Endoscopic treatment of primary benign central airway tumors: Results from a large consecutive case series and decision making flow chart to address bronchoscopic excision.

BACKGROUND: Benign tracheo-bronchial neoplasms are rare, but potentially dangerous conditions with life threatening consequences. Tumor removal should be pursued by methods minimizing the procedural stress. The role of endoscopic treatment, as an alternative to open surgery, remains controversial. OBJECTIVES: report the twelve-years endoscopic experience in Rome, Italy. Fifty-seven benign tracheo-bronchial tumors were diagnosed and 130 tracheo-bronchial resections by rigid bronchoscopy performed. METHODS: we identified histotypes associated with higher recurrence rate and assessed their relationship with gender, age and tracheo-bronchial location. We provided data on safety and complications and suggested a decision making flow chart to address the patients to endoscopic resection. RESULTS: complete eradication after a single procedure without recurrence at 2 years was obtained in 63.1% of cases (36/57). Need of a second intervention within few months but no further recurrence at follow up was seen in a further 8.8% (5/57). Histotypes associated with recurrence were papillomas and inflammatory polyp. Seven patients (12.3%) were addressed to surgery because of multiple recurrence. Ten patients (17.5%) were lost at follow up. In case of recurrence, the bronchial biopsy was always repeated and no malignant transformation was observed. No major complications, pneumothorax or pneumomediastinum occurred. CONCLUSIONS: endoscopic treatment of benign tracheo bronchial tumors is safe and effective, provided that the procedure is carefully and systematically planned. The rate of eradication is satisfactory and the incidence of complications negligible. This will encourage this approach as first line treatment especially in patients, frequently elderly people, having increased surgical risk due to concomitant respiratory failure or major comorbidities.

Syndrome of iron pill inhalation in four patients with accidental tablet aspiration: Severe airway complications are described.

Iron pill inhalation represents a uncommon cause of syntomatic endobronchial foreign bodies. Unlike foreign body, the direct contact of iron tablet onto the bronchial mucosa results in severe bronchial damage in addition to obstruction and local irritation. Four patients with Iron Pill Inhalation Syndrome are described. All but one patient developed irreversible bronchial stenosis as late post inflammatory complication. Bronchoscopic features and clinical evolution are described in order to reduce the risk of severe side-effects in patients highly suspected for iron pill aspiration.

Excess sludge reduction by biological way: from experimental experience to a real full scale application.

The aim of this study was to investigate the ability of a biological process applied in the sludge line and based on the alternation of oxic and anoxic phases, to minimize the waste sludge production. After some tests in pilot scale, the process was applied in a real municipal wastewater treatment plant of 35,000 PE trying out one setting of working experimental conditions. A rate of the recycle flow was conditioned in a treatment basin, maintaining an HRT of 10 days. The control device operated for the 50% of time in the ORP range between -400 and -200 mV, and for the 50% in the ORP range between -200 and +50 mV. The mass balance defined an actual observed growth yield equal to 0.09 kgTVSkgCODr(-1), and the heterotrophic yield values, assessed by batch tests, seemed to be a suitable marker for the sludge reduction and for the energy uncoupling.

From conventional activated sludge to alternate oxic/anoxic process: the optimisation of winery wastewater treatment.

The paper deals with the results obtained as nitrogen removal and energy savings in a wastewater treatment plant located in the Province of Trento where the vineyards grow on about 1,500 ha (19% of total vineyards of the Province). In the plant the municipal and pre-treated winery wastewater were co-treated. The optimal effluent quality and the reduction of energy consumption were achieved changing the total oxidation process to an alternate cycles (AC) one and applying a remote control system for three months. The characterization of the influent highlighted a remarkable variability of the mass loads mainly determined by the cyclic winemaking periods. The AC application allowed the system to cope with the intense variations of influent nitrogen loadings and to obtain a stable quality of the effluent with an average TN concentration less than 10 mg NL(-1). The nitrogen loading rate (NLR) up to 0.227 Kg TN m(-3) d(-1) was tolerated by the elevated AC control level device to assure successful denitrification performances (from 70% to 90%) also in conditions of COD/TN lower than 7. Comparing the AC with the pre AC conditions, a total energy saving in the range of 13-23% was estimated. Moreover, the specific energy consumptions were reduced to 59% despite the increment of the influent mass loadings.

Exploring the potential of membrane bioreactors to enhance metals removal from wastewater: pilot experiences.

The potential of membrane bioreactors to enhance the removal of selected metals from low loaded sewages has been explored. A 1400 litre pilot plant, equipped with an industrial submerged module of hollow fibre membranes, has been used in three different configurations: membrane bioreactor, operating in sequencing batch modality, for the treatment of real mixed municipal/industrial wastewater; membrane-assisted biosorption reactor, for the treatment of real leachate from municipal landfills; continuously fed membrane bioreactor, for the treatment of water charged with cadmium and nickel ions. The results show that: (a) in treating wastewaters with low levels of heavy metals (< one milligram per litre concentration), operating high sludge ages is not an effective strategy to significantly enhance the metals removal; (b) Hg and Cd are effectively removed already in conventional systems with gravitational final clarifiers, while Cu, Cr, Ni can rely on a additional performance in membrane bioreactors; (c) the further membrane effect is remarkable for Cu and Cr, while it is less significant for Ni. Basically, similar membrane effects recur in three different experimental applications that let us estimate the potential of membrane system to retain selected metal complexes. The future development of the research will investigate the relations between the membrane effect and the manipulable filtration parameters (i.e., permeate flux, solids content, filtration cycle).

Treatment of winery wastewater in a conventional municipal activated sludge process: five years of experience.

A full-scale wastewater treatment plant where municipal and winery wastewaters were co-treated was studied for five years. The experimental results showed that suspended solids, COD, nitrogen and phosphorous were effectively removed both during the treatment of municipal wastewater and the cotreatment of municipal and winery wastewater. The sludge production increase from 4 tons to 5.5 tons per day during the harvesting and wine making period. In any case the specific sludge production was 0.2 kgMLVSS per kgCOD(removed) despite the organic loading increasing. About 70% of the COD was removed through respiration. Also the energy demand increased from 6,000 to 7,000 kWh per day. The estimated costs for the treatment of the winery wastewater was 0.2-0.3 Euros per m3 of treated wastewater. With reference to the process efficiency, the nitrogen removal was just 20%. The co-treatment of municipal and winery wastewater in conventional activated sludge processes can be a feasible solution for the treatment of these streams at relatively low costs.

Anaerobic co-digestion of sludge with other organic wastes and phosphorus reclamation in wastewater treatment plants for biological nutrients removal.

This paper deals with the performances obtained in full scale anaerobic digesters co-digesting waste activated sludge from biological nutrients removal wastewater treatment plants, together with different types of organic wastes (solid and liquid). Results showed that the biogas production can be increased from 4000 to some 18,000 m3 per month when treating some 3-5 tons per day of organic municipal solid waste together with waste activated sludge. On the other hand, the specific biogas production was improved, passing from 0.3 to 0.5 m3 per kgVS fed the reactor, when treating liquid effluents from cheese factories. The addition of the co-substrates gave minimal increases in the organic loading rate while the hydraulic retention time remained constant. Further, the potentiality of the struvite crystallisation process for treating anaerobic supernatant rich in nitrogen and phosphorus was studied: 80% removal of phosphorus was observed in all the tested conditions. In conclusion, a possible layout is proposed for designing or upgrading wastewater treatment plants for biological nutrients removal process.

Application of a membrane bioreactor for the treatment of low loaded domestic wastewater for water re-use.

This paper describes the demonstrative scale application of a membrane biological reactor (MBR) for low loaded domestic wastewater with low attitude to biological treatment (carbon/nitrogen approximately 5). The biological process was managed by the automatically controlled alternate cycles allowing for re-use purposes with a remarkable reduction of the operational costs. The global process evaluation revealed the system capability of obtaining high nitrogen removal (effective nitrogen removal of 69%) thanks to its high flexibility related to the hourly loading fluctuation. Moreover, high removal of heavy metals and polycyclic aromatic hydrocarbons (PAH) was obtained due to the perfect retention capability of the membranes. In-depth studies were conducted to determine the process behaviour for activated sludge over aeration and with addition of exogenous carbon. Limitation of sludge over aeration and energy savings were observed with a gradient air supplying method. The addition of exogenous carbon (acetic acid up to carbon/nitrogen approximately 9) led to complete nitrogen removal (Ed = 96%) and permitted biological phosphorus uptake. In conclusion, it was been found that the coupled process alternated cycles-MBR had the capacity to remove COD, BOD, N, P and suspended solids, as well as heavy metals and organic micropollutants, resulting in high quality effluent suitable for re-use purposes.

Anaerobic codigestion of waste activated sludge and OFMSW: the experiences of viareggio and treviso plants (Italy).

The paper presents the results of two full-scale applications of the anaerobic co-digestion process of waste activated sludge together with the organic fraction of municipal solid wastes. The experiences were carried out at Viareggio and Treviso wastewater treatment plants (Italy). In the first plant, 3 tons per day of source sorted OFMSW were co-digested with waste activated sludge, increasing the organic loading rate from 1.0 to 1.2 kgTVS/m3d. This determined a 50% increase in biogas production. At Treviso WWTP, which has been working for 2 years, some 10 tons per day of separately collected OFMSW are treated using a low-energy consumption sorting line, which allows the removal of 99% and 90% of metals and plastics respectively. In these conditions, the biogas yield increased from 3,500 up to 17,500 m3/month. Industrial costs were evaluated less than 50 Euro per ton of organic waste, while the payback time was calculated as two years.

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.

Treatment of mixed municipal and winery wastewaters in a conventional activated sludge process: a case study.

The possibility of co-treating municipal and winery wastewaters in a conventional activated sludge process was studied at full scale. The wastewater treatment plant considered in this paper operated an extended-oxidation process during vintage (four month per year) and a pre-denitrification/ oxidation process during the rest of the year. The experimentation showed that good performances, in terms of COD and nitrogen removal, could be obtained in both cases: 90% and 60%, for COD and nitrogen removal, respectively. Thanks to the high solid retention times applied to the system (up to 48 days) the waste activated sludge production was low (0.20 kgMLVSS/kgCODremoved) and respiration was the main process for carbon removal. Nitrification was always satisfactory while the behaviour of the denitrification process during vintage was not totally understood and further studies are going on.

Anaerobic digestion of organic solid wastes: process behaviour in transient conditions.

This paper presents the study of the variations of the process parameters during transient conditions when substrates with different biodegradability were fed to a pilot-scale anaerobic digester. The two substrates used in the experiments were the mechanically selected organic fraction of municipal solid wastes and a blend of mechanically selected and separately collected organic fraction of municipal solid wastes. Two transient conditions were studied: the mesophilic-thermophilic passage and the increase of the organic loading rate in thermophilic conditions. It was shown that enhanced fractions of biodegradable substrates determined a greater perturbation of the system and needed longer time to reach a new stable condition. The volatile fatty acids concentration and their indirect measure, alkalinity determined upon pH 4, was the more useful parameter to understand the process behaviour because of its sensitivity to the process variations.

The under sink garbage grinder: a friendly technology for the environment.

The use of garbage grinders is not a usual practice in Europe, but it is in other countries around the world (e.g., North America, Japan and Australia). Sometimes, garbage grinders are accused of producing problems in sewers and wastewater treatment plants and are prohibited by environmental protection laws. In this study, the different impacts determined by the use of this technology were considered to show the positive impacts of its use. In particular, it was shown that garbage grinders enable the disposal of household organic wastes with advantages for the wastewater treatment processes because of an increase in the carbon/nutrients ratio in the wastewater. This is particularly important for biological nutrients removal processes. Daily specific contributions for person equivalent (PE) due to organic waste disposal through garbage grinders were found to be equal to 75 gCODPE(-1) d(-1) for carbon (as COD), 2.5 gNPE(-1) d(-1) for nitrogen and 0.25 gPPE(-1) d(-1) for phosphorous, respectively. Those determined a value of 30 for the COD/N ratio. Moreover, no problems with solids settling in sewers were noted. These results were extensively compared with literature data. The economical balance showed that the use of garbage grinders allowed a global saving of some 17 Euro year(-1) for a three people family. Important benefits are also gained from an environmental point of view (e.g, organic wastes disposal nutrients removal in wastewater treatment and increase in biogas production with energy reclamation).

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.

The AF-BNR-SCP process as a way to reduce global sludge production: comparison with classical approaches on a full scale basis.

The paper presents a comparison between the performances of two full scale wastewater treatment plants operating in Italy, considering the mass balances including P treatments, and results coming from an analysis of 16 similar plants in Europe and USA, in order to evaluate sludge overproduction due to chemical P removal adoption. Specific production of 9.5 and 12.5 kgTS/P.E.y were found for a BNR and denitrification plant scheme respectively. These results were compared, on a mass balance basis, with the performances coming from the adoption of the integrated waste/wastewater cycles, in which OFMSW fermentation is used as C source to promote BNR performances and P removal from anaerobic supernatants as struvite crystals. ASM2 simulations are used to verify the advantages coming from this approach in terms of sludge reduction. A complete mass balance of the process is carried out, and it is shown that this last process allows us to achieve the lowest sludge production among the processes considered, coupling this with the economic benefits coming from OFMSW disposal and struvite crystallisation.

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.

Phosphorus removal from a real anaerobic supernatant by struvite crystallization.

In this paper the phosphorus removal from a real anaerobic supernatant through the crystallization of struvite and or hydroxyapatite was investigated. A comparison between experimental results on phosphorus crystallization carried out in a fluidized-bed reactor (FBR) on a bench-scale and on a half-scale plant is presented, together with a double saturational model able to describe all experimental results, independent of the different geometry of the reactors, the distinct contact times and the unlike products obtained. Experimental results show that removal efficiencies are very satisfactory, and the maximum phosphorus removal is of 80%.

Two-phase anaerobic digestion of source sorted OFMSW (organic fraction of municipal solid waste): performance and kinetic study.

The results of a two-phase system operated in different conditions, treating the source-sorted organic fraction of municipal solid waste (SS-OFMSW), coming mainly from fruit and vegetable markets, are presented. Hydraulic retention time (HRT) in the hydrolytic reactor and in the methanogenic reactor and also the temperature in the hydrolytic reactor (mesophilic and thermophilic conditions) are varied in order to evaluate the effect of these factors. The methanogenic reactor is always operated within the thermophilic range. Optimum operating conditions are found to be around 12 days (total system) using the mesophilic range of temperature in the first reactor. Specific gas production (SGP) in these conditions is around 0.6 m3/kg TVS. A kinetic study is also carried out, using the first and the step diffusional models. The latter gives much better results, with fitted constants comparable to other studies. Finally, a comparison with a one-phase system is carried out, showing that a two-phase system is much more appropriate for the digestion of this kind of highly biodegradable substrate in thermophilic conditions.

Rheology of sludge from double phase anaerobic digestion of organic fraction of municipal solid waste.

In this paper experimental results on the anaerobic digestion of sewage sludge and organic fraction of municipal solid waste (OFMSW) by using a double phase process are reported. The long-term experiment has been carried out on a pilot scale plant, performed in different sets of operative conditions, during which granulometric distributions of particles in sludges and rheological properties of sludges were monitored. A significant fluidification of sludge was evidenced in the meso-thermo process, especially taking into account the variation in sludge behaviour from the first to the second phase. In the thermo-thermo process a fluidification higher than that shown in meso-thermo conditions is not observed, this suggesting that better results in terms of sludge conditioning can be obtained in a long time spent in thermophilic anaerobic digestion. Total volatile solids (TVS) and total fixed solids (TFS) become the most important parameters when mathematical modelling is applied to these processes. In the acidogenic phase, hydraulic retention time (HRT) and temperature are used to determine rigidity coefficient (RC), while only temperature is needed for yield stress (YC). Organic loading rate (OLR) and specific gas production (SGP) exert an important role in methanogenic phase description.