Job opportunities and potential trend for water and wastewater treatment

Hi everyone,  I am a MSc Environmental Engineering student in Germany. My background is water and wastewater treatment engineering. I am going to graduate soon, so I would like to ask few things about job and opportunities: 1. Which kinds of knowledge should I prepare to work in this field? Studying at the university is very interesting and gives students solid background. But sometimes I feel like it is more theoretical for researching and lacking of practical skills for working. So which other skills are required to be a wastewater treatment engineer?  2. I will try to find jobs in both Germany, Europe, or my home country Vietnam. Which countries in Europe may have prospects for job seeking in this field? 3.  My interest is biological wastewater treatment. If possible, I would like focus on a technology/field/trend that could be potential for future development. Could you suggest me some potential ones?  I really appreciate your sharing! Thank you very much for your time!