Basic situation of pesticide wastewater
Pesticide Wastewater types:
Wastewater from pesticide and herbicide manufacturing sites, it’s likely to have cholrine and benzene organic compounds
Sources of wastewater and minor waste streams:
Pesticde wastewater are mainly from pesticide and herbicide manufacturing processes, and there are different production line encompassed manufacturing and packaging of Acetamiprid and imidacloprid, malathion, nicosulfuron, imazethapyr, clethodim and etc.
Pesticide wastewater with this specific pesticide manufacturer are mainly originated from major steps and processes such as systhesis, manufacturing, find out more from the content below:
Production and Formulation:
Cleaning and Equipment Maintenance:
Cooling and Heating: These processes can also generate wastewater, particularly in liquid pesticide formulation.
Production Processes: The manufacturing process itself generates wastewater containing chemical residues, active pesticides, and other byproducts.
Synthesis and Refining: Steps such as using autoclaves, fermentation vessels, refining equipment, drying equipment, and separation equipment can generate wastewater.
Preparation and Post-treatment: These steps in the production of pesticides contribute significantly to wastewater generation.
Auxiliary Processes:
Cooling and Heating: Circulating cooling water systems and heating processes contribute to wastewater volumes.
Vacuum Equipment and Waste Gas Treatment: These processes can also generate wastewater.
Laboratories: Laboratory activities involving chemicals and testing contribute to wastewater.
Daily Maintenance and Formulation:
Equipment Washing: Cleaning of blending tanks, mixing equipment, and other process areas can lead to wastewater generation, washing of equipment, lines, and process areas, especially between batches of different products, is a major source of wastewater.
General Cleaning: Flushing of floors and process areas generates wastewater.
Rainwater: Initial rainfall in and around processing areas can become contaminated and require treatment.
Main pollutants, special substances and content within the pesticide wastewater:
Mixed wastewater from various manufacturing processes and steps of pesticides and herbicides, with different types of organic pollutants and intermediates, the specific content is unknown yet prior to trial testing on electrochemical oxidation.
Main salt components and their relevant content:
Content A: Some 9000 tons of sodium sale wastewater is mainly sodium chloride, with a salt content/sanility of 14.18%
Content B: Some 3000 tons of wastewater with ammonium salt, mainly ammonium sulfate and ammonium chlorides, with a salt content of 34.07%
Content C: Some 6000 tons of wastewater with lower salt content at 7.6%, mainly with sodium chlorides.
2. Site conditions
These water tanks are 18,000 cubic meters in existence, and the production plant has closed down. No new water will be produced. It takes about a year to complete the processing, so the future processing capacity of the system is 50 tons/day.
3. Experimental principle
This experiment uses the principle of electrochemical oxidation and uses BDD electrode as the core reaction device to finally convert the organic matter in the water sample into CO2 and H2o.
4. Electrodes Stacks for Electrochemical Oxidation of Pesticide Wastewater
We fabricated an electrode stacks with boron doped diamond BDD anodes and titanium cathodes, working as the basic components of an electrochemical reactor dedicated to treat pesticide wastewater from this specific pesticide manufacturer, it’s a new apporach to conduct treatability testing and locating a way to realize bench scale testing and pilot scale enigneering solution toward these pesticide wastewater.
Electrode stacks with two boron doped diamond BDD anodes and three Titanium cathodes are placed within a beaker at size of 1000 mL, with supporting pipes and exhuast auxiliary holes ready, therefore we can intialize trial testing of pesticide wastewater via electrochemical oxidation treatment technology once electricity applied, while monitoring and controlling the voltages and current, to keep the current density at a controllable level.
4.1 Anode:
Two BDD electrodes with a single crystal silicon substrate, to form a surface area of 200cm2, BDD anodes are selected as they have unmatched performances with direct oxidation of persistent pesticide molecules via direct electron transferring among the anodic catalyst materials and pesticides molecules, and given the wider electrochemical potential window and capaability to generate reactive oxidizing agents to realize indirect oxidation of pesticide molecules and other persistent organic pollutants.
4.2 Cathode:
Three titanium electrodes are selected as cathodes, combination of BDD anode and titanium cathodes emited so far the best performance within our conceptual design and prototyping processing, electrode stacks with the BDD anodes and Titanium cathodes, both are non-active electrodes, demonstrated the great oxygen evolution overpotential and oxidation power, and hydroxyl radicals and other reactive oxygen species could be generate via electrogeneration processes, and adsorbed on the BDD anodes with proper boron content, surface termination and etc.
5. Experimental operation
Take 900 mL of water samples and place them in a beaker; put in the BDD electrode module (the actual area of the anode is 150cm2), heat the water sample to a constant temperature of 7oC; connect the power supply, adjust the current intensity to 4.5A, and begin to degrade. During the degradation process, the water sample was stirred with a magnetic stirrer to make it uniform. Samples are taken at regular intervals, the current and voltage values are recorded, and the temperature and pH value is measured.
6. Experimental phenomenon
Before degradation, the water sample was brown-black; during the degradation process, the color gradually faded; a small amount of brown precipitation was produced.
Check the above chart to find out the treatment processes and results of relevant steps and processes:
Pesticides wastewater with high cocentration of ammonium salt
Mesuring parameters, TOC at mg/L
