Shanghai Xinlun Paper Co. Ltd. is a recycle paper mill located in Shanghai, China. The mill produces 130,000 tonnes (~287 million pounds) of coated paperboard and 50,000 tonnes (110 million pounds) of deinked waste pulp.
Shanghai Xinlun Paper was upgrading its pulping and paper-making process. As this was taking place, new regulations came into effect that required the mill to invest in secondary wastewater treatment so it could meet stringent effluent limits of 100 mg/l chemical oxygen demand (COD), 30 mg/l biochemical oxygen demand (BOD), and 200 mg/l total suspended solids (TSS). Shanghai Xinlun Paper needed a technology that would also allow the mill to further expand its wastewater treatment plant in the future.
In order to comply with the stringent effluent limits, Shanghai Xinlun Paper turned to ADI Systems for a wastewater treatment solution.
The ADI® sequencing batch reactor (SBR) that was selected is comprised of two 10,800 m3 (2.85 MG) reactors and centrifugal blowers that supply air to fine-bubble sock-type diffusers. In addition to the SBR, the treatment system includes coarse and fine screening, primary clarifiers, an equalization basin, pumping station, and a nutrient addition system.
ADI Systems supplied process design for the project, as well as equipment including proprietary air-sealed decanters, a fine-bubble aeration system, and selected control valves and nutrient metering pumps. Assistance with equipment and site layout, as well as start-up assistance, was also provided.
The project was completed on a fast-track basis so that Shanghai Xinlun Paper could bring its new paper machine online within the required time frame. The batch-fed SBR eliminates short-circuiting of untreated effluent to the sewer and maximizes COD removal efficiency. It responds to changing conditions, which is important in industrial systems such as this.
The system is automatically controlled by a programmable logic controller (PLC) system with a personal computer operator interface. The energy-saving aeration system is controlled by online dissolved oxygen control, resulting in significant cost savings for the paper mill.
ADI Systems was presented with a “Benefit to Society” award by the Consulting Engineers of New Brunswick for its work on the project.