Direct quantification of bacterial biomass in influent, effluent and activated sludge of wastewater treatment plants by using flow cytometry.

A rapid multi-step procedure, potentially amenable to automation, was proposed for quantifying viable and active bacterial cells, estimating their biovolume using flow cytometry (FCM) and to calculate their biomass within the main stages of a wastewater treatment plant: raw wastewater, settled wastewater, activated sludge and effluent. Fluorescent staining of bacteria using SYBR-Green I + Propidium Iodide (to discriminate cell integrity or permeabilisation) and BCECF-AM (to identify enzymatic activity) was applied to count bacterial cells by FCM. A recently developed specific procedure was applied to convert Forward Angle Light Scatter measured by FCM into the corresponding bacterial biovolume. This conversion permits the calculation of the viable and active bacterial biomass in wastewater, activated sludge and effluent, expressed as Volatile Suspended Solids (VSS) or particulate Chemical Oxygen Demand (COD). Viable bacterial biomass represented only a small part of particulate COD in raw wastewater (4.8 +/- 2.4%), settled wastewater (10.7 +/- 3.1%), activated sludge (11.1 +/- 2.1%) and effluent (3.2 +/- 2.2%). Active bacterial biomass counted for a percentage of 30-47% of the viable bacterial biomass within the stages of the wastewater treatment plant.

Biological treatment of winery wastewater: an overview.

The treatment of winery wastewater can realised using several biological processes based both on aerobic or anaerobic systems using suspended biomass or biofilms. Several systems are currently offered by technology providers and current research envisages the availability of new promising technologies for winery wastewater treatment. The present paper intends to present a brief state of the art of the existing status and advances in biological treatment of winery wastewater in the last decade, considering both lab, pilot and full-scale studies. Advantages, drawbacks, applied organic loads, removal efficiency and emerging aspects of the main biological treatments were considered and compared. Nevertheless in most treatments the COD removal efficiency was around 90-95% (remaining COD is due to the un-biodegradable soluble fraction), the applied organic loads are very different depending on the applied technology, varying for an order of magnitude. Applied organic loads are higher in biofilm systems than in suspended biomass while anaerobic biofilm processes have the smaller footprint but in general a higher level of complexity.

Membrane bioreactors for winery wastewater treatment: case-studies at full scale.

The membrane bioreactor technology (MBR) is nowadays a suitable alternative for winery wastewater treatment, thanks to low footprint, complete suspended solids removal, high efficiency in COD abatement and quick start-up. In this paper, data from two full-scale MBRs equipped with flat-sheet membranes (plant A and plant B) are presented and discussed. COD characterisation by respirometry pointed out the high biodegradability degree of both wastewater, with a strong prevalence of the readily biodegradable fraction. An extended version of Activated Sludge Model No. 3 was used to fit the experimental OUR profiles and to assess the maximum growth rate of heterotrophic biomass on sludge samples collected at both sites; the stoichiometric yield coefficients were also calculated. Sludge filterability and dewaterability were investigated with batch tests; laboratory results confirmed the field observations. Finally, some considerations are listed, aimed at defining possible key-issues for optimal process design and operation.

Respirometric techniques for assessment of biological kinetics in constructed wetland.

The aim of this research was the development of a procedure to measure biological kinetics of organic matter oxidation and nitrification in constructed wetland, by using respirometric techniques. Columns simulating cores of vertical subsurface flow systems were investigated. The oxygen uptake rate (OUR) of the columns was calculated on the basis of the difference of DO concentrations measured continuously at the top and at the bottom of the column. From the respirogram, the following kinetic parameters have been evaluated: maximum rate of oxidation of readily biodegradable COD, maximum rate of nitrification, endogenous respiration of the biomass grown inside the bed. In order to improve the interpretation of the respirograms, additional respirometric tests were carried out on the wetland columns by using pure substrates, such as acetate (carbon source) and ammonium (substrate for nitrification). The kinetic parameters obtained from respirograms can be useful for control and design of constructed wetlands or for improving nutrient and carbon mass balances.

Biomass active fraction evaluated by a direct method and respirometric techniques.

The knowledge of the active biomass amount and its characterisation is of primary importance for the management and for the design of wastewater treatment plants on the basis of the recently developed models. OUR curves obtained in aerobic exponential growth tests are proposed by several authors as an indirect method to estimate the active fraction. The aim of this work is the application of a direct method to measure the viable biomass based on flow cytometry techniques and the comparison with the active fraction obtained from respirometric tests. To assess the viable fraction of a biomass expressed in terms of COD concentration it is necessary to estimate the biovolume of viable bacteria and to know the specific carbon content per cell. For the investigated activated sludge samples, the bacterial biomass measured by FCM was 588 mgCOD L(-1) on average in a two-months period. This value of active fraction corresponds to 14% of particulate COD. Active biomass values measured with the respirometric approach were consistent but generally higher than those obtained by FCM.

A comparison among different methods for evaluating the biomass activity in activated sludge systems: preliminary results.

In order to improve activated sludge plant operation (achieving higher efficiency and cost savings) beside influent and effluent characteristics and working parameters (e.g. dissolved oxygen, total and volatile suspended solids, pH, recirculation flow rate, etc.), the biomass activity should be monitored, the bacteria being responsible for the pollutant degradation. Since conventional cultivation based methods are inadequate to quantify environmental microorganisms (due to scarce number of cultivable microorganisms and time-consuming procedures) several "non-conventional" techniques were applied in this study, in order to compare the obtainable information and their routine feasibility. Different measurements (VSS concentration, Oxygen Uptake Rate, microbial counts by cultural and biomolecular methods--MPN-PCR, ATP content, dehydrogenase activity, microbial cell viability and enzymatic activity) were carried out on mixed liquor samples, taken from a municipal activated sludge plant (440,000 p. e.). The preliminary results of the research are presented in this paper.

Experimental validation of a single-OUR method for wastewater RBCOD characterisation.

Wastewater characterisation is of primary importance for the correct design and management of a treatment plant. The aim of this work was the evaluation of a new rapid and easy to use respirometric technique for the characterisation of readily biodegradable COD (RBCOD). When the necessary calibration curve is obtained, the RBCOD assessment procedure needs less than 30 minutes. On the contrary, conventional techniques require some hours. The first step consists in calculating a calibration curve in order to point out the correlation between oxygen consumed and known amount of added Sodium Acetate. To a well aerated biomass (in order to remove residual readily biodegradable substrate) a known amount of Sodium Acetate is added and the related OUR is measured. The oxygen consumed (delta DO) is related to the added COD (as Sodium Acetate). Therefore, the RBCOD concentration in wastewater samples can be obtained according to the following steps: (1) measure delta DO; (2) multiply delta DO by the Volume of aerated mixed liquor used in the test; (3) from the calibration curve, calculate the readily biodegradable COD equivalent to Acetate; (4) estimate RBCOD concentration multiplying the wastewater sample volume tested in the reactor. Some advantages of this technique are described in the paper.

Terbinafine in the treatment of non-immunocompromised compassionate cases of bronchopulmonary aspergillosis.

Conventional treatments of broncho-pulmonary aspergillosis are often ineffective and result in associated side-effects. Terbinafine (a new allylamine derivative), although as active against Aspergillus in vitro as amphotericin B and itraconazole, is less effective in rodent models because of a rapid hepatic first-pass effect. As terbinafine is metabolized differently in humans, the aim of this work was to evaluate this drug, for the first time, in the treatment of seven immunocompetent patients with lower respiratory tract mycotic infections unresponsive to the usual antimycotic drugs. Diagnosis was based on identification of fungal isolates, worsening of respiratory function tests, chest radiographs and computerized tomographic (CT) scan changes, positive skin test, aspergillin precipitins and clinical history. Terbinafine was administered at doses ranging from 5 to 15 mg kg-1 day-1 depending on the clinical severity of the disease, and was given for 90-270 days depending on clinical progress and compliance. In three patients A. fumigatus was suppressed with resolution of signs and symptoms; four patients showed transitory A. fumigatus suppression with marked clinical and radiological improvement. During relapses no resistance to terbinafine was observed. No significant side-effects were detected. Terbinafine appeared to be as effective as amphotericin B and itraconazole in the treatment of bronchopulmonary aspergillosis in nonimmunocompromised patients. These preliminary results suggest that controlled studies are warranted.

Selection and evaluation of recipients for heart-lung and lung transplantation: the Niguarda Hospital experience.

Between January 1989 and February 1993, 52 patients were evaluated at Niguarda Hospital for lung or heart and lung transplantation. Of the 35 that entered the waiting list, a total of 19 were transplanted (14 at other institutes before our surgical programme became operative, and 5 at our hospital). Recipient selection and evaluation criteria, and timing of transplantation in the different diseases are discussed.

A gas-chromatographic determination of the ppb levels of volatile halogenated hydrocarbons in water for injections.

Some volatile halogenated hydrocarbons have been found in commercial large volume parenterals (LVPs) prepared from untreated or treated (disinfected) water. To monitor the presence of volatile halogenated hydrocarbons in the source water and also in the water for injections, a low cost and sufficiently simple procedure has been developed, specifically for the following components: 1,1,1 trichloroethane, 1,1,2 trichloroethylene, 1,1,2,2 tetrachloroethylene, carbon tetrachloride, chloroform, dichlorobromomethane and dibromochloromethane. A Head-space technique coupled with ECD-gaschromatography was used. The procedure is thoroughly discussed in the article, including the results of a ring test for a preliminary validation of this method.

Metabolites of chlorinated solvents in blood and urine of subjects exposed at environmental level.

After a two-level selection, 141 blood donors living in Milan, Italy, were analyzed for their content of plasma and urinary trichloroacetic acid (TCA) and trichloroethanol (TCE). Environmental levels of exposure to trichloroethylene (TRI) and tetrachloroethylene (PER) through drinking water and air were also measured. The plasma TCA levels were in the range of previously found concentrations. Relationships among plasma and urinary metabolites were found and discussed.