The Party’s meeting reiterated the importance of ecological civilization construction. Nature is the fundamental condition for human survival and development.
Respecting, adapting to, and protecting nature are inherent requirements for building a modern socialist country in all respects.
We must firmly establish and practice the concept that “lucid waters and lush mountains are invaluable assets,” and plan development from the perspective of harmonious coexistence between humanity and nature.
Project Background
Baiquanshan Ecological Park, located in Ulanqab City, Inner Mongolia, is an open comprehensive park integrating leisure, sightseeing, and tourism. It plays a significant role in enhancing the image of the local central city, improving the living environment, and showcasing the city’s historical and cultural heritage.
However, due to the rapid economic development of the park in recent years, the surrounding buildings have proliferated, leading to a significant increase in domestic sewage, which has caused considerable harm to the park’s water environment.
To improve the quality of the local living environment and promote ecological civilization construction in the park, Kaiquan undertook the sewage treatment project for Ulanqab Baiquanshan Ecological Park.
Breaking away from the original method of directly discharging sewage into surrounding ponds for infiltration, a green and clean sewage treatment solution was brought to this “urban green island.”
Project Challenges
The park is located inland, far from the ocean, and has a typical mid-latitude semi-arid continental monsoon climate. The four seasons are characterized by long, cold winters. The average annual temperature is between 0 and 6℃, with average winter temperatures below -15℃ and an average of 47 to 75 days of sub-zero temperatures below -20℃. The maximum frost depth is 184cm.
Extremely Low Winter Temperatures Lead to Poor Nitrification
Due to extremely low winter temperatures and frequent strong winds, outdoor temperatures can reach as low as -30℃, and the frost layer is deep. Typically, in biological treatment processes, as the water temperature decreases, the activity of microorganisms used for wastewater treatment gradually declines, and the capacity for organic matter removal, nitrification, and denitrification also gradually decreases.
When the temperature is below 12℃, the activity of microorganisms at room temperature drops sharply, and the nitrification effect is significantly reduced; when the temperature is around 4℃, most microorganisms enter a dormant period or even die, and nitrification in the wastewater treatment system almost stops.
Large fluctuations in water volume significantly impact the biological system.
Water volume fluctuates greatly with the seasons, with high volumes in summer and low volumes in winter, resulting in a significant impact on the biological system. Furthermore, the effluent requirements differ between summer and winter.
Solutions
To address the challenges posed by low winter temperatures and deep frost in this project, the following measures were implemented:
Sedimented shaft installation to ensure optimal site temperature.
Except for antifreeze measures on exposed pipelines, the main body of the integrated wastewater treatment equipment is designed and installed in a sedimented shaft. The equipment is installed below the frost line, with the upper part serving as the settling and operating layer. Auxiliary electric heating facilities are installed within the sedimented shaft.
Since actual operation, without the electric heating facilities, the internal temperature has remained stable at around 12℃. In summer, good natural ventilation within the sedimented shaft maintains a temperature of around 20℃, ensuring a suitable equipment environment temperature.
The KQWT system boasts strong resistance to shock loads and excellent low-temperature adaptability.
This project involves the construction of a new wastewater treatment plant, utilizing the Kaiquan KQWT-A integrated wastewater treatment product. The biological treatment stage employs a two-stage AO-MBBR process, allowing for switching between pure biofilm and sludge-film coupling methods, adapting to shock loads and low-temperature winter conditions. The equipment uses segmented influent, prioritizing the use of raw water carbon sources for denitrification, resulting in high carbon source utilization. Phosphorus removal utilizes specialized adsorption filter media, supplemented by chemical agents, further improving phosphorus removal stability and significantly reducing sludge production.
Multiple preset operating modes ensure flexible operation.
In this project, the Kaiquan KQWT-A integrated wastewater treatment product can be used to expand the aerobic section of the two-stage AO-MBBR process in winter, increasing aerobic retention time and better ensuring nitrification efficiency in cold regions during winter, based on actual influent conditions.
Project Outcomes
This project has a design capacity of 120 tons/day, with a treatment process of “pre-clarification – two-stage AO (MBBR) – sedimentation – filtration – disinfection”. After treatment, the effluent consistently meets the Class A standard of the “Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants” (GB18918-2002) and the greening standard in the “Water Quality Standard for Urban Reclaimed Wastewater for Miscellaneous Uses”.
Furthermore, the effluent from the wastewater treatment plant can be used for greening irrigation in summer, while wastewater is discharged externally in winter. The direct operating cost of the project (electricity and chemical costs) is 0.37 yuan/m³ in summer and 0.78 yuan/m³ in winter.
The stable operation of this wastewater treatment plant plays a vital role in protecting the local environment and has significant social, economic, and environmental benefits.
