Using electrical resistivity tomography to assess the effectiveness of managed aquifer recharge in a salinized coastal aquifer

Over 40 years, the detrital aquifer of the Plana de Castellón (Spanish Mediterranean coast) has been subjected to seawater intrusion because of long dry periods combined with intensive groundwater exploitation. Against this backdrop, a managed artificial recharge (MAR) scheme was implemented to improve the groundwater quality. The large difference between the electrical conductivity (EC) of the ambient groundwater (brackish water due to marine intrusion) and the recharge water (freshwater) meant that there was a strong contrast between the resistivities of the brackish water saturated zone and the freshwater saturated zone. Electrical resistivity tomography (ERT) can be used for surveying similar settings to evaluate the effectiveness of artificial recharge schemes. By integrating geophysical data with lithological information, EC logs from boreholes, and hydrochemical data, we can interpret electrical resistivity (ER) with groundwater EC values and so identify freshwater saturated zones. Using this approach, ERT images provided a high-resolution spatial characterization and an accurate picture of the shape and extent of the recharge plume of the MAR site. After 5 months of injection, a freshwater plume with an EC of 400–600 μS/cm had formed that extended 400 m in the W-E direction, 250 m in the N-S direction, and to a depth of 40 m below piezometric level. This study also provides correlations between ER values with different lithologies and groundwater EC values that can be used to support other studies.     

Mitigation of energy intensity of an industrial off-gas cleaning system using process engineering solutions

In smelting processes, a large amount of off-gas emission is often generated, which can cause serious environmental and plant hygiene problems if not properly treated. Off-gas cleaning systems extract and treat the hazardous emissions, and ensure that the smelter operation is in accordance with environmental and industrial hygiene regulations. To this end, it is paramount that a well-designed control structure be incorporated into the system. In this work a plantwide control design procedure is applied to an industrial nickel smelter furnace off-gas cleaning system. We first approach the problem by conducting a steady-state analysis based on a nonlinear model of the process, where the objective is to determine how to achieve safe, clean and economic operation in terms of energy consumption. Results reveal that a large amount of energy can be saved by controlling the temperature in the furnace freeboard at its upper bound (active constraint). For the same reason, the temperatures in the two louvers (active constraints) should be controlled at their respective upper bounds so to minimize air intake into the system. The selection of the “unconstrained” variable to be controlled is found by applying the self-optimizing control technique, and the results indicate that a small loss is acceptable when one of the manipulated variables is fixed at its nominal optimal operating point, a highly desirable choice from an operational viewpoint. The bottleneck of the system is identified as the fans' discharge pressures when we allow the feed rate as a degree of freedom. Furthermore, a design change consisting of the installation of an auxiliary air intake in the smelter furnace shows to be a very effective economic alternative to minimize energy consumption. A control structure is then designed where the issue is to keep pressures in the system well within the negative region by determining the configuration of the regulatory and supervisory control layers such that acceptable dynamic performance in face of known, deterministic disturbance is achieved. Nonlinear dynamic simulations are performed to validate the suggested control structure for both modes of operation in the original system and in the proposed design change. The results showed that both regulatory and supervisory designs should make use of the simplicity of decentralized PI control schemes associated with some cascaded configurations so as to boost the disturbance rejection capabilities of the system.     

Microbial fuel cell-induced production of fungal laccase to degrade the anthraquinone dye Remazol Brilliant Blue R

Environmental Chemistry Letters - The anthraquinone dye Remazol Brilliant Blue R is largely used in the textile industry. However, its removal from wastewaters is costly and complex. Many methods...     

Valuing third sector sustainability organisations – qualitative contributions to systemic social transformation

The number and diversity of civil society or third sector sustainability organisations (TSSOs) have increased in recent decades. TSSOs play a prominent role in local approaches to sustainability. However, the contributions made by TSSOs are not fully understood, beyond a limited suite of quantifiable outputs and impacts. In this qualitative study, we examine how four TSSOs from two Australian regions, Tasmania and Queensland's Sunshine Coast, contribute to social transformation beyond discrete outputs. We examine the operation, ethos, scope and influence of these organisations over time. In so doing, we identify three common ways in which these organisations facilitate social change: by (i) enhancing social connectivity through boundary work; (ii) mobilising participatory citizenship and (iii) contributing to social learning. We conclude that TSSOs contribute significantly to the systemic social conditions that enable change for sustainability and the development of community resilience and well-being, but do so in ways undervalued by existing metrics, formal evaluation processes and funding models. Clearer recognition of, and strategic emphasis on, these qualitative contributions to social transformation is vital in ensuring that TSSOs remain viable and effective over the long term.     

Impact of biofumigation with solarization on degradation of pesticides and heavy metal accumulation

A greenhouse study was conducted to evaluate the effect of biofumigation (with sheep and chicken manure) combined with solarization on the dissipation of pesticides (pyrifenox, DDT and dieldrin), and on soil metals accumulation. The treatments consisted of a control, and soil disinfestations by biofumigation combined with solarization (B+S) for two, four, five, six consecutive years. B+S enhanced the dissipation of pyrifenox with regard to control treatment. Significant differences were not detected among plots disinfected with B+S for consecutive years. On the other hand, B+S had no effect on the dissipation of DDT and dieldrin, probably due to the resistance of these pesticides to microbial degradation and/or high temperatures. Biofumigation is considered to be an environmentally safe practice, since no accumulation of heavy metals such as Cd, Co, Cu, Cr, Pb, Ni, or Zn was observed after the subsequent application of organic matter through the treatments.     

Variation partitioning of species data matrices: estimation and comparison of fractions

Establishing relationships between species distributions and environmental characteristics is a major goal in the search for forces driving species distributions. Canonical ordinations such as redundancy analysis and canonical correspondence analysis are invaluable tools for modeling communities through environmental predictors. They provide the means for conducting direct explanatory analysis in which the association among species can be studied according to their common and unique relationships with the environmental variables and other sets of predictors of interest, such as spatial variables. Variation partitioning can then be used to test and determine the likelihood of these sets of predictors in explaining patterns in community structure. Although variation partitioning in canonical analysis is routinely used in ecological analysis, no effort has been reported in the literature to consider appropriate estimators so that comparisons between fractions or, eventually, between different canonical models are meaningful. In this paper, we show that variation partitioning as currently applied in canonical analysis is biased. We present appropriate unbiased estimators. In addition, we outline a statistical test to compare fractions in canonical analysis. The question addressed by the test is whether two fractions of variation are significantly different from each other. Such assessment provides an important step toward attaining an understanding of the factors patterning community structure. The test is shown to have correct Type I. error rates and good power for both redundancy analysis and canonical correspondence analysis.     

Studies on the adsorption and kinetics of photodegradation of a model compound for heterogeneous photocatalysis onto TiO(2)

An investigation was made on the adsorption and kinetics of photodegradation of potassium hydrogenphthalate in an aqueous suspension of TiO(2). Two models, Langmuir and Freundlich, were used to describe the adsorption process and the model proposed by Langmuir-Hinshelwood (L-H) was employed to describe the kinetics of the photodecomposition reactions of hydrogenphthalate. The results of the adsorptions were fitted to the models proposed by Langmuir and Freundlich. Adsorption was found to be a function of the temperature, with adsorption capacity increasing from 2.4 to 4.5 mg/g when the temperature rose from 20 to 30 degrees C. The kinetic model indicates that the rate constant, k, of the first order reaction, is high in the 10.0 to 100 mg/l interval, which is coherent with the low value of the adsorption constant, K. The results fitted to the L-H model led to an equation that, within the range of concentrations studied here, theoretically allows one to evaluate the photodegradation rate.     

Environmental analysis of a construction and demolition waste recycling plant in Portugal – Part II: Environmental sensitivity analysis

Part I of this study deals with the primary energy consumption and CO₂eq emissions of a 350 tonnes/h construction and demolition waste (CDW) recycling facility, taking into account incorporated, operation and transportation impacts. It concludes that the generated impacts are mostly concentrated in operation and transportation, and that the impacts prevented through material recycling can be up to one order of magnitude greater than those generated.However, the conditions considered for the plant’s operation and related transportation system may, and very likely will, vary in the near future, which will affect its environmental performance. This performance is particularly affected by the plant’s installed capacity, transportation fuel and input CDW mass. In spite of the variations in overall primary energy and CO₂eq balances, the prevented impacts are always higher than the generated impacts, at least by a factor of three and maybe even as high as 16 times in particular conditions. The analysis indicates environmental performance for variations in single parameters, except for the plant’s capacity, which was considered to vary simultaneously with all the others. Extreme best and worst scenarios were also generated to fit the results into extreme limits.     

Overcoming socio-ecological vulnerability through community-based social learning: the case of Lomba do Pinheiro in Porto Alegre,Brazil

ABSTRACT

Community-based initiatives and collective learning practices are key themes in sustainability transition processes. This paper presents the results of a participatory study that investigated a local initiative in the community of Lomba do Pinheiro in south Brazil to examine social learning processes in the context of socio-ecological vulnerability. In this community, a group composed of local residents and members representing the public sector and local educational institutions has promoted several learning-oriented actions aimed at restoring a degraded local watershed and improving residents’ livelihoods. This study used social learning as a lens through which the initiative enacted by this group may be understood, and analysed how local conditions, determined by a context of vulnerability, have influenced local processes. We applied a multi-dimensional analytical framework that included individual, collective, and territorial dimensions. The analysis focused on the leading group, the individuals who comprise it, and their actions in the territory, while considering local constraints. Our findings highlight the importance of (1) shared values, mutual trust, and affective bonds for group cohesion as well as concerted action, equalisation of diverse languages within the group, knowledge integration, and initiative persistence; (2) a practical-reflexive approach based on a sequence of actions that catalyses group learning and facilitates advancement within the wider community; and (3) the role of inter-sectoral articulations and the establishment of partnerships to support actions. This paper raises questions about the limits of an exclusively bottom-up approach to solve complex problems in the context of extremely precarious conditions.