There was 2 stage interview where first interview with formal language (English) and informal language in second interview (Cantonese).
First stage interview process included introducing myself, description on related course and experience in wastewater field. Second stage, Interviewer asking the technical process on wastewater treatment such as chemical, physical and biological process.
Interviewer explain the job scope for technical and theoretical part.
The bonus point of perception was friendly and helpful employer.