What kinds of waste does the ISS dispose of? To mind come:
Excrement is not recycled. The ISS does not have a composting station. Urine is mostly recycled. However, the concentrated brine that results becomes trash that either is returned to the Earth's atmosphere to burn up or is vented (although might not be a good idea).
Water used for washing is similarly mostly recycled. The gray water from urine and washing becomes new wash water (and sometimes new drinking water). Water in the form of excess humidity in the air is recycled as drinking water.
- household items like torn clothes or a broken toilet brush
Clothing typically doesn't get worn out on the ISS. It gets thrown out well before that. The ISS does not have a laundry. Astronauts toss their underwear after three or four uses. For cosmonauts, it's a bit longer.
- poisonous chemicals (resulting from what?)
Some potentially hazardous materials are brought up to the ISS as, for example, experiments on crystal growth. These are supposed to be well isolated. Equipment and materials outgas. The environmental control and life support systems either collects those or vents the gases into space.
The most common poisonous chemical, carbon dioxide, is created by humans. There has been an experiment to use water and CO2 to create methane and oxygen, but it didn't work well. The CO2 scrubbed from the breathing atmosphere is mostly vented.
That's a sizable fraction of the trash sent to be incinerated by reentry into the Earth's atmosphere.
In addition to the above, there are
- Used canisters / tanks such as those use to send water, oxygen, and nitrogen to the ISS
- Equipment, etc., from experiments that have concluded or stuff that is being upgraded
- Used office supplies such as pencils, pens, and paper
- Printed instructions such as specific instructions for a spacewalk that has been successfully concluded or steps for an experiment that will not be repeated.
Given the huge added expense of sending stuff back to the Earth's surface and reused, it's oftentimes cheaper to treat it as trash.