Water Treatment Plant

It sounds as though at that sort of flowrate the solution being proposed is highly capital-cost- and operating-cost-intensive. There may be some space issues to address as part of such a solution.

Perhaps a package carbon filter might be a better way to remove the organics? It would also lower the pH slightly.

Get the facility's process engineer involved. Early.

I am aware of the capital costs are going to run the town into the 5 to 750 000 dollar area. The carbon filters you suggested would that be the GAC, Granular activated carbon? we are already adding PAC, or Powdered activated carbon to our process. as for a process engineer i am the closest thing to that at the plant ..As for the space issues there is no shortage for space as i have a 13L/sec 1950's lime soda plant i am in the process of getting removed from the building freeing up over 700 sq.ft.

Have you looked into magnetic ion exchange resins? MIEX claim to have a cost effective method of removing dissolved organic carbon - that would minimize your THM issue.

1. This page talks about the same type of application as yours, and gives the names of some US water treatment plants that have tried it - maybe ask there and see how it worked out..
   

Ya i had some info on the ion exchange and have been told it would help by a couple sales men from different companies but when i ask for more in depth explanations on how this works i get dead ends. i have an idea how the process works but what kind of regeneration chemicals and what would be the upkeep costs after the initial costs? would greatly appreciate more info.

There's an address and telephone number (USA) in the left margin second page of the MIEX pdf link above - they'd be the ones to tell you about it.

Thank you for the information artsmith.

You're welcome.

A bit basic, but I don't suppose you pre-chlorinate? I.e. upstream of flocculation/sedimentation. This used to be done (in UK anyway) before THMs became an issue, as it improved settlement. But that's when all the organics are still present, so worst THM problem. Nowadays chlorine is added later, preferably just before the final water storage tank.

Cheers.........Codey

no we don't pre-chlorinate they use to do this cause chlorine is an oxident and for well water it helped with the iron and maganeses removal. we use potassium permanganate as an oxident in the raw water it is a better oxident and doesn't produce the thm's. The first water plant i operated we pre chlorinated there but the chlorine also had a 45-60min detention time before it got to the plant. We had to stop when they got the new nano membrane filtration plant operational.

Most have gone to RO systems fed by wells to get around the surface water organic problems. The problem is finding low to no THMs without producing water that turns out to be corrosive. You will have an uphill chemistry battle from this time forward with the surface water and because of cost, your long term solution is likely wells and a RO system.

Contact the Marco Island utlility people to find out how to work with surface water.

Ya Ro systems are nice they have their uses but they also have major issues in older distribution systems as the wonderful engineers that recommend these new marvels of science and treatment forget about a little scale called the Langelier scale. and even perfectly neutral water is highly corrosive as it takes takes back the minerals you just pressurized out of the water off the walls of the pipes causing a higher than normal number of water breaks. usually takes about 2 to 3 months for this wonderful side effect of pure water to rear its ugly head. than you end up fighting with chemicals again as you have to add inhibitors, and hardness back into the water. Been there done that operated a ro over nano plant they are nice they run themselves almost just have to make sure you have all plastic pipe and that's only in a perfect world that happens.

The easiest and cheapest way is to add a small amount of ammonia to the drinking water. Ammonia (NH3) reacts with the chlorine in water to form chloramines (NH2Cl, NHCl2, NCl3). These components do tie up the free chlorine but are still disinfectants. You may need longer contact times for disinfection. There are CT charts to help you with that aspect. The process is called chloramination.

If you are a member of the American Water Works Association (AWWA) or any of its affiliates you should be able to acquire a good reference book on chloramination. They also sell to non-members at slightly higher costs. I am retired but I did use Clifford Whites book called The Handbook Of Chlorination. There are other good books available and I suggest browsing the AWWA bookstore.

I was asked to assist a plant with high TOC and with methane. They were pre-chlorinating the well before it reached the plant. We ran a pilot for several years including full scale and finally switched to peroxide as pretreatment (to control biofouling mostly). We were an early entry of peroxide treatment in municipal water. Ammonia was added to the water as it exited the plant. It worked wonderfully at little capital expense.

yes i have looked into the adding of the ammonia already but in the province i am in they are strongly pushing the towns and municipalities away from chloramination. thank you for the suggestion they all help out. i am leaning towards the MIEX magnetic ion exchange. i have the in house room for the needed equipment and it has had some of the best results in the reduction of the thm issues as well.

Kel

I admit to not knowing anything about the MEIX system. It sounds a lot like the anion exchange systems to remove organic material. They often use chloride as the exchange ion. It was used quite a bit at one time but seems to have fallen from favour. We did have problems with ion balance. Alkalinity would be lowered and we would lose 1-2 notches of pH. If sulfate was present at higher levels, it would be removed first and use up exchange capacity. You had to watch the pH/alkalinity and adjust constantly. The downstream water would be very corrosive to plumbing.

I will try to read up on MEIX and then try to get a better response. You may want to talk to other resin experts like Rohm and Haas and then see what they say about MEIX. You can sometimes learn a lot from competitors. Good Luck with your project and if I can get a chance to read on MEIX I will let you know.

thank you for the interest and help it is much appreciated. From what i can tell i can use my potassium permanganate as a recharger as it is an oxidizer. and i am already using the potassium in the pre treatment to oxidize organics and for taste and odor control. I have found most of the MIEX units to be in australia with 5 or 6 trials in the USA and at least 2 units in the USA in operation. I also just got some more info from Mequipco a supplier that i have been working with on this issue. They are also a supplier for the GE membrane filters. ZeeWeed systems i believe if memory serves me correctly. i was also interested in trying to get some info if running an ultra membrane unit after my rapid gravity filters would work.