Hi Kirti,
I don't really see a good use case why you should do such thing.
You can get the value of an environment variable by using a data item with the name of the Environment Variable and setting exposure to "Environment - read the corresponding Environment Variable from System Manager". You can then use this data item in your process.
If the parameter you want to pass to the process as startup parameter is not dependend / fixed for the respective environment, then just pass it as "normal" parameter and don't (mis)-use an environment variable.
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Cheers Astrid
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Cheers [FirstName]