With the rise of adblockers, using advertisements may not be the most profitable method to monetize the site. Normally adblockers block Javascript which would block Google Adsense and most ad networks. If you want to use ads and don't like Google Adsense, you can try BuySellAds. You need a certain amount of traffic to join their network but with BuySellAds, you sell ad space directly to advertisers via the BuySellAds website and if you have unsold slots, you can set a backfill which means you can display ads from Ad networks like Google Adsense for unsolds slots.
Another thing you can do is charge employers for listing vacancies on your website, maybe either on a monthly subscription basis or a one time payment for each vacancy ad.