Arianna Callegari

Online monitoring of priority and dangerous pollutants in natural and urban waters

Purpose – Advancements in real-time water monitoring technologies permit rapid detection of water quality, and threats from waste loads. Water Framework Directive mandating the establishment of Member States’ water resources monitoring, presence of hazardous contaminants in effluents, and perception of vulnerability of water distribution system to attacks, have spurred technical and economic interests. The paper aims to discuss these issues. Design/methodology/approach – As alternative to traditional analyzers, chemosensors, operate according to physical principles, without sample collection (online), and are capable of supplying parameter values continuously and in real-time. Their low selectivity and stability issues have been overcome by technological developments. This review paper contains a comprehensive survey of existing and expected online monitoring technologies for measurement/detection of pollutants in water. Findings – The state-of-the-art in online water monitoring is presented. Application ...

Effects of process operating conditions on the autotrophic denitrification of nitrate-contaminated groundwater using bioelectrochemical systems

Nitrates have been detected in groundwater worldwide, and their presence can lead to serious groundwater use limitations, especially because of potential health problems. Amongst different options for their removal, bioelectrochemical systems (BESs) have achieved promising results; in particular, attention has raised on BES-driven autotrophic denitrification processes. In this work, the performance of a microbial electrolysis cell (MEC) for groundwater autotrophic denitrification, is assessed in different conditions of nitrate load, hydraulic retention time (HRT) and process configuration. The system obtained almost complete nitrate removal under all conditions, while nitrite accumulation was recorded at nitrate loads higher than 100mgNO3-L-1. The MEC system achieved, in different tests, a maximum nitrate removal rate of 62.15±3.04gNO3--Nm-3d-1, while the highest TN removal rate observed was 35.37±1.18gTNm-3d-1. Characteristic of this process is a particularly low (in comparison with other reported works) energy consumption: 3.17·10-3±2.26·10-3kWh/gNO3-N removed and 7.52·10-2±3.58·10-2kWhm-3 treated. The anolyte configuration in closed loop allowed the process to use less clean water, while guaranteeing identical performances as in other conventional configurations.

Industrial wastewater treatment with a bioelectrochemical process: assessment of depuration efficiency and energy production

Development of renewable energy sources, efficient industrial processes, energy/chemicals recovery from wastes are research issues that are quite contemporary. Bioelectrochemical processes represent an eco-innovative technology for energy and resources recovery from both domestic and industrial wastewaters. The current study was conducted to: (i) assess bioelectrochemical treatability of industrial (dairy) wastewater by microbial fuel cells (MFCs); (ii) determine the effects of the applied organic loading rate (OLR) on MFC performance; (iii) identify factors responsible for reactor energy recovery losses (i.e. overpotentials). For this purpose, an MFC was built and continuously operated for 72 days, during which the anodic chamber was fed with dairy wastewater and the cathodic chamber with an aerated mineral solution. The study demonstrated that industrial effluents from agrifood facilities can be treated by bioelectrochemical systems (BESs) with >85% (average) organic matter removal, recovering power at an observed maximum density of 27 W m-3. Outcomes were better than in previous (shorter) analogous experiences, and demonstrate that this type of process could be successfully used for dairy wastewater with several advantages.

Feedstock and process influence on biodiesel produced from waste sewage sludge

Disposal of sewage sludge is one of the most important issues in wastewater treatment throughout Europe, as EU sludge production, estimated at 9.5 million tons dry weight in 2005, is expected to approach 13 million tons in 2020. While sludge disposal costs may constitute 30-50% of the total operation costs of wastewater treatment processes, waste sewage sludge still contains resources that may be put to use, like nutrients and energy, that can be recovered through a variety of approaches. Research has shown that waste sewage sludge can be a valuable and very productive feedstock for biodiesel generation, containing lipids (the fats from which biofuels are extracted) in amounts that would require large areas cultivated with typical biodiesel feedstock, to produce, and at a much lower final cost. Several methods have been tested for the production of biodiesel from sewage sludge. To date, among the most efficient such process is pyrolysis, and in particular Microwave-Assisted Pyrolysis (MAP), under which process conditions are more favorable in energetic and economic terms. Sludge characteristics are very variable, depending on the characteristics of the wastewater-generating service area and on the wastewater treatment process itself. Each sludge can be considered a unique case, and as such experimental determination of the optimal biodiesel yields must be conducted on a case-by-case basis. In addition to biodiesel, other pyrolysis products can add to the energetic yield of the process (and not only). This paper discusses how feedstock properties and process characteristics may influence biodiesel (and other products) yield from pyrolytic (and in particular, MAP) processes, and discusses future possible technological developments.

Online Monitoring Technologies For Drinking Water Systems Security

More stringent constraints placed nowadays on water companies to provide high quality drinking water, increasing water resources scarcity in many areas of the planet, forcing water companies to work on marginal water bodies for supply, and the threat of hostile actions by political extremists and terrorist groups, that may willingly and deliberately cause contamination of an otherwise safe supply, are recent issues that have spurred demand for more efficient and comprehensive online water monitoring technologies. Traditionally, quality parameters associated with drinking water provision were monitored using routine grab samples followed by laboratory analysis. This approach only allowed to capture small data sets, mostly unrepresentative of the true variance at the source, and allowed potentially important events to occur undetected. This paper examines state-of-the-art technologies for online monitoring of water quality in supply water systems, and reports some recent application examples.

Formulation And Preliminary Application Of An Integrated Model Of Microbial Fuel Cell Processes.

Microbial Fuel Cells (MFCs) are bioelectrochemical systems that directly convert chemical energy contained in organic matter bioconvertible substrate into electrical energy. Since the mid-90’s, researchers have attempted to simulate the bioelectrochemical activity of MFCs: in this paper, in order to develop an enhanced model capable of describing a complex bacterial community, such as that of a MFC, an earlier model formulated by Pinto et al. (2010) has been integrated with the ASM2d model, representing complex biological systems with multiple substrates (Henze et al., 2013). The resulting model is herein described, together with its application to long series of MFC operational data. Results are discussed, confirming the good performance of the new model.

Comparative application of different risk assessment models and implications on resulting remediation options

The issue of contaminated soils and their productive recovery is a quite controversial environmental and economic problem with important consequences for its social, public health and sustainability aspects. The sheer number and characteristics of the polluted sites are so large and varied, and the definition of priorities related to their remediation interventions so site-dependent, that proper characterization and final environmental quality goals reflect a strategic importance. One of the possible approaches to site specific approach and site priority ranking can be that of carrying out, respectively, absolute and comparative analysis procedures. An important aspect to be solved is represented by the necessity to consider not only the potential risk to public health, but also the best possible financial return from the investments for remediation, especially when carried out with public money. In this paper, different contaminated sites’ risk assessment approaches are considered, compared and their applicability to support sustainable policies discussed using a case study.

Nom Removal from Freshwater Supplies by Advanced Separation Technology

Natural Organic Matter (NOM) present in drinking water supplies is not known to have any direct effects on human health; however, its reactivity with dissolved and particulate species significantly impacts on water quality and treatment needs. It is known nowadays that NOM can be removed by a variety of methods, including molecular sieving through nanofiltration membranes, coagulation with subsequent floc separation, oxidation followed by biofiltration and sorption processes including chemisorption (ion exchange), and physical adsorption (activated carbon). Evolution of water-related directives and more restrictive standards for drinking water, however, constitute the requirements for investigating new, more efficient and cost-effective treatment processesThe paper contains an overview on the state-of-the-art methods for NOM removal from supply waters, then describes a new technology, developed and patented by the research center of Veolia Environment, which effectiveness has been tested and validated on the supply water source of a plant located in Brittany (France).

Application of Membrane and Membrane-Like Technologies for State-of-the-art Wastewater Treatment

Membrane Bioreactors (MBR’s) are at the present time considered a key technology in wastewater treatment, either as a final process, or considering further additional options of water reuse, which is an emerging issue in many water-scarcity areas throughout the world. MBR technology has proved to provide reuse-quality water, and offers the unique capability to allow such upgradings while minimizing both the needs of available space and of building additional structures in an existing plant. In this paper, typical MBR projects, representing large- to small-scale applications, examples of plant upgrading, hybrid concepts, and different flow concepts, as well as examples of membrane like applications are illustrated.

Assessment of arsenic removal efficiency by an iron oxide-coated sand filter process

Arsenic is among the most dangerous contaminants which can limit groundwater use for drinking water consumption. Among the most diffused As-removal technologies around the world, adsorptive media systems are usually favored for relatively low cost and simplicity of operation. This study examines the performance of a laboratory-scale iron oxide-coated sand (IOCS) column filter, to remove arsenic (arsenate (As[V]) and arsenite (As[III])) from groundwater. This technology could be adopted in small communities, as it showed consistent removal rates of 99% with an easy-to-operate process. Some considerations about the possible introduction of such technology in developing countries are provided, highlighting the general impacts to human health related to high arsenic concentrations in groundwater. This, among other adsorption processes, could be recommended as a sustainable mean of ensuring good drinking water quality in developing regions, reducing human health impacts.