As mentioned earlier, solids in the wastewater can be an issue. Solids are fairly easy to address because they can be removed mechanically.
For the most part, solids in brewery wastewater is composed of small grain particles and yeast. But bigger things will make their way down the drain, such as wrenches, TC fittings, pallet chunks, shrink wrap, etc.
A good starting place is quality screens in the floor drains- with employees trained to dump the screenings in the trash (not down the drain, duh). Usually the screens that come with the drains are inadequate, you should have some custom stainless steel screen fabricated locally using perforated stainless steel sheet or screen. Screens that are easy to remove, easy to clean, and easy to reinstall are important; otherwise the screen will magically disappear. Good screens like this are most important in the brewhouse and packaging areas. Less important in the cellar and warehouse spaces. An even better idea is to not put the solids in the drain in the first place, side stream them.
Solids will actually grow in your wastewater tank. Wild yeast and bacteria find a warm sugary wastewater tank an ideal place to grow. In time these critters will form a thick, stinky sludge at the bottom of your tank. For this reason it is important to drain or pump off the bottom of your tank. By draining/pumping off the bottom of your tank you get rid of these solids slowly so they aren’t able to form a thick sludge. This thick sludge can get to a toothpaste-like consistency. Not what you want; it stinks and it takes up space in your tank.
I’ve encountered several breweries who have a settling tank designed in to their wastewater system. I don’t like this idea, for the above reasons. Solids you put down the drain will settle, but then they’ll grow and in no time (~1 month) the settling tank is full and wastewater is skimming across the top and out the pipe.
It’s a good idea to have a septic tank pump truck come suck out your tank at least once a year. They will remove all water and solids in your tank and give you an opportunity to inspect your tank and equipment and do any maintenance. Don’t use their hoses! Hopefully this makes sense. Get your own, 2″ for light duty applications and 3″ for the big jobs. The best wastewater hose on the planet in my opinion is Goodyear Green Hornet. It’s burly, lightweight, and works great for both suction and discharge applications. Make sure you have a water hose available when sucking out the tank, this makes the job easier, better, and faster.
Sometimes a municipality will apply temperature restrictions. As mentioned above, the most cost effective method to lower the temperature of your wastewater is by storing the water until it cools or adding cold water to your system. There is such a thing as a wastewater cooling tower, but this is a game you don’t want to play.