Michele Notarnicola

Advanced treatment for municipal wastewater reuse in agriculture. UV disinfection: parasite removal and by-product formation

Abstract This paper reports the experimental results of a pilot-scale (100 m 3 /h) investigation, carried out at the West Bari (S. Italy) municipal wastewater treatment plant, focused on parasite removal and disinfection by-product (DBP) formation during the UV disinfection of clarified (CL) and clarified-filtered (F) secondary municipal effluents at doses necessary for achieving the Italian microbial limit for unrestricted reuse of wastewater in agriculture (2 CFU/100ml of total coliforms). The investigation demonstrated that parasites like Giardia lamblia cysts and Cryptosporidium parvum oocysts were both significantly affected by UV radiation and that potential UV-promoted formation of DBPs (nitro-phenols and N-nitroso-amines) did not occur according to GC/MS and LC/MS analytical evidences. O&M costs ranged from 17.5 up to 35/1000 m 3 for effluent F and CL respectively.

Modeling hydroxyl radical distribution and trialkyl phosphates oxidation in UV-H2O2 photoreactors using computational fluid dynamics.

Advanced Oxidation Processes (AOPs) promoted by ultraviolet light are innovative and potentially cost-effective solutions for treating persistent pollutants recalcitrant to conventional water and wastewater treatment. While several studies have been performed during the past decade to improve the fundamental understanding of the UV-H(2)O(2) AOP and its kinetic modeling, Computational Fluid Dynamics (CFD) has only recently emerged as a powerful tool that allows a deeper understanding of complex photochemical processes in environmental and reactor engineering applications. In this paper, a comprehensive kinetic model of UV-H(2)O(2) AOP was coupled with the Reynolds averaged Navier-Stokes (RANS) equations using CFD to predict the oxidation of tributyl phosphate (TBP) and tri(2-chloroethtyl) phosphate (TCEP) in two different photoreactors: a parallel- and a cross-flow UV device employing a UV lamp emitting primarily 253.7 nm radiation. CFD simulations, obtained for both turbulent and laminar flow regimes and compared with experimental data over a wide range of UV doses, enabled the spatial visualization of hydrogen peroxide and hydroxyl radical distributions in the photoreactor. The annular photoreactor displayed consistently better oxidation performance than the cross-flow system due to the absence of recirculation zones, as confirmed by the hydroxyl radical dose distributions. Notably, such discrepancy was found to be strongly dependent on and directly correlated with the hydroxyl radical rate constant becoming relevant for conditions approaching diffusion-controlled reaction regimes (k(C,OH) > 10(9) M(-1) s(-1)).

Chloride extraction for quality improvement of municipal solid waste incinerator ash for the concrete industry

Coal ash from power stations has long been used successfully in the cement industry as binders in several Portland formulations. This is not the case for municipal solid waste (MSW) ash as chloride concentrations, ranging from 10 to 200 g kg – 1 dry weight in the bottom and fly ash, respectively, exceed the maximum allowable concentration in most cement mixtures. To reduce chloride content in MSW bottom ash, a laboratory investigation was carried out based on the exhaustive washing in tap water. The influence of operative parameters such as temperature, granulometric properties and solid/liquid ratio of extraction was evaluated. In addition to optimization of the mentioned operative parameters for full-scale application, the paper gives preliminary indications on mechanistic aspects of the washing operation.

Air Pollution from a Large Steel Factory: Polycyclic Aromatic Hydrocarbon Emissions from Coke-Oven Batteries

Abstract A systematic investigation of solid and gaseous atmospheric emissions from some coke-oven batteries of one of Europe’s largest integrated steel factory (Taranto, Italy) has been carried out. In air monitoring samples, polycyclic aromatic hydrocarbons (PAHs) were consistently detected at concentrations largely exceeding threshold limit values. By means of PAHs speciation profile and benzo (a)pyrene (BaP) equivalent dispersion modeling from diffuse sources, the study indicated that serious health risks exist not only in working areas, but also in a densely populated residential district near the factory.

Grey water in buildings: a mini-review of guidelines, technologies and case studies

ABSTRACT The aim of the work is to describe the state-of-the-art on the reuse of grey water at building level taking into account (i) the grey water characteristics and amounts produced, (ii) the recycling guidelines, (iii) the treatment systems and reuse technologies, also considering the removal of micro-pollutants as xenobiotic organic compounds, and (iv) an overview of case studies for developed countries. The mini-review highlights how the existing technologies allow the safe reuse of grey water. Attention must be given to the removal of micro-pollutants especially when the discharge takes place in surface water. With reference to 12 case studies of buildings which adopt non-conventional technologies with the aim to optimise energy consumptions, results showed how the use of non-conventional technologies for water is very limited. However, adopting an integrated approach to water-energy, it is possible to use more effectively the water for energy purposes as in the cases of cooling/heating systems.

The role of weathering on fly ash charge distribution during triboelectrostatic beneficiation

Triboelectrostatic beneficiation of coal combustion fly ashes with high-unburned carbon contents can produce low-carbon ash products having value as mineral admixtures and meeting technical requirements for replacing cement in concrete. This capability is a result of establishing bipolar charge on mineral ash versus carbon particles where, typically, unburned carbon attains positive surface charge and ash attains negative surface charge under the tribocharging conditions employed in triboelectrostatic technologies. However, long-term exposure of fly ash to weathering conditions, such as moisture or high humidity, before beneficiation is known to dramatically diminish carbon-ash separation efficiencies. Although experimentation has shown that water soluble surface species can be redistributed on fly ash particles after exposure to moisture, which could affect the extent of charging and polarities, measurement of the actual amount of charge and polarity on particles after weathering exposure versus after removal of surface moisture has not been accomplished. Hence, a new experimental methodology was developed and applied to measure charge distributions on tribocharged ash and carbon particles in a fly ash that had been exposed to weathering conditions for 6 months before and after removal of the surface moisture. Weathered ash particles were found to have an average zero charge, whereas carbon particles attained an average negative charge, opposite of the normal polarity for carbon. Although the extent of uncharged particles decreased and ash particles attained an average negative charge after drying, carbon particles attained only an average zero charge. These changes were reflected in very small increases in carbon-ash separation efficiency, in contrast to previous beneficiation tests in which fly ash drying led to significant increases in carbon-ash separation efficiency. It is suggested that removal of surface moisture in the absence of other processes like surface ion redistribution would beneficially impact carbon-ash triboelectrostatic beneficiation.

In situ remediation of contaminated marinesediment: an overview

Sediment tends to accumulate inorganic and persistent hydrophobic organic contaminants representing one of the main sinks and sources of pollution. Generally, contaminated sediment poses medium- and long-term risks to humans and ecosystem health; dredging activities or natural resuspension phenomena (i.e., strongly adverse weather conditions) can remobilize pollution releasing it into the water column. Thus, ex situ traditional remediation activities (i.e., dredging) can be hazardous compared to in situ techniques that try to keep to a minimum sediment mobilization, unless dredging is compulsory to reach a desired bathymetric level. We reviewed in situ physico-chemical (i.e., active mixing and thin capping, solidification/stabilization, chemical oxidation, dechlorination, electrokinetic separation, and sediment flushing) and bio-assisted treatments, including hybrid solutions (i.e., nanocomposite reactive capping, bioreactive capping, microbial electrochemical technologies). We found that significant gaps still remain into the knowledge about the application of in situ contaminated sediment remediation techniques from the technical and the practical viewpoint. Only activated carbon-based technologies are well developed and currently applied with several available case studies. The environmental implication of in situ remediation technologies was only shortly investigated on a long-term basis after its application, so it is not clear how they can really perform.

Use of CFD for Wastewater Disinfection Process Analysis: E.coli Inactivation with Peroxyacetic Acid (PAA)

Historically, the priority in disinfection reactor design has been microbial inactivation with a high factor of safety, neglecting other processes such as disinfection byproduct (DBP) formation and chemical use minimization. With heightened awareness and regulation of DBPs, advanced chemical engineering principles and practices are being employed in disinfection process analysis and design in order to minimize DBP production while ensuring sufficient microbial inactivation. Computational fluid dynamics (CFD) is increasingly popular as a tool to evaluate reactor performance and assess design concepts. This study presents the results of CFD analyses of two disinfection reactors with very different aspect ratios and design, but being characterized by the same theoretical hydraulic residence time (i.e., 30 minutes). Both reactors were used to inactivate E. coli with the novel disinfectant peroxyacetic acid (PAA). CFD calculations were performed for inactivation of E. coli (10000 CFU/100 mL) with PAA concentrations of 4 and 8 mg/L. Calculations were carried out for two serpentine reactors with aspect ratios (channel width to water depth) of 2:1 and 1:3. In the second reactor, perforated baffle plates were placed at the end of each channel in an attempt to promote uniform flow. Both reactors achieved adequate removal of organisms, but displayed non-ideal hydrodynamics, with significant recirculation regions that reduced the volume available for reaction and promoted short-circuiting. CFD simulations emphasized that reactor hydrodynamics impacts on the specific disinfection performances inducing different ratio of reactor volume active during the disinfection process.

Plasma-Textured Teflon: Repulsion in Air of Water Droplets and Drag Reduction Underwater

A superhydrophobic behavior can be obtained by properly modifying the surface topography of Teflon or other fluorinated polymers having an inherent hydrophobic character. According to this strategy, we have micro/nanotextured Teflon both as plane material (sheets) and as three-dimensional (3D) object (spheres) with a single step plasma process. The obtained textured Teflon samples were compared with those made of pristine Teflon in air, in terms of repulsion of impacting water droplets, and underwater, in terms of air layer behavior under static and dynamic conditions. The latter case was investigated by subjecting the spheres to a vertical fall in water. Modified surfaces present nanofilaments on the top of micrometric vertical structures, which can increase the air retaining capacity, resulting in a biomimicry effect due to a similarity with the Salvinia molesta leaf. On this surface, repulsion of impacting water droplets can be as fast as previously reached only on heated solids. Also, the air layer over the modified spheres underwater is shown to play a role in the observed reduction of hydrodynamic drag onto the moving object.

Filamentary superhydrophobic Teflon surfaces: Moderate apparent contact angle but superior air-retaining properties.

HYPOTHESIS Micro-scale textured Teflon surfaces, resulting from plasma etching modification, show extremely high water contact angle values and fairly good resistance to water penetration when hit by water drops at medium-high speed. This behavior is more pronounced when these surfaces present denser and smaller micrometric reliefs. Tailoring the top of these reliefs with a structure which further stabilizes the air may further increase resistance to wetting (water penetration) under static and dynamic conditions. EXPERIMENTS Conditions of the oxygen fed plasma were tuned in order to explore the possibility of obtaining differently topped structures on the surface of the polymer. Scanning Electron Microscopy (SEM) was used to explore topography and X-ray Photoelectron Spectroscopy (XPS) to assess chemical similarity of the modified surfaces. Beside the usual advancing and receding water contact angle (WCA) measurements, surfaces were subjected to high speed impacting drops and immersion in water. FINDINGS At milder, i.e. shorter time and lower input power, plasma conditions formation of peculiar filaments is observed on the top of the sculpted reliefs. Filamentary topped surfaces result in a lower WCA than the spherical ones, appearing in this sense less superhydrophobic. However, these surfaces give rise to the formation of a more pronounced air layer when placed underwater. Further, when hit by water drops falling at medium/high speed, they show a higher resistance to water penetration and a sensitively lower surface-liquid contact time. The contact time is as low as previously observed only on heated solids. This behavior may be ascribed to the cavities formed beneath the filaments which, similarly with the salvinia leaf structures, require a surplus of pressure to be filled by water. Also, it suggests a different concept of superhydrophobicity, which cannot be expected on the basis of the conventional water contact angle characterization.