LO SCAVO DELLA VILLA PIGNETO SACCHETTII resti della Villa Pigneto Sacchetti, progettata da Pietro da Cortona, sono stati localizzati e parzialmente scavati nel 1992. Lo scavo ha rivelato che il Casino è sopravvissuto appena sopra il livello di fondazione e che anche le parti più interne del ninfeo e della grotta sono sopravvissute. I risultati dello scavo consentono una rivalutazione della correttezza delle piante del XVIIII secolo. Due fasi di sviluppo sono state riconosciute — inizialmente una piccola fontana, e successivamente una villa di più grandi dimensioni con un ninfeo e una grotta. La villa è risultata essere di progetto originale e non una ristrutturazione di un edificio gia esistente, come creduto in precedenza. L'analisi dei resti archeologici e dei documenti che sono sopravvissuti consente una rivalutazione della datazione della costruzione, con una prima fase risalente alia metà del 1637 ed una seconda ad un periodo che va dal 1638 al 1644. I reperti archeologici sono pochi, ma la presenza di una serie di vasi da fiori con disegni araldici papali è degna di nota.

By introducing a mixed population of nitrifiers encapsulated in gel lens beads a more selective nitrification process was found in treatment of settled sewage in lab scale at a hydraulic retention time (HRT) of about 30 to 60 minutes. The reaction rates for oxidation of soluble chemical oxygen demand (SCOD) were found to vary between 25 to 150 mg/L x h while nitrification takes place around 50 mg nitrogen per hour and litre reaction volume. However, based on this SCOD removal in the nitrification step, a consequent post-denitrification process without nitrate recycle and dosage of external carbon sources has been proven to reach substantial nitrate elimination of up to 20 mg nitrogen per litre at COD/N-ratios of approx. 6 in settled sewage. At such COD/N-ratios, suitable nitrogen elimination seems to be possible, because the bioflocs of settled sewage, produced so far by SCOD oxidation and entrapment of particulate COD, are passing through the nitrification process having a substantial contribution to the denitrification rate additionally to the remaining SCOD.

No abstract

Tabelle. Literaturdaten für Ozondosis, -verbrauch und TS-Reduktion.

The overall energy consumption of domestic wastewater treatment plants (WWTPs) increases with treatment efficiency. Approximately 30 to 45 kWh per people equivalent and year is mostly necessary for advanced nitrogen and phosphorus removal, while the aeration contains the main part of approximately 60%. A new process using encapsulated nitrifiers on gel lens beads is introduced to overcome the high energy consumption of aeration. A more selective nitrification process was found at a nitrification rate of between 50 and 60 mg nitrogen per hour and litre reaction volume corresponding to a hydraulic retention time (HRT) of about 30 to 60 minutes while the soluble Chemical Oxygen Demand (COD) removal could be less than 30% depending on operational conditions of the bio-reactor. The latter enables internal use of wastewater's COD for a post denitrification. For the new process the energy consumption as well as total volume of bio-reactor are much less (approximately 30 to 50% for both) than conventional processes due to the low sludge age for COD and nitrate removal and the avoidance of internal wastewater recycle. Therefore, self-sufficient energy operation of domestic WWTPs operating with advanced treatment efficiency could become possible, if energy recovery by anaerobic sludge digestion is included.