I see two difficulties to overcome in your application. One is to get
Excel to accept your data as you expect to see it. That can be done by
formatting appropriate cells as text before the hh:mm:ss data is
entered.

The other difficulty *may* be the way your data is laid out. Your
examples, 0:35 and 16:00 for instance, are a little puzzling: is the
first one "zero hours, 35 minutes" or "zero minutes, 35 seconds"? If
there is a mix of the two formats, for instance if the first value is 0
min 35 sec and the second is 16 hrs 0 min, you'll have to find a way to
indicate the difference to Excel so you can sum hours, minutes, and
seconds separately.

If it comes down to summing minutes, for instance, your formula will
look like
=MOD(SUM(B1:B10),60)
where B1:B10 is the range of cells containing minutes.

To sum hours, again assuming hours are all collected in A1:A10, the
formula is
=SUM(A1:A10)+INT(SUM(B1:B10)/60)
This sums hours and converts minutes to hours.