Burying Holy Items (Geniza)
Question
What is done with Torah scrolls , the atzei chayim, the cloth that covers the Torah, tefillin , the straps, the boxes that cover it, the mezuzah, the mezuzah itself when they’re found Pasul or need to be buried
Answer
Shalom!
Thank you for your question.
As a genera rule, ritual items that become worn out or otherwise unusable are to be put in “geniza” and are not to be thrown in the garbage. The type of geniza that is required depends on the holiness of the item. Although many people associate geniza with burial, it is not entirely true. Items that require geniza may simply be stored in a safe and honorable place, but they are indeed, usually buried.
Objects defined as “Kedusha” are the holiest of ritual objects, most notably, a Torah scroll and mezuza scroll. Such items may never be disposed of even when they are no longer fit for use. So too, any item that accompanies items of “Kedusha” are known as “Tashmishei Kedusha” and they too require geniza. Such items include the Torah covers, mezuza cases and the plastic Tefillin Boxes.
Objects defined as “Kedusha,” require what is known as “strict geniza” and when burying them one must first place them in a protective container of some sort and only then are they buried. Many cemeteries have designated plots for this purpose.
Objects defined as “Tashmishei Kedusha” can be wrapped in anything and then buried.
Objects that accompany items of “Tashmishei Kedusha” are known as “Tashmish D’tashmishei Kedusha.” Such items include the protective covers that "Tashmishei Kedusha" are stored in, Like the material bag, that one keeps the Tefillin inside, (the outer plastic bag, has no Kedushah).
The lowest level of geniza-requiring items are common mitzva objects, such as tzitzit strings. Such items don’t truly need geniza and may be discarded in any dignified manner, such as by wrapping them and then placing them in the household garbage. However, we are told that those who bury Tzitzit strings are worthy of blessing.
Source
Megilla 26b; Rambam, Sefer Hamitzvot, negative 65; OC 21:1, 154:5; Aruch Hashulchan 154:8