Rheological Characteristics of Municipal Thickened Excess Activated Sludge (TEAS): Impacts of pH, Temperature, Solid Concentration and Polymer Dose

Rheological characterization of sludge is known to be an essential tool to optimize flow, mixing and other process parameters in wastewater treatment plants. This study deals with the characterization of thickened excess activated sludge in comparison to raw primary sludge and excess activated sludge. The effects of key parameters (total solid concentration, temperature, and pH) on the rheology and flow behavior of thickened excess activated sludge were studied. The rheological investigations were carried out for total solid concentration range of 0.9–3.7 %w/w, temperature range of 23–55 °C, and pH range of 3.6–10.0. Different rheological model equations were fitted to the experimental data. The model equations with better fitting were used to calculate the yield stress, apparent, zero-rate, infinite-rate viscosities, flow consistency index, and flow index. The decrease in concentration from 3.7 to 3.1 %w/w resulted in a drastic reduction of yield stress from 27.6 to 11.0 Pa, while a further reduction of yield stress to 1.3 Pa was observed as solid concentration was reduced to 1.3 %w/w. The viscosity at higher shear rate (>600 s−1) decreased from 0.05 Pa·s down to 0.008 Pa·s when the total solid concentration was reduced from 3.7 to 0.9 %. Yield stress decreased from 20.1 Pa down to 8.3 Pa for the Bingham plastic model when the temperature was raised from 25 to 55 °C. Activation energy and viscosity also showed decreasing trends with increasing temperature. Yield stress of thickened excess activated sludge increased from a value of 6.0 Pa to 8.3 Pa when the pH was increased from 3.6 to 10.0. The effect of polymer dose on the rheological behavior of the thickening of excess activated sludge was also investigated, and the optimum polymer dosage for enhanced thickener performance was determined to be 1.3 kg/ton DS

Impact of system factors on the water saving efficiency of household grey water recycling

Copyright © 2010 Taylor & Francis. This is an Author's Accepted Manuscript of an article published in Desalination and Water Treatment Volume 24, Issue 1-3 (2010), available online at: http://www.tandfonline.com/10.5004/dwt.2010.1542A general concern when considering the implementation of domestic grey water recycling is to understand the impacts of system factors on water saving efficiency. Key factors include household occupancy, storage volumes, treatment capacity and operating mode. Earlier investigations of the impacts of these key factors were based on a one-tank system only. This paper presents the results of an investigation into the effect of these factors on the performance of a more realistic ‘two tank’ system with treatment using an object based household water cycle model. A Monte-Carlo simulation technique was adopted to generate domestic water appliance usage data which allows long-term prediction of the system's performance to be made. Model results reveal the constraints of treatment capacity, storage tank sizes and operating mode on percentage of potable water saved. A treatment capacity threshold has been discovered at which water saving efficiency is maximised for a given pair of grey and treated grey water tank. Results from the analysis suggest that the previous one-tank model significantly underestimates the tank volumes required for a given target water saving efficiency

Predictive model of biliocystic communication in liver hydatid cysts using classification and regression tree analysis

<p>Abstract</p> <p>Background</p> <p>Incidence of liver hydatid cyst (LHC) rupture ranged 15%-40% of all cases and most of them concern the bile duct tree. Patients with biliocystic communication (BCC) had specific clinic and therapeutic aspect. The purpose of this study was to determine witch patients with LHC may develop BCC using classification and regression tree (CART) analysis</p> <p>Methods</p> <p>A retrospective study of 672 patients with liver hydatid cyst treated at the surgery department "A" at Ibn Sina University Hospital, Rabat Morocco. Four-teen risk factors for BCC occurrence were entered into CART analysis to build an algorithm that can predict at the best way the occurrence of BCC.</p> <p>Results</p> <p><b>I</b>ncidence of BCC was 24.5%. Subgroups with high risk were patients with jaundice and thick pericyst risk at 73.2% and patients with thick pericyst, with no jaundice 36.5 years and younger with no past history of LHC risk at 40.5%. Our developed CART model has sensitivity at 39.6%, specificity at 93.3%, positive predictive value at 65.6%, a negative predictive value at 82.6% and accuracy of good classification at 80.1%. Discriminating ability of the model was good 82%.</p> <p>Conclusion</p> <p>we developed a simple classification tool to identify LHC patients with high risk BCC during a routine clinic visit (only on clinical history and examination followed by an ultrasonography). Predictive factors were based on pericyst aspect, jaundice, age, past history of liver hydatidosis and morphological Gharbi cyst aspect. We think that this classification can be useful with efficacy to direct patients at appropriated medical struct's.</p

Comparison of the application of low concentration and 80% phenol solution in pilonidal sinus disease

Objectives Many conservative methods have been applied in the treatment of pilonidal sinus disease (PSD). The most commonly used conservative treatment is 80% phenol solution. Our observations demonstrated that 80% phenol solution caused much destruction in the sacrococcygeal region. Design In this study low concentrations of phenol were used with the aim of reducing the unwanted side-effects of high-concentration phenol without reducing the therapeutic effects. Participants We treated 112 patients (18 women, 94 men) with PSD using phenol solution. Patients were divided into two groups: Group A was treated with a 40% solution of phenol solution, and Group B was treated with an 80% solution of phenol solution. Setting All patients were treated on an outpatient basis. One mL of low (40%) or high (80%) concentration phenol solution was injected into the main sinus orifice. During the check it was observed and noted whether there was skin necrosis, fatty tissue necrosis or abscesses. Main outcome measures The mean age was 27.4 years (6–44). The median length of symptoms was seven months (0.5–132). In the 2.8 years (1–6) of mean follow-up period, the disease recurred in 13 (11.6%) patients. Results This treatment procedure was well-tolerated by all the patients except for those who had unwanted results. No patients in group A had skin necrosis, and only one had abscesses. In group B two patients had abscesses, and three had skin necrosis. Fatty tissue necrosis was seen in one patient in Group A and in five patients in Group B. Recurrence rates were four (7.4%) cases in Group A and nine (15.5%) cases in Group B. Conclusions It is possible to treat patients in a shorter time with a considerably smaller loss of working time, since the destruction of peripilonidal adipose tissue and skin is less. Therefore, the use of low-concentration phenol solution is an option to be considered in the treatment of PSD.PubMe

ИНФЕКЦИОННЫЕ ОСЛОЖНЕНИЯ ПОСЛЕ ТРАНСПЛАНТАЦИИ ПЕЧЕНИ В ОТДЕЛЕНИИ РЕАНИМАЦИИ И ИНТЕНСИВНОЙ ТЕРАПИИ В УСЛОВИЯХ ОДНОГО ЦЕНТРА

Introduction. Despite the advances in antibiotherapy and critical care management, infectious complications remain among the leading complications after liver transplantation related with mortality and morbidity. This study analysis the incidence and pattern of infections and possible prognostic factors of infectious compli- cations retrospectively in a single center. Patients and Methods. Results of 30 consecutive patients with a primary liver transplantation history in a single center between August 2011 and August 2012 and a positive culture result in the first month in the ICU were analysed retrospectively. Results. During the first 1 month stay in the ICU postoperatively 30 (13,63%) patients had at least 1 infection. Total number of infections were 68. Mortality rate of the infected patients was 53,3% (n = 16). Among these infections, 25 (36,76%) of them were in deep surgical sites. Eighteen of the 30 patients (60%) were infected with a single microorganism. Eleven patients (36,66%) had a single infection episode. Microorganism were gram negative in 52 (76,47%) of the infections, gram positive in 14 (20,58%) of the infections, rest of the 2 (2,94%) infections were due to Candidiasis. Among the possible risk factors contributing to mortality, there was a statistically significant dif- ference (p &lt; 0,001) between the platelet counts of the mortality and surviving groups of the patients. Conclu- sion. Infections are among the preventable risk factors for mortality and morbidity after liver transplantation. Our data reveals a significant relation between trombocytopenia and mortality among the infected patients. Further studies focusing on this relation would expose the mechanisms and any possible contribution in cli- nical management of the patients. Цель исследования – провести ретроспективный анализ заболеваемости и характер инфекции, а также возможных прогностических факторов летальности в условиях одного центра. Материалы и методы исследования. Ретроспективно были изучены результаты лечения 220 пациентов с трансплантацией пе- чени в период между августом 2011 года и августом 2012-го. У 30 пациентов наблюдались инфекционные осложнения с положительными результатами посевов в первый месяц интенсивной терапии в условиях одного центра. Результаты исследования. В течение первого месяца пребывания в отделении интен- сивной терапии после операции 30 (13,63%) пациентов имели по крайней мере одну инфекцию. Об- щее число случаев инфекции было 68. Смертность среди инфицированных пациентов составила 53,3% (n = 16). Среди этих инфекций 25 (36,76%) были интраабдоминальными. Восемнадцать из 30 пациентов (60%) были инфицированы одним возбудителем. Одиннадцать пациентов (36,66%) имели один эпизод инфекции. Микроорганизмы были грамотрицательными в 52 (76,47%) случаях, грамположительными в 14 (20,58%) случаях, остальные 2 случая (2,94%) инфекций были обусловлены кандидозом. Среди воз- можных факторов риска, влияющих на смертность, была статистически достоверно выявлена (р &lt; 0,001) связь между количеством тромбоцитов и летальностью пациентов. Заключение. Инфекции являются одними из предотвратимых факторов риска смертности и заболеваемости после трансплантации печени. Наши данные свидетельствуют о значимой связи между тромбоцитопенией и смертностью среди инфи- цированных пациентов. Дальнейшие исследования, посвященные этому вопросу, внесут весомый вклад в клиническое ведение таких больных в будущем.

Medical conditions in autism spectrum disorders

Autism spectrum disorder (ASD) is a behaviourally defined syndrome where the etiology and pathophysiology is only partially understood. In a small proportion of children with the condition, a specific medical disorder is identified, but the causal significance in many instances is unclear. Currently, the medical conditions that are best established as probable causes of ASD include Fragile X syndrome, Tuberous Sclerosis and abnormalities of chromosome 15 involving the 15q11-13 region. Various other single gene mutations, genetic syndromes, chromosomal abnormalities and rare de novo copy number variants have been reported as being possibly implicated in etiology, as have several ante and post natal exposures and complications. However, in most instances the evidence base for an association with ASD is very limited and largely derives from case reports or findings from small, highly selected and uncontrolled case series. Not only therefore, is there uncertainty over whether the condition is associated, but the potential basis for the association is very poorly understood. In some cases the medical condition may be a consequence of autism or simply represent an associated feature deriving from an underlying shared etiology. Nevertheless, it is clear that in a growing proportion of individuals potentially causal medical conditions are being identified and clarification of their role in etio-pathogenesis is necessary. Indeed, investigations into the causal mechanisms underlying the association between conditions such as tuberous sclerosis, Fragile X and chromosome 15 abnormalities are beginning to cast light on the molecular and neurobiological pathways involved in the pathophysiology of ASD. It is evident therefore, that much can be learnt from the study of probably causal medical disorders as they represent simpler and more tractable model systems in which to investigate causal mechanisms. Recent advances in genetics, molecular and systems biology and neuroscience now mean that there are unparalleled opportunities to test causal hypotheses and gain fundamental insights into the nature of autism and its development

Imaging in assessing hepatic and peritoneal metastases of gastric cancer: a systematic review

<p>Abstract</p> <p>Background</p> <p>Hepatic and peritoneal metastases of gastric cancer are operation contraindications. Systematic review to provide an overview of imaging in predicting the status of liver and peritoneum pre-therapeuticly is essential.</p> <p>Methods</p> <p>A systematic review of relevant literatures was performed in Pubmed/Medline, Embase, The Cochrane Library and the China Biological Medicine Databases. QUADAS was used for assessing the methodological quality of included studies and the bivariate model was used for this meta-analysis.</p> <p>Results</p> <p>Totally 33 studies were included (8 US studies, 5 EUS studies, 22 CT studies, 2 MRI studies and 5 18F-FDG PET studies) and the methodological quality of included studies was moderate. The result of meta-analysis showed that CT is the most sensitive imaging method [0.74 (95% CI: 0.59-0.85)] with a high rate of specificity [0.99 (95% CI: 0.97-1.00)] in detecting hepatic metastasis, and EUS is the most sensitive imaging modality [0.34 (95% CI: 0.10-0.69) ] with a specificity of 0.96 (95% CI: 0.87-0.99) in detecting peritoneal metastasis. Only two eligible MRI studies were identified and the data were not combined. The two studies found that MRI had both high sensitivity and specificity in detecting liver metastasis.</p> <p>Conclusion</p> <p>US, EUS, CT and ¹⁸F-FDG PET did not obtain consistently high sensitivity and specificity in assessing liver and peritoneal metastases of gastric cancer. The value of laparoscopy, PET/CT, DW-MRI, and new PET tracers such as ¹⁸F-FLT needs to be studied in future.</p