Mark-k

Once a day wordpress deletes all trashed items which had been in the trash for more then N days, where N stands for the value of EMPTY_TRASH_DAYS constant which may be defined in wp-config.php file.
This plugin presents a different way to control the number of trashed days. Instead of manually editing wp-config.php which is usually not convenient and somewhat dangerous, you can set the number of days in a settings page. 
In addition there is a tool to empty the cache from Items older the a specified number of days.
Usage: 
Get to the settings page via the menu “Options” >> “Empty trash” 
Get to the delete trash tool page via the menu “Tools” >> “Empty trash”
Network considerations: 
The plugin was not tested in a network installation, but it should work gibing the individual site admin a control over his trash which is possibly different then other sites on the network. 
The plugin do not have network wide settings
Important: 
For better or worse the plugin employs exactly the same deleting algorithm used by the wordpress version running the site.
Limitations: 
The plugin will not be able to function well if you have EMPTY_TRASH_DAYS set in your wp-confing.php

Trash emptier

Provides a configurable control over the trash emptying algorithm wordpress uses without changing wp-config.php

mohamad wael

Kt-cleanpress is a plugin designed to clean and optimize WordPress. It will give you the following options:
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Clean Posts: which will let you remove all posts marked as Trash / Pending / Draft with all their related contents from the database, and then it will defragment it.
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Clean Pages: will do the same things described in Clean Posts, but it will process the pages.
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Clean Comments: will do the same things described in Clean Posts, but it will process the Spam / Unapproved / Trash Comments.
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Clean Post Revisions: Whenever a post is edited and saved WordPress automatically creates a backup to which one can revert. This option will remove all posts backups.
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Clean Auto Draft: This is a left over from the process of creating a new WordPress page or post and not saving it as a draft of publishing it.
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Clean Other Left Overs: Will remove navigation menus that are created but not saved, and all their related data, and will also remove unneeded lock and last entries in the database.
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Clean Empty Categories / Tags: Will delete all categories/Tags that do not have any post or link associated with them but will not remove the default WordPress categories.
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Optimize The Tables: Reclaim unused space and defragment the data file.
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</ol>

Trash emptier vs KT-CleanPress