I. Project Background 

A pesticide factory in Gansu Province, a major pesticide production base in Northwest China, has long faced the dual pressures of wastewater treatment and resource recovery. The wastewater generated during its production process contains high concentrations of organic solvents (such as toluene and xylene) and pesticide intermediates (such as pyridine and chlorobenzene compounds), with a COD (chemical oxygen demand) as high as 20,000-30,000 mg/L, and also contains a large amount of recyclable resources. 
Traditional treatment processes using chemical precipitation have three major drawbacks:
1. Resource Waste: The recovery rate of target components is less than 60%, resulting in an annual loss of over 200 tons of organic solvents;
2. Secondary Pollution: The precipitate contains heavy metals and organic matter, requiring additional treatment, with annual hazardous waste disposal costs exceeding 3 million yuan;
3. Low Efficiency: The single-stage treatment cycle is as long as 4-6 hours, which cannot meet the needs of continuous production.

II. Mixer Settler Solution
After comparing various options, the factory introduced the our MCG-2000 mixer settler, 3-stage mixer-settler countercurrent extraction customization. Our mixer settler three core advantages:

High-efficiency separation capability:
Mixer-setter interstage combination freely, 5-15 stages in series support, with a single mixer-settler processing capacity of 10-40 m³/h; Low-speed stirring (50-500 rpm) and clarification with gravity,reduces separation time to <30 seconds, increasing efficiency by 80% compared to traditional separation equipment.

Corrosion resistance and long service life
The mixer settler is integrally molded from PPH material, and the agitator and piping are made of SS316L, withstanding strong acid environments with pH ≤ 1 and organic solvent corrosion; The seamless structure eliminates the risk of leakage, extending the equipment's life by 3-5 years compared to traditional separation equipment.

Intelligent control
An integrated PLC system monitors parameters such as pH, ORP, and flow rate in real time, supporting remote fault diagnosis; Automatic adjustment of the extractant flow rate ensures stable effluent COD <80 mg/L, achieving a 100% compliance rate.

III. Mixer-settler Process Flow and Results

1. Process Flow Design

First-stage mixer settler extraction: After adjusting the pH of the wastewater to 2-3, it is countercurrently contacted with an organic extractant (such as MIBK) at a volume ratio of 1:2, achieving an extraction rate of 85% for the target component.

Second-stage mixer settler clarification: Interfacial entrainment is eliminated through corrugated packing, resulting in a suspended solids content of <10ppm in the effluent.

Third-stage mixer settler microfiltration: An internal 0.2μm ceramic membrane filter ensures an organic matter content of <5ppm and reduces the residual amount of impurities such as antimony and bismuth to below 0.005%.

Back-extraction and regeneration: The loaded organic phase is back-extracted with 4mol/L hydrochloric acid to obtain a high-purity intermediate (purity ≥99.9%), with an extractant recycling rate of 98%.

2. Results

Significantly improved resource recovery rate:
Organic solvent recovery rate increased from 60% to 95%, saving over 5 million yuan in procurement costs annually;
Pesticide intermediate purity increased from 80% to 99.9%, allowing for direct reuse in production and reducing raw material consumption by 20%. Significant Environmental Benefits: Hazardous waste generation reduced by 80%, saving 2.4 million yuan annually in disposal costs; effluent COD reduced to 60-80 mg/L, meeting the Class I standard of the "Water Pollutant Discharge Standard for Pesticide Industry" (GB 31577-2015).

Economic Optimization: Cost per ton of wastewater treated reduced from 180 yuan to 120 yuan, a decrease of 33%; Equipment operated continuously for 12 months without failure, reducing maintenance costs by 40%.

IV. Analysis of Technological Innovations

Synergistic Extraction System Development: 
Addressing the emulsification problem of traditional TBP systems, Our developed TOPO-N1923 synergistic extractant, increasing the antimony-bismuth separation coefficient to 20.9, a 40% increase in efficiency compared to the MIBK system.

Multi-Stage Countercurrent Process Optimization:
By dynamically adjusting the rotation speed (2000-4000 rpm) and the ratio (O/A), the single-stage extraction time was shortened to 5 seconds, increasing stage efficiency by 50%. Green Solvent Substitution: Replacing kerosene with new solvents reduces VOC emissions by 90%, while also lowering emulsification risks and reducing extractant consumption by 40%.

V. Customer Feedback and Industry Impact
The plant's technical director stated, "The Shandong Liancui extraction tank completely solved our bottleneck problem. The equipment is easy to operate, provides accurate data, and our team provided full technical support, completing the process from design to commissioning in just 30 days." After the project went into operation, the plant became the first pesticide company in Northwest China to achieve "zero wastewater discharge" and was selected for the Ministry of Industry and Information Technology's "Recommended Directory of Green Manufacturing System Solution Providers" based on its resource recycling model. 

VI. Future Outlook
As the pesticide industry moves towards high efficiency, low toxicity, and environmental friendliness, we will continue to deepen technological innovation:
Ultra-purification technology: Developing novel extractants containing nitrogen and sulfur functional groups to achieve pesticide intermediate purity >99.999%;
AI process optimization: Introducing machine learning models to predict the optimal parameter combination, shortening the process debugging cycle by 70%;
Integrated solutions: Exploring extraction-membrane separation-adsorption coupling processes to drive resource utilization towards 100%.