Bioreactors for treatment of VOCs and odours – A review

Volatile organic compounds (VOCs) and odorous compounds discharged into the environment create ecological and health hazards. In the recent past, biological waste air treatment processes using bioreactors have gained popularity in control of VOCs and odour, since they offer a cost effective and environment friendly alternative to conventional air pollution control technologies. This review provides an overview of the various bioreactors that are used in VOC and odour abatement, along with details on their configuration and design, mechanism of operation, insights into the microbial biodegradation process and future R&D needs in this area.     

Potential for enhanced phytoremediation of landfills using biosolids – a review

Despite the use of recyclable materials increasing worldwide, waste disposal to landfill remains the most common method of waste management because it is simple and relatively inexpensive. Although landfill disposal is an effective waste management system, if not managed correctly, a number of potential detrimental environmental impacts have been identified including soil and ground water contamination, leachate generation, and gas emissions. In particular, improper post-closure treatment of landfills or deterioration of the conventional clay landfill capping were shown to result in land degradation which required remediation to secure contaminants within the landfill site.Phytoremediation is an attractive technology for landfill remediation, as it can stabilize soil and simultaneously remediate landfill leachate. In addition, landfill phytoremediation systems can potentially be combined with landfill covers (Phytocapping) for hydrological control of infiltrated rainfall. However, for the successful application of any phytoremediation system, the effective establishment of appropriate, desired vegetation is critical. This is because the typically harsh and sterile nature of landfill capping soil limits the sustainable establishment of vegetation. Therefore, the physicochemical properties of landfill capping soils often need to be improved by incorporating soil amendments. Biosolids are a common soil amendment and will often meet these demanding conditions because they contain a variety of plant nutrients such as nitrogen, phosphate, potassium, as well as a large proportion of organic matter. Such amendment will also ameliorate the physical properties of the capping soils by increasing porosity, moisture content, and soil aggregation. Contaminants which potentially originate from biosolids will also be remediated by activities congruent with the establishment of plants and bacteria.     

On-line production of ferrate with an electrochemical method and its potential application for wastewater treatment – A review

A number of studies on the oxidation of various organic/inorganic contaminants by ferrate(VI) were reported in the 1980s and 1990s. The exploration of the use of ferrate(VI) for water and wastewater treatment has been well addressed recently. However, challenges have existed for the implementation of ferrate(VI) technology in practice due to the instability of a ferrate solution or high production cost of solid ferrate products. The research has been carried out aiming at the generation and application of ferrate(VI) in situ. This paper thus reviews ferrate chemistry and its overall performance as a water treatment chemical, discusses the factors affecting the ferrate yield efficiency using the electrochemical method, and finally, summarises the work on the production and use of ferrate in situ which is currently under study.     

Is trade liberalisation bad for the environment? A review of the economic evidence

The continued growth in world trade and investment flows has led to a renewed interest among researchers and policy makers in the potential impact that trade liberalisation policy may have on the environment. The aim of this paper is to provide a balanced and accessible summary of the findings of recent economic research on the impact of growth in international trade and investment on environmental quality.     

Oxy-fuel coal combustion—A review of the current state-of-the-art

Carbon dioxide emissions will continue being a major environmental concern due to the fact that coal will remain a major fossil-fuel energy resource for the next few decades. To meet future targets for the reduction of greenhouse gas (GHG) emissions, capture and storage of CO₂ is required. Carbon capture and storage technologies that are currently the focus of research centres and industry include: pre-combustion capture, post-combustion capture, and oxy-fuel combustion. This review deals with the oxy-fuel coal combustion process, primarily focusing on pulverised coal (PC) combustion, and its related research and development topics. In addition, research results related to oxy-fuel combustion in a circulating fluidised bed (CFB) will be briefly dealt with.During oxy-fuel combustion, a combination of oxygen, with a purity of more than 95 vol.%, and recycled flue gas (RFG) referred to as oxidant is used for combusting the fuel producing a gas consisting of mainly CO₂ and water vapour, which after purification and compression, is ready for storage. The high oxygen demand is supplied by a cryogenic air separation process, which is the only commercially available mature technology. The separation of oxygen from air as well as the purification and liquefaction of the CO₂-enriched flue gas consumes significant auxiliary power. Therefore, the overall net efficiency is expected to be decreased by 8–12% points, corresponding to a 21–35% increase in fuel consumption. Alternatively, ion transport membranes (ITMs) are proposed for oxygen separation, which might be more energy efficient. However, since ITMs are far away from becoming a mature technology, it is widely expected that cryogenic air separation will be the selected technology in the near future. Oxygen combustion is associated with higher temperatures compared with conventional air combustion. Both fuel properties as well as limitations of steam and metal temperatures of the various heat exchanger sections of the boiler require a moderation of the temperatures in the combustion zone and in the heat-transfer sections. This moderation in temperature is accomplished by means of recycled flue gas. The interdependencies between the fuel properties, the amount and temperature of the recycled flue gas, and the resulting oxygen concentration in the combustion atmosphere are reviewed.The different gas atmosphere resulting from oxy-fuel combustion gives rise to various questions related to firing, in particular, with respect to the combustion mechanism, pollutant reduction, the risk of corrosion, and the properties of the fly ash or its resulting deposits. In this review, detailed nitrogen and sulphur chemistry was investigated in a laboratory-scale facility under oxy-fuel combustion conditions. Oxidant staging succeeded in reducing NO formation with effectiveness comparable to that typically observed in conventional air combustion. With regard to sulphur, a considerable increase in the SO₂ concentration was measured, as expected. However, the H₂S concentration in the combustion atmosphere in the near-flame zone increased as well. Further results were obtained in a pilot-scale test facility, whereby acid dew points were measured and deposition probes were exposed to the combustion environment. Slagging, fouling and corrosion issues have so far been addressed via short-term exposure and require further investigation.Modelling of PC combustion processes by computational fluid dynamics (CFD) has become state-of-the-art for conventional air combustion. Nevertheless, the application of these models for oxy-fuel combustion conditions needs adaptation since the combustion chemistry and radiative heat transfer is altered due to the different combustion gas atmosphere.CFB technology can be considered mature for conventional air combustion. In addition to its inherent advantages like good environmental performance and fuel flexibility, it offers the possibility of additional heat exchanger arrangements in the solid recirculation system, i.e. the ability to control combustion temperatures despite relatively low flue gas recycle ratios even when combusting in the presence of high oxygen concentrations.     

Inexact fuzzy-stochastic mixed-integer programming approach for long-term planning of waste management – Part A: Methodology

In this study, an inexact fuzzy chance-constrained two-stage mixed-integer linear programming (IFCTIP) approach is proposed for supporting long-term planning of waste-management systems under multiple uncertainties in the City of Regina, Canada. The method improves upon the existing inexact two-stage programming and mixed-integer linear programming techniques by incorporating uncertainties expressed as multiple uncertainties of intervals and dual probability distributions within a general optimization framework. The developed method can provide an effective linkage between the predefined environmental policies and the associated economic implications. Four special characteristics of the proposed method make it unique compared with other optimization techniques that deal with uncertainties. Firstly, it provides a linkage to predefined policies that have to be respected when a modeling effort is undertaken; secondly, it is useful for tackling uncertainties presented as intervals, probabilities, fuzzy sets and their incorporation; thirdly, it facilitates dynamic analysis for decisions of facility-expansion planning and waste-flow allocation within a multi-facility, multi-period, multi-level, and multi-option context; fourthly, the penalties are exercised with recourse against any infeasibility, which permits in-depth analyses of various policy scenarios that are associated with different levels of economic consequences when the promised solid waste-generation rates are violated. In a companion paper, the developed method is applied to a real case for the long-term planning of waste management in the City of Regina, Canada.     

Use of artificial roughness for performance enhancement of solar air heaters—a review

The performance characteristics of a solar air heater can effectively be improved by providing artificial roughness in the form of protrusions and dimples of various shapes, sizes, and orientations on the underside of heated surface. An extensive literature review on artificial roughness elements has been carried and the correlations developed for heat transfer and friction factor for roughened solar air collector have been discussed and presented in this paper. The performance parameter has also been computed and compared with various kinds and shapes of roughness geometries using correlations developed by various investigators. The optimum values of the roughness parameters obtained by several investigators have also been discussed.     

Rehabilitation options for inland waterways impacted by sulfidic sediments – A synthesis

The build up of reduced inorganic sulfur in the sediments of inland wetlands and creeks is an emerging risk for the management of inland waterways and is a direct result of secondary salinisation. Inappropriate management of these sediments can lead to a number of adverse environmental outcomes, the most dramatic of which is the extreme acidification of inland waterways, but can also include deoxygenation and the release of heavy metals. This paper explores possible management options for reducing the impact of sulfidic sediments on inland waterways based on previous research into ameliorating the impact of acid mine and acid rock drainage and coastal acid sulfate soils. The main strategies explored include minimising the formation of sulfidic sediments in the first instance, rehabilitation of impacted waterways, or isolation of the water body from the surrounding environment.     

Decision support for adaptive action – assessing the potential of geographic visualization

This study explores the role of geographic visualization for supporting the implementation of climate change adaptation. Interviews and group discussions with planners and decision makers indicate that geographic visualization bears primary potential for communicative purposes. In order to respond to analytical needs a high level of interactivity including the exploration of background data and the ability to link the tools with own databases were some of the key requirements made by the participants. The study concludes that more than better climate predictions, awareness and involvement may be precisely what is needed to narrow the implementation gap in climate change adaptation.     

Shared values for the marine environment – developing a culture of practice for marine spatial planning

Though still relatively new, the development of marine spatial planning has been based on the on the premise that as a rational planning process, it can be applied following universal principles and steps informed by land-based inspired theoretical underpinnings. However, within this process, differences between marine and terrestrial environments are being overlooked, potentially affecting the way in which the marine environment is understood and valued, and the development of a culture of practice for, and specific to, marine spatial planning. By framing planning as a cultural construct, this paper aims to explore the extent to which land-based rationales are affecting the development of a marine spatial planning culture of practice, with its own ethos and shared values. A culturalised planning model adapted from [Knieling, J. and Othengrafen, F. (2015). Planning culture—a concept to explain the evolution of planning policies and processes in Europe? European Planning Studies, 23(11), 2133–2147] is used as a framework. Whilst acknowledging the importance of the contributions from land-based planning and the ecological sciences, the findings suggest that those unconscious beliefs and perceptions affecting society’s understanding of the marine environment should contribute to informing shared values for marine spatial planning practice.     

The political economy of certificates for land use in Germany – experimental evidence

Certificate trading schemes have been discussed as a cost-efficient means of reducing urban land consumption in Germany by capping and reallocating permissions to conduct building projects. However, in contrast to the established cap & trade systems for emissions, reputation-seeking politicians would be in charge of buying and trading certificates – an aspect not considered to date. We thus present a laboratory experiment that captures politicians’ incentives connected to electoral cycles in a cap & trade scheme for land consumption, whereby tradable certificates are auctioned and grandfathered in equal shares. We find the cap & trade system to be efficient at large; yet, there are several politically relevant distortions that are aggravated by self-serving incentives. We thus identify potential problems to a cap & trade system for urban land consumption that could substantially reduce both its assumed superior efficiency and its political feasibility.     

A tool for building community resilience? A case study of the Lewes Pound

In the last decade, “resilience” has gained increasing recognition as a theoretical framework for understanding and managing change in complex social–ecological systems. Resilience assessments are increasingly used to inform sustainability initiatives, strategies, and policies. The Lewes Pound represents a new complementary currency model in the UK, aiming to build community resilience. However, there have been no empirical studies to date assessing the socio-economic impacts of this model. This article addresses the need to understand how such currencies function by measuring whether the Lewes Pound is capable of building resilience. This is done by developing a novel framework for estimating economic, social, and environmental outcomes, which uses a mixed-methods approach. Findings suggest that complementary currencies can enhance social-ecological resilience through awareness-raising and changes in consumption. Although economic localisation – a key indicator – is lacking, there is evidence that the Lewes Pound has developed social interactions and changed consumption patterns of its users.     

Geological storage of CO2 in saline aquifers—A review of the experience from existing storage operations

The experience from CO₂ injection at pilot projects (Frio, Ketzin, Nagaoka, US Regional Partnerships) and existing commercial operations (Sleipner, Snøhvit, In Salah, acid-gas injection) demonstrates that CO₂ geological storage in saline aquifers is technologically feasible. Monitoring and verification technologies have been tested and demonstrated to detect and track the CO₂ plume in different subsurface geological environments. By the end of 2008, approximately 20 Mt of CO₂ had been successfully injected into saline aquifers by existing operations. Currently, the highest injection rate and total storage volume for a single storage operation are approximately 1 Mt CO₂/year and 25 Mt, respectively. If carbon capture and storage (CCS) is to be an effective option for decreasing greenhouse gas emissions, commercial-scale storage operations will require orders of magnitude larger storage capacity than accessed by the existing sites. As a result, new demonstration projects will need to develop and test injection strategies that consider multiple injection wells and the optimisation of the usage of storage space. To accelerate large-scale CCS deployment, demonstration projects should be selected that can be readily employed for commercial use; i.e. projects that fully integrate the capture, transport and storage processes at an industrial emissions source.     

A model for assessing habitat fragmentation caused by new infrastructures in extensive territories – Evaluation of the impact of the Spanish strategic infrastructure and transport plan

The aim of the present work is to design a model for evaluating the impact of planned infrastructures on species survival at the territorial scale by calculating a connectivity index. The method developed involves determining the effective distance of displacement between patches of the same habitat, simplifying earlier models so that there is no dependence on specific variables for each species. A case study is presented in which the model was used to assess the impact of the forthcoming roads and railways included in the Spanish Strategic Infrastructure and Transport Plan (PEIT, in its Spanish initials).This study took into account the habitats of peninsular Spain, which occupies an area of some 500,000 km². In this territory, the areas deemed to provide natural habitats are defined by Directive 92/43/EEC. The impact of new infrastructures on connectivity was assessed by comparing two scenarios, with and without the plan, for the major new road and railway networks. The calculation of the connectivity index (CI) requires the use of a raster methodology based on the Arc/Info geographical information system (GIS). The actual calculation was performed using a program written in Arc/Info Macro Language (AML); this program is available in FragtULs (Mancebo Quintana, 2007), a set of tools for calculating indicators of fragmentation caused by transport infrastructure (http://topografia.montes.upm.es/fragtuls.html).The indicator of connectivity proposed allows the estimation of the connectivity between all the patches of a territory, with no artificial (non-ecologically based) boundaries imposed. The model proposed appears to be a useful tool for the analysis of fragmentation caused by plans for large territories.     

Is research keeping up with changes in landscape policy? A review of the literature

Several innovative directions for landscape policy development and implementation have emerged over recent years. These include: (i) an expansion of scope to include all landscape aspects and landscape types, (ii) an increased emphasis on public participation, (iii) a focus on designing measures appropriate for different contexts and scales, and (iv) encouraging support for capacity-building. In this paper, we evaluate the extent to which these policy directions are reflected in the practice of academic landscape research. We evaluate all research papers published in three leading landscape journals over six years, as well as published research papers relating directly to the European Landscape Convention. The latter, which was adopted in 2000, establishes a framework for landscape protection, planning and management in Europe and is to date the only international legal instrument of its kind. Results indicate that whilst policy innovations do not appear to be a major stimulus for academic research, studies nevertheless address a range of landscape aspects, types and scales (albeit with a slight bias towards bio-physical landscape aspects). However, geographical representativeness of research is weak and dominated by the United States and northern/western Europe, and research capacity likewise appears to be unevenly distributed. Landscape research is also limited in the extent to which it involves stakeholders or develops innovative methods for doing so, notwithstanding that this remains a key challenge for policy-makers. Results point to the potential for landscape research to address areas (topical and geographical) which have received little attention to date, as well as suggesting mutual benefits of stronger links between policy and academia.     

The role of parental behaviour for the development of behaviour specific environmental norms – The example of recycling and re-use behaviour

Based on the norm activation theory we developed assumptions about how parents may influence specific pro-environmental behaviours (i.e. re-use of paper and recycling) of their children (age 8–10). A sample of 206 parent-child-dyads were investigated using questionnaires recording norm activation model variables for children (i.e. awareness of need, awareness of consequences, personal norm, subjective norm, pro-environmental behaviour), as well as communication behaviour and actual behaviour of parents. For both behaviours (re-use and recycling) two separate structural equation models were tested (N = 206 and N = 194). Model fit statistics indicate a good fit of empirical data and model structure for both behaviours, supporting our assumption that the norm activation model can be applied to pro-environmental behaviour of young children. Communication behaviour of parents had a different influence on the two respective behaviours. While parents seemed to influence their children's recycling behaviour via sanctions and their own behaviour, re-use of paper was mainly influenced via communication of problem knowledge.     

What are the barriers to successful community-based climate change adaptation? A review of grey literature

ABSTRACT

Across the Global South, community-based adaptation (CBA) projects are increasingly being implemented in an effort to respond effectively and sustainably to the impacts of climate change, with a particular focus on people’s livelihoods. Despite an increase in the number of CBA projects being implemented, detailed analysis and evaluation of their efficacy and the barriers faced in achieving successful outcomes is lacking. This study draws on an analysis of grey literature (i.e. project and donor reports) to explore the barriers faced in achieving effective CBA. An extensive global search of online project evaluations yielded 25 documents comprising 69 projects from which this analysis is based. This paper first presents an overview of the 69 projects and highlights any trends. Second, this paper describes the barriers to CBA according to three broad themes: socio-political, resource, and physical systems and processes. Following this is a discussion of the most prevalent barriers: cognitive and behavioural, financial, and human resources. Third, this paper discusses the key findings elucidated from this review. This includes the need for greater sharing of project reports and findings so lessons can be learned across spatial and temporal scales, and the disparity between critical academic literature on CBA and what is implemented in practice.     

Optimization of Fenton oxidation pre-treatment for B. thuringiensis – Based production of value added products from wastewater sludge

Fenton oxidation pretreatment was investigated for enhancement of biodegradability of wastewater sludge (WWS) which was subsequently used as substrate for the production of value- added products. The Response surface method with fractional factorial and central composite designs was applied to determine the effects of Fenton parameters on solubilization and biodegradability of sludge and the optimization of the Fenton process. Maximum solubilization and biodegradability were obtained as 70% and 74%, respectively at the optimal conditions: 0.01 ml H₂O₂/g SS, 150 [H₂O₂]₀/[Fe²⁺]₀, 25 g/L TS, at 25 °C and 60 min duration. Further, these optimal conditions were tested for the production of a value added product, Bacillus thuringiensis (Bt) which is being used as a biopesticide in the agriculture and forestry sector. It was observed that Bt growth using Fenton oxidized sludge as a substrate was improved with a maximum total cell count of 1.63 × 10⁹ CFU ml^?1 and 96% sporulation after 48 h of fermentation. The results were also tested against ultrasonication treatment and the total cell count was found to be 4.08 × 10⁸ CFU ml^?1 with a sporulation of 90%. Hence, classic Fenton oxidation was demonstrated to be a rather more promising chemical pre-treatment for Bt - based biopesticide production using WWS when compared to ultrasonication as a physical pre-treatment.     

The cost effectiveness of radon mitigation in existing German dwellings – A decision theoretic analysis

Radon is a naturally occurring inert radioactive gas found in soils and rocks that can accumulate in dwellings, and is associated with an increased risk of lung cancer. This study aims to analyze the cost effectiveness of different intervention strategies to reduce radon concentrations in existing German dwellings. The cost effectiveness analysis (CEA) was conducted as a scenario analysis, where each scenario represents a specific regulatory regime. A decision theoretic model was developed, which reflects accepted recommendations for radon screening and mitigation and uses most up-to-date data on radon distribution and relative risks. The model was programmed to account for compliance with respect to the single steps of radon intervention, as well as data on the sensitivity/specificity of radon tests. A societal perspective was adopted to calculate costs and effects. All scenarios were calculated for different action levels. Cost effectiveness was measured in costs per averted case of lung cancer, costs per life year gained and costs per quality adjusted life year (QALY) gained. Univariate and multivariate deterministic and probabilistic sensitivity analyses (SA) were performed. Probabilistic sensitivity analyses were based on Monte Carlo simulations with 5000 model runs. The results show that legal regulations with mandatory screening and mitigation for indoor radon levels >100 Bq/m³ are most cost effective. Incremental cost effectiveness compared to the no mitigation base case is 25,181 € (95% CI: 7371 €–90,593 €) per QALY gained. Other intervention strategies focussing primarily on the personal responsibility for screening and/or mitigative actions show considerably worse cost effectiveness ratios. However, targeting radon intervention to radon-prone areas is significantly more cost effective. Most of the uncertainty that surrounds the results can be ascribed to the relative risk of radon exposure. It can be concluded that in the light of international experience a legal regulation requiring radon screening and, if necessary, mitigation is justifiable under the terms of CEA.     

In Search of Stability – Investigating Flexible and Stable Production Strategies for an Optimised Steel Plant

It is crucial for a steel making production system to operate at the lowest possible production cost, while satisfying stability and reliability conditions. To plan future production strategies, it is therefore important to be able to model the system behaviour when internal and external parameters are changed. In this study the sensitivity and stability of an optimised solution, of an integrated steel plant, have been investigated. The solution’s sensitivity has been analysed taking both internal process changes and external price variations into account, through applying both simulation and optimisation. The analysis also includes both costs and environmental issues such as carbon dioxide and sulphur emissions. Based on the methodology suggested, it is possible to determine the stability of the system solution, including both economic and environmental performance.