Yan'an Environmental Protection Bureau. The industrial wastewater treatment work certificate is a national qualification occupational certificate. It is a qualification certificate for workers to apply for jobs, hold a job, and start a business. It is the main basis for employers to recruit and hire workers. According to the national online query of qualification certificates, the Industrial Wastewater Treatment Worker Certificate can be applied for at the Yan'an Environmental Protection Bureau. The sewage (wastewater) treatment worker professional qualification certificate is a first-class qualification certificate, which is divided into elementary, intermediate and advanced.