One of China’s Largest Pulp and Paper Mills Selects ADI-SBR
Location: China • Sector: Pulp & Paper
The Guangzhou Paper Ltd. mill is one of the largest paper mills in China. The paper mill is located in Guangzhou city centre on the shore of the Pearl River in southern China and has chemi-thermomechanical pulping, sulfite pulping, groundwood pulping, and paper-making operations.
The Client’s Needs:
New effluent regulations required Guangzhou Paper to install a secondary wastewater treatment system. The paper mill needed a system that would help it meet discharge limits for chemical oxygen demand (COD), biochemical oxygen demand (BOD), and total suspended solids (TSS) of 200 mg/l, 30 mg/l, and 200 mg/l, respectively.
After undertaking a careful review of competing systems and technologies, Guangzhou Paper selected ADI Systems to resolve its wastewater treatment problem. ADI Systems proposed a sequencing batch reactor (ADI-SBR) for this important project.
ADI Systems’ scope of supply included process design, detailed design of SBR internals, operator training, start-up and commissioning. It also involved selected equipment including 15 ASD decanters, a jet aeration system, instrumentation, control valves, and a distributed control system (DCS) for monitoring and automatic control. The Changsa Design Institute provided detailed design for the system.
The high-strength portion of the mill wastewater was pretreated in an existing high-rate activated sludge system. The low-strength wastewater was pretreated in two large dissolved air flotation (DAF) units. The SBR system was designed to treat the combined high- and low-strength streams after pretreatment.
The SBR was comprised of five 14,000 m3 (~3.7 MG) reactors and centrifugal blowers that supply air to the jet aeration system. The SBR was automatically controlled by the DCS, and the aeration system was controlled by online dissolved oxygen monitors to help minimize operating costs.
The design wastewater characteristics and effluent limits for this system were as follows:
|Flow||70,000 m3/d (18.5 mgd)||-|
|BOD||325 mg/l||30 mg/l|
|COD||750 mg/l||200 mg/l|
|TSS||200 mg/l||60 mg/l|
Guangzhou Paper was very satisfied with the SBR system’s performance due to its excellent BOD removal rate, low maintenance, low operating costs, ease of operation, and its reliability. The paper mill was especially pleased with the system's capability to handle higher-than-design COD, BOD, and TSS concentrations. For these reasons, when the mill later relocated to a different location in China, ADI Systems was once again selected to design Guangzhou Paper's wastewater treatment system. ADI Systems provided SBR equipment and start-up services.