Ezio Ranieri

Removal and accumulation of Cu, Ni and Zn in horizontal subsurface flow constructed wetlands: Contribution of vegetation and filling medium

This study investigated the accumulation and removal of Cu, Ni and Zn in two horizontal subsurface flow constructed wetlands for domestic wastewater treatment, which differ by shape, presence of macrophytes and water depth. Between March and December 2007, the three metals were measured in the influent and effluents of the two systems. Average percentage removal rates were extremely low for Cu (3% and 9% in the two beds) and higher for Zn and Ni (between 25 and 35%). Under higher Zn influent concentrations, it was found to be between 78-87%, which is in agreement with other literature data. During the peak standing crop season (August), biomasses of the different parts of Phragmites australis (stems, leaves and flowers, roots and rhizomes) were analysed in terms of weight and heavy metal concentration in order to assess heavy metal distribution among the tissues. It was found that the plants contribute to total heavy metal removal to a lesser extent than the filling medium. Aboveground tissues remove 34% of Cu, 1.8% of Ni and 6.2% of Zn % and, once harvested, their disposal does not appear to pose a problem for the environment. If heavy metals are present at high concentrations in the horizontal subsurface flow bed influent, over time, their accumulation in the filling medium could necessitate special care in the beds management to avoid release into the surrounding environment.

BTEX removal in pilot-scale horizontal subsurface flow constructed wetlands

Abstract Benzene, toluene, ethylbenzene, and xylenes (BTEX) are commonly encountered pollutants. The focus of the present work is on the removal of BTEX using pilot-scale constructed wetlands (CWs). Experiment carried out in three similar pilot-scale horizontal sub-surface flow constructed wetlands with an area of 35 m2 (each), two of which were planted with different macrophytes (Phragmites australis and Typha latifolia), while an unplanted one was used as control. A number of hydraulic tests were carried out using lithium bromide as tracer, to assess the hydraulic residence time. Residence time distributions for the two CWs indicated that the Typha field was characterized by a void volume fraction (porosity) of 0.16 and exhibited more ideal plug flow behavior (Pe = 29.7) compared with the Phragmites field (Pe = 26.7), which had similar porosity. The measured hydraulic residence times in the planted fields were 35.8, 36.7, and 34.1 h for Typha, Phragmites, and unplanted respectively, at wastewater flow r...

Clogging influence on metals migration and removal in sub-surface flow constructed wetlands.

Chromium (Cr) and Nickel (Ni) removal from secondary effluent has been evaluated in a four year research program to determine the effectiveness of Sub-Surface Flow (SSF) Constructed Wetlands (cw(s)). Tests were performed in small scale (10 l/h) and full scale (150 m(3)/d) SSF cw(s). Metals removal was also assessed as a function of increased clogging that occurred in the cw(s) over the course of the study. Cr and Ni content were evaluated in sediments at various locations along the flow path and in plant tissues by sampling Phragmites australis roots, stems and leaves. Clogging was evaluated by measuring hydraulic conductivity at the same sampling locations at the beginning and at the end of the experiment. Residence Time Distribution (RTD) curves were also assessed at the beginning and after 48months; the skewness of the RTDs increased over this period. Proportionality between increasing clogging and sediment accumulation of metals was observed, especially for Ni. Adsorption to the original matrix and the accumulated sediment is a removal mechanism consistent with available data.

Critical analysis of the integration of residual municipal solid waste incineration and selective collection in two Italian tourist areas

Municipal solid waste management is not only a contemporary problem, but also an issue at world level. In detail, the tourist areas are more difficult to be managed. The dynamics of municipal solid waste production in tourist areas is affected by the addition of a significant amount of population equivalent during a few months. Consequences are seen in terms of the amount of municipal solid waste to be managed, but also on the quality of selective collection. In this article two case studies are analyzed in order to point out some strategies useful for a correct management of this problem, also taking into account the interactions with the sector of waste-to-energy. The case studies concern a tourist area in the north of Italy and another area in the south. Peak production is clearly visible during the year. Selective collection variations demonstrate that the tourists’ behavior is not adequate to get the same results as with the resident population.

A Rationale for Pollutograph Evaluation in Ungauged Areas, Using Daily Rainfall Patterns: Case Studies of the Apulian Region in Southern Italy

In the context of the implementation of sustainable water treatment technologies for soil pollution prevention, a methodology that try to overcome the lack of runoff quality data in Puglia (Southern Italy) is firstly tackled in this paper. It provides a tool to obtain total suspended solid (TSS) pollutographs in areas without availability of monitoring campaigns. The proposed procedure is based on the relationship between rainfall characteristics and pollutant wash-off. In particular, starting from the evaluation of the observed regional rainfall patterns by using a rainfall generator model, the storm water management model (SWMM) was applied on five case studies located in different climatic subareas. The quantity SWMM parameters were evaluated starting from the drainage network and catchments characteristics, while the quality parameters were obtained from results of a monitoring campaign conducted for quality model calibration and validation with reference to the pollutograph’s shape and the peak-time. The research yields a procedure useful to evaluate the first flush phenomenon in ungauged sites and, in particular, it provides interesting information for designing efficient and sustainable drainage systems for first flush treatment and diffuse pollution treatment.

Metals removal from stormwater by commercial and non-commercial granular activated carbons.

Removing dissolved metals from urban storMwater may be required to protect aquatic species in particular watersheds. This research examined the adsorption of zinc and copper on 12 granular activated carbons, of which six were obtained commercially and six were produced by thermal activation of agricultural byproducts in the laboratory. Batch studies were used to obtain single solute distribution coefficients at pH 7. Copper distribution coefficients were higher than those for zinc on each of the 12 adsorbents. Granular activated carbon (GAC) produced from nutshells was less effective than that produced from rice materials (straw and hulls). The rice-derived GACs had the highest zinc distribution coefficients, and the commercial GACs typically exhibited higher copper distribution coefficients. Distribution coefficients for zinc and copper typically were higher for the materials tested in this study than in previous research, possibly because of the lower dissolved metal concentrations used, which were chosen to represent highway stormwater. Adsorption isotherms were obtained for zinc and copper adsorption on one commercial GAC and on activated rice hulls in buffered laboratory water and in highway stormwater. The constituents in stormwater caused a reduction in sorption of zinc and copper of up to 80%. The results suggest that 1 kg of activated rice hulls could treat up to 7 m3 of stormwater for zinc or 46 m3 of copper before exhaustion at the 90th percentile dissolved concentrations in California highway stormwater. The higher stormwater concentration and lower GAC affinity of zinc means that this constituent typically will limit adsorption system design for removal of multiple metals from stormwater.

Process enhancement for maximization of methane production in codigestion biogas plants

Purpose – The purpose of this paper is to develop improvements in the efficiency of the codigestion process. Design/methodology/approach – Two pilot plants, fed by different compositions of manure and industrial organic waste, generating biogas by mesophilic and thermophilic anaerobic fermentation, respectively, were analysed. Findings – It was observed that these processes do not commonly operate at maximum theoretical efficiency. Research limitations/implications – The limiting factor in the process was found to be the hydrolysis of the digested material. Practical implications – A technical solution had been suggested: implementing a secondary (after) storage phase which has the purpose of exploiting, by promoting enhanced hydrolysis, the substrate potential that remains undigested after the traditional process. Originality/value – The proposed configuration opens to original variations in the anaerobic digestion schemes.

Sampling, characterisation and processing of solid recovered fuel production from municipal solid waste: An Italian plant case study:

This article presents the classification of solid recovered fuel from the Massafra municipal solid waste treatment plant in Southern Italy in compliancy with the EN 15359 standard. In order to ensure the reproducibility of this study, the characterisation methods of waste input and output flow, the mechanical biological treatment line scheme and its main parameters for each stage of the processing chain are presented in details, together with the research results in terms of mass balance and derived fuel properties. Under this study, only 31% of refused municipal solid waste input stream from mechanical biological line was recovered as solid recovered fuel with a net heating value (NC=HV) average of 15.77 MJ kg−1; chlorine content average of 0.06% on a dry basis; median of mercury <0.0064 mg MJ−1 and 80th percentile <0.0068 mg MJ−1. The solid recovered fuel produced meets the European Union standard requirements and can be classified with the class code: Net heating value (3); chlorine (1); mercury (1).

Soil Pollution Prevention and Remediation

1DICATECh, Polytechnic University of Bari, Via Orabona 4, 70125 Bari, Italy 2Department of Civil and Environmental Engineering, University of California, Davis, 3105 Ghausi Hall, One Shields Avenue, Davis, CA 95616, USA 3School of Environmental Engineering, Technical University of Crete, 73100 Chania, Greece 4Dipartimento di Ingegneria Strutturale, Edile e Geotecnica, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy