Ultrasound and microwave techniques for assisting ageing on lees of red wines.

Ageing on lees is a slow process that carries microbiological and economic risks in the wineries. This study evaluates the possibility of enhancing the extraction of different compounds from the lees, using combined strategies, such as ultrasound (US) or microwaves (MW) and the addition of inactive dry yeasts (IDY), to reduce the lees ageing time. The complete chemical analysis of the wine was done, amino acids, polysaccharides, colour and volatile compounds, together with the sensory analysis. The combined treatments increased the release of total polysaccharides, mannoproteins and total monosaccharides in the wines, and some amino acids like proline. However, wines treated with US and MW, with and without lees, showed a decrease in tannins and colour intensity, and in some volatile compounds like fatty acid esters, acetates and terpenes. The wines treated with IDY and MW were the best valued for their floral and red berry flavours and less astringency.

[Anxiety level of the healthcare workers of an obstetric unit during the COVID-19 pandemic]. / Nivel de ansiedad de los profesionales de sala de partos durante la pandemia por COVID-19.

BACKGROUND: Work-related stress, fear of becoming infected, and the lack of means to combat the COVID-19 pandemic, added to the situation of lockdown at home could lead to a strong impact on mental health.The objective was to determine the level of anxiety through the State-Trait Anxiety Inventory, STAI completed by the professionals of a delivery room who treated COVID-19-positive pregnant women. MATERIAL AND METHODS: Descriptive cross-sectional study in an obstetric area in Barcelona from March 14th to May 24th, 2020. Study population: healthcare staff over 18 years old, without diagnosed anxiety disorders prior to the pandemic.The main parameters to study were the level of «state anxiety¼ and «trait anxiety¼ according to the STAI questionnaire.Descriptive and inferential statistics were performed. The level of statistical significance used was p<.05. RESULTS: Seventy-seven professionals participated in this study.The mean score for «state anxiety¼ was 26.3 points (p-value = .067) and for «strait anxiety¼, 14.3 points (p-value = .091).It was observed that the professionals who had children (p-value = .048) and the professionals who stated that their family economic income had decreased (p-value = .026) showed higher average scores of «state anxiety¼. A positive association was observed between years of working experience and the level of «state anxiety¼, observing statistically significant differences, p-value = .030. CONCLUSIONS: The professionals who had suffered a reduction in their income together with those who lived with children presented higher scores of «state anxiety¼.

Noise levels during cesarean delivery: a prospective observational study.

BACKGROUND: Excessive noise has negative implications for both clinicians and patients. Emergency cesarean deliveries require rapid co-ordination and communication, possibly increasing noise pollution. We aimed to determine if noise levels in the Labor and Delivery operating room were higher during emergency cesarean deliveries than during non-emergency cesarean deliveries. METHODS: We conducted a prospective observational study measuring noise levels in Labor and Delivery operating rooms at a single academic medical center. Sound meters placed on anesthesia machines and events charted in the electronic medical record were used to correlate noise levels to clinical activity. Noise levels in all cesarean deliveries were recorded for one year. Deliveries were classified into two groups: non-emergency (routine or urgent) and emergency. We compared noise levels of the groups at eight time points of interest: anesthesia provider enters operating room (T1), induction (T2), five minutes before incision (T3), three minutes before incision (T4), one minute before incision (T5), time of incision (T6), delivery (T7), and five minutes before initiating emergence (T8). RESULTS: Noise levels were measured for 440 cesarean deliveries. Forty were classified emergency and 400 non-emergency (304 routine, 96 urgent) procedures. Emergency cesarean deliveries were noisier at all eight time points, although the absolute difference in decibels between the two groups was modest. The difference in noise level reached statistical significance at five time points (T1, T2, T5, T6, and T7). CONCLUSION: Noise levels were higher during emergency than during non-emergency cesarean deliveries.

Phakic intraocular lenses: Recent advances and innovations. / Lentes intraoculares fáquicas: recientes avances e innovaciones.

Phakic intraocular lenses (pIOL) are recommended when counselling refractive surgery candidates presenting with high ametropia or ocular surface and/or corneal conditions that contraindicate corneal refractive surgery. This review aims to present the state-of-the-art regarding pIOL models currently available in Europe, addressing their newer indications and recent design innovations. These include, in the case of posterior chamber pIOLs, the addition of a central hole to improve aqueous humour circulation, the availability of larger optical zones, and multifocal optics for the compensation of presbyopia. The review also highlights their good safety and efficacy results, as well as the role of patient education to ensure adequate outcomes in the medium-long term. The indications of pIOLs in special situations, as well as bi-lensectomy, a procedure that most pIOL patients may eventually require as they age and develop cataracts, are also addressed.

Model extension, calibration and validation of partial nitritation-anammox process in moving bed biofilm reactor (MBBR) for reject and mainstream wastewater.

In the paper, the extension of mathematical model of partial nitritation-anammox process in a moving bed biofilm reactor (MBBR) is presented. The model was calibrated with a set of kinetic, stoichiometric and biofilm parameters, whose values were taken from the literature and batch tests. The model was validated with data obtained from: laboratory batch experiments, pilot-scale MBBR for a reject water deammonification operated at Himmerfjärden wastewater treatment and pilot-scale MBBR for mainstream wastewater deammonification at Hammarby Sjöstadsverk research facility, Sweden. Simulations were conducted in AQUASIM software. The proposed, extended model proved to be useful for simulating of partial nitritation/anammox process in biofilm reactor both for reject water and mainstream wastewater at variable substrate concentrations (influent total ammonium-nitrogen concentration of 530 ± 68; 45 ± 2.6 and 38 ± 3 gN/m3 - for reject water - and two cases of mainstream wastewater treatment, respectively), temperature (24 ± 2.8; 15 ± 1.1 and 18 ± 0.5°C), pH (7.8 ± 0.2; 7.3 ± 0.1 and 7.4 ± 0.1) and aeration patterns (continuous aeration and intermittent aeration with variable dissolved oxygen concentrations and length of aerated and anoxic phases). The model can be utilized for optimizing and testing different operational strategies of deammonification process in biofilm systems.

Multi-Sensor Data Fusion for Real-Time Surface Quality Control in Automated Machining Systems.

Multi-sensor data fusion systems entail the optimization of a wide range of parameters related to the selection of sensors, signal feature extraction methods, and predictive modeling techniques. The monitoring of automated machining systems enables the intelligent supervision of the production process by detecting malfunctions, and providing real-time information for continuous process optimization, and production line decision-making. Monitoring technologies are essential for the reduction of production times and costs, and an improvement in product quality, discarding the need for post-process quality controls. In this paper, a multi-sensor data fusion system for the real-time surface quality control based on cutting force, vibration, and acoustic emission signals was assessed. A total of four signal processing methods were analyzed: time direct analysis (TDA), power spectral density (PSD), singular spectrum analysis (SSA), and wavelet packet transform (WPT). Owing to the nonlinear and stochastic nature of the process, two predictive modeling techniques, multiple regression and artificial neural networks, were evaluated to correlate signal parametric characterization with surface quality. The results showed a high correlation of surface finish with cutting force and vibration signals. The signal processing methods based on signal decomposition in a combined time and frequency domain (SSA and WPT) exhibited better signal feature extraction, detecting excitation frequency ranges correlated to surface finish. The artificial neural network model obtained the highest predictive power, with better behavior for the whole data range. The proposed on-line multi-sensor data fusion provided significant improvements for in-process quality control, with excellent predictive power, reliability, and response times.

How does the microbial load affect the quality of equine cool-stored semen?

Contaminating bacteria present in stallion ejaculates may compromise sperm quality during storage. Different procedures have been used to reduce the load of microorganisms in semen and avoid bacterial growth during storage. The aims of this study were: 1) to evaluate different techniques to eliminate bacteria in semen 2) to study the relationship between total microflora load (TML) and ROS production; and 3) to determine if TML affects the functionality of cool-stored sperm. Ejaculates from 11 stallions were split and processed in 3 ways: A. extended semen; B. conventional centrifuged semen, and C. Single layer centrifugation through Androcoll-E (SLC). All samples were preserved in INRA 96 at 5 °C for 72 h. Aliquots from native semen and from different treatments were taken for bacteriological analysis at T0, T24, T48 and T72h of storage and Total microbial load (TML: CFU (colony-forming units/ml) was calculated. The ROS production (dichlorodihydrofluorescein diacetate for H2O2, dihydroethidium for superoxide anion and CellROX deep red for total ROS), viability (YO-PRO-1-Ethidium) and lipid peroxidation (BODIPY-C11) were assessed by flow cytometry, and motility by CASA. The bacteria isolated were Corynebacterium spp, Arcanobacterium spp, Bacillus spp, Dermobacter, Staphylococcus spp, Streptococcus spp, Penicilium spp. TML of semen showed correlations with live sperm (r: -0.771), dead sperm (r: 0.580), H2O2 production (r: 0.740), and total ROS production (CellROX (+)) (r: -0.607), Total motility (r: 0.587), Progressive motility (r: -0.566), VCL (r: -0.664), VSL (r: -0,569), VAP (r: -0.534) (p ≤ 0.05). SLC removed 99.34% of the microbial load, which was assicated with a significanlty reduced H2O2 production (p ≤ 0.05). However, only samples treated with Androcoll-E had a higher total ROS production (CellROX +) (p ≤ 0.05). These results suggest that CellROX stain probably identifies superoxide production rather than H2O2 and this higher superoxide production may reflect an intense sperm functionality. The bacterial load increased the production of H2O2 in cool-stored semen which was associated with lower tolerance to refrigeration. SLC was the sperm processing technique that was most efficient at removing bacteria, reducing H2O2 production and selecting the most functional sperm.

Application of enzyme preparations for extraction of berry skin phenolics in withered winegrapes.

Postharvest withering of grapes strongly affects the content and extractability of phenolic compounds in the production of sfursat, fortified and passito wines. This work evaluated the effectiveness of enzymes applied individually and/or in multi-enzyme blends, on the extraction of anthocyanins, oligomeric flavanols and polymeric flavanols from withered grape skins during simulated maceration. The study was performed on Vitis vinifera L. cv. Nebbiolo and Barbera because of their different skin phenolic profile and cell wall composition. Our findings highlight that the relationship between skin mechanical properties (berry skin break force and energy) and extraction yield of phenolic compounds is variety dependent. Significant correlations were found between the skin softening associated with cell wall degradation and the extraction of anthocyanins and flavanols in Nebbiolo, for which polygalacturonase, individually or in multi-enzyme blends, plays an important role. In Barbera, the extractability of phenolic compounds was not affected by the presence of exogenous enzymes.

Development of an analytical method for the determination of the misuse in sports of boldenone through the analysis of urine by on-line coupling liquid chromatography-gas chromatography-combustion-isotope ratio mass spectrometry.

Boldenone (Bo), androsta-1,4-dien-17ß-ol-3-one, is an anabolic androgenic steroid not clinically approved for human application. Despite this, many cases are reported every year of athletes testing positive for Bo or its main metabolite 5ß-androst-1-en-17ß-ol-3-one (BoM). Recently the capability of different human intestinal bacteria to produce enzymes able to modify endogenous steroids in Bo has been demonstrated. When a urinary concentration of Bo and/or BoM between 5 and 30 ng/mL is measured a complementary analysis by gas chromatography combustion isotope ratio mass spectrometry (GC-C-IRMS) must be carried out to discriminate the endogenous or exogenous origin. In the present work, a novel analytical method that couples LC-GC by means of the TOTAD interface with C-IRMS is described. The method is based on a first RPLC separation of unacetyled steroids, followed by acetylation and automated on-line LC-GC-C-IRMS, which includes a second RPLC clean-up of acetyl Bo and BoM, isolation of the two fractions in a fraction collector and their consecutive analysis by GC-C-IRMS. The method has been applied to the analysis of urine samples fortified at 5 and 10 ng/mL, where it has shown a good performance.

Evaluation of two-step haemoglobin screening with HemoCue for blood donor qualification in mobile collection sites.

BACKGROUND AND OBJECTIVES: Inaccuracy of fingerstick haemoglobin compromises donor's health and losses blood donations. We evaluated the benefit of double haemoglobin screening with HemoCue. STUDY DESIGN AND METHODS: Blood donors underwent fingerstick screening by HemoCue and were driven for donation if capillary haemoglobin was within the regulatory range. Those failing were drawn venous blood and donated if their venous haemoglobin determined with HemoCue was acceptable. RESULTS: Of 276 605 donor clinic visits, 10 011 (3·6%) were assessed by two-step haemoglobin screening using HemoCue, because of low (n = 9444) or high (n = 567) capillary haemoglobin. Among these, 2561 (25·6%) were deemed eligible [recovered donations]. The recovery rate was 23·8% and 55·0% among donors presenting with low and high capillary haemoglobin, respectively. In both categories of attempted donations, capillary and venous haemoglobin with HemoCue correlated significantly in recovered donors (R(2)  ≈ 0·5-0·7) but not in deferred visits (R(2)  < 0·15). Venous haemoglobin with HemoCue and by haematological analyzer significantly correlated in all donations attempts (R(2)  ≈ 0·7). Donors presenting with low capillary haemoglobin showed small bias between capillary and venous haemoglobin by HemoCue (-2·4 ± 6·2 g/l), fingerstick haemoglobin and venous haemoglobin with counter (1·3 ± 7·3 g/l), and venous haemoglobin with HemoCue and counter (3·7 ± 3·9 g/l). This bias was slightly greater in donors with high capillary haemoglobin (-7·5 ± 7·8, 13·7 ± 7·5, and 6·2 ± 7·5, respectively). Double haemoglobin screening by HemoCue reached an accuracy of 87·3% for qualifying donors presenting with low fingerstick haemoglobin. CONCLUSIONS: Double haemoglobin measurement with HemoCue [fingerstick and venous blood if required] is feasible and allows a significant recovery of blood donations.

Quality assessment of buffy-coat-derived leucodepleted platelet concentrates in PAS-plasma, prepared by the OrbiSac or TACSI automated system.

BACKGROUND AND OBJECTIVES: Buffy-coat (BC)-derived platelet concentrates (PCs) are the predominant product for platelet transfusion in many countries. Two automated systems, OrbiSac and TACSI, have been introduced in blood centres to prepare these PCs, as an alternative to the manual method. We compared the in vitro quality of PCs prepared by both methods during standard storage. STUDY DESIGN AND METHODS: Twenty primary BC pools were split into two parts, which were processed with OrbiSac and TACSI system to obtain OrbiSac PCs (O-PCs) and TACSI PCs (T-PCs), respectively. On days 1, 5 and 7 of standard storage, samples were taken and the following analysed: cell count, metabolic variables, platelet function and content of activation and proinflammatory substances. RESULTS: Both the OrbiSac and TACSI systems produced PCs that meet the standards for platelet products in terms of platelet and leucocyte content. In vitro evaluation pointed to the similar preservation of platelet metabolism (pH, glucose, bicarbonate and lactate) in O-PCs and T-PCs. Moreover, there were no significant differences between O-PCs and T-PCs as regards the hypotonic shock response or in the platelet aggregation profile. The OrbiSac system caused greater platelet activation, which resulted in higher concentrations of sCD62P, RANTES and sCD40L on the day the PCs were prepared. CONCLUSION: The systems OrbiSac and TACSI can be used to produce buffy-coat-derived PCs whose cell content, platelet function and metabolism are similar during standard storage. However, the preparation with the OrbiSac system induces a transient increase in platelet activation and release of proinflammatory substances.

Initial proximal obstruction of ventriculoperitoneal shunt in patients with preterm-related posthaemorrhagic hydrocephalus.

BACKGROUND/AIMS: Obstruction is the most common complication of ventriculoperitoneal shunts in patients with hydrocephalus. Despite technical advances, rates of obstruction have barely decreased and remain at over 40% of cases. Patients suffering from preterm-related posthaemorrhagic hydrocephalus are considered a group with a particularly high risk of obstruction. The aim of the present study was to review our series of patients with preterm-related posthaemorrhagic hydrocephalus and analyse the occurrence of the first ventricular shunt obstruction as well as the related clinical and radiological factors. METHODS: We conducted a retrospective review of 103 cases treated from 1982 to 2010. Descriptive analysis, raw and adjusted bivariate correlations and survival analysis were performed. RESULTS: Over the course of the follow-up, 42 patients presented at least one episode of obstruction that required proximal revision. Medium-opening pressure valves were associated with a higher rate of obstruction compared to low-opening pressure valves; however, in our series this association became statistically significant only in patients with a weight of over 2,000 g at the time of surgery (odds ratio 6.75). The occurrence of previous infection and the development of late slit ventricle syndrome were also significantly associated with obstruction of the ventricular catheter (odds ratios 3.35 and 4.27, respectively). CONCLUSIONS: Rates of shunt obstruction in preterm-related posthaemorrhagic hydrocephalus remain high but do not seem to be higher than in other groups of paediatric hydrocephalus. Prevention of infection and the use of the appropriate type of valve design can help to decrease the incidence of proximal shunt obstruction, which in turn could decrease the incidence of symptomatic slit ventricle syndromes.

Evaluation of deammonification process performance at different aeration strategies.

In a deammonification process applied in the moving bed biofilm reactor (MBBR) oxygen is a crucial parameter for the process performance and efficiency. The objective of this study was to investigate different aeration strategies, characterised by the ratio between non-aerated and aerated phase times (R) and dissolved oxygen concentrations (DO). The series of batch tests were conducted with variable DO concentrations (2, 3, 4 mg L(-1)) and R values (0-continuous aeration; 1/3, 1, 3-intermittent aeration) but with the same initial ammonium concentration, volume of the moving bed and temperature. It was found that the impact of DO on deammonification was dependent on the R value. At R=0 and R=1/3, an increase of DO caused a significant increase in nitrogen removal rate, whereas for R=1 and R=3 similar rates of the process were observed irrespectively of the DO. The highest nitrogen removal rate of 3.33 g N m(-2) d(-1) (efficiency equal to 69.5%) was obtained at R=1/3 and DO=4 mg L(-1). Significantly lower nitrogen removal rates (1.17-1.58 g N m(-2) d(-1)) were observed at R=1 and R=3 for each examined DO. It was a consequence reduced aerated phase duration times and lesser amounts of residual nitrite in non-aerated phases as compared to R=1/3.

Dissolved oxygen as a factor influencing nitrogen removal rates in a one-stage system with partial nitritation and Anammox process.

A biofilm system with Kaldnes biofilm carrier was used in these studies to cultivate bacteria responsible for both partial nitritation and Anammox processes. Due to co-existence of oxygen and oxygen-free zones within the biofilm depth, both processes can occur in a single reactor. Oxygen that inhibits the Anammox process is consumed in the outer layer of the biofilm and in this way Anammox bacteria are protected from oxygen. The impact of oxygen concentration on nitrogen removal rates was investigated in the pilot plant (2.1 m3), supplied with reject water from the Himmerfjärden Waste Water Treatment Plant. The results of batch tests showed that the highest nitrogen removal rates were obtained for a dissolved oxygen (DO) concentration around 3 g O2 m(-3) At a DO concentration of 4 g O2 m(-3), an increase of nitrite and nitrate nitrogen concentrations in the batch reactor were observed. The average nitrogen removal rate in the pilot plant during a whole operating period oscillated around 1.3 g N m(-2)d(-1) (0.3 +/- 0.1 kg N m(-3)d(-1)) at the average dissolved oxygen concentration of 2.3 g O2 m(-3). The maximum value of a nitrogen removal rate amounted to 1.9 g N m(-2)d(-1) (0.47 kg N m(-3)d(-1)) and was observed for a DO concentration equal to 2.5 g O2 m(-3). It was observed that increase of biofilm thickness during the operational period, had no influence on nitrogen removal rates in the pilot plant.

Application and comparison of four selected procedures for the isolation of cell-wall material from the skin of grapes cv. Monastrell.

In order to choose an appropriate cell-wall material (CWM) isolation procedure in grapes cv. Monastrell, four different standard procedures have been tested, and a comparison made of the amount of cell-wall material obtained, its composition and morphology. The CWM was isolated as the 70% ethanol insoluble residue (de Vries method), as the absolute ethanol insoluble residue filtered sequentially through nylon mesh (Nunan method), as the insoluble residue in sodium deoxycholate-phenol-acetic acid-water (Selvendran method) and as the N-[2-hydroxyethyl]-piperazine-N'-2-ethanesulfonic acid (HEPES) insoluble residue (Vidal method). All extractions were done in triplicate and the efficiency of the extractive procedure established. Carbohydrates, proteins, and phenolic compounds were analysed, as the main constituents of CWM. The morphology of the isolated CWM was visualized by scanning electron microscopy (SEM). The Selvendran method had the highest efficiency, while the Nunan method had the lower one. Regarding the carbohydrates composition, the four different CWM were rich in uronic acids and glucose, together with varying amounts of arabinose, xylose, mannose and galactose. The Selvendran method had the lower value of total carbohydrates and the CWM shows more plasmatic membrane impurities in SEM images. The chemical results of the Vidal and de Vries methods were quite similar, but the Vidal method was more time consuming than the de Vries method. According to the results, the de Vries method was chosen to produce a representative cell-wall material fraction from Monastrell grapes skin.

The influence of the magnetoelastic interaction on the magnetocaloric effect in ferrimagnetic systems: a theoretical investigation.

In this work the magnetocaloric effect is theoretically investigated considering a microscopic model Hamiltonian, which describes a magnetic system formed by two sublattices of different magnetic ions coupled by exchange and magnetoelastic interactions. We analyze systematically several profiles of the ferrimagnetic arrangements that were studied earlier without the magnetoelastic interaction. The influence of changing the magnetoelastic parameters on the magnetization, isothermal entropy change and adiabatic temperature change curves are investigated. Depending on the model parameters, the magnetic system shows a first-order magnetic phase transition leading to high direct and inverse magnetocaloric effect, besides two simultaneous first-order magnetic phase transitions which were predicted. A constant ΔS(T) = 0.4 J mol(-1) K(-1) is obtained in the simulated system in a temperature interval of 50 K, around 110 K.

Understanding the inverse magnetocaloric effect in antiferro- and ferrimagnetic arrangements.

The inverse magnetocaloric effect occurs when a magnetic material cools down under applied magnetic field in an adiabatic process. Although the existence of the inverse magnetocaloric effect was recently reported experimentally, a theoretical microscopic description is almost nonexistent. In this paper we theoretically describe the inverse magnetocaloric effect in antiferro- and ferrimagnetic systems. The inverse magnetocaloric effects were systematically investigated as a function of the model parameters. The influence of the Néel and the compensation temperature on the magnetocaloric effect is also analyzed using a microscopic model.

A one-stage system with partial nitritation and anammox processes in the moving-bed biofilm reactor.

The ability of bacterial cultures to create biofilm brings a possibility to enhance biological wastewater treatment efficiency. Moreover, the ability of Anammox and Nitrosomonas species to grow within the same biofilm layer enabled a one-stage system for nitrogen removal to be designed. Such a system, with Kaldnes rings as carriers for biofilm growth, was tested in a technical pilot plant scale (2.1 m(3)) at the Himmerfjärden Waste Water Treatment Plant (WWTP) in the Stockholm region. The system was directly supplied with supernatant originating from dewatering of digested sludge containing high ammonium concentrations. Nearly 1-year of operational data showed that during the partial nitritation/Anammox process, alkalinity was utilised parallel to ammonium removal. The process resulted in a small pH drop, and its relationship with conductivity was found. The nitrogen removal rate for the whole period oscillated around 1.5g N m(-2)d(-1) with a maximum value equal to 1.9 g N m(-2)d(-1). Parallel to the pilot plant experiment, a series of batch tests were run to investigate the influence on removal rates of different dissolved oxygen conditions and addition of nitrite. The highest nitrogen removal rate (5.2g N m(-2)2d(-1)) in batch tests was obtained when the Anammox process was stimulated by the addition of nitrite. In the simultaneous partial nitritation and Anammox process, the partial nitritation was the rate-limiting step.

Nitrogen removal rates at a technical-scale pilot plant with the one-stage partial nitritation/Anammox process.

Traditional nitrification/denitrification is not suitable for nitrogen removal when wastewater contains high concentrations of ammonium nitrogen and low concentrations of biodegradable carbon. Recently, a deammonification process was developed and proposed as a new technology for treatment of such streams. This process relies on a stable interaction between aerobic bacteria Nitrosomonas, that accomplish partial nitritation and anaerobic bacteria Planctomycetales, which conduct the Anammox reaction. Simultaneous performance of these two processes can lead to a complete autotrophic nitrogen removal in one single reactor. The experiments where nitrogen was removed in one reactor were performed at a technical-scale moving-bed pilot plant, filled with Kaldnes rings and supplied with supernatant after dewatering of digested sludge. It was found that a nitrogen removal rate obtained at the pilot plant was 1.9 g m(-2) d(-1). Parallel to the pilot plant run, a series of batch tests were carried out under anoxic and aerobic conditions. Within the batch tests, where the pilot plant's conditions were simulated, removal rates reached up to 3 g N m(-2)d(-1). Moreover, the batch tests with inhibition of Nitrosomonas showed that only the Anammox bacteria (not anoxic removal by Nitrosomonas) are responsible for nitrogen removal.

Combined partial nitritation/Anammox system for treatment of digester supernatant.

One-year (2004) comprehensive investigations in a semi-industrial pilot plant (5 m3) were carried out with the aim of assessing the influence of operational parameters on the partial nitritation/Anammox system performance. In the system designed as a moving-bed biofilm reactor, the influent nitrogen load to the Anammox reactor was progressively increased and a stable Anammox bacterial culture was obtained. Interaction between subsequent aerobic and anaerobic conditions in the partial nitritation and Anammox reactors, respectively, granted conditions to remove nitrogen through the nitrite route. It implies that the oxygen supply can be limited to a high extent. A control strategy for the partial nitritation step relied on concomitant adjustment of the air supply with a variable influent nitrogen load, which can be monitored by both pH and conductivity measurements. In the Anammox reactor, an influent nitrite-to-ammonium ratio plays a vital role in obtaining efficient nitrogen removal. During the 1-year experimental period, the Anammox reactor was operated steadily and average nitrogen removal efficiency was 84% with 97% as the maximum value.