Biopotentiality as an index of environmental compensation for composting plants

The Biopotentiality Index is a landscape ecology indicator, which can be used to estimate the latent energy of a given land and to assess the environmental impacts due to the loss of naturalness on a landscape scale. This indicator has been applied to estimate the effectiveness of the measures put in place to provide an environmental compensation for the revamping of a composting plant. These compensation measures are represented by a green belt with a minimum width of 25 m all around the plant, representing both a windbreak and a buffer zone, and by two wide wooded zones acting as core natural areas.This case-study shows that the compensation index could be used as a key tool in order to negotiate the acceptance of waste treatment plant with the population.     

Application of Biobarriers for Groundwater Containment at Fractured Bedrock Sites

Biological barriers are a beneficial application of biofilms that aim at reducing the hydraulic conductivity (K) in geological formations. Several studies have shown the potential benefits of creating such barriers either by stimulating the indigenous microbial community (biostimulation) or injecting bacteria (bioaugmentation). For example, laboratory experiments show that groundwater microorganisms attached to a ceramic surface and generated a biofilm as thick as 1,100 μm. In a limestone fracture, this bacterial community clogged a single fracture up to 99.2 percent within 22 days. At the field scale, applications in porous aquifers led to a five‐fold decrease in K after 2.5 days of biostimulation, and a bioaugmentation with a starved, adapted bacterial culture decreased K by 99.4 percent. One promising development of the biobarrier concept is a field application at a fractured bedrock site. Using a multidisciplinary approach and focusing on a well‐characterized fracture system, a field trial was undertaken in Southern Ontario to measure the extent of bioclogging and the stability over time. This article focuses on the literature pertinent to the preparation of this field trial and presents the innovative approach selected to monitor the bioclogging in such a challenging environment.     

The circular economy in China

This article makes an attempt to answer the three questions of why China is devoting its full effort to promoting a circular economy, what a circular economy is, and how to implement a circular economy in China. The evolutionary process of a circular economy in China, from introduction of the concept and the relevant actions of national decision making to demonstration of the system nationwide, has taken only around 6 years, with strong encouragement from politicians and the urgent need to cope with environmental pollution and a severe shortage of natural resources. The circular economy in China is now being actively implemented at three levels: enterprises, eco-industrial parks, and regions. The consolidated theoretical bases of ecology and economics have helped the circular economy to define its position as a new economic model to effectively resolve the problems of resources and the environment. In this regard, material flow management is naturally a unique planning and management method for implementation of a circular economy, and eco-efficiency is a good indicator to measure circular economic activities. Of particular significance has been initiation of the legislative process for the Circular Economy Law, which is among a number of initiatives developing core policies for a circular economy in China. Stringent enforcement of a set of policies for energy saving and pollution abatement nowadays in China will certainly create an enabling environment for the development of a circular economy.     

How to negotiate remediation projects with regulatory agencies

The news that a company has been identified as a potentially responsible party (PRP) at a federal or state Superfund site usually sends a current of fear through the company's management. Even executives with experience in Superfund projects foresee a lengthy, complicated process that involves enormous expenditures and a possible public relations disaster. The author argues, however, that the Superfund process can be managed in a cost-effective way, prevent reactive responses, inaction, and ineffective action, and applying the business acumen that enabled the company to prosper in the first place. This article explores a critical aspect of the remediation process—negotiation of settlements with regulatory agencies (EPA or a state department of environmental protection)—and details the practical steps needed to conduct those negotiations. It also describes common mistakes that can be avoided. For brevity and clarity, it is assumed that the company in question is the only PRP that has received a notice letter from the regulatory agency.     

Adsorption removal of pollutants by active cokes produced from sludge in the energy recycle process of wastes

This study proposes a recycling system of sludge into active cokes and the fundamental examinations for the application were carried out. In the system, active cokes were produced by carbonizing pellets of sludge in a steam stream. Pyrolysis gas yielded by carbonization can be available to a fuel for a steam generation boiler. The exhaust heat from the boiler is used sequentially for drying of sludge. The active cokes are applied to the adsorbent for dioxin removal in exhaust gas from incinerators of wastes, or for purification of gas obtained in a gasification process of wastes, particularly removal of H2S. The used adsorbent is not recycled, but incinerated in the furnace without a desorption process to decompose adsorbed dioxin or to oxidize H2S for a sequential desulfurization process of SO2. Dry pellets of sludge were carbonized in a quartz tube reactor under various atmospheres. The micro pore structure and the adsorption performance of the cokes produced without activation process were examined. The micro pore structure was influenced by the temperature, the sort of flow gas (N2, CO2 and steam) and carbonization time, and the active cokes produced under the condition of the temperature 823 K for 60 min in the steam atmosphere had a largest specific surface area in the diameter less than 5 nm. The amount of benzene adsorption as an alternative substance of dioxin into the active cokes had a similar quality to a commercial active char produced from coal if it was evaluated by adsorption per a unit specific surface area. This fundamental knowledge must be reflected to an optimum design for development of a simple continuous process to produce the active cokes by a fluidized bed type of the carbonization furnace.     

Experimental research on emission and removal of dioxins in flue gas from a co-combustion of MSW and coal incinerator

This paper describes the experimental study of dioxins removal from flue gas from a co-combustion municipal solid waste and coal incinerator by means of a fluidized absorption tower and a fabric filter. A test rig has been set up. The flow rate of flue gas of the test rig is 150-2000 m3/h. The system was composed of a humidification and cooling system, an absorption tower, a demister, a slurry make-up tank, a desilter, a fabric filter and a measurement system. The total height of the absorption tower was 6.5m, and the diameter of the reactor pool was 1.2 m. When the absorbent was 1% limestone slurry, the recirculation ratio was 3, the jet rate was 5-15 m/s and the submerged depth of the bubbling pipe under the slurry was 0.14 m, the removal efficiency for dioxins was 99.35%. The concentration of dioxins in the treated flue gas was 0.1573 x 10(-13)kg/Nm3 and the concentration of oxygen was 11%. This concentration is comparable to the emission standards of other developed countries.     

In situ hypochlorous acid generation for the treatment of syntan wastewater

A new treatment process was employed to treat wastewater generated from a factory manufacturing syntan (synthetic tannin). In this treatment process, in-situ production of hypochlorous acid was achieved by the use of an aqueous sodium chloride solution for chlorine production. As the graphite anode and stainless steel cathode zones were kept unseparated, the hypochlorous acid was produced by electrolysis. The hypochlorous acid was utilized for the oxidation of organic matter present in the wastewater. The results showed that for an initial COD concentration of 10,000 mg/l, a turbidity of 277 NTU, a tannin concentration of 4000 mg/l, a temperature of 27±1°C, a current density of 42.5 mA/cm², a sodium chloride content of 3% and an electrolysis period of 210 min showed an effluent COD concentration of 230 mg/l, a turbidity of 9 NTU, a tannin concentration below the detection limit and a temperature of 37±2°C.     

烟气脱硫喷淋塔的容积负荷与本体设计

提出了以喷淋塔的容积负荷——平均容积吸收率为控制指标的本体设计路线。在目前已有的设计、运行经验基础上，根据烟气的SO2进口浓度、要求的吸收效率等来确定喷淋塔容积。讨论了容积吸收率不同角度的定义，给出了采用容积吸收率进行喷淋塔本体设计的步骤。     

The financial and economic feasibility of rural household biodigesters for poor communities in South Africa

Given the persistence of systemic poverty in, most notably, the rural parts of South Africa, the question is whether the use of biodigesters as a source of energy offers potential solutions to some of the difficulties and development needs faced by people in these areas. At the core, this translates into whether this technology would be financially and economically feasible for installation and use by rural households. Here we conduct both a financial and an economic cost-benefit analysis in one such community based on survey data from 120 households. Analysis of these data and supporting literature reveals that a biodigester is not a financially feasible investment for a rural household. Substantial economic benefits are, however, found to make a biodigester a worthwhile investment from a broader societal perspective. This is a compelling argument for further study and the consideration of government support in the light of broader economy-wide benefits.     

Multi-criteria GIS-based siting of an incineration plant for municipal solid waste

Siting a municipal solid waste (MSW) incineration plant requires a comprehensive evaluation to identify the best available location(s) that can simultaneously meet the requirements of regulations and minimise economic, environmental, health, and social costs. A spatial multi-criteria evaluation methodology is presented to assess land suitability for a plant siting and applied to Santiago Island of Cape Verde. It combines the analytical hierarchy process (AHP) to estimate the selected evaluation criteria weights with Geographic Information Systems (GIS) for spatial data analysis that avoids the subjectivity of the judgements of decision makers in establishing the influences between some criteria or clusters of criteria. An innovative feature of the method lies in incorporating the environmental impact assessment of the plant operation as a criterion in the decision-making process itself rather than as an a posteriori assessment. Moreover, a two-scale approach is considered. At a global scale an initial screening identifies inter-municipal zones satisfying the decisive requirements (socio-economic, technical and environmental issues, with weights respectively, of 48%, 41% and 11%). A detailed suitability ranking inside the previously identified zones is then performed at a local scale in two phases and includes environmental assessment of the plant operation. Those zones are ranked by combining the non-environmental feasibility of Phase 1 (with a weight of 75%) with the environmental assessment of the plant operation impact of Phase 2 (with a weight of 25%). The reliability and robustness of the presented methodology as a decision supporting tool is assessed through a sensitivity analysis. The results proved the system effectiveness in the ranking process.     

Assessment of plasma gasification of high caloric waste streams

Plasma gasification is an innovative technology for transforming high calorific waste streams into a valuable synthesis gas and a vitrified slag by means of a thermal plasma. A test program has been set up to evaluate the feasibility of plasma gasification and the impact of this process on the environment. RDF (refuse derived fuel) from carpet and textile waste was selected as feed material for semi-pilot gasification tests. The aim of the tests was: (1) to evaluate the technical feasibility of making a stable synthesis gas; (2) to characterize the composition of this synthesis gas; (3) to define a suitable after-treatment configuration for purification of the syngas and (4) to characterize the stability of the slag, i.e., its resistance to leaching for use as a secondary building material. The tests illustrate that plasma gasification can result in a suitable syngas quality and a slag, characterized by an acceptable leachability. Based on the test results, a further scale-up of this technology will be prepared and validation tests run.     

Liability and Compensation for Oil Pollution Damage: Some Current Threats to the International Convention System

The carriage of oil is indispensable to the industrialized nations. In this respect, the carriage of oil is undertaken as a service to society as a whole with its individual members deriving benefits from its carriage to varying degrees. Consequently, after examining the four Conventions in the international system of compensation for oil pollution from ships, it is argued that the general citizenship of those nations pay, in exceptional cases, for a small share of the risk, which is created in part by the citizens, as users of oil. The paper proposes the creation of a fund of last resort that could be conceived either at a regional level or a national level and financed through (indirect) taxation on the population as a whole. This type of fund could have a wider use in the field of marine pollution and protection of marine resources.     

Polyols and Polyurethanes from Hydroformylation of Soybean Oil

This paper compares physical and mechanical properties of polyurethanes derived via the hydroformylation approach and is a part of our study on the structure–property relationships in polyurethanes created from vegetable oils. The double bonds of soybean oil are first converted to aldehydes through hydroformylation using either rhodium or cobalt as the catalyst. The aldehydes are hydrogenated by Raney nickel to alcohols, forming a triglyceride polyol. The latter is reacted with polymeric MDI to yield the polyurethane. Depending on the degree of conversion, the materials can behave as hard rubbers or rigid plastics. The rhodium-catalyzed reaction afforded a polyol with a 95% conversion, giving rise to a rigid polyurethane, while the cobalt-catalyzed reaction gives a polyol with a 67% conversion, leading to a hard rubber having lower mechanical strengths. Addition of glycerine as a cross-linker systematically improves the properties of the polyurethanes. The polyols are characterized by DSC. The measured properties of polyurethanes include glass transition temperatures, tensile strengths, flexural moduli, and impact strengths.     

Results from Three Field Tracer Experiments on the Neighbourhood Scale in the City of Birmingham UK

The physical processes governing flow and pollutantdispersion at the neighbourhood scale, a spatial scaleintermediate between the street scale and the city scale, is notwell understood. Furthermore, it is not clear whether a traditional approach using averaged characteristics such as theaerodynamic roughness length is sufficient to predict the concentration field at this scale. To investigate pollutant dispersion in a real urban area, three field experiments were designed within the UK-URGENT programme sponsored by NERC. Theexperiments were performed in the City of Birmingham using a finite duration release of inert, non-toxic and non-depositingtracers, vis. perfluoromethylcyclohexane (PMCH) and perfluoromethylcyclopentane (PMCP). Measurements were taken using air bag samplers placedin an arc at 3.5 km (first experiment) and 1 km (second andthird experiments) from the source; some trap samplers wereplaced outside the main arc in the outskirts of the city. Measurements were analysed in the laboratory using anovel gas-chromatography technique. Data so obtained werecompared with predictions from a simple steady-state modeland a time-dependent model. The concentration-time serieswere very asymmetrical with a sharp rise, a plateau followedby a relatively slow decrease and finally a long-livedplateau above (or possibly very slow decrease to) thebackground level.     

Use of cement dust in the manufacture of vitrified sewer pipes

Waste by-pass cement dust was added in different percentages ranging from 2% to 10% to a standard mix for sewer pipes manufacture, as a substitute for expensive feldspar. It was found that a mix consisting of 45% kaolin, 36% ball clay, 9% grog and 10% by-pass dust and fired at a temperature of 1300 degrees C for 4 h yielded samples that meet the standards. It was possible to reach a water absorption of 4%, a modulus of rupture of 7.8 MPa and a resistance to acids and alkalis conforming with standard values. A test pipe was fabricated by vacuum extrusion using the suggested composition and was found to withstand a hydraulic pressure of 14 MPa for one minute without the appearance of any cracks.     

Photochemical Kinetic Modeling of Degradation of Aqueous Polyvinyl Alcohol in a UV/H<Subscript>2</Subscript>O<Subscript>2</Subscript> Photoreactor

This study presents a photochemical kinetics model to describe the degradation of water-soluble PVA (Polyvinyl Alcohol) polymer in a UV/H₂O₂ batch reactor. Under the effect of UV light, the photolysis of hydrogen peroxide into hydroxyl radicals can generate a series of polymer scission reactions. For a better understanding and analysis of the UV/H₂O₂ process in the cracking of the PVA macromolecules, a chemical reaction mechanism of the degradation process and a relevant photochemical kinetics model are developed to describe the disintegration of the polymer chains. Taking into account the probabilistic fragmentation of the polymer, the statistical moment approach is used to model the molar population balance of live and dead polymer chains. The model predicts the PVA molecular weight reduction, the acidity of the solution, and hydrogen peroxide residual. In addition to previously published data collected in this laboratory, a new set of experiments were conducted using a 500 mg/L PVA aqueous for different hydrogen peroxide/PVA ratios for model validation. Measurements of average molecular weights of the polymer, hydrogen peroxide concentrations and pH of the PVA solution were determinant factors in constructing a reliable photochemical model of the UV/H₂O₂ process. Experimental data showed a decrease in the PVA molecular weight and a buildup of the solution acidity. The experimental data also served to determine the kinetics rate constants of the PVA photochemical degradation and validate the model whose predictions are in good agreement with data. The model can provide a comprehensive understanding of the impact of the design and operational variables.     

Uncertainties of a Regional Terrestrial Biota Full Carbon Account: A Systems Analysis

We discuss the background and methods for estimating uncertainty in a holistic manner in a regional terrestrial biota Full Carbon Account (FCA) using our experience in generating such an account for vast regions in northern Eurasia (at national and macroregional levels). For such an analysis, it is important to (1) provide a full account; (2) consider the relevance of a verified account, bearing in mind further transition to a certified account; (3) understand that any FCA is a fuzzy system; and (4) understand that a comprehensive assessment of uncertainties requires multiple harmonizing and combining of system constraints from results obtained by different methods. An important result of this analysis is the conclusion that only a relevant integration of inventory, process-based models, and measurements in situ generate sufficient prerequisites for a verified FCA. We show that the use of integrated methodology, at the current level of knowledge, and the system combination of available information, allow a verified FCA for large regions of the northern hemisphere to be made for current periods and for the recent past.     

Steady-state design of vertical wells for liquids addition at bioreactor landfills

The rate at which liquids can be added to a vertical well, the lateral zone of impact of the well, and the liquids volume needed to wet the waste within the zone of impact of the well are the key inputs needed to design a vertical well system. This paper presents design charts that can be used to estimate these inputs as a function of municipal solid waste properties (porosity, hydraulic conductivity, and anisotropy ratio), well dimensions (radius and screen length), and injection pressure. SEEP/W modeling was conducted to estimate the key design inputs for a range of conditions practically encountered for a vertical well installed in landfilled waste. The flow rate, lateral zone of impact of a well, liquids volume added, and injection pressure were normalized with the waste properties and well dimensions to formulate dimensionless variables. A series of design charts were created to present dimensionless steady-state flow rate, lateral zone of impact, and the dimensionless liquid volume needed to reach a steady-state condition, as a function of dimensionless input variables. By using dimensionless variables formulated for this work, these charts permit the user to estimate the steady-state design variables described above for a wide range of configurations and conditions beyond those simulated without the need for further modeling. The results of the study suggest that the lateral extent of the well can be estimated using Darcy’s equation and assuming saturated unit-gradient vertical flow regime below the well bottom. An example problem is presented to illustrate the use of the design charts. The scenario described in the example problem was also modeled with SEEP/W, and the results were compared with those obtained from the design charts to demonstrate the validity of design charts for scenarios other than those used for the development of the design charts. The methodology presented in this paper should be thought of as a means to provide a set of bounds that an engineer can use along with their judgment in the design of a system for a specific site.     

Mathematical modeling of biomass fuels formation process

The increasing demand for thermal and electric energy in many branches of industry and municipal management accounts for a drastic diminishing of natural resources (fossil fuels). Meanwhile, in numerous technical processes, a huge mass of wastes is produced. A segregated and converted combustible fraction of the wastes, with relatively high calorific value, may be used as a component of formed fuels. The utilization of the formed fuel components from segregated groups of waste in associated processes of co-combustion with conventional fuels causes significant savings resulting from partial replacement of fossil fuels, and reduction of environmental pollution resulting directly from the limitation of waste migration to the environment (soil, atmospheric air, surface and underground water). The realization of technological processes with the utilization of formed fuel in associated thermal systems should be qualified by technical criteria, which means that elementary processes as well as factors of sustainable development, from a global viewpoint, must not be disturbed. The utilization of post-process waste should be preceded by detailed technical, ecological and economic analyses. In order to optimize the mixing process of fuel components, a mathematical model of the forming process was created. The model is defined as a group of data structures which uniquely identify a real process and conversion of this data in algorithms based on a problem of linear programming. The paper also presents the optimization of parameters in the process of forming fuels using a modified simplex algorithm with a polynomial worktime. This model is a datum-point in the numerical modeling of real processes, allowing a precise determination of the optimal elementary composition of formed fuels components, with assumed constraints and decision variables of the task.