scholarly journals Relationships among Permeability, Membrane Roughness, and Eukaryote Inhabitation during Submerged Gravity-Driven Membrane (GDM) Filtration

2020 ◽  
Vol 10 (22) ◽  
pp. 8111
Author(s):  
Dongwhi Lee ◽  
Yun Jeong Cha ◽  
Youngbin Baek ◽  
Shin Sik Choi ◽  
Yunho Lee
Keyword(s):  
Low Cost ◽  
Biomass Concentration ◽  
Critical Factor ◽  
High Biomass ◽  
High Biological Activity ◽  
Polyvinylidene Difluoride ◽  
Filtration System ◽  
Gravity Driven ◽  
Membrane Roughness ◽  
One Year

Gravity-driven membrane (GDM) filtration is one of the promising technologies for decentralized water treatment systems due to its low cost, simple operation, and convenient maintenance. The objective of this study was to evaluate the permeability of submerged GDM filtration with three different membranes, i.e., polyethersulfone and polyvinylidene difluoride ultrafiltration (PES-UF and PVDF-UF) and polytetrafluoroethylene microfiltration membrane (PTFE-MF). The GDM system was operated using lake water for about one year. The determined average permeability values were high for PVDF-UF (192.9 L/m2/h/bar (LMH/bar)) and PTFE-MF (80.6 LMH/bar) and relatively lower for PES-UF (46.1 LMH/bar). The observed higher permeability for PVDF-UF and PTFE-MF was thought to be related to the rougher surface of these two membranes compared to PES-UF. The fouling layers of PVDF-UF and PTFE-MF were characterized by high biomass and the presence of a number of nematodes, while PES-UF showed a thin fouling layer with no nematode. The relatively high and fluctuated permeability of PVDF-UF and PTFE-MF could thus be attributed to the high biological activity of nematodes making the fouling layer more loose and porous. This was supported by a good linear relationship among the permeability, biomass concentration, and the number of nematodes in the fouling layers. These results provide important insights into membrane selection as a critical factor affecting the flux performance of the GDM filtration system for a decentralized drinking water supply.

scholarly journals Towards developing a low-cost gravity-driven arsenic filtration system using iron oxide nanoparticle-loaded PU foam

2020 ◽  
Vol 55 (3) ◽  
pp. 234-248
Author(s):  
Arundhati Pillai ◽  
M. Amin F. Zarandi ◽  
Faten B. Hussein ◽  
Krishna M. Pillai ◽  
Nidal H. Abu-Zahra
Keyword(s):  
Developing Countries ◽  
Iron Oxide ◽  
Low Cost ◽  
Water Sources ◽  
Easy Access ◽  
Iron Oxide Nanoparticle ◽  
Pu Foam ◽  
Filtration System ◽  
Gravity Driven ◽  
Oxide Nanoparticle

Abstract Arsenic contamination of water sources is a global problem, affecting numerous (especially developing) countries across the world. Exposure to exorbitantly high concentrations reaching 400 parts per billion of arsenic in water sources lead to numerous health complications, including the development of respiratory, neurological, and cancerous diseases. This study focused on developing an innovative, low-cost, and gravity-driven filtration system using a novel iron oxide nanoparticle-loaded polyurethane (PU) foam by which people in developing countries may have easy access to an effective, affordable, and easily fabricated filtration system. After successfully synthesizing the new iron oxide nanoparticle-loaded PU foam, effectiveness of the foam was tested by developing a filtration system consisting of vertical polyvinyl-chloride tubing inserted with 10 and 20 cm of PU foams. Samples of arsenic-contaminated water with known concentrations of 100 and 200 ppb were run through each of the systems numerous times for one and five run cases. The system with 20 cm of PU foam and five runs successfully filtered out around 50–70% of the arsenic from the 100 and 200 ppm samples. The filtration process was quite fast (and hence practical) with each run completing in 5–10 minutes' time. Future research is expected to improve this promising start.

Treatment of wastewater by constructed wetland in small settlements

2000 ◽  
Vol 41 (1) ◽  
pp. 69-72 ◽  
Author(s):  
S.Ç. Ayaz ◽  
I. Akca
Keyword(s):  
Environmental Pollution ◽  
Constructed Wetland ◽  
Pilot Plant ◽  
Low Cost ◽  
Experimental System ◽  
Suspended Solid ◽  
Loading Conditions ◽  
Treatment Performance ◽  
Per Capita ◽  
One Year

The constructed wetland is a low-cost technology to control environmental pollution. The system is especially suitable for small settlements. An innovative constructed wetland technology is described in this paper. A pilot plant was used to assess the performance of the system. The experimental system consists of two serial connected tanks that settled up with fillers and Cyperus as treatment media. Wastewater is recycled periodically upward and downward between the two tanks. The treatment performance was monitored in different loading conditions in a one-year period. The average COD removal efficiency of 90% was observed at 122 g COD/m2.day average loading conditions. Other average removal values in the same conditions are as follows: suspended solid 95%, TKN 77%, total nitrogen 61%, PO4-P 39%. The land requirement for this system will be 0.82 m2 per capita when applying as full-scale system.

Study on the Manufacture of Microfluidic Chip with Coated Glass

2012 ◽  
Vol 548 ◽  
pp. 254-257 ◽  
Author(s):  
Yan He ◽  
Bai Ling Huang ◽  
Yong Lai Zhang ◽  
Li Gang Niu
Keyword(s):  
Microfluidic Chip ◽  
Low Cost ◽  
Microfluidic Channel ◽  
Critical Factor ◽  
Wet Etching ◽  
Microfluidic Chips ◽  
Etching Technique ◽  
Chip Quality ◽  
Wet Chemical ◽  
Wet Chemical Etching

In this paper, a simple and facile technique for manufacturing glass-based microfluidic chips was developed. Instead of using expensive dry etching technology, the standard UV lithography and wet chemical etching technique was used to fabricate microchannels on a K9 glass substrate. The fabrication process of microfluidic chip including vacuum evaporation, annealing, lithography, and BHF (HF-NH4F-H2O) wet etching were investigated. Through series experiments, we found that anneal was the critical factor for chip quality. As a representative example, a microfluidic channel with 20 m of depth, and 80 m of width was successfully prepared, and the channel surfaces are quite smooth. These results present a simple, low cost, flexible and easy way to fabricate glass-based microfluidic chips.

Low-Cost Filtration System to Treat First-Flush Stormwater

2009 ◽  
Vol 9 (5-6) ◽  
pp. 347-355 ◽  
Author(s):  
B. Kus ◽  
J. Kandasamy
Keyword(s):  
Low Cost ◽  
First Flush ◽  
Filtration System

scholarly journals Tracking the Evolution of Riverbed Morphology on the Basis of UAV Photogrammetry

2021 ◽  
Vol 13 (4) ◽  
pp. 829
Author(s):  
Teresa Gracchi ◽  
Guglielmo Rossi ◽  
Carlo Tacconi Stefanelli ◽  
Luca Tanteri ◽  
Rolando Pozzani ◽  
...  
Keyword(s):  
Management Practices ◽  
Low Cost ◽  
3D Models ◽  
Vegetation Coverage ◽  
Detection Analysis ◽  
Digital Terrain ◽  
Fluvial Dynamics ◽  
Aerial Vehicle ◽  
One Year ◽  
Short Time

Unmanned aerial vehicle (UAV) photogrammetry has recently become a widespread technique to investigate and monitor the evolution of different types of natural processes. Fluvial geomorphology is one of such fields of application where UAV potentially assumes a key role, since it allows for overcoming the intrinsic limits of satellite and airborne-based optical imagery on one side, and in situ traditional investigations on the other. The main purpose of this paper was to obtain extensive products (digital terrain models (DTMs), orthophotos, and 3D models) in a short time, with low costs and at a high resolution, in order to verify the capability of this technique to analyze the active geomorphic processes on a 12 km long stretch of the French–Italian Roia River at both large and small scales. Two surveys, one year apart from each other, were carried out over the study area and a change detection analysis was performed on the basis of the comparison of the obtained DTMs to point out and characterize both the possible morphologic variations related to fluvial dynamics and modifications in vegetation coverage. The results highlight how the understanding of different fluvial processes may be improved by appropriately exploiting UAV-based products, which can thus represent a low-cost and non-invasive tool to crucially support decisionmakers involved in land management practices.

scholarly journals Full in-Office Guided Surgery with Open Selective Tooth-Supported Templates: A Prospective Clinical Study on 20 Patients

2018 ◽  
Vol 15 (11) ◽  
pp. 2361 ◽  
Author(s):  
Francesco Mangano ◽  
Uli Hauschild ◽  
Oleg Admakin
Keyword(s):  
Clinical Study ◽  
Low Cost ◽  
Prospective Clinical Study ◽  
3D Printer ◽  
Guided Surgery ◽  
Operative Complications ◽  
Edentulous Patients ◽  
One Year ◽  
Single Crowns ◽  
Surgical Templates

Background: Guided implant surgery appears to have several benefits, such as the possibility of inserting flapless implants in a prosthetically driven manner, avoiding dangerous anatomical structures. However, to date, only a few surgeons routinely use guided surgery in partially edentulous patients. Aim: To present the results obtained with tooth-supported surgical templates characterized by an innovative open design with selective support, and manufactured via a full in-office procedure with a low-cost desktop 3D printer. Methods: Over a two-year period (2016–2018), all partially edentulous patients with one to three missing teeth (in maxilla and/or mandible), referred to a private dental practice for restoration with dental implants, were considered for inclusion in this prospective clinical study. An intraoral scanner (CS 3600®, Carestream Dental) and cone beam computed tomography (CS 9300®, Carestream Dental) were used to acquire the 3D information on the patients. Guided surgery software (SMOP®, Swissmeda) was used to plan the surgeries and to design open, selective, tooth-supported templates that were fabricated with a stereolithographic (SLA) desktop 3D printer (XFAB2000®, DWS). Guided implant surgeries were performed and patients were followed for a period of one year. The study outcomes were fit and stability of surgical templates, duration (time) of surgery, intra and post-operative complications, and implant stability and survival. Results: Twenty (20) partially edentulous patients (9 males, 11 females; mean age 54.4 ± 9.4 years) were included in the study; 28 open, selective, tooth-supported templates were designed with the aim of inserting 38 implants. Among the surgical templates, 24 had optimal fit and stability, three had optimal fit and sufficient stability, and only one had inadequate fit and unsatisfactory stability and was therefore not suitable for clinical use. The average time of the intervention was 15.7 ± 5.2 min per template. No intra-operative complications were reported, but one implant was not stable at placement and had to be removed. In total, 36 implants were restored with 10 two-unit fixed partial prostheses and 16 single crowns. All implants were successfully functioning at one year, even if, in two single crowns, minor prosthetic complications (abutment screw loosening) occurred. Conclusions: Full in-office guided surgery with open, selective, tooth-supported templates seem to represent a clinically predictable surgical procedure to restore partially edentulous patients. Further studies are needed to confirm these positive outcomes.

scholarly journals Seasonal Influence on the Performance of Low-Cost NO2 Sensor Calibrations

Sensors ◽  
2021 ◽  
Vol 21 (23) ◽  
pp. 7919
Author(s):  
Sjoerd van Ratingen ◽  
Jan Vonk ◽  
Christa Blokhuis ◽  
Joost Wesseling ◽  
Erik Tielemans ◽  
...  
Keyword(s):  
Low Cost ◽  
Added Value ◽  
Sensor Data ◽  
Sensor Technology ◽  
Monitoring Networks ◽  
Technical Problems ◽  
Eu Directive ◽  
Short Period ◽  
No2 Sensor ◽  
One Year

Low-cost sensor technology has been available for several years and has the potential to complement official monitoring networks. The current generation of nitrogen dioxide (NO2) sensors suffers from various technical problems. This study explores the added value of calibration models based on (multiple) linear regression including cross terms on the performance of an electrochemical NO2 sensor, the B43F manufactured by Alphasense. Sensor data were collected in duplicate at four reference sites in the Netherlands over a period of one year. It is shown that a calibration, using O3 and temperature in addition to a reference NO2 measurement, improves the prediction in terms of R2 from less than 0.5 to 0.69–0.84. The uncertainty of the calibrated sensors meets the Data Quality Objective for indicative methods specified by the EU directive in some cases and it was verified that the sensor signal itself remains an important predictor in the multilinear regressions. In practice, these sensors are likely to be calibrated over a period (much) shorter than one year. This study shows the dependence of the quality of the calibrated signal on the choice of these short (monthly) calibration and validation periods. This information will be valuable for determining short-period calibration strategies.

scholarly journals CVDentus bur for epithelial abrasion in the treatment of melanin pigmentation: case report

RSBO ◽  
2018 ◽  
Vol 1 (3) ◽  
pp. 186
Author(s):  
Katiane Vieira Menezes Leite ◽  
Patrícia Oliveira de Souza ◽  
Jussania Fonseca da Paz ◽  
Ana Beatriz Franco Fernandes ◽  
Leonardo Fernandes da Cunha ◽  
...  
Keyword(s):  
Case Report ◽  
Low Cost ◽  
Melanin Pigmentation ◽  
Alternative Approach ◽  
Safe Technique ◽  
Dark Color ◽  
One Year ◽  
Fast Procedure ◽  
Interesting Alternative

Introduction: The gingival melanin hyperpigmentation (GMH) is resulted from an abnormal deposition of melanin, but it is not a pathology. However, GMH is an esthetic problem for some people. Some alternatives of treatment for this situation exist. The epithelial abrasion has been an interesting alternative because it has a satisfactory esthetic outcome, is a fast procedure, of easy execution, and low cost. Recently, tips adapted in ultrasound (CVDentus) can bean alternative approach. Objective: To report a clinical case of GMH treated by the technique of the epithelial abrasion with association of instrument adapted in ultrasound. Case report: Patient aged 28 years, melanoderm, sought treatment due to esthetic dissatisfaction because of intense dark color in the maxillary gingiva. The GMH removal was proposed through the technique of the epithelialabrasion CVD bur. Conclusion: The technique of epithelial abrasion using CVD bur was effective in removing GMH at one-year follow-up showing to be easy and safe technique.

scholarly journals Impact of pretreatment on defluoridation of drinking water by bone char adsorption

2016 ◽  
Vol 4 (1) ◽  
Author(s):  
Adam Teusner ◽  
Rhett Butler ◽  
Pierre Le Clech
Keyword(s):  
Drinking Water ◽  
Low Cost ◽  
Feed Solution ◽  
Hollow Fibre ◽  
Human Consumption ◽  
Bone Char ◽  
Subsequent Removal ◽  
Filter Performance ◽  
Point Of Use ◽  
Gravity Driven

Fluoride concentrations in drinking water in excess of 1.5 mg L-1 are unsafe for human consumption. To reduce excess fluoride intake, developing countries must use low-cost, point-of-use defluoridation techniques. Although previous work has extensively assessed defluoridation using bone char (BC), most of the advanced studies have been based on the use of fluoridated distilled water as a feed solution. In the present study, BC columns were challenged with a range of model solutions, mimicking various pretreatment options. As a result, the relative impact of dissolved organic carbon (DOC) and suspended solids (SS) on the performance of BC filters was assessed. In addition, the performance of a gravity-driven, hollow fibre ultrafiltration (UF) module was examined with regards to the potential for use as a pretreatment option. SS were observed to severely clog the columns and cause the complete cessation of flow. The subsequent removal of SS by UF improved the general filter performance as well as increasing the BC lifetime by 50 %. The UF module achieved a reduction in DOC of 34 ± 6 %, resulting in an additional 30 % increase in the lifetime of the BC column.

scholarly journals Assessment of low-cost, non-electrically powered chlorination devices for gravity-driven membrane water kiosks in eastern Uganda

Waterlines ◽  
2021 ◽  
Vol 40 (2) ◽  
pp. 92-106
Author(s):  
Lukas Dössegger ◽  
Alan Tournefier ◽  
Laura Germann ◽  
Nicola Gärtner ◽  
Timon Huonder ◽  
...  
Keyword(s):  
Supply Chain ◽  
Low Income ◽  
Membrane Filtration ◽  
Low Cost ◽  
Evaluation Criteria ◽  
Sustainable Supply Chain ◽  
User Friendliness ◽  
Local Supply ◽  
Gravity Driven ◽  
Eastern Uganda

Recontamination during transport and storage is a common challenge of water supply in low-income settings, especially if water is collected manually. Chlorination is a strategy to reduce recontamination. We assessed seven low-cost, non-electrically powered chlorination devices in gravity-driven membrane filtration (GDM) kiosks in eastern Uganda: one floater, two in-line dosers, three end-line dosers (tap-attached), and one manual dispenser. The evaluation criteria were dosing consistency, user-friendliness, ease of maintenance, local supply chain, and cost. Achieving an adequate chlorine dosage (∼2 mg/L at the tap and ≥ 0.2 mg/L after 24 h of storage in a container) was challenging. The T-chlorinator was the most promising option for GDM kiosks: it achieved correct dosage (CD, 1.5–2.5 mg/L) with a probability of 90 per cent, was easy to use and maintain, economical, and can be made from locally available materials. The other in-line option, the chlorine-dosing bucket (40 per cent CD) still needs design improvements. The end-line options AkvoTur (67 per cent CD) and AquatabsFlo® (57 per cent CD) are easy to install and operate at the tap, but can be easily damaged in the GDM set-up. The Venturi doser (52 per cent CD) did not perform satisfactorily with flow rates > 6 L/min. The chlorine dispenser (52 per cent CD) was robust and user-friendly, but can only be recommended if users comply with chlorinating the water themselves. Establishing a sustainable supply chain for chlorine products was challenging. Where solid chlorine tablets were locally rarely available, the costs of liquid chlorine options were high (27–162 per cent of the water price).

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