Mathias Glaus

The major parameters on biomass pyrolysis for hyperaccumulative plants – A review

Phytoextraction is one of the main phytoremediation techniques and it has often been described as a potentially feasible in situ soil decontamination method of large amounts of heavy metals, organic pollutants and explosive compounds. As this remediation technique is approaching extensive on-field experimentation and commercialization, research focus is on investigating new ways to achieve the valorisation of its by-products. Biomass pyrolysis represents a key step to numerous valorisation options and it is characterized by differential output products that are determined by the operating conditions of the process and the characteristics of the input. However, when used to valorise plants that have undergone significant metal uptake, this strategy involves some new aspects related to harvest, procedure and final product reutilization. This paper reviews the studies made on biomass pyrolysis of plants with emphasis on the differential quality and distribution of pyrolysis products in relation with the variables of the process and the metal-rich phytoextraction feedstock properties. By investigating these parameters, this survey provides indications on ways to optimize the valorisation of phytoremediation by-products through biomass pyrolysis.

Economic viability and critical influencing factors assessment of black water and grey water source-separation sanitation system.

The black water and grey water source-separation sanitation system aims at efficient use of energy (biogas), water and nutrients but currently lacks evidence of economic viability to be considered a credible alternative to the conventional system. This study intends to demonstrate economic viability, identify main cost contributors and assess critical influencing factors. A technico-economic model was built based on a new neighbourhood in a Canadian context. Three implementation scales of source-separation system are defined: 500, 5,000 and 50,000 inhabitants. The results show that the source-separation system is 33% to 118% more costly than the conventional system, with the larger cost differential obtained by lower source-separation system implementation scales. A sensitivity analysis demonstrates that vacuum toilet flow reduction from 1.0 to 0.25 L/flush decreases source-separation system cost between 23 and 27%. It also shows that high resource costs can be beneficial or unfavourable to the source-separation system depending on whether the vacuum toilet flow is low or normal. Therefore, the future of this configuration of the source-separation system lies mainly in vacuum toilet flow reduction or the introduction of new efficient effluent volume reduction processes (e.g. reverse osmosis).

Dynamic Waste Management (DWM):Towards an evolutionary decision-making approach

To guarantee sustainable and dynamic waste management, the dynamic waste management approach (DWM) suggests an evolutionary new approach that maintains a constant flow towards the most favourable waste treatment processes (facilities) within a system. To that end, DWM is based on the law of conservation of energy, which allows the balancing of a network, while considering the constraints of incoming (h1) and outgoing (h2) loads, as well as the distribution network (ΔH) characteristics. The developed approach lies on the identification of the prioritization index (PI) for waste generators (analogy to h1), a global allocation index for each of the treatment processes (analogy to h2) and the linear index load loss (ΔH) associated with waste transport. To demonstrate the scope of DWM, we outline this approach, and then present an example of its application. The case study shows that the variable monthly waste from the three considered sources is dynamically distributed in priority to the more favourable processes. Moreover, the reserve (stock) helps temporarily store waste in order to ease the global load of the network and favour a constant feeding of the treatment processes. The DWM approach serves as a decision-making tool by evaluating new waste treatment processes, as well as their location and new means of transport for waste.

A spatial analysis of hierarchical waste transport structures under growing demand.

The design of waste management systems rarely accounts for the spatio-temporal evolution of the demand. However, recent studies suggest that this evolution affects the planning of waste management activities like the choice and location of treatment facilities. As a result, the transport structure could also be affected by these changes. The objective of this paper is to study the influence of the spatio-temporal evolution of the demand on the strategic planning of a waste transport structure. More particularly this study aims at evaluating the effect of varying spatial parameters on the economic performance of hierarchical structures (with one transfer station). To this end, three consecutive generations of three different spatial distributions were tested for hierarchical and non-hierarchical transport structures based on costs minimization. Results showed that a hierarchical structure is economically viable for large and clustered spatial distributions. The distance parameter was decisive but the loading ratio of trucks and the formation of clusters of sources also impacted the attractiveness of the transfer station. Thus the territories’ morphology should influence strategies as regards to the installation of transfer stations. The use of spatial-explicit tools such as the transport model presented in this work that take into account the territory’s evolution are needed to help waste managers in the strategic planning of waste transport structures.

Dynamic Waste Management (DWM): A new step towards industrial ecology

The load caused by growing volumes of collected residues produces a pressure both on the environment and on the population. Presently, wastes are no longer considered just simple residues, but also resources which can be reused or recovered. Various tools are now available to help compare the various options in waste management. These tools lead to a linear management of the systems. In addition, they generate a division of flow streams and do not allow an optimal use of the available materials. An industrial ecology perspective requires one to move towards a systemic approach. Based on the law of conservation of energy, the Dynamic Waste Management approach (DWM) studies the behaviour of systems to insure a constant supply of favourable waste management options (WMO) and to reduce the global load within these systems. The flow distribution in a global system rests on the principle that the available volumes and the transportation influence the validity of the hierarchical organisation of WMO. Adhering to the philosophy of industrial ecology, the DWM offers a dynamic and evolutionary alternative to reduce the impacts generated by inadequate waste management. The present article exposes the characteristics of the proposed approach, and presents an example of its application in order to demonstrate the advantages of the DWM.

Service area size assessment for evaluating the spatial scale of solid waste recovery chains: A territorial perspective

Waste recovery is an integrated part of municipal solid waste management systems but its strategic planning is still challenging. In particular, the service area size of facilities is a sensitive issue since its calculation depends on various factors related to treatment technologies (output products) and territorial features (sources waste production and location). This work presents a systemic approach for the estimation of a chains service area size, based on a balance between costs and recovery profits. The model assigns a recovery performance value to each source, which can be positive, neutral or negative. If it is positive, the source should be included in the facilitys service area. Applied to the case of Montreal for food waste recovery by anaerobic digestion, the approach showed that at most 23 out of the 30 districts should be included in the service area, depending on the indicator, which represents around 127,000 t of waste recovered/year. Due to the systemic approach, these districts were not necessarily the closest to the facility. Moreover, for the Montreal case, changing the facilitys location did not have a great influence on the optimal service area size, showing that the distance to the facility was not a decisive factor at this scale. However, replacing anaerobic digestion by a composting plant reduced the break-even transport distances and, thus, the number of sources worth collecting (around 68,500 t/year). In this way, the methodology, applied to different management strategies, gave a sense of the spatial dynamics involved in the recovery chains design. The map of optimal supply obtained could be used to further analyse the feasibility of multi-site and/or multi-technology systems for the territory considered.

Modeling or dynamic simulation: a tool for environmental management in mining?*

Abstract The buoyancy of the minerals market, due to price and demand continually rising, maintains an increased interest for investors in mining. However, it is a sector particularly facing many negative environmental impacts, technical and environmental conditions to which are added the meeting of financial and production goals. Nevertheless in lockstep together, risk management of these extractive activities on environment – in this age where the society’s level of awareness in ecological balance has evolved – continues to fuel discussions and interventions. Therefore, it becomes unavoidable to manage more effectively the environmental factors around mines. This study aims to propose the integration of environmental management (EM) tools based on dynamic simulation (DS) for mining. This research is structured in four main topics: (1) the dynamics of open-pits system, (2) the management of their environmental effects, (3) the EM tools at the disposal of managers and (4) the proposed EM by DS. The results show that the challenges are numerous and the volume of DS approaches in mining is constantly growing, even if only few are directed towards EM. Some approaches of DS in a few open-pits with the proven effectiveness, show a new opportunity to investigate.

Global model MOHYSE, a new tool to assess the effect of hydro-meteorological phenomena in the tropics

In this research the adaptation to tropical conditions of a Canadian global hydrological model (GHM) called MOHYSE was performed, and the efficiency of its hydrological response was evaluated. A hydrological modeling study over central watersheds of the Gulf of Mexico was performed and various indices were calculated to evaluate the GHM response. Additionally, the GHM was compared with a semi-distributed hydrological model (SDHM) to determine which of the models was closest to the hydrograph observed in the study area. The results indicate that both models adequately fit to tropical conditions; however the MOHYSE obtained better results in the statistical analysis compared to the SDHM, mainly with the Nash-Sutcliffe efficiency coefficient. Likewise, these results have direct application in the analysis of flood risk areas and could serve as an useful tool for policy makers.