Search

This study shows the evaluation of the possible use of the freshwater bivalve Dreissena polymorpha for the removal of some recalcitrant contaminants, namely many pharmaceuticals and drugs of abuse that are not sufficiently removed from civil wastewaters. This mollusk has an enormous filtering capability and is highly resistant to natural and anthropogenic stresses and to a significant bioaccumulation of lipophilic contaminants. All these characteristics may be particularly useful for the removal of compounds not easily eliminated by conventional wastewater treatment processes. To verify this hypothesis an experimental study was conducted at the pilot scale using a pilot plant installed in the largest wastewater treatment plant of Milan (Milano-Nosedo, Italy). First, we presented results obtained in several preliminary tests in order to evaluate the capability of zebra mussel specimens to survive in different wastewater mixtures,its filtering capacity and the possible influence of bio- and photo-degradation in the abatement of the molecules of interest. Finally, data obtained in the final tests demonstrated a capacity of this filter-feeder to reduce the concentrations of several pharmaceuticals and drugs of abuse higher than that obtained by the simple natural sedimentation, suggesting a possible implementation of the bio-filtration process in wastewater management.

A series of experimental tests has been conducted to investigate the efficiency and the by-product generation of high dose ozonation (10 to 60 mg O3 L-1) for complete colour removal from a treated effluent with an important component of textile dyeing wastewater. The effluent is discharged into an effluent-dominated stream where no dilution takes place, and thus, the quality requirement for the effluents is particularly strict. Three contact times were adopted: 30, 60 and 90 min. Colour was measured as absorbance at 426, 558 and 660 nm wavelengths. The experimental work showed that at 50 mg L-1 colour removal was complete and at 60 mg O3 L-1 the final aldehyde concentration ranged between 0.72 and 1.02 mg L-1. Glyoxal and methylglyoxal concentrations were directly related to colour removal, whereas formaldehyde, acetaldehyde, acetone and acrolein were not. Thus, the extent of colour removal can be used to predict the increase in glyoxal and methylglyoxal concentrations. As colour removal can be assessed by a simple absorbance measurement, in contrast to the analysis of specific carbonyl compounds, which is much longer and complex, the possibility of using colour removal as an indicator for predicting the toxic potential of ozone by-products for textile effluents is of great value

The paper is a review of previous research on secondary effluent disinfection by peracetic acid (PAA) integrated with new data about the effect of a preliminary flash-mixing step. The process was studied at bench and pilot scale to assess its performance for discharge in surface water and agricultural reuse (target microorganisms: Escherichia coli and faecal coliform bacteria). The purposes of the research were: (1) determining PAA decay and disinfection kinetics as a function of operating parameters, (2) evaluating PAA suitability as a disinfectant, (3) assessing long-term disinfection efficiency, (4) investigating disinfected effluent biological toxicity on some aquatic indicator organisms (Vibrio fischeri, Daphnia magna and Selenastrum capricornutum), (5) comparing PAA with conventional disinfectants (sodium hypochlorite, UV irradiation). PAA disinfection was capable of complying with Italian regulations on reuse (10 CFU/100 mL for E. coli) and was competitive with benchmarks. No regrowth phenomena were observed, as long as needed for agricultural reuse (29 h after disinfection), even at negligible concentrations of residual disinfectant. The toxic effect of PAA on the aquatic environment was due to the residual disinfectant in the water, rather than to chemical modification of the effluent.

Increasing urbanization across the world has led to increased research on ecology in urban settings in the last decade. Urban ecological studies have investigated both impacts of urban development on native ecosystems and the dynamics of urban environments themselves as ecosystems. In both areas of research, streams of urban areas have an important part to play because their position in the landscape makes these ecosystems particularly vulnerable to impacts associated with landcover change. Urban stream ecosystems are affected by multiple stressors and their effects are synthetized in the “urban stream syndrome” theorized in Walsh et al. 2005. Consistent symptoms of the urban stream include flashier hydrograph, elevated concentrations of nutrients and contaminants, altered channel morphology and stability and reduced biodiversity, with increased tolerant species. These ecological effects are often accompanied by other symptoms not observed in all urban areas, such as reduced baseflow and increased suspended solids. In impaired freshwater ecosystems, it is known that ecological integrity can be subdivided into two components, structural and functional integrity. Structural indicators of ecosystem health may be defined as the qualitative and quantitative composition of biological communities. Fish and macroinvertebrate assemblages have been the main focus for assessing structural integrity, although a variety of alternative targets such as benthic algal communities, protozoans, and macrophytes have also been used. Macroinvertebrate assemblages play a central ecological role in many stream ecosystems and are among the most ubiquitous and diverse organisms in fresh waters. Macroinvertebrates are easily recognizable and classifiable and some taxa are representative of every different habitat and condition (sensibility or tollerance to pollution and environmental changes) and so it is easy to aggregate results of macrobenthos analyses into synthetic indeces (such as STAR_

Although water quality improvement is generally the primary objective of treatment wetlands, the creation of habitats is an inevitable outcome of these projects. Macroinvertebrate are often early colonists of new created wetlands, with abundance and diversity approaching high levels within a few years from wetland construction. A deeper knowledge of the biodiversity hosted in these environments is needed to evaluate if newly created ponds are appropriate management tools for biological conservation. The effectiveness of the interventions provided by Parco Pineta di Appiano Gentile e Tradate (a regional park in Lombardy, Italy) in freshwater ecosystem management and restoration has been evaluated, considering a set of natural, artificial and constructed wetlands spread within the park territory. Considering the macroinvertebrate community and analyzing the biodiversity hosted in all the considered wetlands, no significant differences were found between artificial and natural ecosystems. Even the constructed wetlands, which were characterized by low water quality and higher pollutants concentrations, presented a biodiversity level which in some cases exceeded that one present in natural ecosystems. Even though biodiversity was similar between wetland typologies, differences in community compositions have been enlightened. The macroinvertebrate community assemblages seemed to be influenced more by the geographical and hydromorphological variables of the ecosystem rather than the physicochemical water characteristics. In particular, water body area and habitat heterogeneity resulted to be the most important variables that influenced the community composition. Seasonal variations in hydrological conditions and resource availability were the main factors that influenced the macroinvertebrate dispersal, evaluated considering life-strategy groups. Although the considered ponds and wetlands presented different features, they all contributed to the local ecological network ev

The presence of different kinds of leaf packs (native or alien) and environmental gradients can affect the composition and abundance of macroinvertebrate assemblages in fresh water ecosystems,but little is known about the interactive effects. Here, we investigated (1) how environmental gradients could influence leaf packs macroinvertebrates and (2) which was the chief factor (among water quality, mass loss of leaf packs, and flow regime) affecting macroinvertebrate assemblages in impaired streams. We analyzed leaf packs in six sites in impaired streams, characterized by waste water discharges and dominated by pollution-tolerant macroinvertebrate species. Using principal component analysis, we defined two environmental gradients as follows: a water quality gradient,related to anthropogenic alteration, and a hydromorphological gradient, mostly related to the catchment features. Our results pointed out that, in the tested conditions, biological metrics, such as functional groups and taxa richness, were chiefly influenced by the water quality gradient, while different leaf types in packs influenced the total taxa richness, but did not cause significant variation in the distribution and abundance of macroinvertebrate functional groups. On the contrary, the mass loss differed for different leaf types and was related to the stream and catchment features (mainly flow). This work showed that, in impaired streams, macroinvertebrate assemblages colonizing leaf packs are more influenced by water quality than by leaf types. Thus, the improvement of waterquality should be the priority in restoration programs and should be achieved before any effort to restore native riparian vegetation

The Lambro-Seveso-Olona (L-S-O) system derives from the human regulation of the natural hydrology of the territory around Milan city area. The average population density in the L-S-O area is among the highest in Italy and Europe. Industry is also highly developed in this basin: chemical, textile, paper, pulp and food industries being the most important ones. Although, at present, the L-S-O system no longer receives the untreated wastewaters of the Milan urban area, treated wastewaters constitute about half of the streamflow. Biotic communities in this river have a long history of poor quality status, having suffered great damage due to domestic and industrial discharges. Recently, new chemical quality standards for macropollutants have been set by the Italian legislation as support for the good ecological status according to the Water Framework Directive (WFD). This new index is very restrictive, and it makes it extremely challenging to achieve the water quality objectives for the L-S-O system. The aim of this study is to analyse through a modelling exercise the restoration possibilities of the L-S-O system, investigating both the source apportionment of the macropollutants, the discharge limits that should be set to achieve the good quality status and their corresponding cost

Benthic macroinvertebrates are widely used as indicators of the health of freshwater ecosystems, responding both to water quality and to the hydromorphological integrity. In urban streams, evaluations can be tricky for the synergistic effects of multiple stressors and confounding factors. In these situations, the most broadly used multimetric indices can be used to assess the overall damage to the invertebrate community and, thus, the overall anthropogenic pressure, but they do not allow to understand the specific causal effects. Particularly, habitat loss due to morphological alterations can be difficult to evaluate, especially due to the often concurrent disturbance caused by water pollution. We used a multivariate approach to focus on the characteristics of the streams and rivers in an urban district and to define which macroinvertebrate metrics should be used to assess the influence of the different kinds of alteration in a severely damaged environment. Some metrics enabling the assessment of habitat loss (ratio of oligochaeta, ratio of filterers) were identified. These metrics may help to raise a better awareness in the evaluation of river restoration success and, thus, in the support of decision-making processes

The increasing use of new generation plastics has been accompanied by the development of standard methods for studying their biodegradability. Generally, test methods are based on the measurement of CO2 production, i.e. the mineralization degree of the tested materials. However, in order to describe the biodegradation process, the determination of the residual amount of tested material which remains in the environment and its chemical characterization can be very important. In this study, the biodegradation in soil of a model polyester (poly(butylene sebacate)) was monitored. Gel Permeation Chromatography and Nuclear Magnetic Resonance (31P-NMR and 1H-NMR) were used in order to obtain information about the polyester structure and the possible by-products that can be found in soil during and at the end of the incubation. The polyester mineralization (i.e. the CO2 production) was tested according to ASTM 5988 standard method for 245 days. When the polyester mineralization was about 21% and 37% (after 78 and 140 days of incubation) and at the end of the process (63% of mineralization, 100% if compared to the cellulose used as reference material), the soil was extracted with chloroform (solvent of the tested substance) and the extracts were analyzed using GPC and NMR acquisitions. The analytical acquisitions showed high molecular weight polyester in soil during the incubation (78 and 140 days): the polyester concentration decreased but its structure remained almost the same with a slow decreasing in molecular weight. At the end of the test (245 days) no film of the polyester could be extracted from the soil: NMR acquisitions and GPC analyses of the extracts suggested a strong degraded structure of the residual polyester. Even if at the end of the process only 63% of carbon had been lost by mineralization, the whole of the added polyester seems to have disappeared after about eight months of incubation, suggesting substantial biomass formation

Contamination of drinking water is a major issue in depressed areas, especially in developing countries. Moreover, in such areas suitable conditions for the determination of E. coli using standard count plate methods could be missing. The level of water contamination and the operational conditions of a city in the Democratic Republic of the Congo were analyzed, and subsequently recreated in laboratory. We tested the efficacy of three fast E. coli detection methods in both optimal and operational conditions, and compared them to standard methods. The results showed that there were no significant differences between the various methods in the different conditions. Thus, fast methods can successfully be used, although a tendency to produce false negatives with low levels of contaminations should be taken in account.

Uno degli elementi critici per una migliore comprensione delle dinamiche ecosistemiche in fiumi e torrenti fortemente modificati e per i processi decisionali relativi ai programmi di riqualificazione fluviale è l’individuazione di quali fattori pongano limiti al corretto sviluppo delle comunità biologiche in una situazione caratterizzata da alterazioni multiple. In particolare, i corpi idrici fortemente modificati che attraversano ambienti urbani o, comunque, di notevole antropizzazione subiscono gli effetti congiunti e sinergici di deterioramenti relativi alla qualità delle acque, al regime idraulico e alla morfologia fluviale. In queste situazioni, è molto spesso difficoltoso definire relazioni causali tra alterazioni specifiche e le risposte delle comunità biologiche usando gli strumenti del biomonitoraggio o i più comuni strumenti statistici quali la regressione lineare. Tali strumenti consentono per lo più la verifica di ipotesi relative alla tendenza centrale dei dati, definendo ad esempio la relazione media tra una metrica biologica e una variabile ambientale. In presenza di alterazioni multiple, tuttavia, il “rumore di fondo” introdotto dalla presenza simultanea dei deterioramenti in vari ambiti della funzionalità fluviale può compromettere la validità di tali tipologie di modelli, fino a renderli non informativi. La distribuzione dei valori delle metriche biologiche lungo gradienti specifici di alterazione assume l’aspetto di “nuvole” di dati apparentemente caotiche. L’uso della regressione quantile, tuttavia, permette di valutare le singole alterazioni come fattori limitanti allo sviluppo delle comunità biologiche, individuando così la relazione causale tra esse. Nell’ambito del Progetto FIUMI, nato dalla collaborazione tra Regione Lombardia, ARPA Lombardia e due atenei lombardi, e in vista della progettazione di interventi di riqualificazione fluviale nel bacino Olona-Lambro, uno dei più fortemente modificati d’Italia, sono state analizzate le relazioni t

The paper reports the results of comparative trials carried out at demonstrative and pilot scale using constructed wetlands for the final polishing of treated effluents (ozonated and non ozonated) which are discharged into a small stream, often dry, whose flow is chiefly made of the effluents themselves. The effluents fed to experimental constructed wetlands had comparable quality for the chief parameters. The removal percent was higher in the case of ozonated effluents for total phosphorus and total nitrogen, especially due to the higher concentration of oxygen, while COD and TSS reval were comparable in the two cases.

In modern intensive agriculture, plastics are used in several applications (i.e. mulch films, drip irrigation tubes, string, clips, pots, etc.). Interest towards the application of biodegradable plastics to replace the conventional plastics is growing because they biodegrade in soil after use and do not produce waste to be disposed of. Ten monomers, which can be applied in the synthesis of potentially biodegradable polyesters, were tested according to ASTM 5988-96 (standard respirometric test to evaluate aerobic biodegradation in soil measuring the carbon dioxide evolution): adipic acid, azelaic acid, 1,4-Butanediol, 1,2-Ethanediol, 1,6-Hexanediol, lactic acid, glucose, sebacic acid, succinic acid and terephthalic acid. Eight replicates were carried out for each monomer for 27-45 days. The numerical code AQUASIM was applied to process the CO2 experimental data in order to estimate values for the parameters describing the different mechanisms occurring to the monomers in soil: i) the first-order solubilization kinetic constant, Ksol (d-1); ii) the first-order biodegradation kinetic constant, Kb (d-1); iii) the lag time in biodegradation, tlag (d); and iv) the carbon fraction biodegraded but not transformed into CO2, Y (-). The following range of values were obtained: [0.006 d-1, 6.9 d-1] for Ksol, [0.1 d-1, 1.2 d-1] for Kb, and [0.32 - 0.58] for Y; tlag was observed for azelaic acid, 1,2-ethanediol, and terephthalic acid, with estimated values between 3.0 e 4.9 d.

The intense use of plastic contributes to increase the amount of municipal waste that are generally disposed in landfill. For some applications and sectors, an important alternative to the conventional plastic materials can be found in the use of the new generation materials: the biodegradable polymers. Their use can be an alternative to landfill disposal and can thus reduce the cost of waste management and the accumulation in the environment. The biodegradable polymers, in fact, are used by microorganisms as source of carbon and are converted by into carbon dioxide (or methane), water and mineral salts of any other element present (mineralization) plus new biomass. Generally, laboratory test methods developed for determining the biodegradability of polymeric material are based on the evaluation of the carbon dioxide production (respirometric test), but in order to completely describe the biodegradation process and to avoid an underestimation of the biodegradation percentage, it is very important to quantify and identify possible by-products and biomass production. The experimental work presents in this thesis concerned the study of the different aspects of the biodegradation of new generation plastics in soil. Particular attention was focused on the fate of the possible by-products of biodegradable polymers (the monomers) and on the determination of the biomass generated during the process. To summarize: 1) The effects of the soil pH on the mineralization of ten monomers, chosen between the most widely used for the synthesis of plastic materials, was evaluated by respirometric tests and the experimental data were used to validate a numerical model that can estimate the amount of carbon used by microorganism for biochemical synthesis. 2) The mineralization of a model polyester was investigated by respirometric tests in different soil mixtures in order to evaluate the effects of the initial soil pH and of the addition of organic matter. 3) The combustion of soil samp

On February 23rd 2010, several thousand tons of fuel oil and other hydrocarbons were poured into the sewerage system of Villasanta (MB), causing the spill of about 3000 m3 of them into the Lambro River and the interruption of the purification activities at the local Wastewater Treatment Plant (WWTP). The effects on the benthic invertebrate communities were analyzed, comparing data collected before and after the accident. The lack of detail of the data collected before the spill and the concurrent presence of various stressors led to the necessity of more detailed analyses, based on a experimental design built over space (upstream and downstream the spill). The ANCOVA and multivariate analysis of the shifts occurred to several diversity, taxonomical and functional metrics in macroinvertebrate assemblages at microhabitat level allowed identifying effects due to the pre-existent impairment, the spill of untreated wastewater, and the oil. The de-oxygenation of water due to the WWTP breakdown affected the taxa richness and caused the disappearance of the most specialized functional groups (e.g. filterers and grazers), especially in riffle areas. The deposition of oil in finer sediments resulted in a considerable reduction of densities in tolerant taxa, thus, paradoxically, increasing Shannon Index values in samples collected downstream the spill. Overall, the greatest short-term damage to invertebrate biodiversity seemed to be caused by the spill of untreated wastewater.

The introduction of artificial ponds is a restoration measure to compensate for wetland habitat loss, but a deeper knowledge of the ecological relationships in these environments is needed. Aim of this work has been to enlighten the differences in macroinvertebrate assemblages in artificial and natural ponds, and to consider the relative importance of several variables in explaining the functional and trophic patterns in each ecosystem. The ultimate purpose has been to gain information about the potential role of artificial ponds in ecological networks. Within Parco Pineta, a regional park in Lombardia, numerous ponds and wetlands are present. 24 of them have been chosen to analyse differences in invertebrate biodiversity. They are natural (16) and artificial (8) ecosystems, two of the latter being part of a constructed wetland system created for wastewater treatment. Environmental characteristics of each pond and taxonomic composition of macroinvertebrates have been monitored. Significant (a=0.05) differences were not found in biodiversity among different wetland typologies. Univariate and multivariate statistics showed that the most significant environmental factors related to community composition were water body area and microhabitat heterogeneity, while water quality seemed to have scarce influence. The presence of fish could be identified as a limiting factor. Further analyses have been carried out involving macroinvertebrate dispersion strategies and functional feeding groups in order to evaluate ecological behaviours and trophic web organization in the different kinds of wetlands

Severe eutrophication of freshwater lakes, with the subsequent risk of algal blooms, has a critical effect on the safety of drinking water supplies in China and is one of the main environmental emergencies in the country. This paper focuses on Chao Lake, a large, shallow eutrophic lake used as a source of drinking water. The study considers the possibilities of improving the lake monitoring system and developing a SCADA system to manage the emergencies relating to water quality in order to meet the need of ensuring safe drinking water to the population of Chaohu City. The paper is presented in sub-sections that reflect the multitasking nature of the study, which focused on: (a) upgrading the monitoring system at lake and water treatment plant levels and also applying remote sensing, to develop a SCADA (Supervisory Control And Data Acquisition) system using neural networks to support prompt and effective management of emergency situations; (b) upgrading water collection and treatment technologies

In the last 20 years, a new generation of materials was developed: the biodegradable plastics. They reduce the accumulation of plastic in the environment and the cost of waste management because they can be fed in composting plants or, if used in agriculture (mulch films), they are applied to the soil and left there. Tenmonomers were chosen among themost used in the synthesis of biodegradable polymers (1,2-ethanediol, 1,4-butanediol, 1,6-hexanediol, adipic acid, azelaic acid, sebacic acid, terephthalic acid, glucose, lactic acid, and succinic acid) and tested according to ASTM 5988- 96 (a standard test method for determining aerobic biodegradation in soil of plastic materials measuring the carbon dioxide evolution). Two sandy loam soils, collected in two different sites in Italy, were used to evaluate the mineralization rate of the monomers. Four tests (two replicates each) were carried out for 27– 39 days. Experimental data show no relevant differences in the respirations of the two soils and in the carbon dioxide productions of the tested monomers. The final mineralization percent was 42–45% for glucose, succinic, and lactic acid and 50–56% for the other monomers.

Structure and function of the Serio River (northern Italy) ecosystem have been evaluated analyzing macroinvertebrate community functional traits. Starting from traits such as Functional Feeding Groups (FFG), Functional Habit Groups (FHG), voltinism and drift behavior, we determined values that can integrate direct measurements of ecosystem attributes and can be used in restoration planning. We collected invertebrates and environmental data in eight sites representative of the longitudinal succession of Serio River environments. High values for most of the ecosystem attributes, indicating good functionality, were confined in three sites of the upstream alpine sector, while downstream the ecosystem was severely impaired and colonized by non-specialized, pioneer communities. The intrinsic information given by ecosystem attributes helped aid the understanding of the health of specific ecosystem functions, thus leading to evaluation of priorities in restoration efforts. This methodology can be a complementary tool in river quality assessment if macroinvertebrate quantitative data are available. Particularly, it can be used in accordance with the new quantitative sampling protocols being adopted in the European Union, and it can define new metrics in a multimetric evaluation system. © 2010 Unione Zoologica Italiana.

The human presence and activities affect the environmental quality of water bodies in different ways. Pressures concern various aspects of the overall environmental quality and their effects are cumulative and synergic. That’s why an integrated approach is needed to understand and assess the importance of each kind of stressors and to define restoration strategies. The research work carried out in the last three years and shown in this thesis concerns impaired river ecosystems and includes, in particular: 1) Integrated study of chemical, hydrological and biological aspects of impaired rivers, especially those affected by multiple alterations in urban environments and, thus, wastewater treatment plant effluent dominated. A case study (Lura stream) is presented. 2) Development of analytical methods for determining organic micropollutants (PAHs, triazines and their main transformation products) in a wide range of surface and wastewater samples (coming from different environments in Italy and Spain) and, consequently, for evaluating the contamination from wastewater treatment plant discharges. 3) Evaluation of the organic micropollutant removal efficiencies of wastewater treatment plants and comparison of the concentrations measured in effluent samples to the environmental quality objectives fixed for surface waters, as most of the receptor flow is made by the discharged effluent itself. 4) Study of the performance of a demonstration scale constructed wetland in removing inorganic and organic contamination from wastewater treatment plant effluents, as a possible strategy for impaired river restoration.

Bioassays were performed by commercially available kits on peracetic acid (PAA) solutions, at different concentrations, and on secondary effluents (from two different wastewater treatment plants) after disinfection at bench-scale, considering both samples containing residual active PAA and the same samples where residual PAA was quenched. Four indicator organisms were used: Vibrio fischeri, Thamnocephalus platyurus, Daphnia magna, and Selenastrum capricornutum. The experiments lead to conclude that Thamnocephalus platyurus is a very sensitive organism, probably not adequate to perform a reliable toxicity assessment of effluents for monitoring purposes.The presence of specific organic compounds deriving from human metabolism and urban pollution, even at very low concentrations, can affect the results of bioassays, especially those performed on Vibrio fischeri. PAA is toxic for bacteria and crustaceans even at concentrations lower than the ones commonly used in wastewater disinfection (2-5 mg/L), while its effect on algae is smaller. The toxic effect on bacteria was expected, as PAA is used for disinfection, but its possible influence on biological processes in the receiving aquatic environment should be considered.Toxicity on crustaceans would confirm the fact that discharging disinfected effluents could raise some environmental problems