Foto del docente

Maurizio Mancini

Associate Professor

Department of Civil, Chemical, Environmental, and Materials Engineering

Academic discipline: ICAR/03 Sanitary and Environmental Engineering


Keywords: sea outfall eutrophication wastewater reuse combined nitrification on site wastewater treatments wastewater engineering biofiltering WWTP automatic management natural wastewater treatments estuarine transition waters

1) Biological tractability of urban sewage and WWP management.

2) Finishing, recovery and reuse of treated urban wastewater.

3) Wastewater discharge in inland/coastal waters and effects on aquatic ecosystems.

4) On site systems for wastewater treatment and reuse in small urban settlements.

THEME 1 - The research concerning biological treatment of urban sewage is developed by three main survey line research:

a) the role of quality and dilution variations of incoming wastewater in conditioning treatment efficiency and output concentrations: main research field is the Bologna WWTP where arecarried out experimentations with the aim to realize a comparison between efficiency foreseen for eachtreatment phases andreal organic matter (BOD)removal, tested, during full scale functioning, indifferent rainy anddilution conditions. Dlgs.152/2006 provides for wastewater collection in drainage system and secondary treatment for all Italian residential built-up area and discharge regulation defines tables of parameter limits. So,in case of combined piping system, collecting such sewage as rain water, becomes important to receive, in primary treatment phases, in rainy weather conditions, a large amount of collected water volumes. Results made possible a precise mathematic formulation to control WWTP input, during critical rainy events, and numerical simulations are developed about active sludge WWTP performances in function of incoming and bypass fluxes.

b) investigations about effects of sewage composition in conditioning nitrogen removal efficiency and biomass health in predenitre-nitre plant: on the wastewater treatment plant of Bologna it has been also studied the effect of BOD/N ratio and presence of grease and oil on nitrification efficiency. By controls about health and activity state of biomass we have defined a mathematical model for description of oxidization-nitrification phenomena based on evaluation of sludge production in function of sludge retention time. Limitation on oxygen transfer efficiency due to oil releases of filamentous microorganisms has been detected as main critical factor for nitrification phase. Sludge retention time as regulation factor for plant management and as an important parameter in conditioning denitrification velocity has been studied in Ravennamunicipal wastewater plant. Results present the behavior of denitrification velocity in function of sludge age in a denitre-nitre plant scheme, using internal and endogenous carbon. According with Pavia University it has been verified the effect of daily variation in organic loadings on biological nitrogen removal. This is a largely diffused problem in Northern Italy where often plants receive weak wastewater or pretreated water by Imhoff tanks.

c) the capability of automatic WWTP management by artificial intelligence technique aimed to provide and minimize system disturbances: variation of incoming loadings is probably the main critical factor for steady functioning of great active sludge treatment plants. The related transitory phases are often cause of decrease in efficiency or even of crash in treatment function. The survey tests innovative techniques for control of active-sludge plants manage-ment based on automatic interpretation of on-line measured data and is carried out in partnership with DEIS Department of Bologna and water section of ENEA Bologna. In ENEA laboratory have been mounted and endowed with on-line measuring instruments one SBR pilot plant and one active sludge steady functioning pilot plant. In collaboration with HERA Bologna are in progress works on full scale plants of Trebbo and Calderara di Reno for mounting on-line data acquisition system in order to make possible to test results at real scale. Treatment of municipal wastewaters usually requires a simple sequence of two biological processes, denitrification that occurs in anoxic conditions, whereas nitrification in aerobic conditions. The automatic detection of the end of such processes allows to optimize the duration of the operational cycles, which usually would be set on a worst-case basis, and thus to reduce costs. Moreover, the recognition of both process-level events is necessary to validate the effectiveness of a cycle, in order to ensure that the effluent is conforming to the required standards. The well-known criteria for on-line monitoring of biological processes (nitrification and denitrification) in a Sequencing Batch Reactor (SBR) for municipal wastewater treatment, are based on the analysis of acquired online signals such as pH, oxide-reduction potential (ORP) and dissolved oxygen (DO).

THEME 2 - a   In a pilot plant in Imola (BO) a few interesting natural systems, utilizable in treatment and wastewater finishing, have been tested about efficiency in disinfection and in phosphorous, nitrogen and BOD removal. Continuous analysis of organic parameters reveal good removal rates for fragmites australis on all parameters and for lemna fragilis on dissolved nitrogen phases with hydraulic retention time more or equal to 2 days. Results point out useful management information about maintenance of steady condition by control of growing transient and biomass extraction.

b)· Experimentations in reclamation and irrigation reuse of large flowrate of domestic wastewater are carried out in Cagliarisystem for treatment-storage-reuse of urban wastewater. The investigation analyzes the removal effect in organic and microbial parameters due to bacterial-algal activity typical of a facultative pond and discuss results in order to test reliability and efficiency with reference to the existing Italian laws about discharge (D.lgs.152/2006) and reuse (D.M.2/5/2006). Data reveal that Simbirizzi artificial basin make possible agricultural recycling and reuse realizing adequate retention time for storage and final finishing of wastewater, and at the same time permits to avoid every discharge in seawater during summer. A mathematical model, just developed by the research components, has been calibrated and utilized in order to describe the evolution of quality of water storage into the Simbirizzi basin and to control the respect of existing law limits about irrigation reuse.

c) ·  Another research line is developed studying the finishing capability provided by the transitory waters regulated by tidal oscillations, before outfalling through canal sea-mouths. On the basis of foregoing experiences of monitoring and numerical modelling of ecosystem phenomena carried out about Piallasse Ravenna, three monitoring campaigns are developed into the basin of the Canal Port in Cesenatico, where the last internal part of the channel has been modelled as an unsteady flow reactor tank and where variations in depth and input/output fluxes are provided by tide, but prevalent freshwater conditions are maintained by the high rate input of treated wastewater. Four fixed point, in output, intermediate and input cells, are monitored in order to verify active phenomena and finishing effects on discharged wastewater in terms of C, and N biological removal. Modelling of oxygen and biomass balances permits to quantify the different role of productive and oxidizing activities, supported by mixed microalgal and bacterial populations, during daily and nightly cycles. A few usual formulations, utilized in aerobic lagoons design, have been tested on the studied system and compared with model results and monitoring data, verifying the capability of scheme plug flow reactor+first order kinetic to interpret the finishing effect on BOD, ammonium and nitrate residual from WWTP.

THEME 3 - Wastewater discharge in inland/coastal waters and effects on aquatic ecosystems is focused by three research field: the intake work of Cervia Saline, the estuary of Marano River receiver of Riccione WWTP effluents and the outfalling system of the Cesenatico harbour channel, which transports treated wastewater coming from Cesena (180.000 AE) and Cesenatico (summer 100.000 AE). Generally harbour channels, having very low ground slope, guarantee a good thermoaline turbulent mixing, for the entire water column, if basin structure presents high pulmonary surface/freshwater loading ratio. So discharged volumes receive a sanitising effect by salinity and pH on microbial contamination and vertical dispersion provides limitation of algal blooms in coastal zone due to intrusion of nutrient in surface stratified freshwater. On the contrary small estuaries with higher ground slope, receiving sea water by tidal oscillations within a few hundred meters from coastal line and high flowrate coming from WWTP, present flow prevalently directed to sea where flush continuously freshwater in surface. According with Bragadin e al. 2003 it has been proposed and calibrated by data from the intake work of the Cervia Saline a simplified scheme of calculations for hydraulic flow dividing the channel into twenty independent cells. At each section flowrate has been calculated in function of water surface enclosed between each section and internal head of the channel, under the hypothesis of negligible flow resistance, flowrate at each section is computed from continuity equation. A different assessment, existing along the Rimini-Cattolica coast, is investigated into the Marano estuary near Riccione. Here higher ground slope permits direct discharge of wastewater into estuaries of small rivers coming from near internal hills. These estuaries receive sea water by tidal oscillations within a few hundred meters from coastal line and present low internal depth (max 1,6-1,8 m). Sea outfall occurs through sea outlet only a few meter large and very low depth  (60-80 cm). Summer hydraulic flow, for high flowrate coming from WWTP and low pulmonary available volumes, is prevalently directed to sea where delivers continuously freshwater in surface. In summer dry weather assessment of morphology tide and currents, it has been modelled, along estuarine transition unsteady flow, the behaviour of velocity, Reynolds n., salinity, dissolved oxygen, P-PO4,N-NH4, N-NO3. Two special campaign of analysis are carried out for calibration. A survey about seawater quality in coastal bathing areas, interested by discharging systems of freshwater, is carried out in the pulmonary system of Cesenatico canal harbour and in the near coastal zone characterized by submerged breakwaters in North direction and by emerged breakwaters in South direction. During summer and in dry weather conditions main part of discharged freshwater come from Waste Water Treatment Plants and from drainage pipe systems and it has been studied dispersion area and profile distribution of freshwater outgoing from harbour canal mouth and discharged in the coastal area. Different effects on thermoaline and oxygen profile, firstly modelled by a 3D numerical model, have been registered in 2007 field experiences. Continuity and profile of submergible breakwaters make these structures more efficient in producing internal stratification than emerged discontinue breakwaters which permit higher internal mixing of water column by incoming and outgoing turbulent flux through mouths.

THEME 4 - Efficiency of small onsite domestic wastewater treatment has been verified by monitoring of a few plant actually active in Romagna, where small active sludge plant (combined system Imhoff tank + Phytotreatment SFS, Imhoff tank + anaerobic filter) are compared with reference to BOD, SS, nitrogen, phosphorous removal. Horizontal and vertical flux systems have been analyzed about efficiency removal, registering often nitrification deficit caused by insufficient oxygen transfer capacity of rooted macrophytes and showing high presence of residual BOD in effluents due to media blockage in case of combined sewer system.  Good results are obtained by introducing biofiltration phases or alternated vertical flux in SFS scheme with the scope of permitting water reclamation and reuse. Pilot plant experiences, carried out in the buildings of the School of Engineering in via Terracini, have been focused the role of hydraulic flow into the filtering medium in conditioning removal efficiency of SFS system using fragmites australis. Data results obtained from the pilot bed can be correctly interpreted by model formulations using process scheme based on first order kinetics mounted on a sequence of serial completely mixed tanks provided by a share dead volume.

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