after day 3. Maximum U-values varied between 35.5 and 263.9W/m2•K. U-values dropped to 88.7-95.0% the initial values just after the active phase, thereafter remaining quasi steady in the range of 2.44-8.15 W/m2•K. Mathematical correlations for U-values from day 1 to 30 fitted best with balanced order polynomials degree four for R2 values of 0.9953 and 0.9999 at a 95% confidence interval. ANOVA tests showed that the values varied significantly (p < 0.05).

A combined multi-parameter sensitivity analysis/frequency array analysis technique was employed to assess the impact of design conditions and matrix-specific properties on the rate of heat loss from a self-heating composting process. This method was specifically used to identify the range of parameters over which a model predicting the overall heat-transfer coefficients (U-values) for the heat loss process are particularly sensitive. The model was found to be most sensitive for the following range of input parameters: the internal diameter of reactor varying from 0.8m to 1.2m, the combined reactor wall and insulation thickness ranging from 4cm to 6cm, the free airspace of the matrix varying from 50% to 60%, the reactor length varying from 1.0m to 1.5m, the thermal conductivity of the organic substrates ranging from 0.1W/m.K to 0.2W/m.K and the preferred thermal conductivity of the insulation material being less than 0.2W/m.K. A second sensitivity analysis was performed to identify which input parameters actually influenced the model’s response the most. This analysis compared the acceptable and unacceptable frequency distributions of each input parameter, with model outputs below a U-value of 4.5W/m2.K being an acceptable composting performance from a thermodynamics consideration. This analysis disclosed the matrix free airspace, the internal diameter of the reactor and the combined thickness of reactor wall and insulation as the most important parameters which should be given high priority when designing invessel compost reactors.

Efficient compost production requires a thorough understanding of the process dynamics in terms of the feedstock materials used and the interactions of the physical properties involved. The main properties affecting the composting process are temperature, moisture content, bulk density, porosity and oxygen availability. In this study, the correlations between a selected set of physical properties of a batch-composting matrix were determined. The key physical changes in the composting materials for a blend of woodchips, chicken manure and mixed green vegetables have been monitored during a 36-day composting period in a 200-L rotary drum. The daily measurements conducted on the solid samples included temperature, pH, volatile solids, bulk density, moisture content, free airspace and substrates particle density while the carbon dioxide release was monitored weekly using jar respiration tests. The results from the compost process monitoring were a maximum temperature rise to 66.3 °C over the first 3 days, a marked decrease in free airspace from 76.3% to 40.0% at the end of the process, a variation in average composting material particle density from 1097 kg/m3 to 2325 kg/m3, and an increase in wet bulk density from 255 kg/m3 to 628 kg/m3. Correlations developed among free airspace, wet bulk density, dry bulk density and wet moisture content were in agreement with previously determined equations from literature. Free airspace varied linearly with both dry and wet bulk densities (R2 value of 0.89 and 0.95, respectively) while the free airspace–wet moisture content profile followed a fourth degree polynomial trend with a correlation coefficient of 0.63.

Azo dyes are used in many industries such as carpet manufacturing, textiles, paint, ink, plastics and cosmetics production processes. The coloured industrial effluent can pose serious problems in the aquatic environment. It is possible to get complete mineralisation of organic pollutants in water by photocatalysts. This study was carried out to examine the feasibility to remove supra black-T dye from carpet dyeing wastewater by photocatalytic degradation on Oak charcoal under sunlight. Adsorption efficiency of dye on charcoal at various pH values and photodegradation with ZnO and TiO2 catalysts were studied. The removal efficiency of charcoal alone was 28 mg dye/g charcoal at pH 8 and 25oC in 60 min which was half that of activated charcoal. Photocatalytic degradation and adsorption with TiO2 and ZnO under sunlight was faster and almost complete removal was observed in shorter times.

Batch adsorption studies were conducted to investigate the potential of Acacia nilotica sawdust as biosorbent for removal of basic Swiss blue dye from wastewater. Sawdust was subjected to formaldehyde pretreatment (FSD) and boiling (BSD). Maximum dye removal was observed after 120 min for all conditions – FSD: 97.5% and BSD: 95.9% at pH 6, 50 mgL−1 dye concentration and 0.2 g/50 mL adsorbent dosage. Adsorption was endothermic and was accompanied by an increase in entropy and a decrease in Gibbs free energy for 288?333 K. Equilibrium data fitted excellently with the Langmuir isotherm (FSD: R² &#61 0.9955, BSD: R² &#61 0.9914). Adsorption kinetics was found to follow pseudo-second-order model (R² > 0.99, FSD and BSD). It can be concluded that formaldehyde-treated sawdust (FSD) can be used as a more efficient and low-cost alternative to the chemically untreated sawdust in aqueous solution for Swiss blue dye removal.

The performance of a laboratory-scale sequencing batch reactor (SBR) of 20-litre capacity was evaluated for simultaneous removal of soluble COD (SCOD), NH4+?N and phosphorus by changing the compositions and concentrations of substrates under different combinations of REACT period. The total cycle period of 10 h comprised 0.5 h FILL period, 8 h REACT period, 1 h SETTLE period and 0.5 h IDLE/DRAW period with the react period being divided into two combinations of anoxic (A) and aerobic (O) react period namely (4 h + 4 h) (A/O) and (3 h + 3 h + 2 h) (A/O/A). The initial SCOD concentration was kept constant at 2000 mg/l while the initial NH4+?N concentrations were taken as 90 mg/l and 180 mg/l as N tentatively. Results for total phosphorus accumulation capacity indicated that the A/O/A combination was more conducive to total phosphorus uptake at 90.26 mg P/g MLVSS than the A/O combination in the aerobic reaction period which followed the initial 3-h anoxic react period.

The conventional COD determination through reflux method, although still much in experimental practice for water and wastewater analysis, is time consuming, complex and prone to a number of errors. A simpler, more rapid, environmentally benign but still precise method would hence be more attractive and is, in point of fact, a pressing need. Contextualised within the concept of Green Chemistry, this review discusses a handful of research papers published to date on microwave-assisted COD determination and brings forward the achievable improvements in COD analysis while using this clean analytical technique.

The paper reviews the state-of-the-art technologies on sludge conditioning and stabilisation. Radiation technology, best contextualised within the concept of Green Chemistry, is yet another developing area of sludge pretreatment. Besides revisiting some important aspects of sludge treatment by composting, this review paper also appraises the application of gamma ray and ultrasound irradiations particularly in sludge pretreatment and sludge composting for monitoring, and to some extent improving, the degradation and subsequent stabilisation of sludge constituents. The scientific principle of each type of radiation and selected research work are discussed, and future needs for applied research are eventually outlined.

In this study, the annual generation of Landfill Gas (LFG) and methane using the Scholl-Canyon model have been predicted for 1998-2030 for five scenarios of landfill management at the Mare Chicose landfill in Mauritius. Using the Approved Large-Scale Methodology AM003 and Approved Baseline Methodology AM0010 of the Approved Methodologies for CDM activities, the carbon dioxide (CO2) emissions reduction and electricity generation capacities for three CO2 emissions intensities from flaring of methane have been estimated for 2008-2030. The total LFG generation has amounted to 319.8-2371.2 Mm³ for 1998-2030. At 50% (v/v), methane content and 60% recovery, the maximum LFG generation and recoverable volume of methane amounted to 1869.5 and 560.9 Mm³ for 2008-2030, respectively. This corresponded to an emissions reduction of up to 421,657.3tCO2e. Potential power generations have been found to vary from 44.6-937 GWhour for the three emissions intensities.