Applicazione di una biomassa termofila MBR per il trattamento di diversi substrati: performance, minimizzazione fanghi e recupero dei residui

Al fine di studiare, comprendere e trovare soluzioni per la gestione dei fanghi di depurazione, nella presente tesi di dottorato sono state svolte attività di ricerca bibliografica e sperimentale. Per quanto concerne la parte bibliografica, in primo luogo si sono studiati i fanghi: attraverso questioni ed elaborazioni dati si è analizzata quantità e qualità dei fanghi in uscita dai depuratori e dalle piattaforme conto terzi. Sono stati valutati i destini dei fanghi e in particolare si sono analizzate le normative europee, nazionale e regionali per lo spandimento dei fanghi in agricoltura. Infine, seguendo i dettami della normativa europea sui rifiuti (2008/98/CE) si sono analizzate sia le tecniche di minimizzazione sia le possibili forme di recupero (materia, energia, congiunto). Dal punto di vista sperimentale, si è deciso di studiare una tecnologia presente sul mercato: il processo termofilo MBR. Tale processo è stato studiato attraverso impianti sia alla scala reale sia alla scala pilota. Per quanto concerne i primi, questi sono stati monitorati e per uno è stato seguito anche lavviamento. Il cuore della tesi, tuttavia, sono le sperimentazioni condotte sugli impianti pilota dove sono stati testati rifiuti liquidi, fanghi e la combinazione di entrambi. Per ogni sperimentazione si sono calcolati i rendimenti di rimozione per i diversi parametri con particolare riferimento alla produzione specifica di fanghi e alla riduzione dei solidi. Infine, sono state proposte differenti configurazioni di installazione del termofilo MBR allinterno di un impianto a fanghi attivi per ridurre i fanghi, con riduzioni anche del 70%

The use of a risk assessment tool based on the Sanitation Safety Planning approach for the improvement of O&M procedures of a wastewater treatment plant in Tanzania

The treatment of wastewater and excreta is one of the major challenges in low-income contexts. The urgency of recovery and reuse of nutrients for agriculture come into contrast with the risks for workers, farmers, and communities. This article presents the development of a risk-based methodology adapted from the Sanitation Safety Planning (SSP) and NaWaTech Safety and operation and management (O&M) planning approaches aimed at improving the wastewater treatment plant (WWTP) of the Municipality of Iringa, Tanzania, selected as case study. The proposed approach is an innovative tool to identify and quantify the risk connected to hazardous events: the methodology was applied at the WWTP in order to identify and assess the risks related to the malfunctioning or to some exceptional events that could pose health risks to workers and nearby communities. The process permitted to identify the risk connected to the hazardous events in order to propose additional control measures for events having medium, high, or very high risk level. These additional control measures were aimed at improving current O&M procedures of the WWTP by the use of simple enhancements requiring low investments, as a first step toward the safeguard of the health of workers, farmers, and nearby communities

Drastic reduction of sludge in wastewater treatment plants: co-digestion of sewage sludge and aqueous waste in a thermophilic membrane reactor

Sewage sludge and aqueous wastes are usually treated in separate facilities. Both may pose specific issues, mainly related to the uncertainty of the recovery/disposal route and costs, for the sludge, and to the extremely variable quantitative and qualitative properties, for the aqueous waste. In the present work, the co-digestion of thickened sludge and aqueous wastes in a Thermophilic Aerobic Membrane Reactor (TAMR) was studied in order to allow the almost complete reduction of sludge directly in wastewater treatment plants (WWTPs). Different conditions (aerobic and alternate aeration) were tested in a pilot plant, at the semi-industrial scale. The TAMR plant was operated at 48°C with constant organic load rate (5 kgCOD m −3 d −1 ) and hydraulic retention time (5 days). The main results obtained are the following: (I) high overall COD (78–97%) and total phosphorus (>60%) removal rate under both the studied aeration conditions; (II) increase of ammonia concentration due to the effective ammonification of organic nitrogen; (III) low specific sludge production (0.04VSS PRODUCED kgCOD REMOVED −1 ) in the thermophilic reactor

Integrating novel (thermophilic aerobic membrane reactor-TAMR) and conventional (conventional activated sludge-CAS) biological processes for the treatment of high strength aqueous wastes

A combination of thermophilic aerobic membrane reactor (TAMR) and conventional activated sludge (CAS) was studied by means of two pilot plants at semi-industrial scale in order to simulate the new configuration adopted in a full-scale facility for the treatment of high strength aqueous wastes. Aqueous wastes with high contents of organic pollutants were treated by means of the TAMR technology, progressively increasing the organic load (3-12 kg(COD)m(-3) d(-1)). A mixture of municipal wastewater and thermophilic permeate was fed to the CAS plant. The main results are the following: achievement of a high COD removal yield by both the TAMR (78%) and the CAS (85%) plants; ammonification of the organic nitrogen under thermophilic conditions and subsequent mesophilic nitrification; capacity of the downstream mesophilic process to complete the degradation of the organic matter partially obtained by the TAMR process and precipitation of phosphorus as vivianite and carbonatehy-droxylapatite in the TAMR plant

Legislation for the reuse of biosolids on agricultural land in Europe: overview

The issues concerning the management of sewage sludge, produced in wastewater treatment plants are becoming more important in Europe due to: (i) the modification of sludge quality (biological and chemical sludge are often mixed with negative impacts on sludge management, especially for land application); (ii) the evolution of legislation (landfill disposal is banned in many European countries); (iii) the technologies for energy and material recovery from sludge are not fully applied in all European Member State. Furthermore, Directive 2018/851/EC introduced the waste hierarchy that involved a new strategy with the prevention in waste production and the minimization of landfill disposal. In this context, biological sewage sludge can be treated in order to produce more stabilized residues: the biosolids. In some European countries, the reuse of biosolids as soil improver/fertilizer in arable crops represents the most used option. In order to control the quality of biosolids used for land application, every Member States, has issued a national regulation, based on European Directive. The aim of this work is to compare the different approaches provided in European Member States for the reuse of biosolids in agricultural soils. A focus on the regulation of countries that reuse significant amount of biosolids for land application was performed. Finally, a detailed study on Italian legislation both at national and regional level is reported