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The DH high-efficiency wastewater purifier integrates physical and chemical reactions, combining technologies such as direct current coagulation, critical flocculation, centrifugal separation, dynamic filtration, and sludge concentration and sedimentation. It is an integrated device that enables rapid multi-stage purification of wastewater within the same tank in a short time frame (25–30 minutes). This device achieves an SS removal rate of up to 99.9%, with a COD removal rate of 40% to 70%. The purifier is a steel tank; its upper-middle part is cylindrical while the lower part is conical. From bottom to top, it consists of a sludge concentration zone, a coagulation zone, a centrifugal separation zone, a dynamic filtration zone, and a clear water zone. DC coagulation and critical flocculation technologies have replaced coagulation tanks; flocculants and coagulant aids are added before and after the pump, and the pump, pipes, and water flow are used to facilitate the hydrolysis of these chemicals, their mixing, and the compression of the double electric layer. After adsorption and neutralization, the mixture enters the tank at high speed in a tangential direction, where rapid adsorption and bridging occur, leading to the formation of flocs. Centrifugal separation involves the introduction of wastewater into the tank at a tangential direction, which creates high-speed swirling currents and thus centrifugal force. Under this force, the suspended particles and flocs in the wastewater are thrown against the walls of the tank; they then slide down along the inner wall of the tank due to the downward swirling currents and their own gravity, reaching the conical sludge concentration area. As the wastewater moves downward in a spiral pattern, it approaches the center, where another upward swirling current is formed. The water in this upward-flowing current is clearer in quality, and it is directed to the upper dynamic filtration area. In the centrifugal separation zone, suspended particles (floc) with a particle size greater than 20 μm are separated from the liquid into the sludge concentration zone. The wastewater is separated by centrifugation and then enters the dynamic filtration zone where adsorption takes place once again. This filtration zone uses suspended filter media based on surface adsorption; these media have a large surface area and strong adsorption capacity, enabling them to retain suspended particles with a size of 5 μm or larger. Filtering is carried out in a dynamic state, so the filter media does not easily get clogged; the adsorbed particulate matter falls off easily and sinks to the centrifugal separation area. As a result, the backwashing cycle for the filter media is long (backwashing once every 0.5 to 1 month). The wastewater is discharged after multiple stages of solid-liquid separation and purification. The separated and filtered suspended particles move into the sludge concentration zone under the action of centrifugal force and gravity. In the upper and middle parts of the conical sludge hopper, due to cohesive forces, the particle clusters come together to form a single entity, remaining in their relative positions as they sink together. In the lower parts of the hopper, the solid content is very high; the liquid in the gaps between particles is pushed out of those gaps, and the solid particles are then concentrated and compressed before being discharged from the bottom of the cone. Generally, the moisture content of the sludge is ≤90% (the amount of waste discharged is only 1/6 that of traditional processes). 3 Typical application processes and characteristics of the DH high-efficiency sewage purifier: For projects related to the renovation of ash and slag water treatment systems or the construction of new such systems in plants such as Guohua Beijing Thermal Power Branch, Guizhou Nayong No. 2 Power Plant, Datang International Tuoketuo Power Generation Co., Ltd., and Beijing Jingfeng Gas Power Generation Co., Ltd., the processes employed vary slightly depending on the existing facilities in those plants and the site conditions. But the basic process system is the same. The following takes the ash and slag water treatment project of the 4×300MW units at Guizhou Nayong No. 2 Power Plant as an example to illustrate the typical process system of the new technology (see Figure 1). Flocculant dosing, coagulant dosing, backwashing, metering pump, pump, sludge skimmer overflow water, unit drainage tank ○ pump, mixing mixer, high-efficiency purifier, cooling tower, cleaning pool ○ pump, recycling, air agitation, sludge tank ○ pump, sludge skimmer. Power plant air supply. Figure 1: Process flow. The ash wastewater treatment system uses 3 sets of DH-CSQ-200 type high-efficiency (cyclone) sewage purifiers (with a treatment capacity of 200 m3/h per unit). To ensure the normal operation of the system in case of accidents or maintenance, 1 set serves as backup equipment. The overflow water from the slag skimmer flows naturally into the drainage tank (an existing facility); this drainage tank serves as a regulating tank. The wastewater from this tank is pumped up using a slurry pump. A coagulation mixer is installed on the pipeline after the pump, and flocculants and coagulant aids are added before and after the mixer respectively, allowing for coagulation to take place within the pipeline. The resulting mixture then enters a high-efficiency (cyclone) wastewater purifier, where it undergoes processes such as centrifugal separation, gravitational separation, dynamic filtration, and sludge concentration. The treated water is discharged from the top of the purifier and flows naturally into the cooling tower. After cooling, the water temperature drops to below 30–35°C, after which it enters the clean water tank. From there, it is pumped back using a recirculation pump for use in sealing the furnace and cooling the chains of the slag skimmer. The thick sludge generated from graywater treatment enters the sludge tank, where it is then pumped back to the slag recovery machine for further processing in a cycle. Taking into account the aforementioned process flow as well as the design and operation characteristics of other power plants, this process has the following advantages: (1) It features a short process flow, a low failure rate, and stable and reliable operation. (2) Strong processing capacity and high efficiency. The equipment can handle a load of SS ≤ 30,000 mg/L, with a maximum of ≤ 90,000 mg/L ； The equipment residence time for wastewater is ≤30 min. (3) Small floor space required: A single unit with a processing capacity of 200 m3/h has a diameter of only 3.6 m ； There is no need for pre-sedimentation tanks, wastewater regulation tanks, sludge tanks, or clean water tanks; they can be designed as ordinary transition tanks to save space. (4) The quality of the treated effluent is good, with SS=5–50 mg/L; this prevents dust accumulation in the cooling tower and water seal tank, and the water can be reused for furnace sealing. (5) It is controlled by a PLC and connected to the plant’s auxiliary control network, offering a high degree of automation and reducing the workload on workers. (6) The equalization tank and sludge tank use forced aeration, eliminating the need for manual tank cleaning. (7) The use of cooling towers in place of plate heat exchangers reduces the project cost, and no large amount of circulating cooling water is required. (8) The equipment produces little wastewater; the sludge concentration is high (SS>230000 mg/L) and the moisture content is low. Depending on the circumstances, the following treatment methods can be employed: a. Press the sludge into cakes using a filter press for transportation outside ； b. Systems equipped with a slag skimmer can discharge sludge to the slag skimmer or slag bin ； c. Systems with a dewatering bin can send the sludge back to the dewatering bin. (9) If a purification device without a filter layer is used, the effluent concentration can be reduced to ≤150 mg/L, and the device itself requires no maintenance, thereby reducing the amount of maintenance work needed. (10) During a 9-day pilot test using the high-concentration ash wash water from Wangtan Power Plant, which contained large amounts of floating ash and bubbles, the vast majority of this floating ash and bubbles were flocculated and settled ； A small number of floating beads can be regularly discharged from the device’s bead discharge port. (11) The equipment only requires one lift to operate, reducing the need for auxiliary equipment and lowering power consumption.