Learn Hardcore Portuguese (Brazil): Este lixo é orgânico.

In traditional grammar, este refers to something close to the speaker. In everyday Brazilian Portuguese, though, many people often use esse where older grammar would expect este.

What is the difference between este, esse, and aquele?

These are all demonstratives:

este = this (traditionally near the speaker)
esse = that (traditionally near the listener)
aquele = that over there / that one over there (far from both)

In modern spoken Brazilian Portuguese, the distinction between este and esse is often weaker, and esse is very common in everyday speech.

So while Este lixo é orgânico is correct, you may also hear Esse lixo é orgânico in real life.

Why is there no article before lixo?

Because este already acts as a determiner.

In English, we say this trash, not this the trash. Portuguese works the same way here:

este lixo = this trash
not este o lixo

The demonstrative already introduces the noun.

What does lixo mean exactly?