The wastewater treatment plant’s control system design is based on modern control concepts, adopting control methods such as distributed control and centralised monitoring management control. The control system uses HollySys’ PLC as its core.

The system comprises a central control room and 4 field PLC control stations. The field PLC control station comprises a programmable logic controller (PLC) system and an inspection instrument, exercising distributed control over the processes in wastewater water treatment plants. These are separately placed in the inlet water pumping station (1# PLC control station), variable power distributor room (2# PLC control station), blower room (3# PLC control station) and sludge dewatering room (4# PLC control station), which uses the LK-series PLC of HollySys. These systems located around the plant are centrally managed from a central control room. High-speed real-time industrial Ethernet is used for the data communication between the central control room and PLC control station.

Wastewater treatment automation system schematic diagram

The whole system uses a secondary network structure, which are the production management network and the production control network, separating real-time data and operation monitoring data, the non-real-time data, and shared resource data into different networks, effectively improving communication efficiency and reducing communication load. The wastewater treatment plant's automation control system's control method is designed with 3 types of control methods, which are the field equipment local manual control, automation control system remote manual control and automation control system remote automatic control. The ranking of the 3 methods in descending order are local manual, remote manual, and remote auto.