In the dyeing and printing industry, high-concentration organic wastewater, due to its high color, poor biodegradability, and complex composition, has long been a major challenge for environmental governance. A large dyeing and printing enterprise in Shanxi Province generates 25,000 tons of wastewater containing benzene compounds and naphthalene sulfonic acid annually. Traditional activated carbon adsorption + biological treatment processes resulted in treatment costs as high as 900 yuan/ton, and the effluent COD fluctuated between 800-1500 mg/L, far exceeding the 200 mg/L limit required by the "Water Pollutant Discharge Standard for Textile Dyeing and Finishing Industry". In 2024, the enterprise introduced our LC-350 centrifugal extractor, achieving a 99.2% COD removal rate and meeting wastewater discharge standards through a "three-stage countercurrent extraction + distillation purification" process, saving over 5 million yuan annually and becoming a benchmark case for green transformation in the dyeing and printing industry.

I. Three Major Bottlenecks of Traditional Processes

1. Low Efficiency and Serious Resource Waste
The original process used activated carbon adsorption, with a single-stage COD removal rate of only 65%, requiring three stages of series treatment. High Energy Consumption and Frequent Secondary Pollution, Traditional distillation methods require 3.5 tons of steam per ton of wastewater, resulting in an annual loss of 150 tons of high-purity dye intermediates, worth over 7.5 million yuan.

2. High energy consumption and frequent secondary pollution.
Each ton of wastewater treated using the original process consumes 3.5 tons of steam, requiring 1.5 million kWh of electricity annually. During high-temperature distillation, dye molecules readily react with impurities to form tar-like substances, clogging equipment and pipes, leading to four monthly shutdowns for maintenance and an annual loss of over 3,000 tons of production capacity.

3. Large investment, poor environmental protection 
 The original process resulted in COD concentrations in the effluent fluctuating between 800-1500 mg/L, exceeding standards in 40% of cases. The company incurs over 3 million yuan in environmental fines annually and invests 2 million yuan in end-of-pipe deep treatment, yet consistent compliance remains difficult.



II. Technological Breakthroughs of the LC-350 Centrifugal Extractor

1. Strong separation in supergravity field, Double the efficiency
The LC-350 centrifugal extractor with rotary speed 12,000 rpm, under centrifugal force, the droplet diameters can be refined to below 50 μm , increasing the mass transfer interface area by 5 times compared to traditional equipment. In the first-stage extraction, the rate of dye intermediate transfer from the aqueous phase to the methyl isobutyl ketone (MIBK) organic phase reaches 1.2 kg/m³·h, with a single-stage extraction rate exceeding 95%.

2. Multi-Stage Countercurrent Process 

We designed a combined process of "pretreatment - three-stage countercurrent extraction - distillation purification":

Pretreatment Stage: adjusting the wastewater pH to 5 adding sulfuric acid, breaking down complexed dyes. After vacuum filtration, the solid moisture content is controlled below 8%.

*Deep Extraction Stage: Using composite extractant MIBK+TBP, the COD of the wastewater was reduced from 5000 mg/L to 180 mg/L after a three-stage countercurrent series process, achieving a dye removal rate of 99.6%.

Resource Regeneration Stage: The dye-rich organic phase, after distillation and purification, reaches a purity of 99.5% and can be directly reused in production.

3. Intelligent Control, Reduced Operation and Maintenance Costs
 The equipment integrates a PLC/DCS control system, monitoring 12 parameters in real time, including rotation speed, interface position, and flow rate. When the dye concentration in the organic phase is detected to be below 98%, the system automatically triggers a back-extraction program, regenerating the extractant through pH adjustment. The solvent loss rate per unit is less than 0.3%.
III. Project Implementation Results and Economic Benefits

1. Significantly Improved Resource Recovery Efficiency
 After 12 months of project operation, the recovery rate of dye intermediates increased from 65% to 99.2%, with an annual recovery of 148 tons of high-purity dye, generating direct revenue of 7.4 million yuan. The back-extraction solution is evaporated and crystallized via MVR to obtain dye crystals with a purity of 98.7%, meeting export standards.

2. Significantly Reduced Environmental Compliance Costs
The effluent COD concentration is consistently below 150 mg/L, far below the 200 mg/L emission limit, reducing annual environmental fines by 3 million yuan. Hazardous waste generation has decreased from 3750 tons/year to 187 tons/year, saving 2.7 million yuan in hazardous waste disposal costs.

3. Continuously Optimized Operating Costs
In terms of energy consumption, the LC-350 equipment consumes only 40 kWh per ton of wastewater treated, 87% lower than traditional distillation methods, saving 1.3 million yuan in electricity costs annually. Activated carbon consumption is reduced to zero, reducing procurement costs by 1.8 million yuan annually. The equipment operates continuously for 360 days without failure, reducing maintenance costs by 45%.

IV. Technological Extension and Industry Impact

1. Modular Design Adapts to Multiple Scenario Needs
The LC-350 equipment adopts a five-unit design, which can be flexibly expanded to ten-stage series connection. A pilot-scale project implemented at a dye intermediate company in Jiangsu Province verified the feasibility of the process using an LC-50 equipment. Wastewater with a raw COD of 32,000 mg/L and a color intensity of 8,000 times was reduced to a COD of 180 mg/L and a color intensity of <10 times after three-stage extraction, directly meeting the requirements for biological influent. The purity of the dye intermediates recovered through back-extraction reached 98.7%, generating annual economic benefits exceeding 5 million yuan.

2. Corrosion-resistant materials extend equipment lifespan. The drum uses a composite structure of 316L stainless steel and fluorine materials, and has operated continuously for 5,000 hours in a strongly acidic environment with a pH ≤ 2 without corrosion or leakage. Data from a hydrometallurgical plant shows that the LC-350 equipment has a lifespan three times longer than traditional equipment, and its total life-cycle cost is reduced by 60%.

3. Intelligent systems drive green transformation. The equipment is equipped with a digital twin model, which can accurately calculate the carbon emission data per ton of product. After the project was implemented, the energy consumption per unit of dye recovery decreased from 1.5 tons of standard coal/ton to 0.2 tons of standard coal/ton, equivalent to the carbon sequestration capacity of planting 8,500 fir trees, helping the company pass the ISO 14064-1 greenhouse gas audit.

V. Customer Testimonials and Industry Recognition

"The LC-350 equipment completely solved our environmental pain points," said the company's technical director. "From process design to equipment commissioning, we completed the entire process transformation in just 18 days. Now our wastewater treatment costs have decreased by 65%, and the dye recovery rate has increased by 34%, truly achieving a win-win situation for both the economy and the environment."

Currently, our company's LC series centrifugal extractors have served hundreds of companies in the chemical, printing and dyeing, and hydrometallurgical industries, becoming a technological benchmark in the field of resource recycling. For companies pursuing efficient and green development, the LC-350 equipment is undoubtedly the ideal choice for solving the problem of high-COD wastewater treatment.