There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Impatti, adattamento e vulnerabilita Le cause e le responsabilita dei cambiamenti climatici sono state trattate sul numero di ottobre della rivista Cda. Approfondiamo l’argomento presentando il documento: “Cambiamenti climatici 2007: impatti, adattamento e vulnerabilita” votato ad aprile 2007 dal secondo gruppo di lavoro del Comitato Intergovernativo sui Cambiamenti Climatici (Intergovernmental Panel on Climate Change). Si tratta del secondo di tre documenti che compongono il quarto rapporto sui cambiamenti climatici.

/pdf/climate-change-2007-impacts-adaptation-and-vulnerability-31xc1cf4d3.pdf

Climate Change 2007: Impacts, Adaptation and Vulnerability.

An overview of brominated flame retardants in the environment.

Polybrominated diphenyl ethers (PBDEs) are used as flame retardants in many types of consumer products. Perhaps as a result of their widespread use and their lipophilicity, these compounds have become ubiquitous in the environment and in people. This review summarizes PBDE concentrations measured in several environmental media and analyzes these data in terms of relative concentrations, concentration trends, and congener profiles. In human blood, milk, and tissues, total PBDE levels have increased exponentially by a factor of ∼100 during the last 30 yr; this is a doubling time of ∼5 yr. The current PBDE concentrations in people from Europe are ∼2 ng/g lipid, but the concentrations in people from the United States are much higher at ∼35 ng/g lipid. Current PBDE concentrations in marine mammals from the Canadian Arctic are very low at ∼5 ng/g lipid, but they have increased exponentially with a doubling time of ∼7 yr. Marine mammals from the rest of the world have current PBDE levels of ∼1000 ng/g lipid, and...

https://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/display.files/fileID/13105

Polybrominated Diphenyl Ethers in the Environment and in People: A Meta-Analysis of Concentrations

The state of desalination and brine production: A global outlook.

This paper presents a hierarchical control architecture for operation of biological wastewater treatment plants. The main goal of this control architecture is conceived being that of avoiding violations of effluent pollution limits while, at the same time, keeping reasonable values for the quality of the effluent as well as for the costs of operating the plant. Regarding the working scenario, the benchmark established within the BSM1 platform is adopted as working scenario to simulate a wastewater treatment plant. A hierarchical structure regulates the dissolved oxygen (DO) of the three aerated tanks based on the ammonium and ammonia nitrogen concentration (NH) in the fifth tank (NH5). The proposed architecture is a two layer cascaded control where the lower level deals with the goal of keeping the process variables to the desired set-points that are determined by the upper layer. The main contribution of the paper is to operate the upper layer under the idea of not keeping a fixed set-point but following simple rules dictated by the process reaction equations. While an Model Predictive Control with feedforward compensation is used for the lower level, an affine function is selected for the higher level. To avoid the total nitrogen in the effluent (N tot,e ) to go over the establish limits, an affine function, implemented with a sliding window, that determines a supplementary external carbon to be added in the first tank. Also effluent violations of NH, (NH e ), limits is tackled by means of a combination of a linear function and an exponential is proposed. As a result, N tot,e violations and NH e violations are avoided.

http://ieeexplore.ieee.org/iel7/7312650/7321255/07321326.pdf

Process based control architecture for avoiding effluent pollutants quality limits violations in wastewater treatment plants

In this paper the environmental impacts of 10 control strategies implemented in the Benchmark Simulation Model No. 1 (BSM1) are evaluated by using Life Cycle Analysis (LCA). The aim is to analyze their environmental profiles in order to identify the main flows contributors to those impacts and to find the existing correlations between the control strategies and the selected impact categories. The knowledge of these correlations allows to assess where are located the main environmental impacts product of the plant's operation under the control strategies evaluated and to take actions in order to reduce them.

Environmental analysis of Wastewater Treatment Plants Control strategies

Anaerobic digestion processes offer the possibility for wastewater treatment while obtaining a benefit through the obtained biogas. This paper aims to continue the effort to adopt data-driven control methods in the case of anaerobic digestion processes. The paper proposes a data-based Internal Model Control approach applied to an anaerobic digestion process. The paper deals extensively with the issue of choosing the reference model and proposing an engineering approach to this issue. The paper also addresses the issue of verifying robust stability, a very important aspect considering the uncertainties that characterize bioprocesses in general. The approach proposed in the paper is validated through a numerical simulation using the Anaerobic Digestion Model No. 1. During the validation of the proposed control solution, the main operating conditions were analyzed, such as the setpoint tracking performance, the rejection of disturbance generated by variations in the influent concentration, and the effect of the measurement noise on the controlled variable.

Anaerobic Digestion Process Control Using a Data-Driven Internal Model Control Method

This paper presents a new perspective on building control strategies for wastewater treatment plants and suggests a new indicator for evaluating the performance of these plants. The proposed approach is closer to the natural way in which these strategies are defined in case of real plants. Thus, the paper presents an incremental method on how to build control strategies, by going sequentially through various control actions, the results of applying a control action leading to the following actions that must be applied. Simultaneously the paper defines a new indicator for evaluating the performance of wastewater treatment plants: Global Warming Potential. This indicator is one component that arises from the Life Cycle Assessment analysis method and has the advantage that it provides information about the global environmental cost of operating the treatment plant. The study was carried out using the platform Benchmark Simulation Model No. 2 (BSM2).

Montse Meneses

Papers

Process based control architecture for avoiding effluent pollutants quality limits violations in wastewater treatment plants

Environmental analysis of Wastewater Treatment Plants Control strategies

Anaerobic Digestion Process Control Using a Data-Driven Internal Model Control Method

New perspective on how to build and evaluate control strategies for wastewater treatment plants

Assessment tool for waste management system: Consideration of social aspects.