One thing to bear in mind here is that 1/30s isn't a long exposure by any stretch of the imagination and it was already too long for your lighting conditions.
Usually, the goal of long exposures is to blur motion in the subject but 1/30s won't give very much blur at all, except for things that are moving rather quickly: by a fluke of arithmetic, something moving at X kilometers per hour will move approximately X centimetres in 1/30s. So, you'd probably get decent blur on a car moving at 40kph but a person walking (about 5kph) would just look fuzzy and indistinct. Somebody who doesn't know about photography would say that the car looks motion blurred but the person just looks out of focus.
However, in your case, the light was so bright that even the relatively fast shutter speed of 1/30s was too slow for your lens at its minimum aperture (highest f-number). A general rule of thumb – known as the "sunny sixteen" rule – is that, in bright sunshine, at an aperture of f/16, you get a roughly correct exposure by using a shutter speed of 1/ISO (so, for example, 1/100s at ISO-100). That suggests that, at f/22, you'd want about 1/50s at ISO-100 so the light must have been very bright indeed for 1/30s to give a completely white frame. (Or you were using higher ISO than that.)
Under those sorts of conditions, the only way you can possibly get a long (or even not-fast!) exposure is to use a neutral density filter ("ND"). These are filters which block some fraction of the light coming into the camera. They look grey because they block all colours of light equally so they don't change the colours in the photograph. The amount that's blocked depends on the density of the filter. Commonly available types are ND2 (lets through only half the light), ND4 (a quarter) and ND8 (an eighth); these are also known as 1-stop, 2-stop and 3-stop, respectively. However, even using an ND8 would only cut your shutter speed from about 1/50s to about 1/6s, which still isn't super-slow. 10-stop ND filters are available but they're very expensive.
Using two ND8's simultaneously would get you down to about 1s exposure but quality can suffer when you put that much glass in front of your lens. In practice, bright sunlight and long exposures don't mix well!