Auto-nucleation and crystal growth of struvite in a demonstrative fluidized bed reactor (FBR).

The experience of P removal by auto-nucleation and crystal growth of struvite (MAP) in a demonstrative plant is proposed. The demonstrative plant is located in a municipal wastewater treatment plant in northern Italy. The trials are a consequence of previous experimentation carried out using silica sand as seed material. Working in metastable conditions the auto-nucleation process is performed, and allows the control of the precipitation and the growth of MAP inside the FBR reactor. No scaling problems are observed in the collecting pipes. After the treatment of 650m3 of anaerobic supernatants, 0.28 tons of granulated crystalline MAP are produced. The chemical analysis shows its possible use in agriculture as fertilizer. Operative costs analysis confirms the SCP as a cheap way to remove and recover P from anaerobic supernatants.

An alternate oxic-anoxic process automatically controlled. Theory and practice in a real treatment plant network.

A simple mathematical model of an alternate oxic-anoxic process has been elaborated. It enables us to optimise the cycle time on the basis of maximum nitrates concentration in the effluent and the desired nitrogen removal performance. At the same time the model can be employed to verify the impact of the variations of flow rate and influent characteristics as well as the operational parameters of the process. Actually, the model confirms the process efficiency but its feasibility in real plants needs a local or remote process control. To verify these theoretical conclusions a real wastewater plant (700 PE) has been upgraded in an alternate oxic-anoxic process. It was implemented with software able to elaborate the data of dissolved oxygen concentration and oxidation reduction potential. Moreover, the evaluation of the flexing points was performed to manage mixer and blowers. A one-year experience of plant management allowed us to obtain very high nitrogen removal. However, the performances were different during wet or dry weather periods. The statistical analysis of probe signals evaluation confirmed the capability of the control device to detect the flexing points during the anoxic phase (70-94%). On the other hand, the capability of detecting the DO signal was lower, in particular when the oxygen demand was similar to the amount of supplied oxygen. The hourly variations of flow rate and mass loading determines different conditions for starting the anoxic phase: over aeration, over loading and the equivalence of oxygen demand and supply, are the main factors determining the blowers stopping.

P removal from anaerobic supernatants by struvite crystallization: long term validation and process modelling.

In this work, a model for phosphorus crystallization in a fluidized bed reactor, able to describe the experimental results obtained during a semiscale pilot plant, is presented. In particular, the validity of the model proposed has been evenly extended with respect to a previous experiment, even at a lower contact time, and the length of each experiment has been increased, in order to verify the behaviour of the process for long term applications and to evaluate the maximum crystal growth of the system. Moreover, the state of the art of the available processes for phosphorus removal from wastewater is presented, together with a detailed review of the several models so far developed to describe the phosphorus crystallization mechanisms.

The monitoring of a two step aerobic-anoxic process with separate biomass to enhance performance in the treatment of liquid industrial wastes.

The paper presents the results of a one-year study of the performance of a full scale plant for the treatment of industrial liquid wastes adopting the alternate cycle process. The carbon and nitrogen removal performances were discussed according to the experimental measurements of maximum nitrification and denitrification rates. It was demonstrated that the nitrification process was the limiting step: it worked with a rate in the range 0.002 - 0.02 KgNH4-N kg(-1)VSS d(-) at 20 degrees C. This was because of inhibition phenomena due to the presence of both complex organic compounds and heavy metals which were not removed by the chemical-physical pre-treatment step. The denitrification process was characterized by a maximum rate ranging from 0.015 to 0.056 Kg NO3-N kg(-1)VSS d(-1) at 20 degrees C, according to the available amount of readily biodegradable COD in the treated wastes. The reliability of the aerobic-anoxic process was determined on the basis of the percentage of successful cycles compared with the performed ones. It was shown that the actual cycles ranged from 50 to 100% of the expected ones, while effective cycles were up to 84% in the first step and up to 60% in the second one. These were related to the carbon to nitrogen ratio. Even if at times the nitrogen and carbon removal yields were not satisfactory, the two step aerobic-anoxic process operated in the alternate cycle mode seems a successful solution for the treatment of liquid industrial wastes.

Systemic methotrexate treatment in early unruptured ectopic pregnancy.

Ectopic pregnancy is one of the most common and dangerous complications of the early pregnancy period. Until now diagnosis has been late because major symptoms occur after tubal rupture and so only demolitive surgery has been possible. At present, with the appearance of ultrasound in obstetrics an earlier diagnosis of this pathology can be made before tubal rupture so medical treatment has become possible. We treated a series of twelve patients with early ectopic pregnancy (9 tubal and 3 with no localized site of implantation) with intramuscular 0.5 mg/kg methotrexate and oral 0.1 mg/kg of folic acid (Citrovorum Factor) on alternate days, in the attempt to reduce hospitalization and obtain more effective and safer medical management. We observed a fall in serum beta-HCG levels after one cycle of treatment in 11 out of 12 patients and after two cycles of therapy in the remaining case. Minimal side-effects were observed in four cases. Three pregnancies occurred after treatment before the advised interval time and ended in blighted ovum. Methotrexate systemic therapy can be considered an elective treatment and a sufficiently safe management in early unruptured ectopic pregnancy when a good clinical selection of patients is performed.

[Destructive cervical amyloidotic spondyloarthropathy in patients undergoing periodic dialysis. Personal experience]. / La spondiloartropatia cervicale destruente amiloidotica nei pazienti in dialisi periodica. Esperienza personale.

The accumulation of amyloid (beta 2-microglobulin) in several organs and tissues of patients in chronic dialysis is a recent pathologic condition. A wide range of cases, supported by specific tests for amyloid on bioptic and autoptic samples, showed a radiographic semiology of osteostructural alterations in various areas which allows amyloidotic condition of bone to be diagnosed with high reliability. In 11 of 62 patients (17.74%) we observed destructive cervical amyloidotic spondyloarthropathy (DCAS). The radiological patterns common to all patients were subchondral sclerosis, erosions of vertebral body plates, widening/narrowing of intervertebral spaces, no/poor osteophytosis. Over-hanging was present in 54.5% of cases, and deformation of vertebral bodies in 45.4%. CT was useful in improving the definition of the various alterations, and in locating others, such as cavitations in vertebral bodies and involvement of apophyseal joints. Constant factors were the association with extravertebral osseous amyloidosis, dyalitic age over 60 months, and the use of Cuprophan membranes for dialysis. The frequent (72.72%) association with alterations involving the lumbar rachis (subchondral sclerosis, erosions and geodes) was suggestive of amyloidotic condition.

Normalization of renal function and blood pressure after dissolution with intra-arterial fibrinolytics of a massive renal artery embolism to a solitary functioning kidney.

The intra-arterial administration of fibrinolytics in a massive embolism to the renal artery of a solitary functioning kidney determined quick normalization of the severe renal failure and hypertension.