Depuration Plants Research Articles

Magnetic Chitosan for the Removal of Sulfamethoxazole from Tertiary Wastewaters.

Magnetic chitosan nanoparticles, synthesized by in situ precipitation, have been used as adsorbents to remove sulfamethoxazole (SMX), a sulfonamide antibiotic dangerous due to its capacity to enter ecosystems. The adsorption of SMX has been carried out in the presence of tertiary wastewaters from a depuration plant to obtain more realistic results. The effect of pH on the adsorption capacity significantly changed when carrying out the experiments in the presence of wastewater. This change has been explained while taking into account the charge properties of both the antibiotic and the magnetic chitosan. The composition of wastewaters has been characterized and discussed as regards its effect on the adsorption capacity of the magnetic chitosan. The models of Elovich and Freundlich have been selected to describe the adsorption kinetics and the adsorption isotherms, respectively. The analysis of these models has suggested that the adsorption mechanism is based on strong chemical interactions between the SMX and the magnetic chitosan, leading to the formation of an SMX multilayer.

Pulsed ultraviolet (PUV) disinfection of artificially contaminated seawater seeded with high levels of pathogen disease indicators as an alternative for the shellfish industry depuration systems

The increase in pathogen levels in seawater threatens the safety of entire aquatic ecosystems. Foodborne pathogens can potentially accumulate in shellfish, especially in filter feeders such as bivalves, requiring an efficient depuration process before consumption. Alternative approaches to promote a cost-efficient purge at depuration plants are urgently needed. A small prototype pulsed ultraviolet (PUV) light recirculation system was designed, and its depuration potential was tested in a seawater matrix artificially contaminated with high levels of microbial pathogens Escherichia coli, Staphylococcus aureus, Salmonella typhimurium, Bacillus cereus and Candida albicans. The analysis of treatment parameters including voltage, number of pulses and duration of treatment was performed to ensure the highest reduction in contaminant levels. Optimal PUV disinfection was attained at 60 pulses/min at 1 kV for 10 min (a UV output of 12.9 J/cm2). All reductions were statistically significant, and the greatest was observed for S. aureus (5.63 log10), followed by C. albicans (5.15 log10), S. typhimurium (5 log10), B. cereus (4.59 log10) and E. coli (4.55 log10). PUV treatment disrupted the pathogen DNA with the result that S. aureus, C. albicans and S. typhimurium were not detectable by PCR. Regulations were reviewed to address the applicability of PUV treatment as a promising alternative to assist in the reduction of microbial pathogens at depuration plants due to its high efficiency, short treatment period, high UV dose and recirculation system as currently employed in shellfish depuration plants.

Improving environmental monitoring of Vibrionaceae in coastal ecosystems through 16S rRNA gene amplicon sequencing

The Vibrionaceae family groups genetically and metabolically diverse bacteria thriving in all marine environments. Despite often representing a minor fraction of bacterial assemblages, members of this family can exploit a wide variety of nutritional sources, which makes them important players in biogeochemical dynamics. Furthermore, several Vibrionaceae species are well-known pathogens, posing a threat to human and animal health. Here, we applied the phylogenetic placement coupled with a consensus-based approach using 16S rRNA gene amplicon sequencing, aiming to reach a reliable and fine-level Vibrionaceae characterization and identify the dynamics of blooming, ecologically important, and potentially pathogenic species in different sites of the northern Adriatic Sea. Water samples were collected monthly at a Long-Term Ecological Research network site from 2018 to 2021, and in spring and summer of 2019 and 2020 at two sites affected by depurated sewage discharge. The 41 identified Vibrionaceae species represented generally below 1% of the sampled communities; blooms (up to ~ 11%) mainly formed by Vibrio chagasii and Vibrio owensii occurred in summer, linked to increasing temperature and particulate matter concentration. Pathogenic species such as Vibrio anguilllarum, Vibrio tapetis, and Photobacterium damselae were found in low abundance. Depuration plant samples were characterized by a lower abundance and diversity of Vibrionaceae species compared to seawater, highlighting that Vibrionaceae dynamics at sea are unlikely to be related to wastewater inputs. Our work represents a further step to improve the molecular approach based on short reads, toward a shared, updated, and curated phylogeny of the Vibrionaceae family.

Impact of Depuration Plants on Nutrient Levels in the North Adriatic Sea

Macronutrients (nitrogen—N; phosphorus—P; silicon—Si) play a crucial role in ocean surface waters stimulating the planktonic primary production; in fact, their concentrations are fundamental for the evaluation of the trophic status of the water body and eutrophication phenomena. Loads of nutrients into the sea are mainly represented by river runoff and depuration plant outflows. For this purpose, in the framework of the AdSWiM project, “Managed use of treated urban wastewater for the quality of the Adriatic Sea” levels of N-NO3, N-NO2, N-NH4, Si-Si(OH)4, P-PO4 (dissolved inorganic phosphorus—DIP) and total dissolved phosphorus (TDP) were determined colorimetrically at two sites in the Gulf of Trieste: Lignano Sabbiadoro and San Giorgio di Nogaro. For each site, during the bathing seasons of 2019 and 2020, a sample from the depuration plant (DP) outflow and another one in the bottom seawater near the discharging pipelines were collected. Results showed a strong dilution effect on nutrient levels passing from DPs to the sea, from one to three orders of magnitude and a low and not harmful concentration in seawater. The outflow composition of the two DPs showed that the main fraction of dissolved inorganic nitrogen (DIN) was represented by N-NO3 for Lignano, while in San Giorgio the major contribution came from N-NH4. Concerning phosphorus, Lignano showed a higher content (about 3 times) of P levels than San Giorgio, but a similar percentage composition, DIP:DOP (77:23), compared to the seawater site one DIP:DOP (2:98). Despite the difference between the DPs, no substantial differences were found in the sea sites, demonstrating the negligible effect of the DP outflows in the nutrient levels in the study area.

Dissolved Potentially Toxic Elements (PTEs) in Relation to Depuration Plant Outflows in Adriatic Coastal Waters: A Two Year Monitoring Survey

The Adriatic Sea is vulnerable to pollution due to its low bathymetry, intense industrial activity, and tourism. In this context, a good depuration plant activity could play a key role for the maintenance of a good environmental quality. In the framework of the AdSWiM project, “Managed use of treated urban wastewater for the quality of the Adriatic Sea”, a study on dissolved potentially toxic element (PTE) levels was carried out to assess the impact of treated urban wastewaters on the quality of the bathing waters in the Adriatic Sea during the 2019 and 2020 summer period. In the present study, three areas along the Italian–Croatian coastline (Gulf of Trieste, Zadar, and Split) were identified for the monitoring of five depuration plant (DP) outflows. Water samples were collected after the treatment inside the DPs, and coastal seawater was sampled in the proximity of the discharging pipelines. Dissolved Hg, Cd, and As levels were determined with an atomic fluorescence spectrometer. Results did not show statistically significant differences between treated wastewater and seawater samples (Hg 10 ± 6 and 10 ± 4, Cd 14 ± 6 and 21 ± 8, As 610 ± 176 and 687 ± 140 ng L−1, respectively), while the geographical area and the seasonality affected the PTE concentration. Furthermore, the levels detected were lower than the European and national limits, indicating a good environmental status of the northern Adriatic Sea waters. The determination of further parameters (nutrients, microbiological indicators) must be investigated to identify possible synergistic effects. However, our results demonstrate the efficiency of DPs investigated, underlining the importance of the wastewater treatment for the protection of the Adriatic Sea.

Inactivation of marine bivalve parasites using UV-C irradiation: Examples of Perkinsus olseni and Bonamia ostreae

Diseases represent a major threat for the bivalve production industry. Their control relies on biosecurity measures to prevent their introduction and limit their spread. When maintained in hatcheries, nurseries and depuration centers, bivalves can become infected from the surrounding water and might release pathogens through wastewater effluents. A major effort was done in controlling the safety of bivalves for human consumption, but, on the other hand, information regarding the resistance of mollusc pathogens to water treatment is scarce. The effect of ultraviolet exposure was tested on two protozoan parasites of marine bivalves, the non-culturable parasite Bonamia ostreae and Perkinsus olseni culturable in DMEM/HAM´s medium. UV exposure experiments were carried out first at the bench scale and then, for P. olseni, at a larger scale mimicking depuration plants, hatcheries and nurseries conditions. At the bench scale, our study indicated that up to 40% of B. ostreae cells and 85% of P. olseni cells died 24 h and 21 days respectively after an exposure to 94 mJ/cm2 of UV-C. After 40 mJ/cm2 exposure, P. olseni density increased between 15 and 21 days of culture suggesting that the parasite is able to recover from low UV intensity exposure. At large scale, no signs of UV recovery were seen in P. olseni cultures, but, at lower intensity (216–244 mJ/cm2), 15% of the parasites remained alive 21 days post exposure. Finally, a minimum dose of 94 mJ/cm2 seems required to inhibit proliferation of parasites and 450 mJ/cm2 to completely kill all parasites. Taken this into account, a dose higher than 450 mJ/cm2 is suggested to properly treat water to avoid dispersion of bivalve protozoan parasites such as P. olseni.

Norovirus Persistence in Oysters to Prolonged Commercial Purification.

Depuration is generally the main treatment employed for bivalve mollusks harvested from contaminated sites. Commercial depuration has demonstrated to be effective for removal of bacterial pathogens, although it probably provides only limited efficacy against human enteric viruses. We evaluated the quantitative reduction of norovirus (NoV) genogroups I and II in naturally contaminated oysters after 1, 4, and 9 days of depuration. The process was conducted in an authorized depuration plant, and NoV concentration was determined by RT-qPCR according to ISO 15216-1:2017 method. Regardless of the NoV genogroup, our results showed no significant reduction in NoV concentration after 1 day of depuration. Higher mean reduction (68%) was obtained after 4 days of treatment, while no further increase was observed after 9 days. Overall, reduction was highly variable, and none of the trials showed statistically significant reduction in NoV RNA concentration at the end of each depuration period. Indeed, NoV concentration remained high in 70% of samples even after 9 days of depuration, with values ranging between 4.0 × 102 and 2.3 × 104 g.c./g. These results indicate that an extension of commercial depuration time does not appear to be effective for reducing or eliminating NoV in oysters.

Use of anionic polymer-coated magnetic beads to pre-concentrate Ostreid Herpesvirus 1 from seawater: Application to a UV disinfection treatment

Ostreid Herpesvirus 1 (OsHV-1) represents a serious threat to shellfish aquaculture worldwide. To minimise its impact, early warning systems able to detect the virus in seawater prior to infection of oysters are of utmost importance. However, monitoring OsHV-1 in seawater is challenging because of its presence at very low concentrations. Thus, a rapid and simple method to pre-concentrate the virus is needed to enable detection. Herein, magnetic beads (MBs) coated with an anionic polymer were used to pre-concentrate OsHV-1 from biological matrices including oyster homogenate and seawater samples. Following virus capture, OsHV-1 DNA detection was performed by quantitative PCR (qPCR). The MB-based approach combined with qPCR attained a limit of detection (LOD) as low as 0.1 viral copy/μL, which was 100 times lower than that of the qPCR alone. This approach was applied to the analysis of OsHV-1 in seawater from an Enhanced Hydro-Optic UV (HOD-UV) disinfection experiment operating at a UV dose of 1360 J/m2 in an open flow system. Our approach enabled detection of the virus in non-treated seawater and not in UV-treated seawater, discrimination that was not possible using qPCR alone. Moreover, the strategy provided data on the pattern of kinetics of the release of the virus in seawater. The approach could find applications in shellfish hatcheries and depuration plants to ensure biosecurity requirements.

Depuration processes affect the Vibrio community in the microbiota of the Manila clam, Ruditapes philippinarum

As filter-feeders, bivalve molluscs accumulate Vibrio into edible tissues. Consequently, an accurate assessment of depuration procedures and the characterization of the persistent Vibrio community in depurated shellfish represent a key issue to guarantee food safety in shellfish products. The present study investigated changes in the natural Vibrio community composition of the Ruditapes philippinarum microbiota with specific focus on human pathogenic species. For this purpose, the study proposed a MLSA-NGS approach (rRNA 16S, recA and pyrH) for the detection and identification of Vibrio species. Clam microbiota were analysed before and after depuration procedures performed in four depuration plants, using culture-dependent and independent approaches. Microbiological counts and NGS data revealed differences in terms of both contamination load and Vibrio community between depuration plants. The novel MLSA-NGS approach allowed for a clear definition of the Vibrio species specific to each depuration plant. Specifically, depurated clam microbiota showed presence of human pathogenic species. Ozone treatments and the density of clams in the depuration tank probably influenced the level of contamination and the Vibrio community composition. The composition of Vibrio community specific to each plant should be carefully evaluated during the risk assessment to guarantee a food-safe shellfish-product for the consumer.

Aerobic treatment of black ripe olive processing streams to reduce biological contamination

A new aeration treatment of black ripe olive streams prior to their vacuum evaporation was studied. It was found that the aeration for two days of these solutions reduced the chemical oxygen demand (COD) of the distillate phase (>80%) generated during their vacuum evaporation; although the temperature (14–38 °C) and the air flow rate (10–50 L air/h/L) had a great influence on this reduction. Moreover, the COD in the distillate was mainly associated with the presence of acetic acid (~400 mg/L) and ethanol (~500 mg/L), the later substance being eliminated by strong aeration. Additionally, the growth of native aerobic microorganisms, mainly Acetobacter, increased the pH of the wastewater to 7–8 units, thus avoiding evaporation of the acetic acid salt formed. These results make the use of the distillate for plant irrigation viable and its discharge into municipal depuration plants possible, given the low COD (<500 mg/L) reached with this new method. Industrial relevanceThe worldwide production of table olives is annually increasing but the management of the solutions generated during olive processing is limiting this expansion, in particular due to their high salt content. Factories are nowadays concentrating these solutions by using vacuum evaporation but the contamination of the distillate is too high. The present work has been carried out based on industry demand for low cost and easy handle technology able to reduce COD in distillates. The results of the present study showed that the content in ethanol and acetic acid of distillates can be reduced to a large extend by simple aerating of the solutions prior to the vacuum evaporation step, and this open the possibility of their reuse for plant irrigation.

Parasite Load and STRs Genotyping of Toxoplasma gondii Isolates From Mediterranean Mussels (Mytilus galloprovincialis) in Southern Italy.

Toxoplasmosis is a zoonotic food-borne disease caused by Toxoplasma gondii, a land-derived protozoan parasite that infects a broad range of terrestrial and aquatic hosts. T. gondii may reach coastal waters via contaminated freshwater runoff and its oocysts may enter into the marine food web. Marine invertebrates as mussels being filter feeders are exposed and may concentrate T. gondii oocysts representing a potential source of infection for animals and humans. The present works investigated the prevalence, parasite burden and genotypes of T. gondii in the Mediterranean mussels (Mytilus galloprovincialis) from southern Italy. We sampled a total of 382 individual Mediterranean mussels from May to August 2018 from seven production sites in the Gulf of Naples (Campania region). An additional sample including 27 farmed Mediterranean mussels was obtained in February 2018 from a mollusk depuration plant in Corigliano Calabro (Calabria region). T. gondii DNA was detected in 43 out of 409 (10.5%) Mediterranean mussels from seven out of eight sampling sites. The number of T. gondii copies/g in the digestive gland ranged from 0.14 to 1.18. Fragment analysis of Short Tandem Repeats (STRs) at 5 microsatellite loci was performed from 10 T. gondii PCR positive samples revealing the presence of five distinct genotypes including one corresponding to type I and four atypical genotypes. These findings suggest potential implications of epidemiological importance for human and animal health because both type I and atypical genotypes could be highly pathogenic.

Analysis of membrane performance in Ni and Co removal from liquid wastes by means of micellar-enhanced ultrafiltration

Heavy metal pollution of civil and industrial wastewaters represents a major problem for the environment since metal ions are non-biodegradable, have a very high toxicity, and some of them have proved to be carcinogenic. If directly discharged in sewers, metal ions may seriously damage the subsequent biological treatments in depuration plants and render treatment sludge not reusable for agriculture. On the contrary, water and sludge reuse should be a primary criterion when planning improvements for wastewater treatment plants and their adaptation to new standards. In this paper, the membrane performance (a monotubular ceramic membrane of molecular weight cutoff: 210 kDa) is investigated in the removal of nickel and cobalt ions from synthetic liquid wastes aimed at water reuse using a micellar-enhanced ultrafiltration process. The ultrafiltration membrane is used with adding an anionic surfactant (sodium dodecyl sulfate (SDS)) in a laboratory scale experimental device. The synthetic liquid waste contains metal ions in a concentration range 10–100 mg/L, and the SDS concentration was 1.15 mg/L, under the critical micellar concentration (CMC). The experiments have been carried out at a fixed temperature of 20°C. The preliminary results show that very good percentage removals of these metal ions are achieved, even if the surfactant was below its CMC.

Adenovirus and Norovirus Contaminants in Commercially Distributed Shellfish

Shellfish complying with European Regulations based on quantification of fecal bacterial indicators (FIB) are introduced into markets; however, information on viruses, more stable than FIB, is not available in the literature. To assess the presence of noroviruses (NoVs) GI and GII and human adenoviruses (HAdV) in domestic and imported mussels and clams (n=151) their presence was analyzed during winter seasons (2004-2008) in north-west Spanish markets through a routine surveillance system. All samples tested negative for NoV GI and 13% were positive for NoV GII. The role of HAdV as viral indicator was evaluated in 20 negative and 10 positive NoV GII samples showing an estimated sensitivity and specificity of HAdV to predict the presence of NoV GII of 100 and 74% (cut-off 0.5). The levels of HAdV and NoVs and the efficiency of decontamination in shellfish depuration plants (SDP) were evaluated analyzing pre- and post-depurated mussels collected in May-June 2010 from three different SDP. There were no statistically significant differences in the prevalence and quantification of HAdV between pre- and post-depurated shellfish and between seawater entering and leaving the depuration systems. Moreover, infectious HAdV were detected in depurated mussels. These results confirm previous studies showing that current controls and depuration treatments limiting the number of FIB do not guarantee the absence of viruses in shellfish.

Aerated lagooning of agro-industrial wastewater: depuration performance and energy requirements

Intensive depuration plants have often shown low reliability and economic sustainability, when utilised for agro-industrial wastewater treatment, due to the particular wastewater properties: high organic load and essential oil concentrations, acidity, nutrient scarcity and qualitative-quantitative variability of effluents. Aerated lagooning systems represent a suitable alternative, because they are able to assure good reliability and low energy requirements, avoiding the drawbacks shown by the intensive depuration plants. In order to optimize performance of the lagooning systems, particularly in terms of energy requirements, depuration processes of aerobic-anaerobic aerated lagoons were investigated, both at full- and laboratory-scale. Citrus processing wastewater were subject to bubble aeration with low flow rates and limited time; the removal rate of organic load was evaluated and energy requirements of different depuration schemes were compared. The experimental investigations in full-scale aerated lagoons showed a low energy supply (0.21-0.59 kWh per kg of COD (Chemical Oxygen Demand) removed with an average value of 0.45 kWh kgCOD –1), an adequate equalisation capability and constantly good depurative performance also with high concentrations of essential oil (500-1000 ppm). The experimental investigations in lab-scale aerated tanks under controlled conditions indicated the possibility of decreasing energy requirements (down to 0.16 kWh kgCOD –1) by reducing aeration power (down to 0.6 W m–3) and limiting aeration time to night 12 hours only, when energy price is lower. In spite of the low aeration, the COD removal rates were on the average six-fold higher compared to the anaerobic tank. Other outcomes indicated an ability of the spontaneous microflora to adapt to high concentrations of essential oils, which however did not provide an increase of the removal rate of the organic load in the experimented scheme.

Irrigation of energy crops with urban wastewater: Effects on biomass yields, soils and heating values

Exploitation of energy crops irrigated with non-conventional water resources on a large scale could decrease negative impacts from fossil fuel use, at the same time saving potable supplies and reducing disposal of polluting effluents in surface water, particularly in environments with water scarcity as Mediterranean basin.To this end, three energy crops (Typha latifolia, Arundo donax and Phragmites australis) were planted in experimental plots and irrigated over a 2-year period with the effluents of an urban wastewater depuration plant. Biomass and energy yields of the crops were evaluated; the effects on the main physical and chemical properties of soils (e.g. pH, EC, SOC, N, P) and leachate (pH, EC, COD) resulting from irrigation with wastewater were compared to those of irrigation with conventional water.In general, treatment with wastewater increased the biomass yield: this may be ascribed to the fertilising value of the wastewater. Irrigation with wastewater did not result in either notable changes of the soil's physical and chemical properties, or risks of soil structure decay, when compared to irrigation with conventional water. Only a slight and insignificant reduction of the soil's hydraulic saturated conductivity was measured.Percolation of contaminants (such as organic compounds and salts) into groundwater reserves was limited, as shown by the analysis of the leachate accumulated in lysimeters after irrigation with wastewater.Heating values measured by calorimetric tests were higher for T. latifolia in comparison to the other experimental species; nevertheless, the higher biomass productivity of A. donax makes the energy yield per unit of cultivated surface much higher than those of T. latifolia and P. australis.Even though the results achieved require further verification by mid- or long-term research, the present investigation shows that herbaceous crops irrigated with wastewater can produce appreciable biomass and energy yields. This is also an environmentally and economically sound way of wastewater disposal.

CONTRACT DELEGATION WITH BARGAINING

I. INTRODUCTION Public procurement is a very important part of economic activity. It accounts for about 20% of gross domestic product (GDP) in the United States and 16% in the European Union (EU) countries. (1) Therefore, is not surprising that many interest groups are at the stake whenever aspects of public procurement procedures are discussed. To limit the influence of these groups, the purpose of legislation in the United States and the European Community has been to unify public procurement procedures and restrict the discretionary power of contracting officers and agencies at lower administrative levels. The Federal Acquisition Regulation (FAR) in 2005 in the United States and directive 2004/18/EC of the European Parliament in 2004 are examples of this. One of the most important aspects in public procurement is the extent to which subcontracting is allowed. Traditionally, subcontracting has been judged negatively. For example, in construction, which amounts to a substantial part of public procurement, the FAR prevents contracts from being awarded to a single firm that supplies both design and engineering services (i.e., requires contract centralization). However, recently most states have legislations that allow for exceptions like the use of the design-build method (i.e., they allow contract decentralization). Lam, Chan, and Chan (2006) report that nowadays more than one-third of the construction projects in the United States and up to 50% in Japan use the design-build approach. Economic theory should explain whether this is because of the increased influence of pressure groups or if there exists an economic rational for this tendency. However, economic theory has had difficulty in explaining the superiority of subcontracting. To see this, consider a general contractor (or principal) who needs two suppliers (or agents) to realize a project. Either, he/she can contract directly both of them, or contract only one supplier and let him/her subcontract the other. Subcontracting obviously implies a loss of control over the subcontractee's contract for the general contractor. However, because he/she can always replicate the same contracts if he/she contracts directly with both suppliers, is not easy to see the advantages of subcontracting. A common assumption in this literature is that the principal has all the bargaining power and can make a or leave it offer to the agent. Regarding public procurement this is a realistic assumption in cases in which there are many suppliers, but fails to apply in cases in which the principal only can choose among a small number of suppliers. For example, this is the case in public procurement of defense systems, aeronautic and space equipment, or specific construction facilities such as water depuration plants, airports, or electric power plants. Although procurement in these cases is also based on fixed-price, cost-reimbursement, and incentive contracts, usually also allows for negotiations. So, section 15.3 of FAR states that are exchanges, in either a competitive or sole source environment, between the Government and offerors, that are undertaken with the intent of allowing the offeror to revise its proposal. These negotiations may include bargaining. Bargaining includes persuasion, alteration of assumptions and positions, give-and-take, and may apply to price, schedule, technical requirements, type of contract, or other terms of a proposed contract. This means that economic theory should take into account that contract design includes bargaining between parties at some stage of the process when contract centralization and decentralization are compared. To analyze this issue, a very stylized model is used to examine the advantages of centralized and decentralized organizations. Two agents work jointly on a project for a principal. Usually, in public procurement this is a contracting officer who represents a public agency. …

Treatment of wastewaters from the green table olive packaging industry using electro-coagulation

The application of electro-coagulation technology for the pre-treatment (or partial-depuration) of the wastewaters from the green table olive packaging industry was investigated. Different electrode materials and operational conditions were examined. The highest depuration rate was obtained using aluminum in the anode and iron in the cathode, current density of 25 mA cm −2 and distance between electrodes of 0.6 cm. In this case, after 50 min of treatment, chemical oxygen demand (COD) elimination reached 40% and most of the initially present phenols and color of the solutions were removed; the pH was also neutralized. Per cubic meter of wastewater, the total consumption of electricity was 0.76 kWh and the aluminum loss in sacrificial electrode 2.15 g. The treated liquid consisted almost entirely of a solution of lactic and acetic acids, which could be reused in packing or treated by conventional depuration plants.

Study of the viral removal efficiency in a urban wastewater treatment plant

Municipal and agricultural wastewater contain a variety of microorganisms and in particular enteric viruses. For the reuse of this treated wastewater it is important to ensure the efficiency of purification treatments and disinfection practices, that have often been insufficient to lower the viral load below the risk level. For this reason, for the routine analysis of recycled waters, the research into pathogenic viruses (e.g. HAV) and classical bacterial parameters (E. coli, enterococci and Salmonella) has to be associated with specific viral indicators such as somatic coliphages, adenovirus and TTV. The results of environmental monitoring, carried out in a wastewater treatment plant, showed the presence of adenovirus DNA in 100% of collected samples and TTV DNA in 95% (19/20) of raw sewage and in 85% (17/20) of the exit samples, while HAV was detected only in 2 samples over 40 (5%). The quantitative analysis has revealed an average reduction of 2 log for adenovirus and 1.58 log for TTV. The bacterial indicators were reduced by 1.74 log and 1.99 log respectively for E. coli and enterococci, while for somatic coliphages an average reduction of 2.2 log was observed. No significant correlation was shown between these parameters, confirming their inadequacy for the virological risk assessment. However the results of adenovirus confirm it as the best indicator to evaluate the efficacy of wastewater depuration plant in eliminating viruses.

Virological investigation on aerosol from waste depuration plants.

Aerosol from activated mud decontamination plants used for the treatment of urban sewage can represent a vehicle for bacteria, virus and fungi. As a result, they become an infective hazard for plant personnel, the general population residing in the surrounding area and the occasional visitor. The present investigation focuses on the identification of enteric-type viruses in this kind of aerosol. The following methods were employed on 214 samples collected in the 1999-2000 period: cell culture (BGM, RD, Hep-2), electron microscopy, and polymerase chain reaction (PCR). Cytopathic effect was mild in 180 samples, and severe in 14, upon their first passage in culture. Virus identification was based on positivity to both electron microscopy (EM) and PCR. Thus, one positive sample was recognized to be of enteric-type virus and two positive samples were recognized as reovirus-type. All samples were negative for Norwalk-type virus or HAV. There was considerable discrepancy between electron microscopy and PCR concerning the number of enteric-type viruses recognized. A possible explanation is contamination with animal-type enterovirus.

Environmental dispersal of Cryptosporidium parvum oocysts and cross transmission in cultured bivalve molluscs.

Two commercially valuable mollusc species ( Ostrea edulisand Tapes decussatus) were experimentally contaminated with Cryptosporidium parvum oocysts. A direct immunofluorescent antibody technique and inclusion/exclusion of the fluorogenic vital dye propidium iodide were used to test for the presence and viability of the oocysts, showing that transmission of contamination occurred between coexisting species. There was a decrease in the viability of oocysts in the initially uncontaminated molluscs as well as a large decrease in the number of oocysts retained when dead molluscs were used as the source of contamination. The results show the potentially important role that these molluscs play in spreading contamination in depuration plants and areas where aquatic organisms are cultivated.