Evaluation of Humoral Response and Protective Efficacy of an Inactivated Vaccine Against Peste des Petits Ruminants Virus in Goats.

Four goats were inoculated with an inactivated peste des petits ruminants virus (PPRV) vaccine. Three unvaccinated goats were kept as controls. After 36 days, the four goats were revaccinated. The immune response was monitored by virus neutralization test showing that two doses of the vaccine were able to stimulate strong immune response in all the vaccinated animals. The vaccinated goat and the controls were challenged with virulent PPRV intranasally. After PPRV challenge, the three control goats showed fever, viremia and virus excretion through mucosal surfaces, whereas the vaccinated goats were fully protected against PPRV infection and replication.

Modelling population dynamics of denitrifying phosphorus accumulating organisms in activated sludge.

In this paper a kinetic model for simulating population dynamics is developed. The aim was to simulate anoxic and aerobic phosphorus accumulating organisms dynamics in a lab-scale sequencing batch reactor (SBR) operating under different conditions. Denitrifying phosphorus accumulating organisms (DNPAOs) successfully competed in almost all the simulated operational conditions tested. Using this model, the anoxic energy disadvantage of DNPAOs was not as strong as using metabolic models. The model was able to predict reasonably well N, P and acetate profiles in the SBR with only a minor modification of the ASM2d default values of the parameters.

Soft sensors for control of nitrogen and phosphorus removal from wastewaters by neural networks.

In this paper, we describe the results of research aimed to evaluate the possibility of using a neural network (NN) model for predicting biological nitrogen and phosphorus removal processes in activated sludge, utilising oxidation reduction potential (ORP) and pH as NN inputs. Based on N and P concentrations predictions obtained via the NN, a strategy for controlling sequencing batch reactors (SBRs) phases duration, optimising pollutants removal and saving energy, is proposed. The NN model allowed us to reproduce the concentration trends (change in slope, or process end), with satisfactory accuracy. The NN results were generally in good agreement with the experimental data. These results demonstrated that NN models can be used as "soft on-line sensors" for controlling biological processes in SBRs. By monitoring ORP and pH, it is possible to recognise the N and P concentrations during different SBRs phases and, consequently, to identify the end of the biological nutrient removal processes. This information can then be used to design control systems.

Influence of primary sedimentation on pre-denitrification system performances.

The effects of suppressing primary sedimentation on nitrogen removal efficiency of a pre-denitrification system have been evaluated for a large municipal wastewater treatment plant. Simulations have been carried out using the STOAT model. For both the process schemes with and without primary sedimentation, nitrification efficiencies are calculated for increasing influent loads of COD, total N and suspended solids. The sensitivity analysis shows that for the usual carbon to nitrogen ratios in the raw influent both the process schemes allow the requested removal efficiencies, whereas for significantly high C/N ratios the scheme with primary sedimentation is preferable.

Experimental considerations on monitoring ORP, pH, conductivity and dissolved oxygen in nitrogen and phosphorus biological removal processes.

An experimental study on monitoring Oxidation Reduction Potential (ORP), pH, Conductivity and Dissolved Oxygen (DO) in an Enhanced Biological Nutrient Removal process has been carried out. In the anaerobic phase, while ORP and conductivity were not reliable in monitoring simultaneously denitrification and P-release, pH showed the best performances. A significant relationship between P-released and pH variation was found. During the aerobic phase both ORP and pH were able to monitor successfully the nitrification, even though pH was much more reliable. pH can be also used for monitoring and control enhanced P-uptake. It has been concluded that, for a reliable and effective control of biological N and P removal processes a more sophisticated control system seems to be necessary.

Biological nutrient removal in a full-scale SBR treating piggery wastewater: results and modelling.

Research activities carried out at ENEA during the last few years allowed development of a Sequencing Batch Reactor (SBR) that is able to remove biologically organic waste, nitrogen and phosphorus and that showed to be particularly suited to obtain low effluent nutrient concentrations even starting from concentrated wastes. This plant, in more than one year of operation, is quite steadily obtaining more than 98% removal of nitrogen, phosphorus and COD. On the basis of the experimental results, a simulation model has been built and calibrated. The model showed the potential to be used for forecasting the behaviour of the process, being able to reproduce a process imbalance that followed the tentative reduction of aeration time.

Implementation, study and calibration of a modified ASM2d for the simulation of SBR processes.

An enhanced process model for SBRs has been developed. Though the basic mechanism largely draws on the Activated Sludge Model n. 2d, its new features are the splitting of the nitrification stage in a two-step process, according to the well known Nitrosomonas-Nitrobacter oxidation sequence, and an improved XPAO dynamics, involved in the anaerobic/aerobic phosphorus removal process. The model was implemented through the DLL technique allowing complied C++ modules to be linked to an ordinary Simulink block diagram. The static sensitivity study revealed that if the parameter vector is partitioned into subsets of biologically related parameters and calibrated separately, the calibration procedure does not present particularly difficult aspects. Trajectory sensitivity showed also to which extent data collection could be optimised in order to improve calibration accuracy. The study of the shape of the error functional generated by parameters couples allows a much more effective calibration strategy.

Selection of denitrifying phosphorus accumulating organisms in activated sludge.

Although anoxic phosphorus uptake has been demonstrated, the conditions that stimulate or inhibit the anoxic uptake are not fully understood. In this study, the possibility of achieving biological excess phosphorus removal in sequencing batch reactors using nitrate as an electron acceptor without including an aerobic phase has been confirmed. The use of an anaerobic/anoxic/aerobic sequencing batch reactor allows anoxic phosphorus uptake to be achieved, in spite of the low fraction of denitrifying phosphorus accumulating organisms present in the inoculum. Biomass characterisation was carried out to determine the denitrifying fraction of the phosphorus accumulating organisms in sequencing batch reactors operating at different operational conditions. With an anaerobic/anoxic/aerobic cycle, it was demonstrated that the disadvantage of denitrifying phosphorus accumulating organisms due to the lower substrate utilisation efficiency in anoxic conditions relative to aerobic conditions, is not so effective to cause the "strictly aerobic" phosphorus accumulating organisms to dominate in the system.

Post-treatments of anaerobic effluents.

Post-treatments are necessary if anaerobic effluents need to be discharged into surface waters, because anaerobic digestion alone is not able to produce effluents that can meet the discharge standards applied in most industrialized countries, particularly for suspended solids, particulate COD, nitrogen, phosphorus and sulphides. This paper has the aim to present some results obtained in the recent years in our laboratory, where different comprehensive processes that include anaerobic digestion have been studied. Discussion will regard: 1) the ANANOX (ANaerobic-ANoxic-OXic) process for the treatment of municipal wastewater; 2) a process studied for the biological removal of C, N and P from piggery wastewater that has a hybrid anaerobic/anoxic reactor as the first treatment step; 3) the use of a Sequencing Batch Reactor for the post-treatment of digested cheese whey mixed with cheese factory cleaning waters.