dirty pages in tempdb

Hello
I have aproblem ofslowjob database (sql server 2008 R2)
Report-MemoryConsumptionshows that2,000,000DIRTYPAGESconstituteabout 80% ofthebuffer.
After testingit was discovered that90% ofDIRTYcomesfromDBTEMP.
My question is:How do I clearDIRTY fromDBTEMP
Andhow to avoidsuch a bigDIRTY inthe future

Thank you