Research experiences on the reuse of industrial waste for concrete production

The aim of this study was to assess the feasibility of concrete production using different kinds of industrial wastes as “recycled aggregate”. The wastes studied in this work were: fly ashes and slags from Electric Arc Furnace (EAF) steel plant; foundry sands produced from foundry dies; slags from lead processing; Waelz slags; solid residues from municipal solid waste incineration (MSWI) plant (with mass-burning kiln and fluidized bed reactor); sludge from industrial wastewater treatment plants. Good compressive strength (similar to natural concrete) was achieved after 28 days of curing by concrete mixtures obtained with the partial replacement (from 7% to 40% by weight) of natural aggregates with slags from lead processing, foundry sands, Waelz slags and bottom ashes from MSW incineration. The worst mechanical and leaching behaviours were shown by concrete samples containing EAF fly ashes and sludge from industrial wastewater treatment. For the residues with the best performance, concrete products (kerbs and flat tiles) were casted. Their mechanical and leaching characterization has shown that the reuse of these residues for concrete product is feasible

Sustainability of Water Safety Plans Developed in Sub-Saharan Africa

In developing countries, the drinking water supply is still an open issue. In sub-Saharan Africa, only 68% of the population has access to improved sources of drinking water. Moreover, some regions are affected by geogenic contaminants (e.g., fluoride and arsenic) and the lack of access to sanitation facilities and hygiene practices causes high microbiological contamination of drinking water in the supply chain. The Water Safety Plan (WSP) approach introduced by the World Health Organisation (WHO) in 2004 is now under development in several developing countries in order to face up to these issues. The WSP approach was elaborated within two cooperation projects implemented in rural areas of Burkina Faso and Senegal by two Italian NGOs (Non-Governmental Organisations). In order to evaluate its sustainability, a questionnaire based on five different sustainability elements and a cost and time consumption evaluation were carried out and applied in both the case studies. Results demonstrated that the questionnaire can provide a useful and interesting overview regarding the sustainability of the WSP; however, further surveys in the field are recommended for gathering more information. Time and costs related to the WSP elaboration, implementation, and management were demonstrated not to be negligible and above all strongly dependent on water quality and the water supply system complexity

An Evidence-Based Survey on Full-Scale Membrane Biological Reactors: Main Technical Features and Operational Aspects

This paper presents the results of a survey on full-scale membrane biological reactors (MBRs) wastewater treatment plants (WWTPs) in Italy. Alongside the main technical characteristics of the Italian MBR plants, the opinions of the plant managers on the operational advantages and disadvantages are described. As reported by the MBR technology suppliers, approximately 290 MBR municipal or industrial WWTPs are in operation in Italy, out of which 242 were studied in this survey. Data from more than one hundred municipal WWTPs were collected; these account for a total capacity of about 2,000,000 population equivalent (PE), which corresponds to 3% of the total organic load treated by the Italian WWTPs with secondary and advanced treatment. Usually, small installations adopt the flat-sheet rather than hollow-fiber membrane configuration. The main reasons why the MBR technology has been preferred to other options are its potential to be used for increasing the treatment capacity of existing plants and its compactness. Moreover, the followed operational advantages have been highlighted: easiness to comply with the discharge limits, removal of pathogens without specific disinfection units, possibility of internal reuse of the effluent, and process automation. Membrane fouling and plant shutdown have been recorded as the most relevant troubles, the last one indeed occurring only occasionally or rarely

Oxygen control and improved denitrification efficiency by dosing ferrous ions in the anoxic reactor

Small concentrations of dissolved oxygen (DO) in the range 0.2–0.4 mg L−1 normally are present in biological pre-denitrification reactors. This situation causes adverse effects on denitrification rate and, consequently, on the process efficiency. The results presented show the possibility to control the DO in the anoxic reactor by dosing ferrous Fe(II) ions. The experiments were carried out on both batch samples and a pilot plant and proved that oxidation of Fe(II) to Fe(III) is very efficient in the DO control. Moreover, Fe(III) reacts with phosphorus which recipitates as ferric orthophosphate. A dose of 6 mgFe2+ L−1 decreased the mean DO concentration from 0.45 to 0.28 mg L−1; as a consequence, the denitrification efficiency (ηDEN) increased from about 65–77%. ηDEN reached up to 89% with 9 mgFe2+ L−1 (50% over the stoichiometric for phosphorus removal) thanks to an average DO concentration of 0.08 mgO2 L−1 in the denitrification stage. The results also highlighted the strong influence of DO (and consequently the dosage of Fe2+) on the specific denitrification rate suggesting to maintain DO concentration in the pre-denitrification reactors lower than 0.2 mg L−1 in order to achieve high operation efficiencies

Linee guida per la valutazione e gestione del rischio nella filiera delle acque destinate al consumo umano secondo il modello dei Water Safety Plan

L’Organizzazione Mondiale della Sanità ha introdotto un decennio fa il modello dei Water Safety Plans (Piani di Sicurezza dell’Acqua, PSA) come il mezzo più efficace per garantire sistematicamente la sicurezza di un sistema idropotabile, la qualità delle acque fornite e la protezione della salute dei consumatori. Il modello, seguito in queste linee guida, persegue una valutazione e gestione dei rischi integrata, estesa dalla captazione al rubinetto, per la protezione delle risorse idriche di origine e il controllo del sistema e dei processi, al fine di garantire nel tempo l’assenza di potenziali pericoli di ordine fisico, biologico e chimico nell’acqua disponibile per il consumo. L’approccio risk-based consente anche una flessibilità del sistema di gestione rispetto a contaminanti emergenti, attualmente non oggetto di monitoraggio sistematico, e/o delle vulnerabilità dei sistemi idropotabili agli impatti diretti e indiretti indotti dai cambiamenti climatici. L’obiettivo delle linee guida, indirizzate ai responsabili e operatori dei sistemi di gestione idrica, alle autorità sanitarie e a tutti i soggetti interessati ai diversi livelli alla qualità delle acque potabili, è fornire, in termini chiari e pragmatici, criteri, metodi e procedure necessari all’implementazione dei PSA nei sistemi di gestione idropotabili in Italia, indipendentemente dalla loro dimensione e bacino di utenza

Technical and environmental characterisation of recycled aggregate for reuse in bricks

Waste mud coming from an aggregate washing plant was formerly used as filling material for a pond, aimed at the recovery of an abandoned quarry. Once completed the filling capacity of the pond, the need for identifying a possible reuse of mud produced by the plant arose in order to avoid landfill disposal. Therefore, mud has been geometrically, physically and chemically characterised for its recovery as construction material. A variety of tests was carried out on mud samples as required by EN technical specifications and by Italian environmental standards, focusing particularly on leaching behaviour. The tested material showed satisfactory physical and chemical properties and a release of pollutants below the limits set by the Italian code. Many mix-designs for the production of unfired bricks made of waste mud, sand and straw, stabilised and non-stabilised with lime, gypsum or cement, were developed. The bricks were tested in order to evaluate mechanical properties and leaching behaviour. Mud bricks provided remarkable compressive strength, even if not suitable for structural elements. The use as interior design to minimise humidity changes and to facilitate a thermal insulation is fostered, thus strengthening the so-called green building economy

Biosolids: What are the different types of reuse?

In recent years, rapid population growth and industrialization have increased the use of natural resources and the production of waste. To develop a circular economy, it is necessary to study and promote alternative long-term solutions for waste disposal, such as reuse and recovery. Wastewater treatment plants (WWTPs) can be an important part of circular sustainability if re-oriented to function as a water resource recovery facilities (WRRFs). In this context, biological sewage sludge (SS) can be treated in order to produce more stabilized residues: biosolids (BS). This paper aims to review the possible alternatives to reuse the BS in order to increase matter recovery. Around 250 papers, reviews, books and conference proceedings have been examined. Authors explored the application of BS on land, such as soil amendment/fertilizer both in agriculture and for interventions on abandoned mine sites, and on engineering fields, in partial or total substitution of virgin materials. The reuse of BS as adsorbent materials and as a source of phosphorus is also discussed

Monitoring rice agropractices in North Africa: a comparison of MODIS and Sentinel-1 results

Agro-monitoring systems need up-to-date information on where, when and how much a crop is cultivated, in particular in developing countries and for food security reasons. Such information can be derived from remote sensing imagery with fast revisiting cycles. In the past, only time series of optical moderate resolution data such as HVRR, SPOT-Vegetation and MODIS provided the necessary high temporal resolution for this kind of applications. These datasets have been successfully used for agro-monitoring activities and to perform retrospective and trend analysis. Due to their moderate to coarse spatial resolution (~ 250 – 1000 m) their applications are limited however to regional to continental scales. In this context, the advent of the Sentinel sensors opens new opportunities, since they provide time series of satellite imagery with decametric spatial resolution and revisit times of 5 days. Studies that fully exploit Sentinel imagery for crop monitoring are therefore needed to assess their potential contribution for i) performing high resolution crop-monitoring activities and, ii) extending time series of information derived from archive coarse resolution imagery with the aim of performing analyses of temporal trends over a reasonably long time span. This contribution presents a comparison of MODIS or Sentinel1 time series for detection (cultivated area and number of seasons) and seasonal dynamics’ analysis (sowing, harvesting and flowering dates) for irrigated rice cultivation in the Senegal River Valley (SRV)for the 2016 dry and wet rice seasons. MODIS time series analysis exploited the PhenoRice algorithm (Boschetti et al., 2017), a rule-based algorithm specifically designed for rice detection and seasonal dynamics monitoring and based on the use of time series of TERRA and AQUA 250 m resolution 16-day Composite Vegetation Indexes (MODIS products MOD13Q1 and MYD13Q1). The SAR data analysis was instead based on analysis of Sentinel-1A time series acquired over the study area from January to December 2016. In particular, the RICEscape software was used for analysing the SAR backscatter (0) temporal profiles both in the VV and in the VH polarization, to define a set of rules allowing to properly identify rice cultivated areas. The algorithm mostly exploits SAR data, although cloud free Landsat-8 Optical images were used to crosscheck and complement the information derived from SAR. This approach was applied to generate rice crop area and Start of Season (SOS) maps for both the dry (sowing in February – April) and the wet (sowing in September – November) rice seasons. Results showed a strong consistency between the thematic maps derived from the two data sources. We observed that, although the rice-classified area is rather different due to the large difference in spatial resolution, the main spatial patterns of estimated sowing dates and crop intensity are quite similar. A comparison between the average values of MODIS and SAR estimated dates after aggregation on a 2x2 km regular grid shows a strong correlation between the sowing dates derived from Sentinel-1 and MODIS data, for both the dry and the wet season of 2016. The comparability of MODIS and Sentinel results is encouraging for the development of innovative services for characterization and monitoring of crop systems. Such systems could in fact exploit both the sufficiently long MODIS time series to characterize the main characteristics of crop systems and their recent evolution, as well as the innovative Sentinel-1 time series for monitoring of present-day and future conditions