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Filamentous Identification

"the Easy Way"

New training program

New Plant Start-ups or starting up after a shutdown

What are some of the things that you need to be critically aware of when starting up a new plant and what are some of the problems that may occur?

Obviously, the main things to be aware of are the manufacturer's design specs, following all standard operating procedures, and making sure the "Critical 5" are met.

What the engineers don't tell you sometimes is that you cannot always start immediately at full-blown speed. This is probably what will happen if you do. . .. . .. High loading and young bugs do not mix well without lots of room to grow.....

There were at least 5-6 feet of foam billowing out the top of the aeration basin, out over the top, all over the ground and even out the overflow spout!!!!

There was foam in the sumps, the drains, in the EQ tank and in the final effluent holding tank. Anywhere the bugs could grow, they did and quite happily as you can see by the evidence of crisp white foam.

There was even foam coming out of the manhole.

When the bacteria are in a high growth phase and young, there almost always is crisp white foam. With a plant start up, in this case with BOD's as high as 20-30,000 and simple sugars from a winery, the bugs were growing like kids in a candy store. During a start-up the levels of the aeration basin must be only at about 1/3 to one half full for the first few days in order to allow room for the foam. As the foam starts to change colors from a crisp white foam to a lighter tan and then to a nice brown color, the levels of the basin can slowly be filled higher to half, 3/4 and then normal operating height. You can always cheat, and add bacteria supplements at a higher dosage to speed up the process along with micronutrients.

Remember that it is always a time and numbers game with bacteria in wastewater treatment. How much time, how many numbers and how much food is there to degrade. The more food, the more time or numbers is needed. Since you are limited by time due to the fixed space allowed in the pieces of equipment in the system and a fixed holding time, the only way to win the game is to change the numbers. You can decrease wasting, play with your RAS or use bacterial supplements.

Here the foam is not as white and is starting to turn a light tan or brown. Less foam is present and the biomass is starting to get a bit older. More floc structures are present and higher life forms are starting to show up.

Here is foam from a papermill that is still young, but not in the start-up phase. You can see the difference in the color of the foam. Definitely light brown.

This is a winery in Australia, you can see by the amount of foam on the picture on the right vs. the one on the left, which was the younger phase with the higher BOD and F/M ratios. Always look at the foam, it can tell you what is going on. Correlate that to your settlometer data, and your microscopic and you should be able to fine-tune your plant.

Always run a settleometer and check the levels of MLSS in the system. Look for how many solids are in the settleometer and track the daily changes. Look for settling rates, cloudiness or clarity. Turbidity, foaming or floating sludge. All of these tell you what is going on in the system.

This is from the winery in Napa during the first week of start-up. There is starting to develop a MLSS as you can see by the solids on the bottom of the settlometer. There are still tons of single celled bacteria evident by the cloudy, turbid water. A few days off still from having a good biomass and less foaming.

This is from a chocolate plant. The MLSS has definitely caught up to the loading. Almost too much MLSS and time to finally start wasting. Free swimming ciliates, and well-defined floc structures were present in this sample. Clear supernatant was present. Eventually, this plant was able to achieve 15-20 TSS and 30 BOD with a loading of 4-8000 COD at times.

This is from a papermill with two aeration basins that had the light brown foam. As you can see, the tank on the left had D.O. problems, evident by the instant floating of the solids in the settlometer.

Many plants like to use antifoams. Actually, as a band-aid in a pinch they work, but what they really do is remove the air, which is critical to the bacteria in a high growth phase, so it takes longer for them to get out of the high growth phase and it also can add extra BOD to the water, so it is a catch 22 using antifoams.

This was a plant start-up at a chocolate manufacturing plant. Again, high foam in the initial start-up phase, although higher doses of initial start-up cultures of bacteria helped reduce the amount of foam and the time of foaming needed to develop a better biomass and more MLSS.

Alternatives to chemicals are to use mechanical means to spray the influent or clean water over the foam and use gravity to compress the foam. Using the influent is the easiest, since you are not diluting the tank with extra water and shortening the retention time in the systems in you use additional clean water.

Simple sprayers can be made or purchased. This was used onsite with just a submersible pump, and some PVC piping.

This was a trial for a chocolate factory and again, influent spray was used to knock down the foam. Side benefits of doing that are it kept down the temperature a little bit, circulated and mixed the aeration basin and helped add a little bit more D.O. to the system as opposed to using chemical antifoams.

Some Plants use spray for older plants with foaming as a physical control method instead of using antifoams.

This was not a start-up but a municipal plant that has problems with filamentous bacteria causing foaming. Influent is used by sprayers on the sides of the basins to knock down the foam and control it while process changes are being implemented

This is from another plant that used spray to knock down foam. Obviously, it is not working too well. Finding the cause of the filaments, and making a process control change would be more effective in controlling the foam and filaments.

Here is another version for filamentous foam control

Although it may help knock down the foam, the best control method is to perform a filamentous identification, learn what type of filament is present and address the root cause. A few process changes may completely get rid of the filaments along with the foaming problem permanently!