Hello Vinay,
There are various ways to handle special characters in SAP MDM.
1. The most effective solution is to not allow the user to enter special characters at the time of entering data using Portal or Data Manager. In both the cases this can be handled with the help of validation check.
Expression for such kind of validation will be
HAS_ALL_CHARS(XXXX,"0","9")
here, replace XXXX with your field. This expression will not allow user to enter any special character in this field.
Also, If you are importing data using Import Manager then definitely you can normalize this field data using Conversion filters.
2. Another way of doing it is by writing an Assignment after the import of data and replacing the special characters by space or NULL. Again you can write an expression accordingly.
In any of the above cases you might have to write more than one expression based on the number of Special characters you have in your field.
3. To use middle ware, but as stated by you , you do not have any middle ware to send the data.
Hope this helps.
BR,
Parul