jQuery.each passes the current element as second parameter of the callback, so you don’t have to reserve this for jQuery:
processRows: ->
$("#my-table>tr").each (index, element) =>
id = $(element).attr("id")
@processRow id
Notice the use of the fat arrow (=>) syntax for the callback function; it binds the function’s context to the current value of this. (this in the callback function is always the same this as the one at the time you defined the function.)