I can't help with your UF but if you want to make the switch to media filtration then please get in touch. Our FilterClear system offers significant advantages over traditional dual media filtration: better filtrate quality, higher filtration rate and lower capital cost. This is achieved by using four media layers which re-stratify based on specific gravity after each backwash. Generally FilterClear does not require chemicals, either for flocculation or for cleaning, so operating costs are low too. We have several references for desalination applications, including a large plant at KAUST, Saudi Arabia. See http://www.bluewaterbio.com/filterclear/ for more information.
One more question, do you pre-treat the water by UF for RO? If that is the case then you cannot avoid UF membranes as SDI will be much higher to clog your RO Membranes if you bypass UF Membranes.
In addition, DOW UF has an exceptional feature which others UF membrane manufactures have, that is Air Scouring, you can increase time of Air Scouring to eliminate the suspended particles accumulation and Air Scouring is also a Scheduled Task while it goes to Backwash after 12 hrs interval.
it is very important which type of raw water you used, if surface water and sea water is raw water used in your system ,the UF pretreatment was suitable choice.
Hi Ali, what do you mean with maintenance costs? Do you mean frequently replacement of UF membranes/modules ? What is the application of UF? Is UF used as pre-treatment System for RO? Do you have any P&ID for review? What is the UF feed water and outlet water quality concerning turbidity, TSS & SDI? Do you have any UF projection from DOW?
I would recommend to check and adjust the time intervals for backwash and CEB and also the related chemicals for CEB and/or CIP. Do you use also a recommended strainer (150 micrometer) at the UF inlet? It seams that the UF is overloaded!
Hi Mohsan. Where are you located? I'll get a Dow representative to support and work through the issues. The Dow UF is exceptional at handling high TSS loads and will outperform media filtration in quality and total recovery, we just have to make sure the system is optimised and working as recommended. What TSS are you running? Presence of metals?
I still strongly recommend keeping with the UF - it is the standard and will have significant advantages over conventional media systems. When was the last CIP? Borehole often has high Iron and can block a UF without much improvement from backwashing. Then a CEB is necessary with Acid or if it is severe then a CIP with citric acid is highly recommended. I had a plant that hit 2.0 bar TMP from metals. 1 CIP and the TMP was back at 0.4 bar. Dow UF fibres are very chemically resistant so cleaning procedures can be harsh without long term damage to the fibres.
Hi Mohsan. Where are you located? I'll get a Dow representative to support and work through the issues. The Dow UF is exceptional at handling high TSS loads and will outperform media filtration in quality and total recovery, we just have to make sure the system is optimised and working as recommended. What TSS are you running? Presence of metals?
UF can function reasonably well up to incoming turbidity of 10 NTU. Anything more & consistent, and you require pre-treatment. There is so much hype around membrane filtration that people have started forgetting that 95% of surface drinking water is processed by conventional methods like effective media filtration.
The problem will come down to an economic analysis.
Is the turbidity issue, a feed problem or filtrate problem?
If turbidity is a feed problem, then pre-treatment is the only solution if you retain UF.
If the turbidity is in the filtrate, then this is a filter maintenance problem, with failed membranes leaking.
On the question of changing to gravity media filters from UF, you need to know what final water turbidity is acceptable. UF will provide a better filtrate if it is maintained, but UF is a more intensive and higher maintenance process. An advantage of UF is the land area required is significantly less. Media filters require a large surface area.
Media filters are simpler in terms of operation and maintenance, but are more sensitive to the chemical dosing systems. If putting in media filters, ensure that you provide filter-to-waste after the backwash to ensure that any particles trapped in the media after backwash do not make it to the water supply.
The decision comes down to money and other constraints.
There are several options for enhancing UF performance and improving the economic situation. If UF quality is not needed multimedia filtration may prove effective and economic in the long run. You will not achieve the same levels of filtration with multimedia as you will with UF. Envirogen is well versed in filtration systems of all types. Envirogen Group has offices all over the world. http://www.envirogengroup.com/contact-us-2/
Are you doing any pre-treatment in front of the UF. Organics, in particular polymers will foul a UF quickly. Depending on the influent turbidity you may not have enough surface area, look to increase capacity of the UF, or perhpas add a small amount of ferric chloride to aid the filtration process.
In general, the use of ultrafiltration is an excellent method of removing turbidity. Ultrafiltration membranes are sensitive to the presence of incoming particles, and some pre-filtration may be a solution to consider, especially if colloids or large particles are present in the source water. I would recommend you look into a media filter in front of the UF, to protect the membrane, but keep the UF in place. The final decision would be based on the final requirement you have for the finished water. As many others have already stated, not enough information is presented to give a specific solution to your issue, but having a membrane UF exposed to unfiltered source material is very likely to result in excessively high maintenance costs and poor filtration performance. Another possibility is membrane failure, leakage or incomplete sealing of the system, resulting in poor quality (turbidity) of your finished water. sam.mason2824@gmail.com.
You mention that turbidity is a problem, if it is a problem in that the influent turbidity is overwhelming the UF then you will need some sort of clarifier ahead of the all technologies regardless of whether they are UF or media filters. I doubt you have turbidity in your effluent after the UF's. If so that is another issue. We do make a granular media that has 3rd party validation for performance and is the best option for media filtration to replace UF. However all media filters have a limit on the influent turbidity they can handle so we need more information. please email me detailed information at sales@wateropolis.com
We are a France based water treatment company providing solutions for the bottling industries (visit http://www.ice-water-treatment.com/en/) over the world. We are familiar with Ultrafiltration processes as well as media filtration, but our experience on Dow UF modules is not that high. We could propose some process assesment of your water treatment and evaluate, based on your operation experience and water characteristics what are the best options for your filration needs. Feel free to transmit me your data, which I would forward to the sales engineer in charge with your geographic area. I hope that we talk soon.
Patrick Ballato - pballato@ice-water-engineering.com