Energy dissipation in sewer fall manholes

In the present literature review paper several experimental investigations on physical and numerical models of drop manholes and vortex drop shafts were considered. The examination of the experimental data led to the definition of a simple empirical equation, initially suggested for one type of drop manhole, to estimate the total head loss coefficient for both drop manholes and vortex drop shafts. The energy efficiency values, as detected by the corresponding physical and numerical tests, of all the drop structure models were also compared. The energy efficiency of vortex drop shafts is larger than in drop manholes, and it reaches easily the 90%. Drop manholes are, instead, characterized by a smaller energy efficiency, which was shown to increase as the drop height augments

Energy head dissipation and flow pressures in vortex drop shafts

Vortex drop shafts are special manholes designed to link sewer channels at different elevations. Significant energy head dissipation occurs across these structures, mainly due to vertical shaft wall friction and turbulence in the dissipation chamber at the toe of the shaft. In the present study two aspects, sometimes neglected in the standard hydraulic design, are considered, namely the energy head dissipation efficiency and the maximum pressure force in the dissipation chamber. Different physical model results derived from the pertinent literature are analyzed. It is demonstrated that the energy head dissipation efficiency is mostly related to the flow impact and turbulence occurring in the chamber. Similarly to the drop manholes, a relation derived from a simple theoretical model is proposed for the estimation of the energy head loss coefficient. The analysis of the pressures measured on the chamber bottom allows to provide a useful equation to estimate the pressure peak in the chamber as a function of the approach flow energy head

The Adsorptive Removal of Bengal Rose by Artichoke Leaves: Optimization by Full Factorials Design

Currently, the dye industry is increasing its production as a consequence of the growing need for their products in different manufacturing sectors, such as textiles, plastics, food, paper, etc... Thereafter, these industries generate very large volumes of effluents contaminated by these dyes, which require proper removal treatment before final discharge of the effluents into the environment. In this study, artichoke leaves were used as an economical and eco-friendly bio-adsorbent for Bengal Rose (BR) dye removal. Bio-adsorbent obtained from artichoke leaves was ground to powder size. The resulting powder was characterized by different methods, such as Brunauer-Emmett-Teller (BET) surface area analysis, scanning electron microscopy(SEM), X-ray Diffraction (XRD), Fourier transfer infrared (FTIR), pH at point of zero charge (pHpzc), equilibrium pH, iodine number, methylene blue number, phenol number, density, Energy dispersive X-ray spectroscopy (EDX) and Thermo-gravimetric analysis (TGA). Thereafter, the bio-adsorbent was used to study its capability for removing BR dye by testing contact time, initial concentration of dye and temperature. The results show that the saturation of bio-sorbent was reached after 40 min and the removal rate of BR dye by artichoke leaves powder (ALP) was 4.07 mg/g, which corresponds to a removal efficiency of 80.1%. A design of experiences (DOE) based on a two-level full factorial design (23) was used to study the effects of different parameters, such as pH, temperature and bio-adsorbent dosage on BR dye removal efficiency. The obtained results show that the highest removal efficiency was 86.5% for the optimized values of pH (4), temperature (80 °C) and bio-adsorbent dosage (8 g/L). Furthermore, a satisfying accordance between experimental and predicted data was observed. The kinetic and isotherm studies show that the pseudo-second order model simulated adequately the obtained data and it was found that Langmuir and Temkin isotherm models are liable and suitable for evaluating the adsorption process performance. Free energy change of adsorption (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°) were furthermore calculated to predict the nature of the adsorption process

Use of Aloe vera as an Organic Coagulant for Improving Drinking Water Quality

The coagulation–flocculation–sedimentation process is widely used for removal of suspended solids and water turbidity reduction. The most common coagulants used to conduct this process are aluminum sulfate and ferric sulfate. In this paper, the use of Aloe vera as a natural-based coagulant for drinking water treatment was tested. The bio-coagulant was used in two different forms: powder as well as liquid; the latter was extracted with distilled water used as a solvent. The obtained results showed that the use of the natural coagulant (Aloe vera) in both powder (AV-Powder) and liquid (AV-H2O) forms reduced the water turbidity at natural pH by 28.23% and 87.84%, respectively. Moreover, it was found that the use of the two previous forms of bio-coagulant for drinking water treatment had no significant influence on the following three parameters: pH, alkalinity, and hardness. The study of the effect of pH on the process performance using Aloe vera as a bio-coagulant demonstrated that the maximum turbidity removal efficiency accounted for 53.53% and 88.23% using AV-Powder and AV-H2O, respectively, at optimal pH 6

Cx26 partial loss causes accelerated presbycusis by redox imbalance and dysregulation of Nfr2 pathway

Mutations in GJB2, the gene that encodes connexin 26 (Cx26), are the most common cause of sensorineural hearing impairment. The truncating variant 35delG, which determines a complete loss of Cx26 protein function, is the prevalent GJB2 mutation in several populations. Here, we generated and analyzed Gjb2+/- mice as a model of heterozygous human carriers of 35delG. Compared to control mice, auditory brainstem responses (ABRs) and distortion product otoacoustic emissions (DPOAEs) worsened over time more rapidly in Gjb2+/- mice, indicating they were affected by accelerated age-related hearing loss (ARHL), or presbycusis. We linked causally the auditory phenotype of Gjb2+/- mice to apoptosis and oxidative damage in the cochlear duct, reduced release of glutathione from connexin hemichannels, decreased nutrient delivery to the sensory epithelium via cochlear gap junctions and deregulated expression of genes that are under transcriptional control of the nuclear factor erythroid 2-related factor 2 (Nrf2), a pivotal regulator of tolerance to redox stress. Moreover, a statistically significant genome-wide association with two genes (PRKCE and TGFB1) related to the Nrf2 pathway (p-value < 4\u202f 7 10-2) was detected in a very large cohort of 4091 individuals, originating from Europe, Caucasus and Central Asia, with hearing phenotype (including 1076 presbycusis patients and 1290 healthy matched controls). We conclude that (i) elements of the Nrf2 pathway are essential for hearing maintenance and (ii) their dysfunction may play an important role in the etiopathogenesis of human presbycusis

Prospective validation of the CLIP score: a new prognostic system for patient with cirrhosis and hepatocellular carcinoma

Prognosis of patients with cirrhosis and hepatocellular carcinoma (HCC) depends on both residual liver function and tumor extension. The CLIP score includes Child-Pugh stage, tumor morphology and extension, serum alfa-fetoprotein (AFP) levels, and portal vein thrombosis. We externally validated the CLIP score and compared its discriminatory ability and predictive power with that of the Okuda staging system in 196 patients with cirrhosis and HCC prospectively enrolled in a randomized trial. No significant associations were found between the CLIP score and the age, sex, and pattern of viral infection. There was a strong correlation between the CLIP score and the Okuda stage, As of June 1999, 150 patients (76.5%) had died. Median survival time was 11 months, overall, and it was 36, 22, 9, 7, and 3 months for CLIP categories 0, 1, 2, 3, and 4 to 6, respectively. In multivariate analysis, the CLIP score had additional explanatory power above that of the Okuda stage. This was true for both patients treated with locoregional therapy or not. A quantitative estimation of 2-year survival predictive power showed that the CLIP score explained 37% of survival variability, compared with 21% explained by Okuda stage. In conclusion, the CLIP score, compared with the Okuda staging system, gives more accurate prognostic information, is statistically more efficient, and has a greater survival predictive power. It could be useful in treatment planning by improving baseline prognostic evaluation of patients with RCC, and could be used in prospective therapeutic trials as a stratification variable, reducing the variability of results owing to patient selection

Shock wave patterns in supercritical junction manholes with inlet bottom offsets

Urban floods are frequently provoked by the failure of drainage systems. Sometimes, the malfunctioning of drainage systems arises from uncertain or complicated hydraulic conditions developing into sewer manholes. Junction manholes represent basic elements for sewers as they enable two or more upstream branches to merge into a single downstream branch. Initial researches mainly investigated the hydraulic behaviour of subcritical junctions with constant branch diameters and an even invert. However, the junction of supercritical flows is the most complex process, mainly due to the likely occurrence of shock waves, breakdowns or choking flows. Furthermore, the sewers laying is commonly characterized by the branch tops alignment. Bottom offsets thus control the manhole inlets when upstream branch heights differ from the downstream one. In this regard, a physical model investigation was carried out at the Laboratory of Hydraulic Constructions (LCH) of the Ecole Polytechnique Fédérale de Lausanne (EPFL). The model reproduced a 45◦ junction manhole with aligned up and downstream branch tops and variable upstream branch diameters. The experimental tests focused on the scenario with supercritical flows entering the junction manhole. First outcomes in terms of flow behaviour and shock waves formation are described

The hydraulic performance of green roofs in urban environments: a brief state-of-the-art analysis of select literature

In the last years green roofs are being used as a control measure for urban stormwater management as they retain, detain and slowly release rainwater. Green roofs present many economic, social and environmental benefits. After a general overview of the main features of green roofs, the paper focuses on the main outcomes highlighted by selected literature studies on the hydraulic performance of green roofs. The hydraulic efficiency has been specifically assessed through the definition of two parameters of great interest to design the tailwater drainage system: the peak reduction and the volume reduction indexes

Supercritical flow in junction manholes under invert- and obvert-aligned set-ups

Junction manholes are a part of urban drainage infrastructures. They merge inlet branches into an outlet branch. Former studies focused on junction flow by considering a specific manhole layout: identical diameters were assigned to the branches and the invert was flush. Nevertheless, engineers are often involved in designing junctions under generalized geometries, with different branch diameters and, sometimes, bottom offsets at manhole inlets. For these junction arrangements, the empirical relations documented in literature are not applicable. An experimental campaign was thus conducted to determine the main flow features of junction manholes under generalized set-ups. The results include a diagram of state to be used if junctions operate under mixed flow conditions. Information regarding the main wave patterns, with detailed discussion of wave features and heights, is provided to support the hydraulic design of junction manholes under the supercritical flow regime

Discharge capacity of junction manholes with bottom drops or top offsets

An adequate operation of combined sewer systems is related to the efficiency of sewer manholes. Sometimes, sewer manholes are designed to convey safely storm water discharges with a return period shorter than the infrastructure life time. In other cases, the manhole discharge capacity is sufficient but the flow structure established in the manhole leads to unacceptable free-surface flow conditions. This poor performance may easily occur in junction manholes, which merge two or more upstream branches into a single downstream collector. The hydraulic behavior of junction manholes under sub- and supercritical flows has been thoroughly studied in the past, mainly on an experimental basis. However, former studies are all referred to a standard junction manhole layout, with a constant diameter assigned to both up- and downstream branches along with a flat manhole invert. Contrarily, diversified set-ups are usually employed in practical cases. Upstream sewer branches are generally characterized by various cross-section profiles. Moreover, the good design practice recommends settling the concerned branches by aligning the branch tops, in order to avoid backwater effects. Given the above, advancement in design procedures for junction manholes is strongly required, mainly with regard to the discharge capacity of junctions characterized by generalized configurations. The present study considers the results of experimental campaigns performed on different physical models of junction manholes. A communal structure with a junction manhole approached by two circular upstream branches, with variable diameters, is considered. Then, junction angles and upstream branch diameters are varied, resulting in different manhole set-ups with inlet bottom drops or top offsets. Selected overload experimental runs are performed to investigate the hydraulic conditions under which the manhole discharge capacity is exceeded. The analysis of the experimental data allowed in outlining a preliminary comparison of discharge capacity of junctions with generalized layouts