Kinetics of Microcystin-LR Removal in a Real Lake Water by UV/H2O2 Treatment and Analysis of Specific Energy Consumption.

The hepatotoxin microcystin-LR (MC-LR) represents one of the most toxic cyanotoxins for human health. Considering its harmful effect, the World Health Organization recommended a limit in drinking water (DW) of 1 µg L-1. Due to the ineffectiveness of conventional treatments present in DW treatment plants against MC-LR, advanced oxidation processes (AOPs) are gaining interest due to the high redox potential of the OH• radicals. In this work UV/H2O2 was applied to a real lake water to remove MC-LR. The kinetics of the UV/H2O2 were compared with those of UV and H2O2 showing the following result: UV/H2O2 > UV > H2O2. Within the range of H2O2 tested (0-0.9 mM), the results showed that H2O2 concentration and the removal kinetics followed an increasing quadratic relation. By increasing the initial concentration of H2O2, the consumption of oxidant also increased but, in terms of MC-LR degraded for H2O2 dosed, the removal efficiency decreased. As the initial MC-LR initial concentration increased, the removal kinetics increased up to a limit concentration (80 µg L-1) in which the presence of high amounts of the toxin slowed down the process. Operating with UV fluence lower than 950 mJ cm-2, UV alone minimized the specific energy consumption required. UV/H2O2 (0.3 mM) and UV/H2O2 (0.9 mM) were the most advantageous combination when operating with UV fluence of 950-1400 mJ cm-2 and higher than 1400 mJ cm-2, respectively.

SARS-CoV-2 in sewer systems and connected facilities.

As for the SARS coronavirus in the 2003 epidemic, the presence of SARS-CoV-2 has been demonstrated in faeces and, in some cases, urine of infected people, as well as in wastewater. This paper proposes a critical review of the state of the art regarding studies on the presence of SARS-CoV-2 in wastewater and sewage sludge, the factors affecting its inactivation and the main proposed treatments. In-vitro tests demonstrated low resistance of SARS-CoV-2 to high temperature, while even significant changes in pH would not seem to determine the disappearance of the virus. In real wastewater and in sewage sludge, to date studies on the influence of the different parameters on the inactivation of SARS-CoV-2 are not available. Therefore, studies involving other HCoVs such as SARS-CoV and HCoV-229E have been also considered, in order to formulate a hypothesis regarding its behaviour in sewage and throughout the steps of biological treatments in WWTPs. Finally, SARS-CoV-2 in wastewater might track the epidemic trends: although being extremely promising, an effective and wide application of this approach requires a deeper knowledge of the amounts of viruses excreted through the faeces and the actual detectability of viral RNA in sewage.

Method for technical, economic and environmental assessment of advanced sludge processing routes.

The legislative framework in force in Europe entails restrictive effluent standards for sensitive areas, and quite severe restrictions on the properties of residual sewage sludge, both for landfill disposal and for agricultural use. Several technologies and management strategies have been proposed and applied in wastewater treatment plants to minimise sludge production and contamination. However, their techno-economic and environmental performance has to be carefully evaluated. The ROUTES project, funded within the EU Seventh Framework programme, aims to find new routes for wastewater treatment and sludge management and thereby guide EU members in their future choices. Within this project, the authors have developed and applied a procedure for techno-economic-environmental assessment of new wastewater and sludge processing lines in comparison to reference plants. The reference plants are model conventional plants that experience different types of problems and the new plants are modified plants in which different innovative technologies have been added to solve these problems. The procedure involves a rating of selected technical issues, estimates of operating costs and an assessment of environmental impacts from a life cycle perspective. This paper reports on the procedure and shows examples of results.

Influence of drinking water treatments on chlorine dioxide consumption and chlorite/chlorate formation.

Disinfection is the last treatment stage of a Drinking Water Treatment Plant (DWTP) and is carried out to maintain a residual concentration of disinfectant in the water distribution system. Chlorine dioxide (ClO2) is a widely used chemical employed for this purpose. The aim of this work was to evaluate the influence of several treatments on chlorine dioxide consumption and on chlorite and chlorate formation in the final oxidation/disinfection stage. A number of tests was performed at laboratory scale employing water samples collected from the DWTP of Cremona (Italy). The following processes were studied: oxidation with potassium permanganate, chlorine dioxide and sodium hypochlorite, coagulation/flocculation with ferric chloride and aluminum sulfate, filtration and adsorption onto activated carbon. The results showed that the chlorine dioxide demand is high if sodium hypochlorite or potassium permanganate are employed in pre-oxidation. On the other hand, chlorine dioxide leads to the highest production of chlorite and chlorate. The coagulation/flocculation process after pre-oxidation shows that chlorine dioxide demand decreases if potassium permanganate is employed as an oxidant, both with ferric chloride and aluminum sulfate. Therefore, the combination of these processes leads to a lower production of chlorite and chlorate. Aluminum sulfate is preferable in terms of the chlorine dioxide demand reduction and minimization of the chlorite and chlorate formation. Activated carbon is the most effective solution as it reduced the chlorine dioxide consumption by about 50% and the DBP formation by about 20-40%.

Metal leaching in drinking water domestic distribution system: an Italian case study.

The objective of this study was to evaluate metal contamination of tap water in seven public buildings in Brescia (Italy). Two monitoring periods were performed using three different sampling methods (overnight stagnation, 30-min stagnation, and random daytime). The results show that the water parameters exceeding the international standards (Directive 98/83/EC) at the tap were lead (max = 363 µg/L), nickel (max = 184 µg/L), zinc (max = 4900 µg/L), and iron (max = 393 µg/L). Compared to the total number of tap water samples analyzed (122), the values higher than limits of Directive 98/83/EC were 17% for lead, 11% for nickel, 14% for zinc, and 7% for iron. Three buildings exceeded iron standard while five buildings exceeded the standard for nickel, lead, and zinc. Moreover, there is no evident correlation between the leaching of contaminants in the domestic distribution system and the age of the pipes while a significant influence is shown by the sampling methods.

Agricultural waste as household fuel: techno-economic assessment of a new rice-husk cookstove for developing countries.

In many rural contexts of the developing world, agricultural residues and the organic fraction of waste are often burned in open-air to clear the lands or just to dispose them. This is a common practice which generates uncontrolled emissions, while wasting a potential energy resource. This is the case of rice husk in the Logone Valley (Chad/Cameroon). In such a context household energy supply is a further critical issue. Modern liquid fuel use is limited and traditional solid fuels (mainly wood) are used for daily cooking in rudimentary devices like 3-stone fires, resulting in low efficiency fuel use, huge health impacts, increasing exploitation stress for the local natural resources. Rice husk may be an alternative fuel to wood for household energy supply. In order to recover such a biomass, the authors are testing a proper stove with an original design. Its lay-out (featuring a metal-net basket to contain the fuel and a chimney to force a natural air draft) allows a mix of combustion/gasification of the biomass occurring in a completely burning fire, appropriate for cooking tasks. According to results obtained with rigorous test protocols (Water Boiling Test), different lay-outs have been designed to improve the performance of the stove. Technical and economic issues have been addressed in the development of such a model; building materials have been chosen in order to guarantee a cost as low as possible, using locally available items. The feasibility of the introduction of the stove in the studied context was assessed through an economic model that keeps into account not only the technology and fuel costs, but also the energy performance. According to the model, the threshold for the trade-off of the stove is the use of rice husk to cover 10-15% of the household energy needs both with traditional fireplaces or with improved efficiency cookstoves. The use of the technology proposed in combination with improved woodstove would provide householders with an appropriate and convenient cooking technology portfolio, increasing the opportunities of choice of the preferred energy system for the user and allowing significant savings for the family budget (up to 50% of the total annual cooking energy expenditure). The proposed model may be used also as a tool for the evaluation of the affordability or for the comparison of different cooking technologies also in other similar contexts, given their specific techno-economic parameter values.

Study of the reuse of treated wastewater on waste container washing vehicles.

The wheelie bins for the collection of municipal solid waste (MSW) shall be periodically washed. This operation is usually carried out by specific vehicles which consume about 5000 L of water per day. Wastewater derived from bins washing is usually stored on the same vehicle and then discharged and treated in a municipal WWTP. This paper presents a study performed to evaluate the reuse of the wastewater collected from bins washing after it has been treated in a small plant mounted on the vehicle; the advantage of such a system would be the reduction of both vehicle dimension and water consumption. The main results obtained by coagulation-flocculation tests performed on two wastewater samples are presented. The addition of 2 mL/L of an aqueous solution of aluminum polychloride (18% w/w), about 35 mL/L of an aqueous solution of CaO (4% w/w) and 25 mL/L of an aqueous solution of an anionic polyelectrolyte (1 ‰ w/w) can significantly reduce turbidity and COD in treated water (to about 99% and 42%, respectively); the concomitant increase of UV transmittance at 254 nm (up to 15%) enables UV disinfection application by a series of two ordinary UV lamps. Much higher UV transmittance values (even higher than 80%) can be obtained by dosing powdered activated carbon, which also results in a greater removal of COD.

From mixed to separate collection of solid waste: benefits for the town of Zavidovici (Bosnia and Herzegovina).

In Bosnia and Herzegovina only 50% of the municipalities have a well-organized service for (mixed) waste collection and disposal. Illegal dumping is very common, in particular in rural areas, which are not regularly served by any service of collection. This situation leads to serious risks for public health and has dangerous environmental impacts. In Zavidovici the municipality is trying to meet high standards in the delivery of services of waste collection, but is constrained by scarce financial and technical resources. Different scenarios for the implementation of a system of separate collection in Zavidovici were elaborated in order to provide a useful tool for decision making by comparing costs and environmental & economic benefits of each scenario. Six scenarios were considered, based on different recovery rates for plastic, paper & cardboard, and metals. Benefits resulting from the implementation of each of the proposed scenarios are compared in terms of savings of landfill volume and costs. The study concludes that the adoption of a system of separate collection could generate positive impacts on all the stakeholders involved in the solid waste management sector in Zavidovici and could contribute to the compliance of European standards in many Central and Eastern European countries as established by a number of national environmental protection strategies.

Techno-economic evaluation for the improvement of MSW collection in Somaliland and Puntland.

This paper is based on a study, which aim is to provide an overview of the current MSW management in the main cities in Somaliland and Puntland and to identify strategies to improve the present situation. In particular, this article illustrates assessments concerning waste collection and technical solutions identified for its improvement, whereas waste treatment and disposal phases will be discussed in a further paper. The survey, which has been carried out in close collaboration with local administrators and technicians, has shown that MSW management is very lacking and needs both structural and operational actions. Waste collection in the surveyed cities covers 65% of population at its best, whereas it is substantially absent in Gardo and Sheik. The extension of waste collection service to the entire population of each city would need investment costs varying between 17,500 USD for Sheik and 200,000 USD for Galkayo, whereas total operational costs would vary between 1.17 USD/ inh/y in Boroma and 5.73 USD/inh/y in Garowe. Anyway, technical interventions are necessary to provide a larger number of citizens with a regular waste collection service and they should be preceded and accompanied by public awareness campaigns on environmental protection and capacity building services addressed to local administrators and technicians.

Recovery of MSWI and soil washing residues as concrete aggregates.

The aim of the present work was to study if municipal solid waste incinerator (MSWI) residues and aggregates derived from contaminated soil washing could be used as alternative aggregates for concrete production. Initially, chemical, physical and geometric characteristics (according to UNI EN 12620) of municipal solid waste incineration bottom ashes and some contaminated soils were evaluated; moreover, the pollutants release was evaluated by means of leaching tests. The results showed that the reuse of pre-treated MSWI bottom ash and washed soil is possible, either from technical or environmental point of view, while it is not possible for the raw wastes. Then, the natural aggregate was partially and totally replaced with these recycled aggregates for the production of concrete mixtures that were characterized by conventional mechanical and leaching tests. Good results were obtained using the same dosage of a high resistance cement (42.5R calcareous Portland cement instead of 32.5R); the concrete mixture containing 400 kg/m(3) of washed bottom ash and high resistance cement was classified as structural concrete (C25/30 class). Regarding the pollutants leaching, all concrete mixtures respected the limit values according to the Italian regulation.

Wells sanitary inspection and water quality monitoring in Ban Nam Khem (Thailand) 30 months after 2004 Indian Ocean tsunami.

This paper reports the results of a study conducted in Ban Nam Khem village, the most hit in Thailand by 2004 Indian Ocean tsunami, aimed to evaluate either the actual state and operation of numerous domestic wells present in the village or the quality of drawn groundwater. Data show that most critical chemical-physical parameters are turbidity, total organic carbon and iron, whereas conductivity has greatly decreased in comparison with the February 2005 monitoring campaign. Furthermore, a high faecal contamination related to both constructive and operational deficiencies was detected in most monitored wells; therefore, measures aimed at improving habits in well operation and favouring water domestic treatment are necessary.

Water monitoring and treatment for drinking purposes in 2004 tsunami affected area-Ban Nam Khem, Phang Nga, Thailand.

University of Brescia and Mahidol University of Bangkok developed a project in Phang Nga province (Thailand), the most damaged by 2004 tsunami. In particular, the study, performed between April and May 2006, dealt with the surface and ground water monitoring in Ban Nam Khem village and the experimental evaluation of possible drinking treatment alternatives. The monitoring highlighted that saline content in the tsunami affected area is decreasing but still very high (conductivity presented values up to 2,600 and 6,230 microS/cm in ground and surface water, respectively); hence, advanced and complicated processes such as reverse osmosis should be adopted to treat such water for drinking purposes. Waiting for ground water salinity to assume acceptable values, activities for the reduction of its organic and microbiological contamination will be started. However, it has to be underlined that the diffusion of drinking water to a greater part of population can be obtained only through the realization of new centralised treatment plants and the improvement of existing ones (serving at the moment about 20% of inhabitants).

Evaluation of drinking water treatment and quality in Takua Pa, Thailand.

After 2004 Indian Ocean Tsunami, which hit and devastated several Countries in Southeast Asia, University of Brescia and Mahidol University started a project on water monitoring and treatment for drinking purposes in Takua Pa district (Thailand), the most damaged by the tsunami. In particular, this paper presents the results of a study conducted to evaluate the effectiveness of Takua Pa drinking water treatment plant and to identify actions that could be adopted to improve its performances. The results show that, even if the effluent usually meets Thai guide values, except for pH which is already too acid in the influent, the plant needs several structural and managerial improvements, such as filtration and sedimentation upgrade, coagulation/flocculation and final disinfection re-organization, use of proper registers to better plan and control employees activities. Moreover, it was determined that water quality in the distribution network is characterized by turbidity and organic matter values higher than those evaluated in the plant effluent.

Reuse of municipal solid wastes incineration fly ashes in concrete mixtures.

This study is aimed at assessing the feasibility of concrete production using stabilized m.s.w. (municipal solid waste) incineration fly ashes in addition to natural aggregates. The tested fly ashes were washed and milled, then stabilized by a cement-lime process and finally were reused as a "recycled aggregate" for cement mixture production, in substitution of a natural aggregate (with dosage of 200-400 kg m(-3)). These mixtures, after curing, were characterized with conventional physical-mechanical tests (compression, traction, flexure, modulus of elasticity, shrinkage). In samples containing 200 kg(waste) m(-3)(concrete), a good compressive strength was achieved after 28 days of curing. Furthermore, concrete leaching behavior was evaluated by means of different leaching tests, both on milled and on monolithic samples. Experimental results showed a remarkable reduction of metal leaching in comparison with raw waste. In some cases, similar behavior was observed in "natural" concrete (produced with natural aggregates) and in "waste containing" concrete.