i have 30000 page review every day and my page RPM is very low, is their any way to increase it? Or any way to block ad having low CPC or CPM ads in google adsense ?
30,000 daily is good traffic and if this does not covert then you need to check your Niche + traffic source. It looks you are getting autosurf or bot traffic that does not convert and you don't get clicks. And 2nd important thing is Niche. For example music or mobile tones related niche pay in cents per lick however finance related and other high paying niches pay $20-$40 easily. When I started working with Adsense then I did some research and prepared lists of high paying niches and I generated $15,000+ earning in last couple of months with those niches. Traffic from Tier 1 countries pays more like US, UK, Canada, Germany, France, etc.
As you are getting 30k page views per month and you are not getting too much from your adsense than you might have to re think about your site traffic. Because the traffic you are getting is almost useless and junk.
I think it's related to your niches you're doing and your traffic sources coming to your website. There're some countries with very low CPC although you have a large number of traffic. So you need to research again your niches, your content, your ads positions and also your traffic sources, you will need to change your targeted countries if it needs.
adsense pays you on CPC. have you tried CPM ad networks/exchanges.. many time CPM network gives you better RPM then adsense. Google has DFP / adx.