scholarly journals A new reactor for denitrification and micro-particle removal in recirculated aquaculture systems

2016 ◽  
Vol 75 (5) ◽  
pp. 1204-1210 ◽  
Author(s):  
A. Boley ◽  
G. Korshun ◽  
S. Boley ◽  
V. Jung-Schroers ◽  
M. Adamek ◽  
...  
Keyword(s):  
Membrane Surface ◽  
Particle Removal ◽  
Membrane Unit ◽  
Biofilm Growth ◽  
Water Parameters ◽  
Sludge Flocs ◽  
Micro Particles ◽  
Denitrification Reactor ◽  
Recirculation Aquaculture System ◽  
Water Analyses

A ‘membrane-denitrification’ reactor (MDR) was developed and tested in a semi-technical recirculation aquaculture system in comparison to a double – without MDR – as reference system. The MDR consisted of a reactor with an ultrafiltration membrane unit for removal of micro-particles (e.g. sludge flocs, bacteria and parasites). Specific carrier material provided surfaces for biofilm growth in a fluidized bed reactor with ethanol as carbon source for denitrification. The continuous motion of these carriers cleaned the membrane surface. With online and laboratory measurements of water parameters and operational data the feasibility of the concept was verified. An advantage is that no chemicals are needed to clean the membranes. Examinations of the fish and water analyses proved an MDR can positively influence cortisol, as a stress marker, and the microflora of the aquatic system.

scholarly journals Air Backwash Efficiency on Organic Fouling of UF Membranes Applied to Shellfish Hatchery Effluents

Membranes ◽  
2018 ◽  
Vol 8 (3) ◽  
pp. 48 ◽  
Author(s):  
Clémence Cordier ◽  
Christophe Stavrakakis ◽  
Patrick Sauvade ◽  
Franz Coelho ◽  
Philippe Moulin
Keyword(s):  
Membrane Surface ◽  
Operating Conditions ◽  
Particle Removal ◽  
Two Phase ◽  
Significant Information ◽  
Dead End ◽  
Biodiversity Preservation ◽  
Organic Fouling ◽  
Uf Membranes ◽  
The Impact

Among all the techniques studied to overcome fouling generated in dead-end filtration, the injection of air during backwashes proved to be the most effective. Indeed, shear stress engendered by the two-phase flow enhanced particle removal on membrane surface. This work aims to study the injection of air to drain the membranes before backwash. Firstly, the efficiency of this backwash procedure was evaluated during the ultrafiltration of seawater on a semi industrial pilot plant using different operating conditions. Then, the treatment of seawater, doped with oyster gametes to simulate the filtration of shellfish hatchery effluents, was performed to confirm the hydraulic performance of the air backwash. Indeed, the release of gametes, expulsed by exotic bivalves in the natural environment, could be a risk for the biodiversity preservation. The impact of air backwash on the integrity of oocytes and spermatozoa was identified using flow cytometry and microscopic analyses. When oyster gametes were added, their retention by ultrafiltration was validated. The impact of air backwash on these species viability was a significant information point for the implementation of this process on shellfish production farms.

Biofilm formation and permeate quality improvement in Gravity Driven Membrane ultrafiltration

2013 ◽  
Vol 14 (2) ◽  
pp. 274-282 ◽  
Author(s):  
A. Chomiak ◽  
J. Mimoso ◽  
S. Koetzsch ◽  
B. Sinnet ◽  
W. Pronk ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Fine Particles ◽  
Packed Bed ◽  
Growth Potential ◽  
Particle Removal ◽  
Permeate Flux ◽  
Biofilm Growth ◽  
Gravity Driven ◽  
Biofilm Development ◽  
Biofilm Structure

The effects of biofilm development on ultrafiltration membranes with regard to permeate stability and permeation rates were investigated using Gravity Driven Membrane (GDM) filtration. The first part of the study aimed at evaluating the influence of the biofilm on permeate flux quality and quantity with regard to Assimilable Organic Carbon (AOC) degradation. In addition, two types of biological pre-treatments were evaluated: slow sand filtration and packed bed bio-reactor, compared to a control (no treatment). Biofilm formation helped to decrease the AOC content of permeate water, compared to the influent. Both pre-treatments additionally reduced the AOC level in the permeate and thus increased its biological stability, however none of the systems were able to guarantee microbiologically stable water. Removal of AOC before the GDM filtration reduced the biofilm growth potential, which in turn influenced its physical structure and enhanced the permeation rates. Influence of inorganic particle removal by pre-sedimentation and its effect on biofilm structure were also studied. Pre-sedimentation of particle populations selected fine and homogeneous particle fractions, which led to the formation of a homogeneous biofilm structure characterised by an increased hydraulic resistance. This was clearly visible between horizontally and vertically installed membranes where the latter ones had a significantly reduced flux despite lower deposited particle mass. The presence of larger, heterogeneous particle fractions counterbalanced the negative effects of the fine particles, which overall resulted in enhanced permeation rates.

Experimental test to evaluate performance of an anaerobic reactor provided with an external membrane unit

1998 ◽  
Vol 38 (8-9) ◽  
pp. 385-392 ◽  
Author(s):  
S. Elmaleh ◽  
L. Abdelmoumni
Keyword(s):  
Membrane Fouling ◽  
Industrial Development ◽  
Particle Deposition ◽  
Membrane Surface ◽  
Cross Flow ◽  
Membrane Unit ◽  
Anaerobic Reactor ◽  
Flux Decline ◽  
Aerobic Reactor ◽  
Sludge Production

The coupling of a wastewater treatment anaerobic reactor with a microfiltration or ultrafiltration membrane is particularly attractive: lower sludge production than in an aerobic reactor, methane production and dissociation of the mean residence times of the different phases. However, the industrial development of such a process is hampered by membrane fouling which can be a result of many causes and require a comprehensive study especially fouling by anaerobic suspensions. In order to simplify the study, the different phases of anaerobic oxidation were separated and this work is focused on the filtration of an anaerobic suspension fed with acetic acid as the sole carbon source at 2 g/l TOC. The effluent quality was excellent without sludge production in spite of large variation of the liquid phase space time. The tested filtration elements were tubular Carbosep membranes. The M14 membrane showed the greatest flux of 120 l/m2 h at 0.5 bar and 25 Pa shear stress and the flux increased to 180 l/m2 h when a baffle was introduced. The main fouling mechanism appears to be the particle deposition on the membrane surface as no flux decline was observed at higher cross-flow velocity.

Behavior of micro-particles in monolith ceramic membrane filtration with pre-coagulation

2004 ◽  
Vol 50 (12) ◽  
pp. 317-325 ◽  
Author(s):  
H. Yonekawa ◽  
Y. Tomita ◽  
Y. Watanabe
Keyword(s):  
Membrane Filtration ◽  
Ceramic Membrane ◽  
Membrane Surface ◽  
Flow Analysis ◽  
Ceramic Membranes ◽  
End Point ◽  
Micro Particles ◽  
Dead End ◽  
Cake Layer ◽  
The Dead

This paper is intended to clarify the characteristics unique to monolith ceramic membranes with pre-coagulation by referring to the behavior of micro-particles. Flow analysis and experiments have proved that monolith ceramic membranes show a unique flow pattern in the channels within the element, causing extremely rapid flocculation in the channel during dead-end filtration. It was assumed that charge-neutralized micro-particles concentrated near the membrane surface grow in size due to flocculation, and as a result, coarse micro-particles were taken up by the shearing force to flow out. As the dead end points of flow in all the channels are located near the end of the channels with higher filterability, most of the flocculated coarse particles are formed to a columnar cake intensively at the dead end point. Therefore cake layer forming on the membrane other than around the dead end point is alleviated. This behavior of particle flocculation and cake formation at the dead end point within the channels are unique characteristics of monolith ceramic membranes. This is why all monolith ceramic membrane water purification systems operating in Japan do not have pretreatment equipment for flocculation and sedimentation.

Removal of micro-particles by microbial granules used for aerobic wastewater treatment

2004 ◽  
Vol 50 (12) ◽  
pp. 147-154 ◽  
Author(s):  
V. Ivanov ◽  
J.-H. Tay ◽  
S.T.-L. Tay ◽  
H.-L. Jiang
Keyword(s):  
Escherichia Coli ◽  
Wastewater Treatment ◽  
Laser Scanning ◽  
Confocal Laser Scanning Microscope ◽  
Flow Cytometer ◽  
Confocal Laser ◽  
Particle Removal ◽  
Bacterial Cells ◽  
Becton Dickinson ◽  
Micro Particles

Microbial granules with a diameter from 0.4 mm to 3.0 mm have been produced by fast sedimentation and retention of microbial aggregates in sequencing batch airlift reactors used for model wastewater treatment. The wastewater was with or without addition of calcium salt. The granules were able not only to degrade organic matter but to remove nano- and micro-particles from wastewater due to microchannels and pores in the matrix of the granules. To detect the removal of 0.1 μm, 0.6 μm, 4.2 μm fluorescent microspheres, and cells of Escherichia coli, stained by permeable nucleic acid stain SYTO9™, the granules were incubated with these particles. The rate of particle removal and their accumulation in the granules was measured by a Fluoview300 confocal laser scanning microscope (CLSM) (Olympus, Japan); a FACSCalibur flow cytometer (Becton Dickinson, CA, USA), and a fluorescence spectrometer LS-50B (Perkin-Elmer, UK). The release or removal of biological and non-biological particles was analyzed by a flow cytometer after DNA staining. Total number of the particles bigger than 0.1 μm in the reactors was approximately 4 × 107 per ml, and 23% of these particles were bacterial cells. The 0.1 μm and 4.2. μm microbeads were accumulated within 250 μm in the upper layer of the microbial granule but externally added cells of Escherichia coli penetrated to the depth of approximately 800 μm in the granules without calcium addition. Microbial granules contained also attached ciliates but accumulation of the particles in protozoan cells was smaller than in the granule matrix. Kinetics of particle sorption was revealed by flow cytometry and fluorescence spectrometry. Almost half of the stained cells of E. coli can be removed by the granules for one hour. The ability of the microbial granules to remove the particles can enhance their function in aerobic treatment of wastewater.

Effect of hydrodynamic and physicochemical changes on critical flux of milk protein suspensions

2002 ◽  
Vol 69 (3) ◽  
pp. 443-455 ◽  
Author(s):  
WIROTE YOURAVONG ◽  
ALISTAIR S. GRANDISON ◽  
MICHAEL J. LEWIS
Keyword(s):  
Whey Protein ◽  
Electrostatic Interactions ◽  
Membrane Surface ◽  
Sodium Caseinate ◽  
Whey Protein Concentrate ◽  
Particle Removal ◽  
Protein Concentrate ◽  
Critical Flux ◽  
Physicochemical Changes ◽  
Repulsive Forces

The critical flux during ultrafiltration of whey protein concentrate and sodium caseinate suspensions was investigated. The weak form of critical flux was found for both suspensions. Critical flux of sodium caseinate was higher than that of whey protein concentrate. This could be due to the differences in particle size of the suspensions, resulting in a slower particle back transportation for small particles (whey proteins) compared to the larger casein micelles. Critical flux increased as crossflow velocity increased and decreased as concentration increased, suggesting that critical flux was determined by competition between rate of particle removal from the membrane surface and rate of particle movement towards the membrane surface. Influence of changing pH, addition of NaCl and CaCl2 on the critical fluxes of both protein suspensions was also studied. Increasing pH led to an increase in critical flux for both protein suspensions, suggesting that electrostatic repulsive forces are involved in determining critical flux in both cases. Addition of NaCl gave rise to a decrease in electrostatic interactions due to an increase in ionic strength and ζ potential, and resulted in a decrease in critical flux for sodium caseinate, but had no significant effect for whey protein concentrate. Addition of CaCl2 resulted in a decrease in the critical flux and had a more pronounced influence than NaCl. These results suggest that, in addition to electrostatic repulsive forces, other factors such as structure of protein may be involved in determining the critical flux.

Minimisation of biomass in an extractive membrane bioreactor

1996 ◽  
Vol 34 (5-6) ◽  
pp. 273-280 ◽  
Author(s):  
L. F. Strachan ◽  
L. M. Freitas dos Santos ◽  
D. J. Leak ◽  
A. G. Livingston
Keyword(s):  
Membrane Bioreactor ◽  
Energy Requirement ◽  
Membrane Surface ◽  
Growth Conditions ◽  
Organic Substrate ◽  
Rubber Membrane ◽  
Biofilm Growth ◽  
Volatile Organic ◽  
Maintenance Energy Requirement ◽  
Biological Methods

Many traditional biological methods for the treatment of wastewater cope poorly with toxic, volatile organic compounds. The extractive membrane bioreactor is a novel process for the treatment of industrial wastewaters containing such compounds which combines extraction across a silicone rubber membrane with biodegradation. Previous work has shown that there is a problem in this system with excess biofilm growth on the membrane surface, resulting in reduced flux of organic substrate across the membrane. The work presented here shows that addition of sodium chloride to the biomedium increases the maintenance energy requirement of the degradative microorganisms and results, in a carbon-limited situation, in a reduction in biofilm growth. Flux of organic substrate was shown to remain high under reduced biofilm growth conditions.

scholarly journals Comparative Performance of Tetraphosphonate and Diphosphonate as Reverse Osmosis Scale Inhibitors

2018 ◽  
Vol 251 ◽  
pp. 03049
Author(s):  
Alexey Andrianov ◽  
Maria Danilycheva ◽  
Stefania Liakaki-Stavropoulou ◽  
Konstantinos D. Demadis ◽  
Roman Efremov
Keyword(s):  
Reverse Osmosis ◽  
Membrane Surface ◽  
Waste Water Treatment ◽  
Feed Solution ◽  
Chemical Additives ◽  
Membrane Unit ◽  
Comparative Performance ◽  
Sharp Drop ◽  
Function Relationship ◽  
Relationship Of

Reverse osmosis (RO) technologies are widely used throughout the world for drinking, industrial and waste water treatment purposes. Proper and economically attractive operation of RO installations should be provided by the correct maintenance of all technical process parameters. One of the significant operational problems is precipitation and deposition of sparingly-soluble salts on the membrane surface, which can be prevented by dosing special chemical additives into the feed solution. The aim of the present work is to reveal the structure/function relationship of phosphonate scale inhibitors, which possess systematic structural similarities and differences. Specifically, two classes of tetraphosphonate (5 additives) and diphosphonate (6 additives) have been tested as calcium carbonate scale inhibitors on the lab membrane unit. It was found that among the family of tetraphosphonates and diphosphonates the inhibitor efficiency increases with elongation –(CH2)– chain, but the longest additives have a sharp drop in inhibition efficiency.

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