Hebei Province Hengshui City Daying Sewage Treatment Plant Upgrading and Renovation Project
In Daying Town, Hengshui, Hebei Province — the “Hometown of Fur in China” — a wastewater treatment plant shouldering environmental responsibility is quietly transforming behind the prosperity of the leather industry. The Daying Wastewater Treatment Plant upgrading and renovation project has a daily treatment capacity of 25,000 m3/d. It was undertaken as an EPC general contracting project by Beifang Ecological Environment Municipal Engineering Technology Co., Ltd. Facing the stringent standard upgrade from Class 1-B to Class 1-A (especially with ammonia nitrogen ≤ 2 mg/L and total phosphorus ≤ 0.4 mg/L), the aeration system of its core process — the oxidation ditch — became the key to breaking through the bottleneck. In 2020, the operation of six Krupp outdoor-type oil-free screw blowers replaced the harsh noise of traditional Roots blowers, delivering a triple transformation of “low energy consumption, quiet operation, and high stability,” creating a vivid model for wastewater standard upgrading in northern industrial towns.
The Dilemma of the Oxidation Ditch: Bottlenecks of the Aeration System Under the Class 1-A Standard
As a classic biological treatment process, the oxidation ditch relies on surface aerators or fine bubble diffusers to drive mixed liquor circulation. The original system at Daying Plant used Roots blowers to drive fine bubble diffusion, which revealed three major dilemmas during the upgrading process: high energy consumption, noise pollution, and extensive control. Particularly under low-temperature conditions in northern winters (≤5°C), the activity of nitrifying bacteria sharply decreases, requiring the aeration system to have more precise dissolved oxygen control capability — a task that is nearly an "impossible mission" for traditional Roots blowers.
Krupp Oil-Free Screw Blower's Technology Breakthrough Initiative
In 2020, the project team deployed six Krupp oil-free screw blowers (outdoor protection type) to build a new aeration matrix, with their innovative value directly addressing the pain points of the oxidation ditch process.
1. Energy-saving revolution: from "electricity hog" to "energy efficiency champion"
Twin-screw positive displacement compression technology increases mechanical efficiency to over 85%. Paired with an intelligent variable frequency system, it achieves stepless air volume regulation. For the 24/7 continuous operation characteristics of the oxidation ditch, it automatically matches water quality load changes. Measured power consumption per ton of aeration decreased by 31%. The low-temperature winter mode automatically increases aeration intensity, ensuring nitrification efficiency and solving the seasonal compliance challenge faced by northern sewage plants.
2. Quiet empowerment: from "noise source" to "invisible guardian"
Original screw meshing silencing design + integrated soundproof enclosure reduces equipment noise at 1 meter to ≤60 dB(A).
A Model of Upgrading and Renovation under the EPC Model
The transformation of Daying Sewage Treatment Plant proves that in the crucial battle of wastewater upgrading and renovation, the innovation in core equipment selection is often more decisive than the choice of process route. With three major breakthroughs — "significantly reduced energy consumption, quiet operation, and stable high efficiency" — the Krupp oil-free screw blower has redefined the technical standard for oxidation ditch aeration.
