Local Liquid also do Grease Traps and Trade Waste.
Some of the more common sizes of trade waste are:
400 litre: About 1/2 of these are concrete. These have a single steel lid over the top of a square tank with no baffle in the middle of the tank. The other half are poly, usually green with a screw lid on top, and a filter under the lid.
1000 litre: Very similar to 1200 litre and 1800 litre below.
1200 litre: These tanks are usually concrete with 2 gatic (heavy round sewer) lids. There is a baffle in the middle of the tank with 2 holes about 75 mm in diameter about half way up the wall of the baffle. There are some around where instead of the holes the baffle starts below where the level of the water sits. Some of these may have steel flat lids instead of gatic lids.
24oo litre: Probably the most common of the larger tanks. Usually concrete with 3 gatic lids or flat steel lids. Same baffle system as the 1000, 1200 and 1800 litre tanks.
2400 litre trade waste with 3 gatic lids, baffle wall in trade waste tank
3000 litre: Not common, but they are usually made from poly, sometimes 2 x 1500 litre tanks joined. Lots of places for fat to collect and hard to clean out.
5000 litre: Things like supermarkets and some of the big hotel chains might have these. They generally have 4 lids covering 3 sections with a baffle between each section