STRATEGIES AND PROJECT CASE OF WASTEWATER TREATMENT PLANTS RENEWAL AND REFORMATION FOR THE DUAL-CARBON GOAL

The Dongfang Wastewater Treatment Plant has adopted the Orbal oxidation ditch process, with a design capacity of 25000 m³/d. However, the existing process has encountered issues such as high equipment failure rates, excessive energy consumption, and large chemical usage. In response to the "Implementation Plan of Carbon Peak in Hainan Province" and "Implementation Plan of Collaborative Efficiency of Carbon Reduction in Hainan Province", the plant underwent an renewal and transformation to implement a new AAO process. This involved replacing the rotating disc aerator with an air suspension blower and changing the surface aeration mode to bottom aeration mode. Without introducing new biochemical treatment structures, these modifications increased the sewage treatment load rate by 28%, resulting in a treatment capacity of 30250 m³/d after transformation. This effectively saved investment for expanding the capacity of the sewage treatment plant. As a result of these renovations, average energy consumption of the plant was reduced by 24%, with a post-transformation average energy consumption of 0.292 kW·h/m³,leading to an annual energy saving of 1026836 kW·h. After the transformation, the carbon emission intensity of the plant amounted to 0.4634 kg CO₂-eq/m³, the annual carbon emission reached 51,17 t CO₂-eq, and a reduction of 18.5% in carbon intensity was achieved. Furthermore, there was a reduction in average chemical drug consumption at the plant. Average PAC consumption decreased by 12.4% to an average of 158.30 g/m³, while sodium acetate consumption decreased by 9%, to an average of 13.99 g/m³. To achieve collaborative efficiency in pollution reduction and carbon reduction at sewage treatment plants, it is essential to integrate intelligent control systems that enable more efficient perception and powerful logic calculation.