Regression of Acanthosis Nigricans with the Addition of Sitagliptin and Pioglitazone.

Acanthosis nigricans (AN) is a cutaneous disorder associated with various diseases. There are few documented cases of regression of AN. We discuss a case of a 48-year old diabetic woman with resolution of AN after treatment with sitagliptin and pioglitazone.

SBR treatment of olive mill wastewaters: dilution or pre-treatment?

The olive-oil extraction industry is an economically important activity for many countries of the Mediterranean Sea area, with Spain, Greece and Italy being the major producers. This activity, however, may represent a serious environmental problem due to the discharge of highly polluted effluents, usually referred to as 'olive mill wastewaters' (OMWs). They are characterized by high values of chemical oxygen demand (COD) (80-300 g/L), lipids, total polyphenols (TPP), tannins and other substances difficult to degrade. An adequate treatment before discharging is therefore required to reduce the pollutant load. The aim of the present paper was to evaluate performances of a biological process in a sequencing batch reactor (SBR) fed with pre-treated OMWs. Pre-treatment consisted of a combined acid cracking (AC) and granular activated carbon (GAC) adsorption process. The efficiency of the system was compared with that of an identical SBR fed with the raw wastewater only diluted. Combined AC and GAC adsorption was chosen to be used prior to the following biological process due to its capability of providing high removal efficiencies of COD and TPP and also appreciable improvement of biodegradability. Comparing results obtained with different influents showed that best performances of the SBR were obtained by feeding it with raw diluted OMWs (dOMWs) and at the lowest dilution ratio (1:25): in this case, the removal efficiencies were 90 and 76%, as average, for COD and TPP, respectively. Feeding the SBR with either the pre-treated or the raw dOMWs at 1:50 gave very similar values of COD reduction (74%); however, an improvement of the TPP removal was observed in the former case.

Application of excess activated sludge ozonation in an SBR Plant. Effects on substrate fractioning and solids production.

This paper provides new insights on the application of the ozonation process for the reduction of the activated sludge production in a sequencing batch reactor (SBR). The study was performed in two identical lab-scale SBRs plant, one for experimental activities (Exp SBR) and one used as control (Control SBR), both fed with domestic sewage. A fraction of the activated sludge collected from the Exp SBR at the end of the aerobic react phase was periodically subjected to ozonation for 30 minutes at three different specific dosages (0.05, 0.07 and 0.37 g O(3)/gSS) and then recirculated before the beginning of the following cycle.Recirculation of the ozonated sludge to the Exp SBR did not appreciably affect the efficiency of the biological nitrogen and carbon removal processes. Nonetheless, an improvement of the denitrification kinetic was observed. Mixed liquor volatile and suspended solids (MLSS and MLVSS, respectively) concentrations in the reactor decreased significantly with time for long term application of the ozonation treatment. Kinetic batch tests on unstressed sludge taken from Control SBR indicated that the different oxidant dosages (0.05, 0.07 and 0.37 g O(3)/gSS) and durations of the ozonation process (10, 20 and 30 minutes) used remarkably affected chemical oxygen demand (COD) and organic nitrogen fractioning. In particular, soluble and biodegradable fractions seemed to be higher at lower dosage and longer contact time.

Remediation of chlorophenol- and phenol-contaminated groundwater by a sequencing batch biofilm reactor.

The paper describes the results of an investigation aimed at evaluating suitability of a lab-scale Sequencing Batch Biofilm Reactor (SBBR) for the remediation of groundwater contaminated by phenol (P) and 2-chlorophenol (2-CP). Kinetics of compound degradation was determined along the bed height in the absence and in presence of effluent recirculation, and with different influent composition (compounds fed separately or in combination in the same stream). SBBR performances with and without recirculation were very satisfactory for all the influent compositions: the system showed 99% removal efficiencies for both phenol and 2-CP and their complete removal was always achieved far before the end of react. In the presence of recirculation, the concentration gradient established during fill was rapidly eliminated and an even biomass distribution along the bed height was formed. Consequently, an acceleration of the elimination process was observed, particularly for phenol that was mostly removed in the first hour of the cycle. When the compounds were fed simultaneously, 2-CP removal kinetics improved probably due to cometabolism. The adsorption phenomena of the toxic compounds on the packing material were studied also, showing about 50% COD removal after 7 hours contact time.

The effect of operating variables on chelant-assisted remediation of contaminated dredged sediment.

The paper shows the results from a number of lab-scale washing treatments using the four chelating agents EDTA, NTA, citric acid and [S,S]-EDDS aiming at the remediation of a real heavy metal-contaminated sediment. Investigation of the influence of chelant type and concentration as well as solution pH was the major focus of the work. The analysis of speciation of metals and chelating agents in solution was carried out through geochemical speciation modelling in order to identify the optimal conditions for the washing process as well as to evaluate the competition phenomena of metal-chelant complexes in solution. The major competing cations were found to be Ca above all and Mg under specific conditions. Among the investigated chelating agents, EDDS appeared to be less affected by competition by major cations while ensuring adequate heavy metal extraction efficiencies. For a 1:1 chelant/metal ratio, the following ranking was observed: EDDS>Cit>NTA>EDTA for As, EDDS>NTA congruent withEDTA>>Cit for Cu, EDDS congruent withEDTA congruent withNTA>Cit for Zn, EDTA>NTA>EDDS>Cit for Pb at pH 5 and EDTA congruent withEDDS congruent withNTA>>Cit for Pb at pH 8. For a 10:1 chelant/metal ratio geochemical modelling indicated that at the equilibrium the extracting solutions were dominated by the free form of the chelating agents, indicating the inability of such species to complex trace metals due the strong interactions existing between heavy metal ions and sediment constituents.

Effect of ozonation on sludge reduction in a SBR plant.

This paper provides new insights on the application of the ozonation process for the reduction of activated sludge production in a Sequencing Batch Reactor. The study was performed on two identical lab-scale SBRs plant, fed with domestic sewage: a fraction (1/3 of the working volume) of the activated sludge from one reactor (Exp SBR) was periodically subjected to ozonation for 30 minutes at 0.05 g O(3)/gSS and then recirculated before the beginning of the cycle; the other reactor was used as control and therefore managed at the same sludge retention time but without the application of ozonation. The effects of the recirculation of the ozonated sludge to the Exp SBR were evaluated in terms of biological nitrogen and carbon removal efficiencies, Mixed Liquor Volatile and Suspended Solids (MLSS and MLVSS, respectively) concentrations, effluent quality and sludge settleability. Besides, characterization of the ozonated sludge was carried out for different oxidant dosages (0.05, 0.07 and 0.37 g O(3)/gSS) and durations of the ozonation process (10, 20 and 30 minutes). The results show that at 0.05 g O(3)/gSS and 30 minutes contact time MLVSS as well as MLVSS/MLSS ratio do not change appreciably. Ozone dosage must be increased much further to obtain a relevant effect.

A kinetic study of chelant-assisted remediation of contaminated dredged sediment.

A study on the remediation of a real heavy metal-contaminated sediment was conducted using the four chelating agents ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), citric acid and the S,S-isomer of the ethylenediaminedisuccinic acid ([S,S]-EDDS). Different chelant washing experiments were carried out at a chelant/total metal content of 1 and 10 mol/mol for treatment durations from 0.5 to 48 h to study the extraction kinetics of trace metals and major cations. The objective was to evaluate the removal efficiency of conventional chelating agents as compared to innovative, biodegradable species. Among the target contaminants, Cd, Cu, Pb and Zn were found to be adequately removed by both EDTA and EDDS, while NTA and citric acid yielded unsatisfactory results in some cases. It was also found that As was a critical contaminant which would require an additional specific treatment step, since the residual concentrations after the washing treatment were still far above the regulatory limit values.

Influence of anaerobic digestion on particle surface charge and optimal polymer dosage.

Anaerobic digestion leads to significant changes of the sludge structural matrix, affecting particle size distribution and dewaterability. The surface charge, determined by means of streaming current, can be effectively used to monitor the complex phenomena of floc disruption, colloid formation and chemical conditioning. To study the relation between surface charge and optimal dosage, two different cationic polyelectrolytes were used: Praestol 644, polymer with high molecular weight and low charge density, and Poly Dadmac, with relatively low molecular weight but high charge density. The optimal Poly Dadmac dosage strictly met the value required to neutralise particle charge whereas the optimal dosage of Praestol 644 indicated that the relevant charge was considerably lower than the one required for charge neutralisation. Mechanisms of action are therefore clearly different. Another objective was to investigate the changes of dewatering characteristics of secondary sludge during anaerobic digestion tests at different inoculum content by determining charge density, and optimal polymer dosage. The optimal polyelectrolyte dosage remains almost constant during digestion at high inoculum, but a significant increase in the first period is observed at low inoculum, thus suggesting that the release of colloidal and supracolloidal material from sludge affects dewaterability, especially in the first days of digestion.

Effect of feed/inoculum ratio on anaerobic digestion of sonicated sludge.

In recent years, relevant interest has been devoted to activated sludge disintegration and solubilisation techniques in order to cope with the biological limitations related to particulate degradation. Mechanical disintegration with ultrasound can efficiently transform insoluble organics into a soluble form: the solubilised organic matter is released from the cells to the bulk phase, thus accelerating the hydrolysis step in the digestion process. Experiments were carried out on bench scale anaerobic reactors fed with either untreated or disintegrated excess sludge, added with a biomass inoculum taken from a full scale anaerobic digester. Digestion tests have been carried out at different feed/inoculum ratios (F/I) in the range of 0.1-2, kinetics of VS reduction has been investigated and a beneficial effect of sonication is observed for all the experimental conditions. Similar beneficial results have also been found for biogas production with a maximum gain of 25% at 0.5 F/I ratio.

Aerobic storage by activated sludge on real wastewater.

Activated sludge processes are often operated under dynamic conditions, where the microbial response can include, besides of growth, several COD removal mechanisms, and particularly the storage in form of polymers. While abundant evidence of aerobic storage under dynamic conditions with synthetic substrates can be found (Majone et al., Water Sci. Technol. 39(1) (1999) 61), there is still little knowledge about COD removal mechanisms with real activated sludge and wastewater. The aim of the present paper is therefore to give a direct evidence of storage phenomena occurring when a real sludge is mixed with influent wastewater and of their influence onto OUR profiles in typical respirometric batch tests. For this purpose, respirometric batch tests were performed on the same sludge by using acetate, filtered wastewater and raw wastewater as carbon source along with determination of acetate uptake and storage polymer formation. Comparison of results obtained has shown that poly-3-hydroxybutyrate (PHB) storage gives always the main contribution to acetate removal and that in the case of wastewater PHB is also formed from other substrates. PHB formation clearly occurs during the high-rate RBCOD-phase, however for wastewater it accounts for only a fraction (18-22%) of overall RBCOD removal, so calling for other unidentified storage compounds or other non-storage phenomena. In the low-rate SBCOD phase of respirogram PHB is clearly utilised in tests with acetate as internal reserve material once the acetate is depleted. In tests with filtered and raw wastewater the PHB concentration decreases much slower, probably because more PHB is formed due to the availability of external SBCOD (soluble and not). Moreover, reported OUR in the SBCOD-phase from filtered or raw wastewater are quite higher than those reported in batch tests with acetate, so confirming a main contribution of external SBCOD. However, the respective contributions for utilisation of previously stored compounds and of external SBCOD cannot be easily separated by the comparison of tests on filtered and raw wastewater, because both substrates are simultaneously present also in tests with the filtered wastewater. As a side consequence, the chemical-physical method for evaluation of true soluble and biodegradable COD tends to overestimate the respirometry-based RBCOD, at least for the wastewater under observation. Even though modelling by ASM3 (Gujer et al., Water Sci. Technol. 39(1) (1999) 183) makes it possible to well describe the whole experimental behaviour, it requires that much more storage compounds are formed than the experimentally observed PHB. These compounds have still to be identified and quantified in order to confirm the conceptual structure of ASM3.

Experimental study on nitrification in a submerged aerated biofilter.

The aim of the present work was to evaluate the performance of a semi-pilot scale BAF in order to obtain a highly polished effluent in terms of removal of organic matter, suspended solids and ammonia and to observe the influence of temperature, pH and nitrite accumulation on the nitrification process. The ammonia removal efficiency during summer and winter and the nitrite accumulation in presence of free ammonia were observed. The biomass density was measured at different filter bed heights and the sludge production from the effluent of the backwashing water was evaluated. The results obtained were used to calibrate a mathematical model for the prediction of the ammonia removal profile in the filter bed and of biomass thickness.

Kaolinite sorption of Cd, Ni and Cu from landfill leachates: influence of leachate composition.

Heavy metal speciation in landfill leachates plays a significant role in determining the mobility during the percolation through soils. The complexation characteristics of landfill leachate directly affects heavy metal solubility and the extent of the interaction with soils, lowering or raising the sorbed amount depending on the relative affinity of the complexed metal and uncomplexed form to soil adsorption sites. In this paper, the adsorption of Cd, Ni and Cu onto kaolinite from three leachates (collected from landfill at different fermentation stage) is studied, also in comparison with metal speciation by two different operative procedures. The heavy metals, at their natural concentration, were divided into operational classes according to an exchange-based procedure and by fractionation on the basis of molecular weight (exchange onto Chelex100 resin and ultrafiltration, respectively). All the experiments were performed also on synthetic solutions designed according to leachate composition and theoretical speciation. The experimental results have shown leachate complexing capacity is strongly dependent on landfill age, and that broad parameters such as COD, DOC, pH, ionic strength and VFA concentration are not able to predict it. It is notheworthy that the strong complexing capacity of leachate can cause extraction of metals from the solid phase instead of adsorption from the liquid one.

Experimental study on carbon removal in biological aerated filters.

The aim of the present work was to evaluate the performance of a pilot-scale BAF in terms of removal of organic matter and suspended solids to obtain a highly polished effluent. The first part of the research was the evaluation of the optimal filter media for a full scale BAF. Mechanical and biological tests were performed over four materials: glass, plastic, pozzolan and expanded clay (Arlita) and the results obtained showed that the plastic spheres and the Arlita particles were the optimal materials for both the mechanical and biological requirements. Hence, a down-flow pilot scale BAF was set up in the laboratory to treat a synthetic medium. As filter media first plastic spheres and then Arlita spheres were used. Carbon removal studies were carried out at several influent COD concentrations, specific removal efficiency and COD profiles along the height of the filter were determined and used to analyze the process. Validation and calibration of a mathematical model formulated for carbon removal, were also performed by using the experimental data obtained. The results showed that this system allows us to achieve the more strict limits on final effluent.

A model to control intermittent aeration phases.

Dealing with intermittent aeration as a useful practice to improve nitrogen removal efficiency of activated sludge plants, the possibility to plan optimal temporisation during daytime was investigated. A mathematical model (NIDEN) that allows us to manage different situations, with respect to influent load, environmental conditions and operating strategy, was then developed. The model represents a useful tool especially to plan the aeration cycles in small and medium sized plants, where high costs of automatic control through on-line instrumentation might not be justified. Once the input variables have been defined and the set-point values for tank nutrient concentration have been fixed, NIDEN gives an optimal phase temporisation, to obtain either the maximum energy saving or the best total nitrogen removal.

The Biological Aerated Filter (BAF) as alternative treatment for domestic sewage. Optimization of plant performance.

The aim of the present study was to investigate the suitability of a Biological Aerated Filter (BAF) plant as an alternative process or an upgrading step for the treatment of domestic wastewater from the city of Rome, Italy. The results obtained through a three years experimental activity on a pilot-scale BAF plant fed with real wastewater showed high process efficiencies and stable performance for both carbon and ammonia oxidation. The effluent quality met, on average basis, 68 mg/L total COD (COD(tot)), 37 mg/L Total Suspended Solids (TSS), 3.3mg/L ammonia-nitrogen (NH(4)(+)-N) and 21.1mg/L nitrate-nitrogen (NO(3)(-)-N). Despite the good performance, the high content of suspended solids in the influent stream caused filter bed clogging and frequent backwashing operations were required. Therefore, in the last part of the experimental activity a pre-treatment step was adopted prior to the biological step, consisting of chemical precipitation by lime addition. The influent quality parameters were consequently modified; for instance the particulate matter content was reduced by about 73%. The process efficiency of both ammonia and organic carbon oxidation did not modify appreciably; however, a beneficial effect was obtained on the frequency of the backwashing phase, which could be reduced by half. Since the new combined chemical-biological system demonstrated to be a valid alternative to the activated sludge treatment plant, a modeling activity was finally performed with the aim of evaluating the design parameters of a full-scale BAF plant fed with the same pre-treated wastewater as used in the experimental activity. The results of this phase are also herewith presented and discussed.

Biological treatment of tannery wastewater in the presence of chromium.

Experiments were carried out to determine the feasibility of treating tannery wastewater containing chromium, an inhibiting compound, with sequencing batch reactors (SBR). The maximum chromium concentration tolerated by microorganisms was determined through aerobic and anoxic batch experiments, and the biomass inhibition process was analyzed in a lab scale reactor at increasing chromium concentrations. The results obtained, in batch experiments and in the SBR reactor, have demonstrated that chromium addition had less influence on the denitrification bacteria than on the nitrification bacteria. In addition, it was observed that nitrification and denitrification rates, at the same chromium concentration, were higher in the SBR reactor than in batch experiments with unacclimated biomass. Experimental results confirm that sequencing batch reactors are able to produce a more resistant biomass, which acclimates quickly to inhibiting conditions. A large amount of chromium was found in the sludge from the reactor, while the effluent was devoid of the inhibiting metal.