From a search engine standpoint deleting articles after 30 days is a really, really, really bad idea as the links to those articles in the search engines will then lead to "404 file not found pages" and search engines absolutely HATE 404 errors. Also, anyone who happens to link to one of your deleted articles from a post on their site suffers as well since it will create a broken link on their site. Again, that will make the search engines cranky toward the other person's site.
If you do what you are proposing to do, after a short while, the search engines will quit indexing your site due to all the 404 errors. I've seen it happen. I've had people contact me on that very issue and ask me to clean up the aftermath, and it's a long drawn out process taking about 4-6 weeks.
Finally if you follow through with this, do not expect a high placement in search engines, and do not expect high page ranking.