High-Density Sedimentation Tank
In scenarios such as water supply purification, advanced wastewater treatment, and hardness and fluoride removal from industrial wastewater, traditional sedimentation tanks often fall into the dilemma of "large footprint, low surface loading rate, poor effluent quality under low-temperature and low-turbidity conditions, and high moisture content in discharged sludge." The high-density sedimentation tank launched by Rihong Environmental integrates rapid mixing, mechanical flocculation, inclined tube (plate) separation, and external sludge circulation and thickening into a single tank. With the "dense floc core" formed by high-concentration sludge return, it operates stably at a surface loading rate far higher than that of conventional sedimentation, producing clear effluent with minimal sludge discharge. It is an ideal choice for upgrading and new construction projects.
I. Product Positioning
The high-density sedimentation tank is a high-efficiency clarification and sedimentation device loaded with inclined tubes (plates), and its essential feature is "external sludge circulation + high-concentration flocs." Raw water and coagulant are instantaneously and uniformly mixed in the rapid mixing zone. After entering the flocculation zone, under the combined action of slow stirring and returned high-concentration sludge, large and dense flocs are formed. Subsequently, the water flow enters the inclined tube (plate) separation zone, where high-speed clarification is achieved by the shallow-pool principle. The bottom sludge is gravity-thickened in the thickening zone, and a portion is returned to the flocculation zone as "seed crystals," while the rest is discharged for dewatering. The entire tank structure is compact, often adopting an integrated or combined steel-reinforced concrete/steel structure, with a significantly reduced footprint compared to traditional processes.
II. Working Principle (Brief)
Raw water + chemicals: Raw water and coagulant (and coagulant aid) enter the system, ready for coagulation reaction.
Rapid mixing zone: After coagulant dosing, intense stirring instantaneously and uniformly disperses the chemicals, completing destabilization and generating initial micro-flocs.
Flocculation zone (sludge return): Under slow stirring, the returned high-concentration sludge acts as "seed crystals" and combines with micro-flocs to form large and dense flocs.
Inclined tube (plate) separation zone: The water flow enters the shallow-pool zone loaded with inclined tubes, where flocs rapidly settle under gravity, and clarified water overflows from the upper collection trough.
Sludge thickening zone: The bottom sludge is gravity-thickened in the thickening zone, further reducing moisture content and increasing the concentration of discharged sludge.
Clarified effluent / sludge circulation: Clarified water is collected and discharged; a portion of the thickened sludge is returned to the flocculation zone for circulation as seed crystals, while the rest is discharged for dewatering and disposal.
Process schematic: Raw water + chemicals → Rapid mixing → Flocculation zone (sludge return) → Inclined tube separation zone (clarified water overflows) → Bottom thickening → Partial return / partial discharge
The core lies in the high-concentration "floc seed crystals" formed by sludge return: the returned sludge provides a large number of already-formed dense particles, and newly generated micro-flocs continue to grow on their surfaces. The flocs are large in size, fast in settling, and strong in impact resistance. Combined with the shallow-pool effect of inclined tubes (plates), the tank maintains excellent effluent quality even at very high surface loading rates.
III. Core Advantages
① High surface loading rate, small footprint Using inclined tube (plate) separation, the surface loading rate is far higher than that of traditional sedimentation tanks, significantly reducing the footprint for the same treatment capacity.
② Sludge return, dense flocs High-concentration sludge return acts as seed crystals, forming large flocs with fast settling speed and impact resistance, operating stably even under low-temperature and low-turbidity conditions.
③ Excellent effluent quality Good removal of SS, TP, and some heavy metals and hardness, often used as an advanced treatment unit for upgrading.
④ Bottom thickening, less sludge discharge Gravity thickening in the thickening zone results in low moisture content of discharged sludge, reducing subsequent dewatering load and disposal costs.
⑤ Zoned chemical dosing, saving chemicals Separate dosing in mixing and flocculation stages allows precise and controllable dosage, saving more chemicals than "one-pot" mixing.
⑥ Modular, easy to retrofit Can be steel-reinforced concrete or integrated steel structure, easily arranged for both new construction and upgrading of existing tanks.
IV. Main Technical Parameters (Reference Range)
Item | Typical Range Reference |
|---|---|
Surface loading rate | Approx. 10 – 25 m³/(m²·h), far higher than traditional sedimentation tanks |
Inclined tube (plate) inclination angle | Usually about 60° (shallow-pool separation) |
Mixing zone retention time | Approx. 1 – 3 min (instantaneous uniformity) |
Flocculation zone retention time | Approx. 10 – 20 min (slow stirring + sludge return) |
Sludge return ratio | Approx. 3% – 10% (maintaining high concentration depending on water quality) |
SS removal rate | Above 90% (depending on raw water) |
TP removal rate | Approx. 80% – 95% (with phosphorus removal chemicals) |
Discharged sludge concentration | Higher than conventional sedimentation sludge discharge (lower moisture content after thickening) |
* The above are typical reference ranges. Actual operation is affected by raw water quality, chemical type and dosage, water temperature, etc. Specific values should be determined by design calculations and on-site parameter tuning.
V. Typical Application Scenarios
Industry / Scenario | Main Removal Targets |
|---|---|
Water supply plants / high-turbidity raw water | Suspended solids, turbidity, algae |
Advanced treatment of municipal wastewater plants | SS, TP (Grade 1A / quasi-Class IV upgrading) |
Industrial wastewater hardness / fluoride removal | Calcium and magnesium hardness, fluoride ions, heavy metals |
Stormwater / combined sewer overflow (CSO) | Rapid clarification of initial stormwater |
Circulating water side-stream filtration pretreatment | Suspended solids, colloids |
Mining / ore washing wastewater | Suspended solids, some metal ions |
VI. Applicable Boundaries and Selection Recommendations
The high-density sedimentation tank excels at high-load clarification and chemical impurity removal (phosphorus removal, hardness removal, fluoride removal, heavy metal precipitation). For wastewater dominated by dissolved organic matter (COD), its removal efficiency alone is limited, and it should be combined with biochemical, filtration, advanced oxidation, and other units. The type of chemicals and return ratio should be determined through small-scale water quality tests. During low-temperature and low-turbidity or high-algae periods, attention should be paid to the uniformity of water distribution in the inclined tube zone and the smoothness of sludge discharge. It should be distinguished from the micro-sand plus carbon sedimentation tank: the high-density sedimentation tank mainly uses "sludge return + inclined tubes," while the micro-sand plus carbon introduces micro-sand loading and powdered activated carbon adsorption, simultaneously addressing odor, color, and micropollutant removal.
FAQ
How much does this equipment cost?
The price varies by treatment capacity, water quality, materials and configuration, so a custom quote is provided based on your actual conditions. We offer free water testing and solution design, with a detailed quote within 1 working day after requirements are confirmed.
What treatment capacity is available? Can it be customized?
Capacity is fully customizable, ranging from tens to thousands of tons per day (e.g. 0.5–30 m³/h), with non-standard design support matched precisely to your inlet/outlet requirements.
How long does delivery take?
Standard equipment typically takes about 2–4 weeks to produce; custom projects depend on scale and process. The delivery date is confirmed at contract signing, with design, manufacturing and shipping progressing on schedule.
Is installation and commissioning included?
Yes. We provide installation, system commissioning, operator training and environmental acceptance assistance, as well as long-term managed operation services on request.
What about after-sales and warranty?
We provide a warranty period and a 24/7 technical hotline, with free repair for non-human faults during the warranty period, plus spare parts supply and regular inspection services.
Small Footprint, High Load, Clearer Effluent
We can provide tank design parameters, chemical adaptation plans, and integrated equipment selection. Welcome to call or leave a message to obtain configuration suggestions for your project.
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