Search for a captured soldier in world war I

[loloroshlo]

My ancestor Jan Frimel was born on may 23, 1886 in Andrespol (a village near Lodz). He is a German and a Protestant.
During world war 1, he served as a soldier in the Russian Imperial army (lower rank). The full name of the unit is the 29th infantry Chernihiv General field Marshal count Dibich-Zabalkan regiment in the 8th infantry division of the 15th army corps
In 1914, he was captured near Allenstein, Prussia. He was in the Celle camp.

I know that in 1922 he was living in Poland.
Please tell me how to find out more about his life in captivity

Thanks