TANKS

Underground Tanks

As we all know, water flows downhill.  Starting with your slab in the brewery, water flows into the drains, to the piping under the slab, then out to sewer or in to an underground tank.  Let’s talk about that underground tank for a bit.

The world is your oyster.  This can tank be big or small, concrete, fiberglass, plastic, steel, or..?  There is no right or wrong, but there is good, better, and best for sure.  Read here for an blog post about a brewery lift station.

Thoughts on size.  Go with the biggest tank you can afford and that you have room for, especially if you have a production brewery with plans to grow over the years.  Big tanks have more headspace, and that headspace can be used when things aren’t going right- such as a pump or power failure.  The headspace can fill a bit before alarm level, and before water starts backing up in the drains.  Having space available allows you to at least finish what you were doing.

A small tank works, but there isn’t much room in the tank.  If the pump fails or power goes out the tank will fill and back up in the drains quickly. It’s also a tight fit for accessory equipment such as level sensors, junction boxes, and any sort of strainer. Bigger is better.

Materials of construction.  I really like using quality plastics in wastewater applications, they don’t corrode and they’re usually inexpensive.  However, due to high temperature and potentially very high temperature underground plastic tanks (prefab septic tanks) should be avoided for a brewery.  In normal circumstances the water will be pushing the upper temperature limits leaving your brewery, averaging about 105F or so.  Most underground plastic tanks are rated for no higher than 120F. There will also be spills and other events leading to water that can be close to 200F in that tank.  A collapsed wastewater tank because of an overflowing hot liquor tank would be a major bummer.

What I do normally use is a precast concrete tank. Temperature is never a problem, they’re inexpensive and readily available.  A urethane coating inside the tank, or an anti-corrosion admix in the concrete helps. Admixes are a whole new world, but for this discussion it’s a material added to the wet concrete and mixed in, making the concrete itself inhospitable to bacterial growth (and corrosion).

Fiberglass tanks are OK, but susceptible to temperature and corrosion.  To match those concerns a special resin needs to be used, making the tank a special order.  And fiberglass tank manufacturers aren’t widespread, so shipping gets expensive. I have looked into offering a custom, prefrab, fiberglass brewery wastewater tank package, but it simply gets too expensive.

A steel tank is asking for trouble due to corrosion. Stainless steel is an option, but it’s expensive and nothing is readily made for an underground, direct burial application.

Ugh. All of this and we’re still on underground tanks…

EQ Tanks

An EQ tank can be a great solution for a medium sized brewery- or even large ones. This type of tank offers a lot of options at a low cost.  For instance the EQ tank can store wastewater produced during the day/week and discharge it overnight, or evenly 24/7. This levels out flow peaks/valleys and that can be tremendously helpful to a small wastewater treatment plant.

However the most common feature of an EQ tank is a place to do pH adjustment, manual or automatic. This type of system is commonly designed by Brewery Wastewater Design. We regularly design small EQ tank and pH adjustment systems. Often times the systems we design have the lift station, EQ tank, and pH adjustment all going on in one tank. It’s underground, out of the way, out of sight, saves space, and allows for expansion. We call this our ‘LipHt System’ and you can read more about it here. Sales pitch out of the way…

The EQ tank itself can be plastic since it’s not buried, but if aesthetics is important it can be an old FV or BBT.  If we’re talking small and simple it could even be an IBC tote.

If going with a plastic tank, I use a heavy duty tank, usually rated for 1.9 SG.  The water in the tank will not have a gravity that high, but it will be fairly high temperature, so the thicker tank wall of a heavy duty tank is more durable over time.

In any type of EQ tank, at a minimum you will need ports for inlet, outlet, and vent.  If there is a recirculation system you will need a mixer supply and return port.  You will want a port at the bottom for annual cleaning, and maybe a port for a level sensor and/or sight glass. What about an overflow? Just like that we have taken a perfectly intact tank and turned it in to swiss cheese.  How to seal all of those tank penetrations?

Bulkhead fittings allow a threaded fitting on the sidewall or top dome of a tank. Sounds great, but they can leak. In areas that will be underwater frequently, at least the bottom 50% of the tank height, I do not recommend poly bulkheads. Go with stainless, you can get them really tight. A poly fitting might snap when getting really tight with large pipe wrenches, then things get ugly.

How to install a bulkhead fitting without getting in the tank? After drilling the correct size hole, tie the bulkhead fitting to a rope (without the nut) and gently drop it into the tank. Use a hook (or an arm) to grab the rope, then slip the fitting into place and put the nut on from outside. Remove the rope. Check it out on YouTube (not my video). You will notice towards the end of the video he installs an ‘eductor’ mixing nozzle. I do not use these and I recommend you don’t either. The reason is this is wastewater and they will plug or get bound up with fibers over time. And they’re inside the tank so you can’t do any maintenance to it. Don’t shoot yourself in the foot!

A helpful addition to an EQ tank is called a calamity tank. Read more about those types of tanks in the next section and here. The general idea behind these tanks is if there is a spill in the brewery (beer, wort, chemical) you can isolate it in the calamity tank, then continue normal operations and dispose of the spill at a later date.

Finally, one big thing to keep in mind is an EQ tank is a great starting place for any future pretreatment you might have in mind.  Are you considering aerobic or anaerobic pretreatment at some point in the future?  You’ll need an EQ tank upstream, any money spent on an EQ tank system will pay dividends in the future as your brewery expands.

Side Stream Tanks

Side streaming is collecting high strength, concentrated wastes at the source and setting it aside for disposal. You are already doing this with your spent grain. You can elaborate on the concept to collect trub and spent yeast. Smaller sources would be lauter plate rinsing, hop back rinsing, fermenter bottoms, returned beer in kegs, fermenter blow off, and beer in hoses or pipes at the beginning or end of a packaging run. Read more about the process of side streaming here, right now we’re going to talk about the tank itself.

Depending on the size of your operation, you may choose to use one big tank or several smaller, portable tanks. With one big tank you would transfer the water to a truck at your brewery. With smaller portable tanks (IBC totes), you would put one in the back of a pickup truck or several on a trailer and haul it offsite. In either case, try to put these tanks outdoors, they’ll stink and are a potential infection source for your product.

Similar to the EQ tank, you will need ports for inlet, outlet, and vent.  You will want a 2^nd port at the bottom for periodic mixing, and smaller hole at the top for a level sensor wire.

Mixing? Side stream crud is high in solids and it can get really thick, like toothpaste. Stirring up the bottom of the tank a few times a year before the material gets hauled off site will give you back some tank capacity. You want a fitting to hook up the pump return hose to, so it doesn’t fly out the top of the tank and create a stinky mess. Been there, done that. Not good.

Also similar to the EQ tank, go with a heavy duty tank here if using a plastic tank. Due to trub and lauter plate rinsings, the water will likely be even hotter than the material in the EQ tank.

Small scale side streaming

A large side streaming tank.

Calamity Tanks

Ph adjustment with calamity tank.

In my vision of a perfect world, all breweries would have a calamity tank. Similar to an EQ tank but more simple. But what the heck is a calamity tank? Read more about the function of a calamity tank here. Again, we’re talking about the tank itself right now.

A calamity tank is a wastewater tank, normally empty, that can be used for spills, bad beer, and storage. Imagine this scenario, during pump over from the whirlpool to the fermenter, someone left a valve open and an entire batch of hot or cold wort just went down the drain. With a calamity tank you would promptly switch valves or add a hose and pump from your lift station into the calamity tank. Once the spill is isolated in this tank you can continue working and get rid of the contents another day.

As with any wastewater tank, depending on the size of your operation, you may choose to use a large or small tank. Or none at all. Most breweries do not install a tank like this. But they are a good idea, especially if your brewery is discharging to a small treatment plant.

In the photo on this page, the EQ tank is underground.  There is a 3-way ball valve along the wall that can send water into the calamity tank if needed.

Level Detection

Well what the heck, might as well really open up that can of worms and talk about level detection.

A good level sensor.

Most people understand a float switch.  They’re simple and fairly inexpensive, but limited in what they can do.  In general terms, it’s a hollow ball that hangs in the tank and inside that ball is a switch.  Most floats can tell you Yes/No, Full/Not Full, Alarm/No Alarm, etc.  You could add more than 1 float to a tank, for instance Pump ON and the high float and Pump OFF at the low float.  Lots of ways to do it.  The trouble is they don’t last forever and they don’t tell you when they’ve failed.  And the hollow ball can fill with water, or the float wires can get tangled so they don’t rise when they should.

There are a lot better options out there for level detection.  I like to use analog level sensors, outputting a 4-20mA signal.  These types of devices can tell you if the tank is 36% full or 63%, or anywhere else.  They’re more specific, more expensive, but the type of signal they can give you is very nice to work with. There are a lot of types of analog level sensors, make sure they work with whatever controller you have and your power supply:

By the way, see here for our controls page. I have had it banged into my head multiple times over the years that controls are easy- until they’re not.

• Pressure Transducer. These are simple, and submersible units are really simple. However with a submersible unit all electronics are submerged in hot, corrosive wastewater 24/7. They simply don’t last that long. Going through the tank wall is good, but you wind up with a hole in the tank that likes to get plugged with yeast and grain particles.
• Ultrasonic Level Transmitter. There are probably more options here than I know. But generally these are installed on the tank dome, and shoot a signal down to the liquid level which bounces back to the transmitter and gives a signal. Non-contact, so they sound great. However foam and steam can cause trouble.
• Conductivity Based. This is generally a hunk of PVC in the tank with many conductivity sensors on it. As the liquid level changes the conductivity sensors measure that change by either becoming submerged or exposed. There will be an electronic unit nearby, but not in the tank, that can convert these multiple conductivity sensor inputs into a 4-20mA output. My personal favorite option at the moment since there are no electronics in the tank.
• Radar Based. Similar to ultrasonic, but can work with foam, steam, and even bulk solids (such as wet or dry grain). More expensive, I have not used this much.

And there are many more options…

With any option, it’s good to have an alarm float near the top of the tank hooked up to an alarm. In the event of catastrophic failure of the primary level sensor, this float will alarm you that something isn’t right out there. No one wants all of their eggs in one basket- or an overflowing wastewater tank.

Septic Tanks

A BREWERY ON SEPTIC? We’re talking about tank here. See here and here for more discussion about a brewery on septic. There is a lot of interest in this area, but as far as I know there are not any good solutions.

To be clear, I am not a septic system designer. But seriously, I get this question all of the time. A brewery on septic isn’t impossible, but it is high maintenance, expensive, problematic, and worse. Imagine a fermenting septic tank with foam trying to escape to as just one example of a problem.

As mentioned in the underground tank section way at the beginning, due to high temperature and potentially very high temperature underground plastic tanks (prefab septic tanks) should be avoided for a brewery.  In normal circumstances the water will be pushing the upper temperature limits leaving your brewery, averaging about 105F or so.  Most underground plastic tanks are rated for no higher than 120F. There will also be spills and other events leading to water that can be close to 200F in that tank.

If you’re doing septic, do it in concrete.