Yes it can. ACHs of all types can return.
When you speak of ACH debit, are you the one initiating the transaction?
When an ACH is processed from the originator for a debit, this means the money is going from somewhere else to their bank account. (Its backwards of what you would think). If you are on the other end, this means the money is LEAVING your account.
If the ACH is a credit, this means its leaving the originator and going to the recieving end.
In an ACH debit, the bank will give the originator the money on good faith until the actual transaction is collected about 3 or 4 days later. If the other bank sends back an NSF, or Account closed, the bank will take the money back from the origiator.
In an ACH credit, the bank will send the money first, then try and deduct the money from the originators bank. This is two step process. The ACH department in the bank is not the same department that handles the originator's/your account. Sometimes its even outsourced. So what happens is the ACH department will send the money, then send a request for the money to be debited from the originator's account. (I know, the Credit and Debit thing doesnt make sense to alot of people) If the originator doesnt have enough money to cover the transaction, they send a note back to the ACH department to reverse the ACH, thus returning it. This is why you might see an ACH deposit and 24 or 48 hours later, it gets removed.
Also remember, anyone I spoke about above can reverse an ACH up to 48 hours. This means even though a Direct Deposit goes through, it can be pulled back.
I own a payroll bureau.