"Know now" vs. "now know"

Solution 1:

I agree with the person who says you would benefit from a 'that', but you might also benefit from a rewording to avoid interruption or misunderstanding in the first place:

'As much as I love the pure sciences, I now realise/recognise that a well-rounded education is valuable.'

If you must stick with the current phraseology, I'd definitely go with 'now know' for that natural flow.

Solution 2:

Particular usage

Your particular usage of 'now', in this case, is the adverb form. It's purpose is to draw attention to a particular point.

Without having read the rest of your essay, I am able to divine that you were likely making acknowledgements, of academic disciplines, other than the pure sciences, though they are your preference.

Now, in order for 'now' to achieve it's proper effectiveness as the conspicuous element pointing to know, it needs to proceed it as a forerunner.

'As much as I love the pure sciences, I know now a well-rounded education is valuable.'

As much as I love the pure sciences, I now know a well-rounded education is valuable.

There is a difference, though a subtle one, the other alternative is, as others suggest here, to use 'that' as a determiner, but that feels clunky without the proper positioning of the adverb.