Efficient (Tube) Settling Tanks

1991 ◽  
Vol 24 (7) ◽  
pp. 223-228 ◽  
Author(s):  
Lazar Ignjatović
Keyword(s):  
Surface Area ◽  
Continuous Flow ◽  
Settling Tank ◽  
Design Flow ◽  
Flowing Water ◽  
Vertical Flow ◽  
Settling Basin ◽  
New Type ◽  
Theoretical Results ◽  
Maximum Design

This paper discusses design principles and theoretical results for a new type of settling tank. Within the settling zone of the tank, sedimentation takes place in tube, as in a quiescent container of equal (3-5 cm) depth. The inlet, sludge and outlet zone are arranged for a continuous-flow rectangular (or circular) basin. A particle that enters the sludge zone is and stays removed, and the sludge can be removed by gravity or pumped from the sludge zone. Hydraulically, the process can be formulated in terms of horizontal-vertical-flow without short-circuiting. Tank loadings are 0.5 L/s per m2 to 1.5 L/s per m2 of tank surface area. The detention period of 15-20 minutes offers the same overall removal efficiency as 4-5 hours for classical one. Variations in flow are of little concern, provided that the maximum design flow is not exceeded. Scum is removed without difficulty from the tank as well as the sludge, and the sludge removal device will also act as a flocculator. This type of settling basin is suitable where sludge volumes are large or where putrefaction of sludge in contact with the flowing water is to be avoided.

Theoretical and Experimental Research of Viscoelastic Damping Limb-Like-Structure Device with Coupling Nonlinear Characteristics

2021 ◽  
pp. 2130002
Author(s):  
Zhen-Hua He ◽  
Zhao-Dong Xu ◽  
Jian-Yang Xue ◽  
Xing-Jian Jing ◽  
Yao-Rong Dong ◽  
...  
Keyword(s):  
Vibration Isolation ◽  
Harmonic Balance Method ◽  
Viscoelastic Damping ◽  
Static Stiffness ◽  
Viscoelastic Damper ◽  
Stiffness Analysis ◽  
Nonlinear Dynamic Equation ◽  
New Type ◽  
Geometrical Effects ◽  
Theoretical Results

The nonlinear characteristic of vibration control systems has attracted increasing attention for its advantage in improving structural performance. In this paper, a new type of viscoelastic damping limb-like-structure (VE-LLS) device is proposed by combing the viscoelastic (VE) damper and limb-like-structure (LLS) together, which possesses coupling nonlinearity characteristic caused by geometric and material factors, as well as a remarkable advantage in improving the control performance. First, to explore the nonlinear geometrical effects on the static stiffness of the VE-LLS device, a formula is derived from static stiffness, and the results are discussed. Second, dynamic analysis is performed of the proposed device considering the coupling geometrical and material nonlinearities in frequency domain, with the real-time effect of frequency and temperature on the mechanical properties of the viscoelastic damper considered in solving the nonlinear vibration equation. The harmonic balance method (HBM) is used to solve the nonlinear dynamic equation. Then, the displacement transmissibility of the VE-LLS device is calculated and assessed. The results indicate that the proposed device possesses excellent vibration isolation performance, and the geometric parameters of the viscoelastic damper have significant nonlinear effect on the performance. Finally, an experiment is carried out of the VE-LLS device to verify the accuracy of the static stiffness analysis. The results show that the theoretical results agree well the experimental ones, and that the theoretical results have high accuracy and reliability.

Enhanced surface hydrophilicity of polylactic acid sutures treated by lipase and chitosan

2018 ◽  
Vol 89 (16) ◽  
pp. 3291-3302 ◽  
Author(s):  
Shuqiang Liu ◽  
Mingfang Liu ◽  
Gaihong Wu ◽  
Xiaofang Zhang ◽  
Juanjuan Yu ◽  
...  
Keyword(s):  
Reaction Time ◽  
Friction Coefficient ◽  
Surface Area ◽  
Polylactic Acid ◽  
The Body ◽  
Optimal Conditions ◽  
Absorbable Sutures ◽  
Surgical Sutures ◽  
New Type ◽  
Enhanced Surface

Polylactic acid (PLA) surgical sutures are a new type of absorbable sutures that can be degraded and absorbed in the body. However, there is high hydrophobicity for the surface of PLA sutures, which leads to poor biocompatibility and cellular affinity. In order to increase the hydrophilicity, the PLA sutures were etched by lipase firstly, and then grafted with chitosan. The results indicate that the optimal conditions of treating PLA sutures by lipase were as follows: 45℃ reaction temperature, 4.5 g/L concentration of lipase and 8 h reaction time. The sutures were etched by lipase and then formed some grooves and a number of hydroxyl (-OH) bonds, which led to increased surface area and hydrophilicity, but a drop in mass and strength. The optimal conditions of grafting chitosan onto PLA sutures were as follows: 4 h reaction time and 3 g/L concentration of chitosan. The chitosan grafted and loaded on the surface of PLA sutures, and in some areas of the sutures the chitosan reunited, which led to a rough surface and large friction coefficient. Finally, the hydrophilicity of the PLA sutures, treated by lipase and then grafted with chitosan, was greatly improved.

Using a continuous flow reactor for aqueous lateral epitaxial overgrowth of low-dislocation-density ZnO layers on honeycomb-patterned structures

CrystEngComm ◽  
2020 ◽  
Vol 22 (3) ◽  
pp. 487-496
Author(s):  
Hou-Guang Chen ◽  
Huei-Sen Wang ◽  
Shu-Han Yang ◽  
Xuan-Chen Lin
Keyword(s):  
Dislocation Density ◽  
Continuous Flow ◽  
Flow Reactor ◽  
Lateral Epitaxial Overgrowth ◽  
Continuous Flow Reactor ◽  
Low Dislocation Density ◽  
Long Duration ◽  
Patterned Structures ◽  
New Type

A new type of continuous flow reactor was used for long-duration lateral epitaxial overgrowth of low-dislocation-density ZnO layers.

Optimization of subsurface vertical flow constructed wetlands for wastewater treatment

2007 ◽  
Vol 55 (7) ◽  
pp. 71-78 ◽  
Author(s):  
G. Langergraber ◽  
Ch. Prandtstetten ◽  
A. Pressl ◽  
R. Rohrhofer ◽  
R. Haberl
Keyword(s):  
Grain Size ◽  
Specific Surface ◽  
Surface Area ◽  
Constructed Wetlands ◽  
Organic Load ◽  
Vertical Flow ◽  
Two Stage ◽  
Main Layer ◽  
Free Drainage ◽  
Stage System

Constructed wetlands (CWs) use the same processes that occur in natural wetlands to improve water quality and are used worldwide to treat different qualities of water. This paper shows the results of an Austrian research project having the main goals to optimize vertical flow beds in terms of surface area requirement and nutrient removal, respectively. It could be shown that a subsurface vertical flow constructed wetland (SSVFCW) operated with an organic load of 20 g COD.m−2.d−1 (corresponding to a specific surface area demand of 4 m2 per person) can fulfil the requirements of the Austrian standard regarding effluent concentrations and removal efficiencies. During the warmer months (May – October), when the temperature of the effluent is higher than 12 °C, the specific surface area might be further reduced. Even 2 m2 per person have been proven to be adequate. Enhanced nitrogen removal of 58 % could be achieved with a two-stage system (first stage: grain size for main layer 1–4 mm, saturated drainage layer; and second stage: grain size for main layer 0.06–4 mm, free drainage) that was operated with an organic load of 80 g COD.m−2.d−1 for the first stage (1 m2 per person), i.e. 40 g COD.m−2.d−1 for the two-stage system (2 m2 per person). Although the two-stage system was operated with higher organic loads a higher effluent quality compared to a single-stage SSVFCW (grain size for main layer 0.06–4 mm, free drainage, organic load 20 g COD.m−2.d−1) could be reached.

Geological Expedition and Analysis on Formation and Evolvement of Erosive Karst Tiankeng: A Case Study of Xingwen World Geopark

2011 ◽  
Vol 250-253 ◽  
pp. 2002-2006
Author(s):  
Wei Shui ◽  
Xing Gui Wang
Keyword(s):  
Flowing Water ◽  
Continuous Processes ◽  
Scenic Spot ◽  
New Type ◽  
Karst Landforms

Erosive Karst Tiankeng has been a new type of Tiankeng Since the Collapsed Karst Tiankeng was found and primarily research by Zhu Xuewen, a famous geologist. But, how the Erosive Karst Tiankeng evolved and developed? How can we find the proofs on formation and evolutional processes of Erosive Karst Tiankeng? Few scholar focused on this new field. According to the first-hand datum by geological Expedition and study in Xingwen World Geopark, the results and datum show that apart from Dayanwan and Xiaoyanwan collapsed karst Tiankeng, there are other karst landforms in Bowang Mount scenic spot of Xingwen World Geopark such us Feiwu Cave, Dao Cave, Cangshuiyan Gorge, Nanxing TanKeng and so on. These typical karst landforms could be regarded as different vestiges of erosive karst Tiankeng of Xingwen World Geopark, which stand for the evolutional processes of erosive karst Tiankeng separately. Moreover, the evolutional processes of erosive karst Tiankeng could be divided into the following continuous processes: an erosive karst Tiankeng develops from the processes of eroding and dissolving & extending of silo Sinkhole, and subsequently degrades to a large gorge or doline. It is worth pointing out that except for erosion of flowing water, at the same time, collapse’s effect has been playing extremely important role in the forming processes of these special erosive landforms.

Effect of dosing regime on nitrification in a subsurface vertical flow treatment wetland system

2012 ◽  
Vol 66 (6) ◽  
pp. 1220-1224
Author(s):  
Suwasa Kantawanichkul ◽  
Walaya Boontakhum
Keyword(s):  
Continuous Flow ◽  
Removal Rate ◽  
Oxygen Demand ◽  
Ammonia Nitrogen ◽  
Synthetic Wastewater ◽  
Experimental Unit ◽  
Vertical Flow ◽  
Treatment Wetland ◽  
Wetland System ◽  
Flow Treatment

In this study, the effect of dosing regime on nitrification in a subsurface vertical flow treatment wetland system was investigated. The experimental unit was composed of four circular concrete tanks (1 m diameter and 80 cm deep), filled with gravel (1–2 cm) and planted with Cyperus alternifolius L. Synthetic wastewater with average chemical oxygen demand (COD) and ammonia nitrogen of 1,151 and 339 mg/L was fed into each tank. Different feeding and resting periods were applied: continuous flow (tank 1), 4 hrs on and 4 hrs off (tank 2), 1 hr on and 3 hrs off (tank 3) and 15 minutes on and 3 hrs 45 minutes off (tank 4). All four tanks were under the same hydraulic loading rate of 5 cm/day. After 165 days the reduction of total Kjeldahl nitrogen and ammonia nitrogen and the increase of nitrate nitrogen were greatest in tank 4, which had the shortest feeding period, while the continuous flow produced the lowest results. Effluent tanks 2 and 3 experienced similar levels of nitrification, both higher than that of tank 1. Thus supporting the idea that rapid dosing periods provide better aerobic conditions resulting in enhanced nitrification within the bed. Tank 4 had the highest removal rates for COD, and the continuous flow had the lowest. Tank 2 also exhibited a higher COD removal rate than tank 3, demonstrating that short dosing periods provide better within-bed oxidation and therefore offer higher removal efficiency.

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