The registration address of dongcheng environmental science and technology ltd. Is at no. 606 southern zhangmura, mayor of dunchou, hebei province, and is represented by legal persons and includes general projects: technical services, technology development, technical advice, technology exchange, technology transfer, technology promotion; oil and gas technology services; technical research and development of biochemical products; sale of chemical products (other than licensed chemical products); sale of specialized chemical products (other than hazardous chemicals); sale of ecological materials; manufacture of synthetic fibres; sale of synthetic fibres; manufacture of high-performance fibres and composite materials; sale of synthetic materials; manufacture of specialized equipment for oil drilling; sale of specialized equipment for oil drilling; sale of plastics and synthetic resin; manufacture of spare parts for construction; sale of spare parts for construction; sale of metal parts for lighting; sale of spare parts and accessories for automobiles; retailing of spare parts for motorcycles; retailing of motorcycles and spare parts; sale of food additives; sale of raw materials for water environment pollution control; management of water pollution; treatment of sewage and their reuse; sale of nickel products; sale of rubber parts; sale of equipment; sale of non-based metal