Yes and no!
Whether or not cat litter can be composted in the HOTBIN is not a simple question as there are several different types of cat litter which will require different methods of disposal.
Clay Cat Litters – Zeolite and Bentonite
The most traditional and generally most affordable type of cat litter comes in a few varieties. The clumping variety is a mixture of traditional and bentonite clay, the advantage of using bentonite clay is that it absorbs much more liquid than traditional clay making it ideal for dealing with liquids in the litter tray.
The white crystalline cat litter is zeolite (or one of its related clay minerals). This is an inorganic chemical and so by definition it will not compost or breakdown in the HOTBIN. Zeolite based cat litter will typically have urine and poo on it which will compost down when the HOTBIN is running over 40°c however the white granules will not and will be visible in final compost.
Are Zeolite Granules any Good for Your Soil/Garden?
Zeolite has similar properties as perlite and vermiculite which are used by gardeners to prevent plant pots drying out – good absorption capacity for water and urine. . Urine is an excellent source of garden nitrogen - urea is the world’s largest man-made fertiliser! Bacteria will decompose the urea in urine and it will eventually return into the soil as plant available nitrogen. Small amounts of zeolite will not harm your heap (or garden), however large quantities will clog the flow of air.
Silica Gel
This is a form of sodium silicate that absorbs liquid, it’s found in the little packets you get in shoe boxes to absorb any moisture during storage. Unfortunately as per the clay based litter silica will not breakdown in the HOTBIN.
Biodegradable Cat Litter Varieties
Granular Based
This type of litter is made from the by-product of human and animal food as well as wood processing industries so is environmentally friendly. However due to its small particle size in raw form and the fact it clumps together when used we would not recommend adding these to the HOTBIN as it could cause problems with airflow in the unit.
Pellet Based
Whilst pelleted cat litters are made from paper or wood which are both biodegradable in their raw form you need to consider what the material ends up like after being exposed to the contents of a litter tray. These pellets absorb liquids and then crumble leaving very small pieces and in the case of wood pellets, sawdust. We believe if added to the HOTBIN in this form the sawdust and fine granules could restrict airflow within the unit and possibly block air pockets altogether if added in large volumes on a regular basis. It is also for this reason that we would not consider these biodegradeable cat litters to be a form of woodchip.
In summary, most forms of cat litter are not compost friendly. We believe that small volumes of biodegradeable cat litter should breakdown in the HOTBIN however we have not tested large volumes so would not currently recommend this.
You can find more information on composting pet waste here.